| **BORROWINGS (Tables)**                          | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
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| SHUSA [Member]                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| **Debt Instrument [Line Items]**                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Schedule of Borrowings and Other Debt Obligation | The following table presents information regarding the holding company's borrowings and other debt obligations at the dates indicated: June 30, 2014 December 31, 2013 Balance EffectiveRate Balance EffectiveRate (in thousands)3.00% senior notes, due September 2015$599,258 3.28% $598,965 3.28%4.625% senior notes, due April 2016474,666 4.85 474,306 4.853.45% senior notes, due August 2018499,232 3.62 499,148 3.62Subordinated notes, due March 2020(1)— — 756,829 5.96Junior subordinated debentures - Capital Trust IV, due March 2034(2)— — 611 12.84Common securities - Capital Trust IV(2)— — 24,742 4.38Junior subordinated debentures - Capital Trust VI, due June 203670,262 7.91 70,262 7.91Common securities - Capital Trust VI10,000 7.91 10,000 7.91Junior subordinated debentures - Capital Trust IX, due July 2036150,000 2.02 150,000 2.04Common securities - Capital Trust IX4,640 2.02 4,640 2.04     Total holding company borrowings and other debt obligations$1,808,058 3.88% $2,589,503 4.50%(1) On February 21, 2014, the subordinated note, with a value of $750.0 million, was converted to 3.0 million shares of SHUSA common stock.(2) In December 2012, a settlement agreement was executed with respect to the Company's Trust PIERS litigation. The settlement agreement required the Company to make additional offers to purchase the Trust PIERS until no Trust PIERS remain outstanding. On February 28, 2014, the Company called and retired the remaining PIERS securities in the amount of $24.7 million.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Santander Bank [Member]                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| **Debt Instrument [Line Items]**                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Schedule of Borrowings and Other Debt Obligation | The following table presents information regarding the Bank's borrowings and other debt obligations at the dates indicated:  June 30, 2014 December 31, 2013 Balance EffectiveRate Balance EffectiveRate (in thousands)8.750% subordinated debentures, due May 2018$497,670 8.91% $497,427 8.91%FHLB advances, maturing through August 2018(1)9,593,309 2.74 8,952,012 3.36Subordinated term loan, due February 2019145,279 6.00 150,273 6.06REIT preferred, due May 2020152,666 13.70 151,918 13.83Subordinated term loan, due August 202234,674 7.77 35,491 7.78     Total Bank borrowings and other debt obligations$10,423,598 3.26% $9,787,121 3.87%(1) In February 2014, the Company restructured $1.7 billion of FHLB advances and extended their maturities by two years. The average rate of these borrowings decreased from 5.39% to 3.43% as a result of the restructuring.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| SCUSA [Member]                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| **Debt Instrument [Line Items]**                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Schedule of Borrowings and Other Debt Obligation | The following tables present information regarding SCUSA's borrowings and other debt obligations at the date indicated(1): June 30, 2014 Balance EffectiveRate (in thousands)SCUSA warehouse line, due July 2014(2)$109,461 2.05%SCUSA warehouse line, maturing on various dates(3)552,268 1.14SCUSA warehouse line, due March 2015(4)250,594 0.99SCUSA warehouse line, due July 2015153,515 1.64SCUSA warehouse line, due September 2015(5)196,880 1.97SCUSA warehouse line, due December 2015464,037 2.18SCUSA warehouse line, due December 2015495,765 0.91SCUSA warehouse line, due January 2016(6)1,318,088 1.15SCUSA warehouse line, due November 2016(7)175,000 1.71SCUSA repurchase facility, maturing on various dates(8)747,342 1.52SCUSA line of credit with related party, due December 2016(9)500,000 2.45SCUSA line of credit with related party, due December 2016(9)1,750,000 2.26SCUSA line of credit with related party, due December 2018(9)750,000 2.59     Total SCUSA revolving credit facilities$7,462,950 1.78% June 30, 2014 Balance Initial Weighted Average Interest Rate Range (in thousands)SCUSA public securitizations, maturing on various dates(10)$12,242,497 0.89% - 2.80%SCUSA privately issued amortizing notes, maturing on various dates(10)6,276,547 1.07% - 1.85%     Total SCUSA secured structured financings$18,519,044 0.89% - 2.80% (1) Balances as of December 31, 2013 are not presented due to SCUSA being accounted for as an Equity Method Investment at that date.(2) In July 2014, the maturity date of this facility was extended to June 2015.(3) Half of the outstanding balance on this facility matures in March 2015 and half in March 2016.(4) This line is collateralized by securitization notes payable retained by SCUSA.(5) This line is held exclusively for unsecured consumer term loans.(6) This line is held exclusively for Chrysler Capital retail loan and lease financing, with lease financing comprising no more than 50% of the outstanding balance upon advance.(7) This line is collateralized by residuals retained by SCUSA.(8) This repurchase facility is collateralized by securitization bonds and residuals retained by SCUSA. No portion of this facility is unsecured. The facility has rolling 30-day and 90-day maturities.(9) These lines are collateralized by securitization notes payable and residuals retained by SCUSA. As of June 30, 2014, $1.6 billion of the aggregate outstanding balances on these credit facilities was unsecured.(10) SCUSA has entered into various securitization transactions involving its retail automotive installment loans and leases. These transactions are accounted for as secured financings and therefore both the securitized retail installment contracts and the related securitization debt issued by special purpose entities, remain on the Condensed Consolidated Balance Sheet. The maturity of this debt is based on the timing of repayments from the securitized assets. |

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| - Definition
Tabular disclosure of information pertaining to short-term and long-debt instruments or arrangements, including but not limited to identification of terms, features, collateral requirements and other information necessary to a fair presentation.
+ References
No definition available.
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