| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)**                                                                 | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               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| **Loans and Leases Receivable Disclosure [Abstract]**                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| Schedule of Loans Receivable                                                                                       | The following table presents the composition of the gross loans held for investment by type of loan and by fixed and variable rates at the dates indicated: March 31, 2015 December 31, 2014 Amount Percent Amount Percent (dollars in thousands)Commercial loans held for investment:       Commercial real estate loans$8,799,757 11.2% $8,739,233 11.5%Commercial and industrial loans18,814,718 24.0% 17,092,312 22.5%Multi-family loans8,552,911 10.9% 8,705,890 11.5%Other commercial(2)2,148,280 2.7% 2,084,232 2.7%Total commercial loans held for investment38,315,666 48.8% 36,621,667 48.2%Consumer loans secured by real estate:       Residential mortgages6,716,182 8.5% 6,773,575 8.9%Home equity loans and lines of credit6,171,981 7.9% 6,206,980 8.2%Total consumer loans secured by real estate12,888,163 16.4% 12,980,555 17.1%Consumer loans not secured by real estate:       Retail installment contracts and auto loans23,386,192 29.8% 22,430,241 29.5%Personal unsecured loans2,696,815 3.4% 2,696,820 3.5%Other consumer(3)1,233,329 1.6% 1,303,279 1.7%Total consumer loans40,204,499 51.2% 39,410,895 51.8%Total loans held for investment(1)$78,520,165 100.0% $76,032,562 100.0%Total loans held for investment:       Fixed rate$46,144,348 58.8% $45,425,408 59.7%Variable rate32,375,817 41.2% 30,607,154 40.3%Total loans held for investment(1)$78,520,165 100.0% $76,032,562 100.0%(1)Total loans held for investment includes deferred loan fees, net of deferred origination costs and unamortized purchase premiums, net of discounts as well as purchase accounting adjustments. These items resulted in a net decrease in loan balances of $1.1 billion as of March 31, 2015 and a net decrease in loan balances of $1.5 billion as of December 31, 2014, respectively. (2)Other commercial primarily includes commercial equipment vehicle funding ("CEVF") leveraged leases and loans.(3)Other consumer primarily includes recreational vehicles ("RV") and marine loans.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| **Financing Receivable, Recorded Investment [Line Items]**                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| Allowance for Credit Losses by Portfolio Segment                                                                   | The activity in the ACL by portfolio segment for the three-month period ended March 31, 2015 and 2014 was as follows: Three-Month Period Ended March 31, 2015 Commercial Consumer Unallocated Total (in thousands)Allowance for loan and lease losses, beginning of period$396,489 $1,679,304 $33,024 $2,108,817Provision for/ (Recovery of) loan losses25,689 813,220 38,275 877,184Other(3)— (27,117) — (27,117)Charge-offs(19,310) (956,811) — (976,121)Recoveries5,999 504,478 — 510,477Charge-offs, net of recoveries(13,311) (452,333) — (465,644)Allowance for loan and lease losses, end of period$408,867 $2,013,074 $71,299 $2,493,240        Reserve for unfunded lending commitments, beginning of period$132,641 $— $— $132,641Provision for unfunded lending commitments(5,000) — — (5,000)Loss on unfunded lending commitments— — — —Reserve for unfunded lending commitments, end of period127,641 — — 127,641Total allowance for credit losses, end of period$536,508 $2,013,074 $71,299 $2,620,881Ending balance, individually evaluated for impairment(2)$79,474 $279,273 $— $358,747Ending balance, collectively evaluated for impairment329,393 1,733,801 71,299 2,134,493        Financing receivables:       Ending balance$38,359,991 $41,522,069 $— $79,882,060Ending balance, evaluated under the fair value option or lower of cost or fair value(1)44,325 1,993,667 — 2,037,992Ending balance, individually evaluated for impairment(2)469,759 2,966,947 — 3,436,706Ending balance, collectively evaluated for impairment37,845,907 36,561,455 — 74,407,362(1)Represents LHFS and those loans for which the Company has elected the FVO.(2)Consumer loans individually evaluated for impairment consists of loans in troubled debt restructuring ("TDR") status (3)The "Other" amount represents the impact on the allowance for loan and lease losses in connection with SCUSA classifying approximately $1.0 billion of RICs as held-for-sale during the quarter ended March 31, 2015.NOTE 5. LOANS AND ALLOWANCE FOR CREDIT LOSSES (continued) Three-Month Period Ended March 31, 2014 Commercial Consumer Unallocated Total (in thousands)Allowance for loan and lease losses, beginning of period$443,074 $363,647 $27,616 $834,337Provision for / (Recovery of) loan losses15,289 343,168 16,873 375,330Charge-offs(29,590) (147,748) — (177,338)Recoveries5,388 72,875 — 78,263Charge-offs, net of recoveries(24,202) (74,873) — (99,075)Allowance for loan and lease losses, end of period$434,161 $631,942 $44,489 $1,110,592        Reserve for unfunded lending commitments, beginning of period$220,000 $— $— $220,000Provision for unfunded lending commitments(40,000) — — (40,000)Reserve for unfunded lending commitments, end of period180,000 — — 180,000Total allowance for credit losses, end of period$614,161 $631,942 $44,489 $1,290,592Ending balance, individually evaluated for impairment$84,147 $156,882 $— $241,029Ending balance, collectively evaluated for impairment350,014 475,060 44,489 869,563        Financing receivables:       Ending balance$34,310,467 $40,002,610 $— $74,313,077Ending balance, evaluated at fair value (1)44,627 1,722,187 — 1,766,814Ending balance, individually evaluated for impairment (2)572,851 845,754 — 1,418,605Ending balance, collectively evaluated for impairment33,692,989 37,434,669 — 71,127,658(1)Represents LHFS and those loans for which the Company has elected the FVO(2)Consumer loans individually evaluated for impairment consists of loans in TDR status                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| Schedule of Non-accrual Loans                                                                                      | The recorded investment in non-accrual loans disaggregated by class of financing receivables is summarized as follows: March 31, 2015 December 31, 2014 (in thousands)Non-accrual loans:   Commercial:   Commercial real estate:   Corporate banking$87,671 $90,579Middle market commercial real estate59,936 71,398Santander real estate capital5,697 5,803Commercial and industrial66,081 54,658Multi-family9,746 9,639Other commercial3,446 4,136Total commercial loans232,577 236,213Consumer:   Residential mortgages212,122 231,316Home equity loans and lines of credit140,321 142,026Retail installment contracts and auto loans671,242 960,293Personal unsecured loans11,809 14,007Other consumer21,970 12,654Total consumer loans1,057,464 1,360,296Total non-accrual loans1,290,041 1,596,509    Other real estate owned ("OREO")52,157 65,051Repossessed vehicles140,801 136,136Other repossessed assets161 11,375Total OREO and other repossessed assets193,119 212,562Total non-performing assets$1,483,160 $1,809,071                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              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| Aging Analysis of Loan Portfolio                                                                                   | The age of recorded investments in past due loans and accruing loans greater than 90 days past due disaggregated by class of financing receivables is summarized as follows: As of March 31, 2015 30-89DaysPastDue GreaterThan 90Days TotalPast Due Current TotalFinancingReceivables(1) Recorded Investment> 90 DaysandAccruing (in thousands)Commercial:            Commercial real estate:            Corporate banking $27,149 $39,407 $66,556 $3,103,860 $3,170,416 $—Middle market commercial real estate 1,224 26,263 27,487 3,963,558 3,991,045 —Santander real estate capital 833 2,092 2,925 1,635,371 1,638,296 —Commercial and industrial 27,440 32,075 59,515 18,799,528 18,859,043 —Multi-family 6,567 4,692 11,259 8,541,652 8,552,911 —Other commercial 6,087 794 6,881 2,141,399 2,148,280 —Consumer:            Residential mortgages 144,471 181,899 326,370 6,687,906 7,014,276 —Home equity loans and lines of credit 34,430 84,504 118,934 6,053,047 6,171,981 —Retail installment contracts and auto loans 2,374,712 177,559 2,552,271 21,853,397 24,405,668 —Personal unsecured loans 110,324 100,137 210,461 2,486,354 2,696,815 84,567Other consumer 42,258 34,576 76,834 1,156,495 1,233,329 —Total $2,775,495 $683,998 $3,459,493 $76,422,567 $79,882,060 $84,567(1)Financing receivables include LHFS.  As of December 31, 2014 30-89Days PastDue GreaterThan 90Days TotalPast Due Current TotalFinancingReceivables(1) RecordedInvestment> 90 DaysandAccruing (in thousands)Commercial:            Commercial real estate:            Corporate banking $18,363 $37,708 $56,071 $3,162,080 $3,218,151 $—Middle market commercial real estate 3,179 33,604 36,783 3,706,317 3,743,100 —Santander real estate capital 4,329 2,115 6,444 1,771,538 1,777,982 —Commercial and industrial 27,071 23,469 50,540 17,060,866 17,111,406 —Multi-family 13,810 5,512 19,322 8,686,568 8,705,890 —Other commercial 5,054 1,245 6,299 2,077,933 2,084,232 —Consumer:       Residential mortgages 165,270 200,818 366,088 6,603,221 6,969,309 —Home equity loans and lines of credit 36,074 86,749 122,823 6,084,157 6,206,980 —Retail installment contracts and auto loans 3,046,943 259,534 3,306,477 19,169,188 22,475,665 —Personal unsecured loans 92,905 111,917 204,822 2,491,998 2,696,820 93,152Other consumer 47,696 30,653 78,349 1,224,930 1,303,279 —Total $3,460,694 $793,324 $4,254,018 $72,038,796 $76,292,814 $93,152(1)Financing receivables include LHFS.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| Schedule of Impaired Loans by Class                                                                                | Impaired loans disaggregated by class of financing receivables are summarized as follows:  March 31, 2015  Recorded Investment(1) UnpaidPrincipalBalance RelatedSpecificReserves AverageRecordedInvestment  (in thousands)With no related allowance recorded:        Commercial:        Commercial real estate:        Corporate banking $36,933 $39,807 $— $37,334Middle market commercial real estate 111,944 156,918 — 119,868Santander real estate capital 2,936 2,936 — 2,959Commercial and industrial 3,931 5,202 — 4,979Multi-family 16,553 16,553 — 19,523Other commercial — — — 44Consumer:        Residential mortgages 21,725 21,725 — 22,567Home equity loans and lines of credit 26,441 26,441 — 26,836Retail installment contracts and auto loans 151,229 196,458 — 149,788Personal unsecured loans 509 509 — 551Other consumer 5,351 5,351 — 5,476With an allowance recorded:        Commercial:        Commercial real estate:        Corporate banking 58,426 68,522 22,569 59,188Middle market commercial real estate 54,298 60,224 16,114 57,198Santander real estate capital 2,761 5,239 342 3,320Commercial and industrial 82,515 95,517 39,103 74,350Multi-family 5,226 6,319 731 5,603Other commercial 1,589 1,650 615 1,761Consumer:        Residential mortgages 136,201 162,550 25,701 133,507Home equity loans and lines of credit 63,224 72,651 4,580 61,678Retail installment contracts and auto loans 2,677,764 3,002,462 237,745 2,241,385  Personal unsecured loans 19,070 19,385 7,519 17,773  Other consumer 16,663 22,617 3,728 16,479Total:        Commercial $377,112 $458,887 $79,474 $386,127Consumer 3,118,177 3,530,149 279,273 2,676,040Total $3,495,289 $3,989,036 $358,747 $3,062,167(1)Recorded investment includes deferred loan fees, net of deferred origination costs and unamortized purchase premiums, net of discounts as well as purchase accounting adjustments.  December 31, 2014  Recorded Investment(1) UnpaidPrincipalBalance RelatedSpecificReserves AverageRecordedInvestment  (in thousands)With no related allowance recorded:        Commercial:        Commercial real estate:         Corporate banking $37,735 $40,453 $— $40,610 Middle market commercial real estate 127,792 172,766 — 114,465 Santander real estate capital 2,982 2,982 — 1,867Commercial and industrial 6,027 15,580 — 9,580Multi-family 22,492 22,492 — 24,762Other commercial 88 88 — 44Consumer:        Residential mortgages 23,408 23,408 — 57,776Home equity loans and lines of credit 27,230 27,230 — 29,152Retail installment contracts and auto loans 148,347 189,663 — 74,173Personal unsecured loans 592 592 — 296Other consumer 5,600 5,600 — 6,973With an allowance recorded:        Commercial:         Corporate banking 59,950 66,328 25,322 56,856 Middle market commercial real estate 60,098 66,024 17,004 89,472 Santander real estate capital 3,878 6,356 364 6,630Commercial and industrial 66,186 74,737 36,115 83,205Multi-family 5,979 7,076 1,475 8,699Other commercial 1,932 1,995 688 1,055Consumer:        Residential mortgages 130,813 156,669 23,628 339,071Home equity loans and lines of credit 60,132 69,374 5,002 57,516Retail installment contracts and auto loans 1,805,006 2,031,134 192,325 902,504Personal unsecured loans 16,476 16,815 6,508 9,506Other consumer 16,295 22,812 3,264 16,889Total:        Commercial $395,139 $476,877 $80,968 $437,245Consumer 2,233,899 2,543,297 230,727 1,493,856Total $2,629,038 $3,020,174 $311,695 $1,931,101(1)Recorded investment includes deferred loan fees, net of deferred origination costs and unamortized purchase premiums, net of discounts as well as purchase accounting adjustments. |
| Schedule of Financing Receivable, by Credit Score                                                                  | Consumer financing receivables for which credit score is a core component of the allowance model are summarized by credit score as follows:March 31, 2015            Credit Score Range(2) Retail installment contracts and auto loans(3) Percent Personal unsecured loans balance Percent Home equity loans and lines of credit Percent  (dollars in thousands)<600 $12,648,832 51.8% $472,501 17.5% $304,669 4.9%600-639 5,221,963 21.4% 439,314 16.3% 283,304 4.6%640-679 2,429,771 10.0% 1,189,155 44.1% 509,672 8.3%680-719 — —% 64,417 2.4% 856,525 13.9%720-759 — —% 72,614 2.7% 1,193,212 19.3%>=760 — —% 76,368 2.8% 2,816,648 45.6%N/A(1) 4,105,102 16.8% 382,446 14.2% 207,951 3.4%Total $24,405,668 100.0% $2,696,815 100.0% $6,171,981 100.0%(1)Consists primarily of loans serviced by third parties. Loans serviced by third parties do not receive refreshed FICO scores. Home equity loans and lines of credit "N/A" range includes the purchased home equity portfolio in run-off.(2)Credit scores updated quarterly.(3)Includes LHFS.NOTE 5. LOANS AND ALLOWANCE FOR CREDIT LOSSES (continued)December 31, 2014            Credit Score Range(2) Retail installment contracts and auto loans Percent Personal unsecured loans balance Percent Home equity loans and lines of credit Percent  (dollars in thousands)<600 $11,731,114 52.2% $491,984 18.2% $286,694 4.6%600-639 4,071,918 18.1% 446,995 16.6% 278,594 4.5%640-679 4,066,539 18.1% 1,163,203 43.1% 514,502 8.3%680-719 — —% 64,610 2.4% 867,323 14.0%720-759 — —% 72,235 2.7% 1,181,245 19.0%>=760 — —% 78,234 2.9% 2,861,721 46.1%N/A(1) 2,606,094 11.6% 379,559 14.1% 216,901 3.5%Total $22,475,665 100.0% $2,696,820 100.0% $6,206,980 100.0%(1)Consists primarily of loans serviced by third parties. Loans serviced by third parties do not receive refreshed FICO scores. Home equity loans and lines of credit "N/A" range includes the purchased home equity portfolio in run-off.(2)Credit scores updated quarterly.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| Schedule of Financing Receivable by LTV                                                                            | Residential mortgage and home equity financing receivables by CLTV range are summarized as follows:March 31, 2015          Residential mortgages(4) Home equity loans and lines of creditCLTV Range(1) Amount Percent Amount Percent  (dollars in thousands)<=80% $5,651,633 80.6% $4,744,219 76.9%80.01 - 90% 426,877 6.1% 495,560 8.0%90.01 - 100% 252,790 3.6% 232,123 3.8%100.01 - 120% 142,295 2.0% 242,189 3.9%120.01 - 140% 48,189 0.7% 82,148 1.3%>140% 44,339 0.6% 73,136 1.2%N/A(2)(3) 448,153 6.4% 302,606 4.9%Total $7,014,276 100.0% $6,171,981 100.0%December 31, 2014          Residential mortgages(4) Home equity loans and lines of creditCLTV Range(1) Amount Percent Amount Percent  (dollars in thousands)<=80% $5,732,061 82.2% $4,951,656 79.8%80.01 - 90% 396,356 5.7% 386,096 6.2%90.01 - 100% 215,803 3.1% 199,850 3.2%100.01 - 120% 143,925 2.1% 215,483 3.5%120.01 - 140% 57,949 0.8% 70,438 1.1%>140% 54,446 0.8% 63,468 1.0%N/A(2)(3) 368,769 5.3% 319,989 5.2%Total $6,969,309 100.0% $6,206,980 100.0%(1)CLTV is inclusive of senior lien balances and updated as deemed necessary. CLTV ranges represent the unpaid principal balance.(2)Residential mortgage "N/A" range represents the unpaid principal balance on loans that are in process and loans which are serviced by others, for which a current CLTV is unavailable, plus deferred loan origination costs, net of deferred loan fees and unamortized purchase premiums, net of discounts as well as purchase accounting adjustments.(3)Home equity loans and lines of credit "N/A" range represents the unpaid principal balance on loans which are serviced by others, for which a current CLTV is unavailable, plus the purchased home equity portfolio in run-off.(4)Includes LHFS.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Schedule of Troubled Debt Restructurings on Financing Receivables, Performing and Nonperforming [Table Text Block] | The following table summarizes the Company’s performing and non-performing TDRs at the dates indicated: March 31, 2015 December 31, 2014 (in thousands)Performing$2,962,052 $2,117,789Non-performing392,256 377,239Total$3,354,308 $2,495,028                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         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| Schedule of Troubled Debt Restructurings                                                                           | The following tables detail the activity of TDRs for the three-month period endedMarch 31, 2015 and March 31, 2014, respectively:  Three-Month Period Ended March 31, 2015 Number ofContracts Pre-ModificationOutstanding RecordedInvestment(1) Post-ModificationOutstanding RecordedInvestment(2) (dollars in thousands)Commercial: Commercial real estate:      Corporate Banking2 $1,448 $1,439 Middle market commercial real estate1 14,439 14,439 Santander real estate capital— — —Commercial and industrial99 11,477 8,448Multi-family— — —Other commercial— — —Consumer:     Residential mortgages(3)46 7,866 7,588 Home equity loans and lines of credit40 3,671 3,671 Retail installment contracts and auto loans  80,560 1,190,272 1,131,418 Personal unsecured loans4,468 5,394 5,356 Other consumer15 920 912Total85,231 $1,235,487 $1,173,271(1)Pre-modification outstanding recorded investment amount is the month-end balance prior to the month the modification occurred.(2)Post-modification outstanding recorded investment amount is the month-end balance for the month that the modification occurred.(3)The post-modification outstanding recorded investment amounts for residential mortgages exclude interest reserves.  Three-Month Period Ended March 31, 2014 Number of Contracts Pre-ModificationOutstanding RecordedInvestment(1) Post-ModificationOutstanding RecordedInvestment(2) (dollars in thousands)Commercial:     Commercial real estate:     Corporate banking2 $3,524 $3,505Middle markets commercial real estate— — —Santander real estate capital— — —Commercial and industrial12 18,793 18,207Multi-family— — —Other commercial1 498 500Consumer:     Residential mortgages(3)79 17,811 17,670Home equity loans and lines of credit26 2,285 2,285Retail installment contracts and auto loans (4)14,059 153,133 123,617Personal unsecured loans— — —Other consumer1 41 42Total14,180 $196,085 $165,826(1)Pre-modification outstanding recorded investment amount is the month-end balance prior to the month the modification occurred. (2)Post-modification outstanding recorded investment amount is the month-end balance for the month that the modification occurred.(3)The post-modification outstanding recorded investment amounts for residential mortgages exclude interest reserves. (4)The number of Retail installment contracts that were modified increased by 1,345 contracts with a corresponding increase of $23.9 million to the Pre-modification outstanding recorded investment and a decrease of $3.3 million to the Post-modification Outstanding Recorded Investment to correct the TDR activity that occurred during the three-month period ended March 31, 2014.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Schedule of Troubled Debt Restructurings Subsequently Defaulted                                                    | The following table details TDRs that became TDRs during the past twelve-month period and have subsequently defaulted during the three-month period endedMarch 31, 2015 and March 31, 2014, respectively. Three-Month PeriodEnded March 31,  2015 2014 Number ofContracts Recorded Investment(1) Number ofContracts Recorded Investment(1) (dollars in thousands)Commercial       Commercial and industrial10 $276 — $—Consumer:       Residential mortgages8 931 12 1,915Home equity loans and lines of credit 5 262 — —Retail installment contracts and auto loans (2)13,355 130,290 187 1,743Unsecured loans64 58 — —Other consumer2 244 — —Total13,444 $132,061 199 $3,658(1)The recorded investment represents the period-end balance at March 31, 2015 and 2014. Does not include Chapter 7 bankruptcy TDRs.(2)The number of Retail installment contracts TDRs that subsequently defaulted increased by 187 contracts with a recorded investment of $1.7 million to correct the subsequently defaulted TDR activity for the three-month period ended March 31, 2014.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Commercial Portfolio Segment [Member]                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| **Financing Receivable, Recorded Investment [Line Items]**                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| Schedule of Loans Receivable by Credit Quality Classification                                                      | The following table reconciles the Company's recorded investment classified by its major loan classifications to its commercial loan classifications utilized in its determination of the allowance for loan losses and other credit quality disclosures at March 31, 2015 and December 31, 2014, respectively:Commercial Portfolio Segment(2)    Major Loan Classifications(1) March 31, 2015 December 31, 2014  (in thousands)Commercial loans held for investment:    Commercial real estate:    Corporate Banking $3,170,416 $3,218,151Middle Markets Real Estate 3,991,045 3,743,100Santander Real Estate Capital 1,638,296 1,777,982Total commercial real estate 8,799,757 8,739,233Commercial and industrial loans(3) 18,814,718 17,092,312Multi-family loans 8,552,911 8,705,890Other commercial 2,148,280 2,084,232Total commercial loans held for investment $38,315,666 $36,621,667 (1)These represent the Company's loan categories based on the SEC's Regulation S-X, Article 9. (2)These represent the Company's loan classes used to determine its allowance for loan and lease losses in accordance with ASC 310-10.(3)    Commercial and industrial loans excluded $44.3 million and $19.1 million of LHFS at March 31, 2015 and December 31, 2014, respectively.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| Schedule of Loans by Credit Quality Indicators                                                                     | Commercial loan credit quality indicators by class of financing receivables are summarized as follows:  Commercial Real Estate        March 31, 2015 Corporatebanking Middlemarketcommercialreal estate Santanderreal estatecapital Commercial and industrial Multi-family Remainingcommercial Total(1)  (in thousands)Regulatory Rating:              Pass $2,861,240 $3,734,460 $1,454,801 $18,167,856 $8,393,127 $2,132,032 $36,743,516Special Mention 80,698 54,607 121,364 339,165 113,198 9,137 718,169Substandard 205,327 172,695 59,370 323,465 45,699 6,670 813,226Doubtful 23,151 29,283 2,761 28,557 887 441 85,080Total commercial loans $3,170,416 $3,991,045 $1,638,296 $18,859,043 $8,552,911 $2,148,280 $38,359,991(1)Financing receivables include LHFS.  Commercial Real Estate        December 31, 2014 Corporatebanking Middlemarketcommercialreal estate Santanderreal estatecapital Commercial and industrial Multi-family Remainingcommercial Total(1)  (in thousands)Regulatory Rating:              Pass $2,910,957 $3,472,448 $1,564,983 $16,495,319 $8,533,427 $2,064,947 $35,042,081Special Mention 83,122 61,166 133,950 237,331 131,677 8,475 655,721Substandard 192,911 174,882 76,232 358,782 40,355 10,311 853,473Doubtful 31,161 34,604 2,817 19,974 431 499 89,486Total commercial loans $3,218,151 $3,743,100$1,777,982$17,111,406$8,705,890$2,084,232 $36,640,761(1)Financing receivables include LHFS.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Consumer Portfolio Segment [Member]                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     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| **Financing Receivable, Recorded Investment [Line Items]**                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     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| Schedule of Loans Receivable by Credit Quality Classification                                                      | Consumer Portfolio Segment(2)    Major Loan Classifications(1) March 31, 2015 December 31, 2014  (in thousands)Consumer loans secured by real estate:   Residential mortgages(3) $6,716,182 $6,773,575Home equity loans and lines of credit 6,171,981 6,206,980Total consumer loans secured by real estate 12,888,163 12,980,555Consumer loans not secured by real estate:   Retail installment contracts and auto loans(4) 23,386,192 22,430,241Personal unsecured loans 2,696,815 2,696,820Other consumer 1,233,329 1,303,279Total consumer loans held for investment $40,204,499 $39,410,895 (1)These represent the Company's loan categories based on the SEC's Regulation S-X, Article 9.(2)These represent the Company's loan classes used to determine its allowance for loan and lease losses in accordance with ASC 310-10.(3)Home mortgages excludes $298.1 million and $195.7 million of LHFS at March 31, 2015 and December 31, 2014, respectively.(4)Retail installment contracts and auto loans excludes $1.0 billion and $45.4 million of LHFS at March 31, 2015 and December 31, 2014, respectively.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| Schedule of Loans by Credit Quality Indicators                                                                     | Consumer credit quality disaggregated by class of financing receivables is summarized as follows:March 31, 2015 Residentialmortgages Home equity loans and lines of credit Retail installment contracts and auto loans Personal unsecured loans Otherconsumer Total(1)  (in thousands)Performing $6,802,154 $6,031,660 $23,734,426 $2,685,006 $1,211,359 $40,464,605Non-performing 212,122 140,321 671,242 11,809 21,970 1,057,464Total consumer loans $7,014,276 $6,171,981 $24,405,668 $2,696,815 $1,233,329 $41,522,069(1)Financing receivables include LHFS.December 31, 2014 Residentialmortgages Home equity loans and lines of credit Retail installment contracts and auto loans Personal unsecured loans Otherconsumer Total(1)  (in thousands)Performing $6,737,993 $6,064,954 $21,515,372 $2,682,813 $1,290,625 $38,291,757Non-performing 231,316 142,026 960,293 14,007 12,654 1,360,296Total consumer loans $6,969,309 $6,206,980 $22,475,665 $2,696,820 $1,303,279 $39,652,053(1)Financing receivables include LHFS.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 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Tabular disclosure of financing receivables (examples of financing receivables include loans, trade accounts receivable and notes receivable) and activity in the allowance for credit losses account.
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Tabular disclosure of financing receivables by credit quality indicator. The credit quality indicator is a statistic about the credit quality of financing receivables. Examples include, but not limited to, consumer credit risk scores, credit-rating-agency ratings, an entity's internal credit risk grades, loan-to-value ratios, collateral, collection experience and other internal metrics.
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Tabular disclosure of financing receivables that are past due but not impaired, financing receivables that are 90 days past due and still accruing, and financing receivables on nonaccrual status.
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Tabular disclosure of the various types of trade accounts and notes receivable and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date. Presentation is categorized by current, noncurrent and unclassified receivables.
+ References
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Tabular disclosure of nonaccrual and past due financing receivables (such as loans and trade receivables), including: (a) the recorded investment in loans and trade receivables, if applicable, on nonaccrual status as of each balance sheet date (b) the recorded investment in loans and trade receivables, if applicable, past due 90 days or more and still accruing.
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| - Definition
Tabular disclosure of financing receivables and troubled debt restructurings.
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