| **RELATED PARTY TRANSACTIONS**            | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             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| **Related Party Transactions [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| 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 for the year ended December 31, 2015. During the first quarter ended March 31, 2016, SBNA transferred and settled $2.3 billion of unfunded commitments to extend credit to an unconsolidated related party for a loss on sale of $6.3 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. A list and description of these agreements can be found in Note 22 to the Consolidated Financial Statements of the Company's Annual Report on Form 10-K for the year ended December 31, 2015.On July 2, 2015, the Company announced that it had entered into an agreement with former SC Chief Executive Officer Thomas G. Dundon (Mr. 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. Also, in connection with and pursuant to the Separation Agreement, on July 2, 2015, Mr. Dundon, the Company, DDFS, SC and Santander entered into an amendment to the Shareholders Agreement (the "Second Amendment"). The Second Amendment amended, for purposes of calculating the price per share to be paid in the event that a put or call option was exercised with respect to the shares of SC Common Stock owned by DDFS, the definition of the term “Average Stock Price” to mean $26.83. 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 ultimately sold in the Call Transaction. The Amended and Restated Loan Agreement provides for a $300.0 million revolving loan which as of March 31, 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.NOTE 15. RELATED PARTY TRANSACTIONS (continued)If consummated , the Company would pay DDFS approximately $928.3 million plus interest that accrued since the Call End Date. To date, the Call Transaction has not been consummated and remains subject to the receipt of the applicable regulatory approvals. The Company’s delivery of its irrevocable notice to consummate the Call Transaction created a contingent forward purchase of all of DDFS equity shares in accordance with ASC 480, Distinguishing Liabilities from Equity. Under this guidance the Company will recognize either a contingent forward asset or liability at fair value based on the movement of SC’s stock price in the market as compared to the proposed fixed settlement price of $26.83 per share. Since July 2, 2015 through March 31, 2016, SC’s stock price is lower than $26.83 which would indicate a potential recognition of a contingent forward purchase obligation. The Company’s estimate of the fair value of the contingent forward purchase obligation, based on its assessment of the likelihood of obtaining the required regulatory approvals and its estimate of the accrued interest, was not material to its consolidated financial statements for the prior periods presented as well as to the current quarter. If regulatory approval is obtained, or if the probability of obtaining the regulatory approvals increases, the Company may have to recognize a material charge to earnings to recognize the change in the fair value of the contingent forward purchase contract. |

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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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