| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Consumer Lending Asset Quality Indicators - FICO and CLTV Range) (Details) - Consumer - USD ($) $ in Thousands** | Mar. 31, 2016 | Dec. 31, 2015 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| Residential mortgages                                                                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | $ 6,439,118   | $ 6,467,755   |
| Home Equity Loans and Lines of Credit                                                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 6,103,844     | 6,146,913     |
| LTV not applicable | Residential mortgages                                                                                                                |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 434,986       | 462,640       |
| LTV not applicable | Home Equity Loans and Lines of Credit                                                                                                |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 271,530       | 282,100       |
| LTV less than or equal to 70% | Residential mortgages                                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 3,841,700     | 3,842,373     |
| LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 3,203,257     | 3,241,188     |
| LTV of 70.01% to 80% | Residential mortgages                                                                                                              |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,454,711     | 1,440,194     |
| LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                                              |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 2,110,106     | 2,088,030     |
| LTV of 80.01% to 90% | Residential mortgages                                                                                                              |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 329,013       | 336,893       |
| LTV of 90.01% to 100% | Residential mortgages                                                                                                             |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 233,019       | 227,494       |
| LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                                             |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 321,276       | 332,064       |
| LTV of 100.01% to 110% | Residential mortgages                                                                                                            |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 58,714        | 64,578        |
| LTV greater than 110% | Residential mortgages                                                                                                             |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 86,975        | 93,583        |
| LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                                             |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 197,675       | 203,531       |
| FICO score not applicable | Residential mortgages                                                                                                         |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 448,926       | 476,858       |
| FICO score not applicable | Home Equity Loans and Lines of Credit                                                                                         |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 191,393       | 188,755       |
| FICO score not applicable | LTV not applicable | Residential mortgages                                                                                    |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 434,206       | 461,839       |
| FICO score not applicable | LTV not applicable | Home Equity Loans and Lines of Credit                                                                    |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 189,921       | 188,060       |
| FICO score not applicable | LTV less than or equal to 70% | Residential mortgages                                                                         |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 13,447        | 12,250        |
| FICO score not applicable | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                         |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 553           | 390           |
| FICO score not applicable | LTV of 70.01% to 80% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,273         | 2,769         |
| FICO score not applicable | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 919           | 305           |
| FICO score not applicable | LTV of 80.01% to 90% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score not applicable | LTV of 90.01% to 100% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score not applicable | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score not applicable | LTV of 100.01% to 110% | Residential mortgages                                                                                |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score not applicable | LTV greater than 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score not applicable | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 0             | 0             |
| FICO score less than 600 | Residential mortgages                                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 348,027       | 362,824       |
| FICO score less than 600 | Home Equity Loans and Lines of Credit                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 279,339       | 290,439       |
| FICO score less than 600 | LTV not applicable | Residential mortgages                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 124           | 128           |
| FICO score less than 600 | LTV not applicable | Home Equity Loans and Lines of Credit                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 10,979        | 11,110        |
| FICO score less than 600 | LTV less than or equal to 70% | Residential mortgages                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 221,524       | 226,185       |
| FICO score less than 600 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 150,526       | 155,306       |
| FICO score less than 600 | LTV of 70.01% to 80% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 61,470        | 69,698        |
| FICO score less than 600 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 75,867        | 79,389        |
| FICO score less than 600 | LTV of 80.01% to 90% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 26,279        | 30,491        |
| FICO score less than 600 | LTV of 90.01% to 100% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 19,021        | 18,279        |
| FICO score less than 600 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 21,222        | 22,373        |
| FICO score less than 600 | LTV of 100.01% to 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 9,100         | 8,441         |
| FICO score less than 600 | LTV greater than 110% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 10,509        | 9,602         |
| FICO score less than 600 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 20,745        | 22,261        |
| FICO score of 600 to 639 | Residential mortgages                                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 238,177       | 252,976       |
| FICO score of 600 to 639 | Home Equity Loans and Lines of Credit                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 262,995       | 265,987       |
| FICO score of 600 to 639 | LTV not applicable | Residential mortgages                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 53            | 1             |
| FICO score of 600 to 639 | LTV not applicable | Home Equity Loans and Lines of Credit                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 8,447         | 8,871         |
| FICO score of 600 to 639 | LTV less than or equal to 70% | Residential mortgages                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 150,320       | 158,290       |
| FICO score of 600 to 639 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 138,913       | 140,277       |
| FICO score of 600 to 639 | LTV of 70.01% to 80% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 40,977        | 43,002        |
| FICO score of 600 to 639 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 83,320        | 83,548        |
| FICO score of 600 to 639 | LTV of 80.01% to 90% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 22,786        | 23,281        |
| FICO score of 600 to 639 | LTV of 90.01% to 100% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 13,105        | 15,585        |
| FICO score of 600 to 639 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 20,173        | 20,766        |
| FICO score of 600 to 639 | LTV of 100.01% to 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 4,091         | 5,238         |
| FICO score of 600 to 639 | LTV greater than 110% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 6,845         | 7,579         |
| FICO score of 600 to 639 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 12,142        | 12,525        |
| FICO Score of 640 to 679 | Residential mortgages                                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 453,001       | 419,770       |
| FICO Score of 640 to 679 | Home Equity Loans and Lines of Credit                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 495,642       | 500,728       |
| FICO Score of 640 to 679 | LTV not applicable | Residential mortgages                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 66            | 230           |
| FICO Score of 640 to 679 | LTV not applicable | Home Equity Loans and Lines of Credit                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 11,587        | 12,534        |
| FICO Score of 640 to 679 | LTV less than or equal to 70% | Residential mortgages                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 257,146       | 252,727       |
| FICO Score of 640 to 679 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 252,008       | 254,481       |
| FICO Score of 640 to 679 | LTV of 70.01% to 80% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 97,181        | 81,552        |
| FICO Score of 640 to 679 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 175,327       | 174,223       |
| FICO Score of 640 to 679 | LTV of 80.01% to 90% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 39,952        | 35,001        |
| FICO Score of 640 to 679 | LTV of 90.01% to 100% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 39,929        | 29,125        |
| FICO Score of 640 to 679 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 31,474        | 32,925        |
| FICO Score of 640 to 679 | LTV of 100.01% to 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 8,262         | 9,101         |
| FICO Score of 640 to 679 | LTV greater than 110% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 10,465        | 12,034        |
| FICO Score of 640 to 679 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 25,246        | 26,565        |
| FICO Score of 680 to 719 | Residential mortgages                                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 769,974       | 792,060       |
| FICO Score of 680 to 719 | Home Equity Loans and Lines of Credit                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 850,848       | 851,662       |
| FICO Score of 680 to 719 | LTV not applicable | Residential mortgages                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 84            | 19            |
| FICO Score of 680 to 719 | LTV not applicable | Home Equity Loans and Lines of Credit                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 11,691        | 14,273        |
| FICO Score of 680 to 719 | LTV less than or equal to 70% | Residential mortgages                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 464,194       | 462,180       |
| FICO Score of 680 to 719 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 430,595       | 431,818       |
| FICO Score of 680 to 719 | LTV of 70.01% to 80% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 167,379       | 183,568       |
| FICO Score of 680 to 719 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 322,550       | 317,260       |
| FICO Score of 680 to 719 | LTV of 80.01% to 90% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 62,961        | 62,670        |
| FICO Score of 680 to 719 | LTV of 90.01% to 100% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 48,935        | 51,659        |
| FICO Score of 680 to 719 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 55,127        | 56,589        |
| FICO Score of 680 to 719 | LTV of 100.01% to 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 7,942         | 9,194         |
| FICO Score of 680 to 719 | LTV greater than 110% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 18,479        | 22,770        |
| FICO Score of 680 to 719 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 30,885        | 31,722        |
| FICO Score of 720 to 759 | Residential mortgages                                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,160,851     | 1,183,942     |
| FICO Score of 720 to 759 | Home Equity Loans and Lines of Credit                                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,155,416     | 1,156,986     |
| FICO Score of 720 to 759 | LTV not applicable | Residential mortgages                                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 108           | 339           |
| FICO Score of 720 to 759 | LTV not applicable | Home Equity Loans and Lines of Credit                                                                     |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 10,456        | 12,673        |
| FICO Score of 720 to 759 | LTV less than or equal to 70% | Residential mortgages                                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 673,413       | 681,473       |
| FICO Score of 720 to 759 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                                          |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 613,886       | 614,748       |
| FICO Score of 720 to 759 | LTV of 70.01% to 80% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 336,181       | 341,934       |
| FICO Score of 720 to 759 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 428,576       | 425,744       |
| FICO Score of 720 to 759 | LTV of 80.01% to 90% | Residential mortgages                                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 65,824        | 72,729        |
| FICO Score of 720 to 759 | LTV of 90.01% to 100% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 54,597        | 55,461        |
| FICO Score of 720 to 759 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 62,879        | 63,840        |
| FICO Score of 720 to 759 | LTV of 100.01% to 110% | Residential mortgages                                                                                 |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 10,846        | 11,024        |
| FICO Score of 720 to 759 | LTV greater than 110% | Residential mortgages                                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 19,882        | 20,982        |
| FICO Score of 720 to 759 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 39,619        | 39,981        |
| FICO Score Equal to or Greater than 760 | Residential mortgages                                                                                           |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 3,020,162     | 2,979,325     |
| FICO Score Equal to or Greater than 760 | Home Equity Loans and Lines of Credit                                                                           |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 2,868,211     | 2,892,356     |
| FICO Score Equal to or Greater than 760 | LTV not applicable | Residential mortgages                                                                      |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 345           | 84            |
| FICO Score Equal to or Greater than 760 | LTV not applicable | Home Equity Loans and Lines of Credit                                                      |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 28,449        | 34,579        |
| FICO Score Equal to or Greater than 760 | LTV less than or equal to 70% | Residential mortgages                                                           |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 2,061,656     | 2,049,268     |
| FICO Score Equal to or Greater than 760 | LTV less than or equal to 70% | Home Equity Loans and Lines of Credit                                           |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,616,776     | 1,644,168     |
| FICO Score Equal to or Greater than 760 | LTV of 70.01% to 80% | Residential mortgages                                                                    |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 750,250       | 717,671       |
| FICO Score Equal to or Greater than 760 | LTV of 70.01% to 90% | Home Equity Loans and Lines of Credit                                                    |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 1,023,547     | 1,007,561     |
| FICO Score Equal to or Greater than 760 | LTV of 80.01% to 90% | Residential mortgages                                                                    |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 111,211       | 112,721       |
| FICO Score Equal to or Greater than 760 | LTV of 90.01% to 100% | Residential mortgages                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 57,432        | 57,385        |
| FICO Score Equal to or Greater than 760 | LTV of 90.01% to 110% | Home Equity Loans and Lines of Credit                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 130,401       | 135,571       |
| FICO Score Equal to or Greater than 760 | LTV of 100.01% to 110% | Residential mortgages                                                                  |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 18,473        | 21,580        |
| FICO Score Equal to or Greater than 760 | LTV greater than 110% | Residential mortgages                                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | 20,795        | 20,616        |
| FICO Score Equal to or Greater than 760 | LTV greater than 110% | Home Equity Loans and Lines of Credit                                                   |          |          |
| **Loans Receivable [Line Items]**                                                                                                                         |          |          |
| Financing receivables                                                                                                                                     | $ 69,038      | $ 70,477      |

| X                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The balance of financing receivables including loans held-for-sale, before allowance for credit losses.
+ References
No definition available.
+ Details**Name:**sov_FinancingReceivableIncludingReceivableHeldForSaleGross**Namespace Prefix:**sov_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_AccountsNotesAndLoansReceivableLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember**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:** |
| X                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sov_HomeEquityLoansandLinesofCreditMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LoanToValueAxis=sov_LtvNotApplicableMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LoanToValueAxis=sov_LtvOf8001To90Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LoanToValueAxis=sov_LTVgreaterthan110Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditScoreFicoAxis=sov_FICOScoreof640to679Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditScoreFicoAxis=sov_FICOScoreof680to719Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditScoreFicoAxis=sov_FICOScoreof720to759Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditScoreFicoAxis=sov_FICOScoreEqualtoorGreaterthan760Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |