| **FAIR VALUE (Fair Value Measurements, Recurring) (Details) (USD $)**                                                                                   | Sep. 30, 2014                                                                                                                                                                                                                                                                                                            | Dec. 31, 2013                                                                                                                                                                                                                                                                                                            |
|---------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | $ 15,062,469,000us-gaap_AvailableForSaleSecurities                                                                                                                                                                                                                                                                       | $ 11,646,240,000us-gaap_AvailableForSaleSecurities                                                                                                                                                                                                                                                                       |
| Trading securities                                                                                                                                      | 122,872,000us-gaap_TradingSecurities                                                                                                                                                                                                                                                                                     | 0us-gaap_TradingSecurities                                                                                                                                                                                                                                                                                               |
| Retail installment contracts held for investment                                                                                                        | 1,026,512,000us-gaap_LoansReceivableFairValueDisclosure                                                                                                                                                                                                                                                                  | 0us-gaap_LoansReceivableFairValueDisclosure                                                                                                                                                                                                                                                                              |
| Mortgage servicing rights                                                                                                                               | 131,791,000us-gaap_ServicingAssetAtFairValueAmount                                                                                                                                                                                                                                                                       | 141,787,000us-gaap_ServicingAssetAtFairValueAmount                                                                                                                                                                                                                                                                       |
| Derivative assets at fair value                                                                                                                         | 273,089,000us-gaap_DerivativeAssets                                                                                                                                                                                                                                                                                      | 222,491,000us-gaap_DerivativeAssets                                                                                                                                                                                                                                                                                      |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 198,974,000us-gaap_DerivativeLiabilities                                                                                                                                                                                                                                                                                 | 239,311,000us-gaap_DerivativeLiabilities                                                                                                                                                                                                                                                                                 |
| US Treasury and government agency securities [Member]                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,503,289,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember                                                                                                                                                                                  | 24,997,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember                                                                                                                                                                                     |
| Corporate debt [Member]                                                                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 2,188,589,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember                                                                                                                                                                                  | 2,218,180,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember                                                                                                                                                                                  |
| Asset-backed securities [Member]                                                                                                                        |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 2,606,381,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                                                                                                                                                                                    | 2,732,230,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                                                                                                                                                                                    |
| Equity securities [Member]                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 10,193,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                                                                                                                                                                                            | 9,841,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                                                                                                                                                                                             |
| State and municipal securities [Member]                                                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,823,114,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                                                                                                                                                                                           | 1,850,149,000us-gaap_AvailableForSaleSecurities/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                                                                                                                                                                                           |
| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 10,193,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                        | 9,841,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                         |
| Trading securities                                                                                                                                      | 0us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                        | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                        |
| Mortgage servicing rights                                                                                                                               | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                            | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                            |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                                           | 0us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                                           |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                                      | 0us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member                                                                                                                                                                                                      |
| Significant Other Observable Inputs (Level 2) [Member]                                                                                                  |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 13,877,817,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                    | 11,583,459,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                    |
| Trading securities                                                                                                                                      | 122,872,000us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 276,093,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                              | 128,949,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                              |
| Mortgage servicing rights                                                                                                                               | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                            | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                            |
| Derivative assets at fair value                                                                                                                         | 295,922,000us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                                 | 256,324,000us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                                 |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 287,145,000us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                            | 273,306,000us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member                                                                                                                                                                                            |
| Significant Unobservable Inputs (Level 3) [Member]                                                                                                      |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,174,459,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                     | 52,940,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                        |
| Trading securities                                                                                                                                      | 0us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                        | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                        |
| Mortgage servicing rights                                                                                                                               | 131,791,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                  | 141,787,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                  |
| Derivative assets at fair value                                                                                                                         | 2,073,000us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                                   | 561,000us-gaap_DerivativeAssets/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 343,000us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                                | 397,000us-gaap_DerivativeLiabilities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member                                                                                                                                                                                                |
| Recurring [Member]                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 15,062,469,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                              | 11,646,240,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                              |
| Trading securities                                                                                                                                      | 122,872,000us-gaap_TradingSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                     |
| Retail installment contracts held for investment                                                                                                        | 1,026,512,000us-gaap_LoansReceivableFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 184,940,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                        | 128,949,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                        |
| Mortgage servicing rights                                                                                                                               | 131,791,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                            | 141,787,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                            |
| Total financial assets                                                                                                                                  | 16,826,579,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                               | 12,173,861,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                               |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Total financial liabilities                                                                                                                             | 287,488,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                             | 273,703,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                                                                             |
| Recurring [Member] | Mortgage banking interest rate lock commitments [Member]                                                                           |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 2,065,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                            | 547,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                              |
| Recurring [Member] | Mortgage banking forward sell commitments [Member]                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         |                                                                                                                                                                                                                                                                                                                     | 2,101,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                              |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 660,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                           |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Total return swap [Member]                                                                                                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 779,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                     | 285,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                     |
| Recurring [Member] | Customer related [Member]                                                                                                          |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 194,028,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               | 225,811,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 160,585,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                          | 198,669,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                          |
| Recurring [Member] | Foreign exchange [Member]                                                                                                          |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 19,067,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               | 11,631,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 15,927,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                          | 9,745,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                           |
| Recurring [Member] | Mortgage servicing [Member]                                                                                                        |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 1,793,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                    | 6,155,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                    |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 226,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                 | 488,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                 |
| Recurring [Member] | Interest rate swap agreements [Member]                                                                                             |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 1,086,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                       |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 16,186,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                 |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Interest rate cap agreements [Member]                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 60,524,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                       |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Option for interest rate cap [Member]                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 60,580,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_OptionforInterestRateCapMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                             |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Other [Member]                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 5,809,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                          | 4,764,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                          |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 6,393,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                     | 4,211,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                                     |
| Recurring [Member] | Fair value [Member]                                                                                                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 3,182,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             | 1,073,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 1,250,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        | 1,924,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        |
| Recurring [Member] | Cash flow [Member]                                                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 10,441,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             | 4,803,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                              |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 24,902,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        | 58,381,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        |
| Recurring [Member] | US Treasury and government agency securities [Member]                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,503,289,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember                                                                                       | 24,997,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember                                                                                          |
| Recurring [Member] | Corporate debt [Member]                                                                                                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 2,188,589,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember                                                                                       | 2,218,180,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember                                                                                       |
| Recurring [Member] | Asset-backed securities [Member]                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 2,606,381,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                                                                                         | 2,732,230,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                                                                                         |
| Recurring [Member] | Equity securities [Member]                                                                                                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 10,193,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                                                                                                 | 9,841,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                                                                                                  |
| Recurring [Member] | State and municipal securities [Member]                                                                                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,823,114,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                                                                                                | 1,850,149,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                                                                                                |
| Recurring [Member] | Mortgage backed securities [Member]                                                                                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 6,930,903,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember                                                                                      | 4,810,843,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember                                                                                      |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]                                                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 10,193,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             | 9,841,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                              |
| Trading securities                                                                                                                                      | 0us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               |                                                                                                                                                                                                                                                                                                                     |
| Retail installment contracts held for investment                                                                                                        | 0us-gaap_LoansReceivableFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                              |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             |
| Mortgage servicing rights                                                                                                                               | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                 | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                 |
| Total financial assets                                                                                                                                  | 10,193,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                              | 9,841,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                               |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Total financial liabilities                                                                                                                             | 0us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                  | 0us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                  |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage banking interest rate lock commitments [Member] |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage banking forward sell commitments [Member]       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         |                                                                                                                                                                                                                                                                                                                     | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                 |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                            |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Total return swap [Member]                               |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                      | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                      |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Customer related [Member]                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                    | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                    |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign exchange [Member]                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                   | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                   |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                              | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                              |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage servicing [Member]                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                       | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                       |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Interest rate swap agreements [Member]                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                          |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                     |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Interest rate cap agreements [Member]                    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                           |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Option for interest rate cap [Member]                    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_OptionforInterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                 |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]                                           |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                             | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                             |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                        | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                        |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair value [Member]                                      |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember           | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember           |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash flow [Member]                                       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                 | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                 |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember            | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember            |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | US Treasury and government agency securities [Member]    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember              | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember              |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate debt [Member]                                  |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember              | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember              |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-backed securities [Member]                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember                |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity securities [Member]                               |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 10,193,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember            | 9,841,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember             |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | State and municipal securities [Member]                  |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                       | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                       |
| Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage backed securities [Member]                      |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember             | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel1Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember             |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]                                                                             |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 13,877,817,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                         | 11,583,459,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                         |
| Trading securities                                                                                                                                      | 122,872,000us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Retail installment contracts held for investment                                                                                                        | 0us-gaap_LoansReceivableFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                              |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 184,940,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                   | 128,949,000us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                   |
| Mortgage servicing rights                                                                                                                               | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                 | 0us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                 |
| Total financial assets                                                                                                                                  | 14,481,551,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                          | 11,968,732,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                          |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Total financial liabilities                                                                                                                             | 287,145,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        | 273,306,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                        |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage banking interest rate lock commitments [Member]                  |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage banking forward sell commitments [Member]                        |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         |                                                                                                                                                                                                                                                                                                                     | 2,101,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                         |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 660,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                      |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Total return swap [Member]                                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 494,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                      |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Customer related [Member]                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 194,028,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                          | 225,811,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                          |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 160,585,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                     | 198,669,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign exchange [Member]                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 19,067,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                          | 11,631,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                          |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 15,927,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                     | 9,745,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                      |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage servicing [Member]                                               |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 1,793,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               | 6,155,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 226,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                            | 488,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                            |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest rate swap agreements [Member]                                    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 1,086,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 16,186,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                            |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest rate cap agreements [Member]                                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 60,524,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Option for interest rate cap [Member]                                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 60,580,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_OptionforInterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                        |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]                                                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 5,801,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                     | 4,750,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 6,335,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                | 4,099,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value [Member]                                                       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 3,182,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember        | 1,073,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember        |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 1,250,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember   | 1,924,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember   |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Cash flow [Member]                                                        |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 10,441,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember        | 4,803,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember         |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 24,902,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember   | 58,381,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember   |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | US Treasury and government agency securities [Member]                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,503,289,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember  | 24,997,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate debt [Member]                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 2,188,589,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember  | 2,218,180,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember  |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Asset-backed securities [Member]                                          |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,431,922,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember    | 2,679,290,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember    |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity securities [Member]                                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                     | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                     |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | State and municipal securities [Member]                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,823,114,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember           | 1,850,149,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember           |
| Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage backed securities [Member]                                       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 6,930,903,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember | 4,810,843,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel2Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]                                                                                 |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,174,459,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                          | 52,940,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             |
| Trading securities                                                                                                                                      | 0us-gaap_TradingSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                                               |                                                                                                                                                                                                                                                                                                                     |
| Retail installment contracts held for investment                                                                                                        | 1,026,512,000us-gaap_LoansReceivableFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                  |                                                                                                                                                                                                                                                                                                                     |
| Loans held for sale                                                                                                                                     | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             | 0us-gaap_LoansHeldForSaleFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             |
| Mortgage servicing rights                                                                                                                               | 131,791,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                       | 141,787,000us-gaap_ServicingAssetAtFairValueAmount/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                       |
| Total financial assets                                                                                                                                  | 2,334,835,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                           | 195,288,000us-gaap_AssetsFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                             |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Total financial liabilities                                                                                                                             | 343,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                            | 397,000us-gaap_LiabilitiesFairValueDisclosure/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                                                                            |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage banking interest rate lock commitments [Member]                      |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 2,065,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                       | 547,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateLockCommitmentsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                         |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage banking forward sell commitments [Member]                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         |                                                                                                                                                                                                                                                                                                                     | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                 |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_ForwardCommitmentsToSellLoansMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                            |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Total return swap [Member]                                                    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 285,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                | 285,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_TotalReturnSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Customer related [Member]                                                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                    | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                    |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_CustomerRelatedDerivativesMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                               |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign exchange [Member]                                                     |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                   | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                   |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                              | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_ForeignExchangeContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                              |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage servicing [Member]                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                       | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                       |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_MortgageServicingRightsMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Interest rate swap agreements [Member]                                        |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                          |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateSwapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                     |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Interest rate cap agreements [Member]                                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_InterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                           |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Option for interest rate cap [Member]                                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= sov_OptionforInterestRateCapMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                 |                                                                                                                                                                                                                                                                                                                     |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]                                                                |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 8,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                         | 14,000us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                        |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 58,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                   | 112,000us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentRiskAxis= us-gaap_OtherContractMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                                  |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value [Member]                                                           |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember           | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_FairValueHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember           |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Cash flow [Member]                                                            |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative assets at fair value                                                                                                                         | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                 | 0us-gaap_DerivativeAssets/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember                 |
| **Financial liabilities:**                                                                                                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Derivative liabilities                                                                                                                                  | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember            | 0us-gaap_DerivativeLiabilities/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis= us-gaap_CashFlowHedgingMember/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember            |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | US Treasury and government agency securities [Member]                         |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember              | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USTreasuryAndGovernmentMember              |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate debt [Member]                                                       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember              | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_CorporateDebtSecuritiesMember              |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Asset-backed securities [Member]                                              |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 1,174,459,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember    | 52,940,000us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_AssetBackedSecuritiesMember       |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity securities [Member]                                                    |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                     | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_EquitySecuritiesMember                     |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | State and municipal securities [Member]                                       |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                       | 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MunicipalBondsMember                       |
| Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage backed securities [Member]                                           |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| **Financial assets:**                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                     |
| Available-for-sale investment securities                                                                                                                | $ 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember           | $ 0us-gaap_AvailableForSaleSecurities/ us-gaap_FairValueByFairValueHierarchyLevelAxis= us-gaap_FairValueInputsLevel3Member/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsRecurringMember/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_MortgageBackedSecuritiesMember           |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258
+ Details**Name:**us-gaap_AssetsFairValueDisclosure**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AssetsFairValueDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562
+ Details**Name:**us-gaap_AvailableForSaleSecurities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313
+ Details**Name:**us-gaap_DerivativeAssets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313
+ Details**Name:**us-gaap_DerivativeLiabilities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value of financial and nonfinancial obligations.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258
+ Details**Name:**us-gaap_LiabilitiesFairValueDisclosure**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LiabilitiesFairValueDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.
+ References
No definition available.
+ Details**Name:**us-gaap_LoansHeldForSaleFairValueDisclosure**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Glossary Loan -URI http://asc.fasb.org/extlink&oid=6517073
+ Details**Name:**us-gaap_LoansReceivableFairValueDisclosure**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746
+ Details**Name:**us-gaap_ServicingAssetAtFairValueAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878
+ Details**Name:**us-gaap_TradingSecurities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_EquitySecuritiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MunicipalBondsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USTreasuryAndGovernmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |