| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Lending Asset Quality Indicators) (Details) (USD $)In Thousands, unless otherwise specified** | Mar. 31, 2015                                                                                                                                                                                                                                                | Dec. 31, 2014                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | $ 79,882,060us-gaap_NotesReceivableGross                                                                                                                                                                                                                     | $ 76,292,814us-gaap_NotesReceivableGross                                                                                                                                                                                                                     |
| Commercial [Member]                                                                                                                    |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 38,359,991us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember                                                                                              | 36,640,761us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember                                                                                              |
| Commercial [Member] | Pass [Member]                                                                                                    |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 36,743,516us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                    | 35,042,081us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                    |
| Commercial [Member] | Special mention [Member]                                                                                         |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 718,169us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                             | 655,721us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                             |
| Commercial [Member] | Substandard [Member]                                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 813,226us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                | 853,473us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                |
| Commercial [Member] | Doubtful [Member]                                                                                                |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 85,080us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                    | 89,486us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                    |
| Corporate banking [Member]                                                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 3,170,416us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember                                                                                              | 3,218,151us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember                                                                                              |
| Corporate banking [Member] | Pass [Member]                                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,861,240us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                    | 2,910,957us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                    |
| Corporate banking [Member] | Special mention [Member]                                                                                  |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 80,698us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                             | 83,122us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                             |
| Corporate banking [Member] | Substandard [Member]                                                                                      |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 205,327us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                               | 192,911us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                               |
| Corporate banking [Member] | Doubtful [Member]                                                                                         |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 23,151us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                   | 31,161us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CorporateBankingCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                   |
| Middle market commercial real estate [Member]                                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 3,991,045us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember                                                                                        | 3,743,100us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember                                                                                        |
| Middle market commercial real estate [Member] | Pass [Member]                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 3,734,460us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                              | 3,472,448us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                              |
| Middle market commercial real estate [Member] | Special mention [Member]                                                               |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 54,607us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                       | 61,166us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                       |
| Middle market commercial real estate [Member] | Substandard [Member]                                                                   |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 172,695us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                         | 174,882us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                         |
| Middle market commercial real estate [Member] | Doubtful [Member]                                                                      |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 29,283us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                             | 34,604us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MiddleMarketCommercialRealEstateLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                             |
| Santander real estate capital [Member]                                                                                                 |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 1,638,296us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember                                                                                                   | 1,777,982us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember                                                                                                   |
| Santander real estate capital [Member] | Pass [Member]                                                                                 |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 1,454,801us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                         | 1,564,983us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                         |
| Santander real estate capital [Member] | Special mention [Member]                                                                      |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 121,364us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                 | 133,950us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                 |
| Santander real estate capital [Member] | Substandard [Member]                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 59,370us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                     | 76,232us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                     |
| Santander real estate capital [Member] | Doubtful [Member]                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,761us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                         | 2,817us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_SantanderRealEstateCapitalMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                         |
| Commercial and industrial [Member]                                                                                                     |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 18,859,043us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember                                                                                                | 17,111,406us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember                                                                                                |
| Commercial and industrial [Member] | Pass [Member]                                                                                     |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 18,167,856us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                      | 16,495,319us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                      |
| Commercial and industrial [Member] | Special mention [Member]                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 339,165us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                               | 237,331us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                               |
| Commercial and industrial [Member] | Substandard [Member]                                                                              |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 323,465us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                  | 358,782us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                  |
| Commercial and industrial [Member] | Doubtful [Member]                                                                                 |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 28,557us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                      | 19,974us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_CommercialAndIndustrialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                      |
| Multi-family [Member]                                                                                                                  |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 8,552,911us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember                                                                                                   | 8,705,890us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember                                                                                                   |
| Multi-family [Member] | Pass [Member]                                                                                                  |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 8,393,127us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                         | 8,533,427us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                         |
| Multi-family [Member] | Special mention [Member]                                                                                       |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 113,198us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                 | 131,677us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                 |
| Multi-family [Member] | Substandard [Member]                                                                                           |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 45,699us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                     | 40,355us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                     |
| Multi-family [Member] | Doubtful [Member]                                                                                              |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 887us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                           | 431us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_MultiFamilyCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                           |
| Remaining commercial [Member]                                                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,148,280us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember                                                                                                         | 2,084,232us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember                                                                                                         |
| Remaining commercial [Member] | Pass [Member]                                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,132,032us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                               | 2,064,947us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PassMember                                               |
| Remaining commercial [Member] | Special mention [Member]                                                                               |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 9,137us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                         | 8,475us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SpecialMentionMember                                         |
| Remaining commercial [Member] | Substandard [Member]                                                                                   |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 6,670us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                            | 10,311us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_SubstandardMember                                           |
| Remaining commercial [Member] | Doubtful [Member]                                                                                      |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 441us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                                 | 499us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherCommercialLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_DoubtfulMember                                                 |
| Consumer [Member]                                                                                                                      |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 41,522,069us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember                                                                                                | 39,652,053us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember                                                                                                |
| Consumer [Member] | Performing [Member]                                                                                                |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 40,464,605us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember             | 38,291,757us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember             |
| Consumer [Member] | Nonperforming [Member]                                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 1,057,464us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember           | 1,360,296us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerPortfolioSegmentMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember           |
| Residential mortgages [Member]                                                                                                         |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 7,014,276us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember                                                                                                      | 6,969,309us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember                                                                                                      |
| Residential mortgages [Member] | Performing [Member]                                                                                   |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 6,802,154us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                   | 6,737,993us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                   |
| Residential mortgages [Member] | Nonperforming [Member]                                                                                |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 212,122us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                  | 231,316us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialMortgageMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                  |
| Home equity loans and lines of credit [Member]                                                                                         |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 6,171,981us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember                                                                                                               | 6,206,980us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember                                                                                                               |
| Home equity loans and lines of credit [Member] | Performing [Member]                                                                   |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 6,031,660us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                            | 6,064,954us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                            |
| Home equity loans and lines of credit [Member] | Nonperforming [Member]                                                                |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 140,321us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                           | 142,026us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_HomeEquityMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                           |
| Retail installment contracts and auto loans [Member]                                                                                   |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 24,405,668us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember                                                                                    | 22,475,665us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember                                                                                    |
| Retail installment contracts and auto loans [Member] | Performing [Member]                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 23,734,426us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember | 21,515,372us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember |
| Retail installment contracts and auto loans [Member] | Nonperforming [Member]                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 671,242us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember | 960,293us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoansAutoFinancingReceivableMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember |
| Personal unsecured loan [Member]                                                                                                       |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,696,815us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember                                                                                                        | 2,696,820us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember                                                                                                        |
| Personal unsecured loan [Member] | Performing [Member]                                                                                 |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 2,685,006us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                     | 2,682,813us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                     |
| Personal unsecured loan [Member] | Nonperforming [Member]                                                                              |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 11,809us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                     | 14,007us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_PersonalUnsecuredLoanMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                     |
| Other consumer [Member]                                                                                                                |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 1,233,329us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember                                                                                                           | 1,303,279us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember                                                                                                           |
| Other consumer [Member] | Performing [Member]                                                                                          |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | 1,211,359us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                        | 1,290,625us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_PerformingFinancingReceivableMember                        |
| Other consumer [Member] | Nonperforming [Member]                                                                                       |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                                             |                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                         |
| Total loans                                                                                                                            | $ 21,970us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                      | $ 12,654us-gaap_NotesReceivableGross/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= sov_OtherConsumerLoansMember/ us-gaap_InternalCreditAssessmentAxis= us-gaap_NonperformingFinancingReceivableMember                      |

| X                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10(3)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 10 -Subparagraph 3 -Article 9
+ Details**Name:**us-gaap_NotesReceivableGross**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_CommercialAndIndustrialLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_CorporateBankingCommercialLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_MiddleMarketCommercialRealEstateLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_MultiFamilyCommercialLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_OtherCommercialLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_OtherConsumerLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_PersonalUnsecuredLoanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_SantanderRealEstateCapitalMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialPortfolioSegmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoansAutoFinancingReceivableMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |