| **RELATED PARTY TRANSACTIONS**            | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
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| **Related Party Transactions [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| RELATED PARTY TRANSACTIONS                | RELATED PARTY TRANSACTIONSThe Company has various debt agreements with Santander. For a listing of these debt agreements, see Note 12 to the Condensed Consolidated Financial Statements of the Company's Annual Report on Form 10-K/A for the year ended December 31, 2015. During the three-month and six-month periods endedJune 30, 2016, SBNA transferred and settled $3.7 billion and $6.0 billion, respectively, of unfunded commitments to extend credit to an unconsolidated related party for a gain on sale of $4.2 million and a loss on sale of $2.1 million; see Note 14. The Company and its affiliates also entered into or were subject to various service agreements with Santander and its affiliates. Each of these agreements was made in the ordinary course of business and on market terms. NOTE 15. RELATED PARTY TRANSACTIONS (continued)On July 2, 2015, the Company announced that it had entered into an agreement with former SC Chief Executive Officer Thomas G. Dundon, Dundon DFS LLC ("DDFS"), and Santander related to Mr. Dundon's departure from SC (the “Separation Agreement”). Pursuant to the Separation Agreement, the Company was deemed to have delivered an irrevocable notice to exercise its option to acquire all of the shares of SC Common Stock owned by DDFS and consummate the transactions contemplated by the call option notice, subject to the receipt of all required regulatory approvals (the "Call Transaction"). At that date, the SC Common Stock held by DDFS (the "DDFS Shares") represented approximately 9.7% of SC Common Stock. The Separation Agreement did not affect Santander’s option to assume the Company’s obligation under the Call Transaction as provided in the Shareholders Agreement that was entered into by the same parties on January 28, 2014. Under the Separation Agreement, because the Call Transaction was not consummated prior to October 15, 2015 (the “Call End Date”), DDFS is free to transfer any or all of the DDFS shares, subject to the terms and conditions of the Amended and Restated Loan Agreement dated as of July 16, 2014 between DDFS and Santander. Because the Call Transaction was not completed before the Call End Date, interest began accruing on the price paid per share in the Call Transaction at the overnight LIBOR rate on the third business day preceding the consummation of the Call Transaction plus 100 basis points with respect to the shares of SC Common Stock that will ultimately be sold in the Call Transaction. The Amended and Restated Loan Agreement provides for a $300.0 million revolving loan which, as of June 30, 2016 and December 31, 2015, had an unpaid principal balance of approximately $290.0 million. Pursuant to the Loan Agreement, 29,598,506 shares of the SC’s Common Stock owned by DDFS are pledged as collateral under a related pledge agreement.On August 31, 2016, Santander exercised its option to become the direct obligor of the Company’s Call Obligation in accordance with the Shareholders Agreement dated as of January 28, 2014 among Mr. Dundon, DDFS, SC and Santander.   It is expected that Santander will subsequently contribute the DDFS Shares to the Company, which will be accounted for by the Company as an equity contribution. To date, the Call Transaction has not been consummated and remains subject to the completion of all conditions and required regulatory approvals. |

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No definition available.
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| - Definition
The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.
+ References
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