| **BASIS OF PRESENTATION AND ACCOUNTING POLICIES** | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     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| **Accounting Policies [Abstract]**                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| BASIS OF PRESENTATION AND ACCOUNTING POLICIES     | NOTE 1. BASIS OF PRESENTATION AND ACCOUNTING POLICIES Introduction  SHUSA is the parent company of Santander Bank, National Association, (the "Bank"), a national banking association, and Santander Consumer USA Holdings Inc. (together with its subsidiaries, "SCUSA"), a consumer finance company focused on vehicle finance. SHUSA is headquartered in Boston, Massachusetts and the Bank's main office is in Wilmington, Delaware. SHUSA is a wholly-owned subsidiary of Banco Santander, S.A. ("Santander").  The Bank’s primary business consists of attracting deposits and providing other retail banking services through its network of retail branches, and originating small business loans, middle market, large and global commercial loans, multi-family loans, residential mortgage loans, home equity loans and lines of credit, and auto and other consumer loans throughout the Mid-Atlantic and Northeastern areas of the United States, focused throughout Pennsylvania, New Jersey, New York, New Hampshire, Massachusetts, Connecticut, Rhode Island, and Delaware. The Bank uses its deposits, as well as other financing sources, to fund its loan and investment portfolios.  SCUSA wholly owns Santander Consumer USA Inc., which is headquartered in Dallas, Texas, and is a full-service, technology-driven consumer finance company focused on vehicle finance.  On January 22, 2014, SCUSA's registration statement for an initial public offering ("IPO") of shares of its common stock (the “SCUSA Common Stock”), was declared effective by the Securities and Exchange Commission (the "SEC"). Prior to the IPO, the Company owned approximately 65% of the shares of SCUSA Common Stock.  On January 28, 2014, the IPO was consummated, and certain stockholders of SCUSA, including the Company and Sponsor Auto Finance Holdings Series LP ("Sponsor Holdings"), sold 85,242,042 shares of SCUSA Common Stock. Immediately following the IPO, the Company owned approximately 61% of the shares of SCUSA Common Stock. In connection with these sales, certain board representation, governance and other rights granted to Dundon DFS LLC ("DDFS") and Sponsor Holdings were terminated as a result of the reduction in DDFS and Sponsor Holdings’ collective ownership of shares of SCUSA Common Stock below certain ownership thresholds, causing the Change in Control.  Prior to the Change in Control, the Company accounted for its investment in SCUSA under the equity method. Following the Change in Control, the Company consolidated the financial results of SCUSA in the Company’s Consolidated Financial Statements. The Company’s consolidation of SCUSA is treated as an acquisition of SCUSA by the Company in accordance with Accounting Standards Codification ("ASC") 805 - Business Combinations (ASC 805). SCUSA Common Stock is now listed for trading on the New York Stock Exchange under the trading symbol "SC".  On July 2, 2015, the Company announced that it had entered into an agreement with former SCUSA Chief Executive Officer Thomas G. Dundon, DDFS, and Santander related to Mr. Dundon's departure from SCUSA (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 SCUSA 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 SCUSA Common Stock held by DDFS ("the DDFS Shares") represented approximately 9.8% of SCUSA 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. Santander is expected to assume the Company’s obligation to purchase the DDFS shares and contribute those shares to SHUSA. 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. In the event the Call Transaction were to be completed after the Call End Date, interest would accrue 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 SCUSA Common Stock that were ultimately sold in the Call Transaction. For additional detail regarding this transaction and the Separation Agreement, refer to the Form 8-K the Company filed with the SEC on July 2, 2015 and Note 14 to these Condensed Consolidated Financial Statements. NOTE 1. BASIS OF PRESENTATION AND ACCOUNTING POLICIES (continued)See Note 3 to the Consolidated Financial Statements for a detailed discussion of the Company's consolidation of SCUSA in accordance with ASC 805. Basis of PresentationThese Condensed Consolidated Financial Statements include the accounts of the Company and its subsidiaries, including the Bank, SCUSA, and certain special purpose financing trusts utilized in financing transactions that are considered variable interest entities ("VIEs"). The Company consolidates VIEs for which it is deemed the primary beneficiary. The Condensed Consolidated Financial Statements have been prepared by the Company, without audit, pursuant to SEC regulations. All intercompany balances and transactions have been eliminated in consolidation. Additionally, where applicable, the Company's accounting policies conform to the accounting and reporting guidelines prescribed by bank regulatory authorities. However, in the opinion of management, the accompanying unaudited Condensed Consolidated Financial Statements reflect all adjustments of a normal and recurring nature necessary to present fairly the Condensed Consolidated Balance Sheets, Condensed Statements of Operations, Condensed Statements of Comprehensive Income, Condensed Statements of Stockholder's Equity and Condensed Statements of Cash Flows for the periods indicated, and contain adequate disclosure to make the information presented not misleading. Reclassifications and Corrections to Previously Reported AmountsCertain prior year amounts have been reclassified to conform to the current year presentation. These reclassifications did not have an impact on the consolidated financial condition or results of operations. The Company has made certain corrections to the September 30, 2014 Condensed Consolidated Statements of Cash Flows and Note 5 thereto. The Company identified and corrected immaterial classification errors with respect to certain cash flows related to loans held for investment, Federal Home Loan Bank ("FHLB") advance repayments and short-term borrowings reported within cash flows in financing activities, as well as classification errors related to certain restricted cash accounts within investing activities. Certain cash flows related to decreases in deferred tax assets have been reclassified from net changes in other liabilities to net changes in other assets within operating cash flows. These changes resulted in increased total cash provided by operating activities and increased total cash used in investing activities by an equal and offsetting amount. There was no net impact to cash provided by financing activities. The reclassification errors did not impact the net change in cash and cash equivalents, total cash and cash equivalents, net income, or any other operating measure.The corrections to Note 5 related to the components of troubled debt restructuring ("TDR") activities for the three-month and nine-month periods endedSeptember 30, 2014. The corrections do not affect the Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Comprehensive Income for the three-month and nine-month periods endedSeptember 30, 2015 and 2014, the Condensed Consolidated Statements of Stockholder's Equity for the nine-month periods endedSeptember 30, 2015 and 2014, or the Condensed Consolidated Balance Sheets at September 30, 2015 and 2014. Significant Accounting Policies Management identified accounting for consolidation, business combinations, the allowance for loan losses and the reserve for unfunded lending commitments, goodwill, derivatives and hedge activities, and income taxes as the Company's most critical accounting policies and estimates, in that they are important to the portrayal of the Company's financial condition and results of operations and require management's most difficult, subjective and complex judgments as a result of the need to make estimates about the effect of matters that are inherently uncertain. These Condensed Consolidated Financial Statements should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2014. As of September 30, 2015, with the exception of the items noted in the section "Changes in Accounting Policies" below, there have been no significant changes to the Company's accounting policies as disclosed in the Annual Report on Form 10-K for the year ended December 31, 2014.  NOTE 1. BASIS OF PRESENTATION AND ACCOUNTING POLICIES (continued) Changes in Accounting Policies  During the first quarter of 2015, the Company adopted the following Financial Accounting Standards Board (the "FASB") Accounting Standards Updates ("ASUs"), none of which had a material impact to the Company's Condensed Consolidated financial statements: •The Company adopted the FASB ASU 2014-01, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects, which allows an entity to make an accounting policy election toaccount for its investments in qualified affordable housing projects using the proportional amortization method, if certain conditions are met. Under this method, an investor would amortize the cost of its investments in proportion to the tax credits and other tax benefits received and will recognize the amortization, net of tax credits and other tax benefits, in the income statement as a component of income tax expense. This ASU is required to be adopted on a retrospective basis for all periods presented. The adoption of this ASU did not have a material effect to the Company’s prior periods’ consolidated financial statements to warrant retrospective application. The cumulative effect of the adoption was recognized in the first quarter of 2015 and was not material to the Company’s Condensed Consolidated Financial Statements. •The Company adopted FASB ASU 2014-04, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40) - Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure, on a prospective basis. Under this ASU, an in-substance repossession or foreclosure occurs when the creditor obtains legal title to the residential real estate property or the borrower conveys all interest in the residential real estate property to the creditor to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The Company’s adoption of this ASU did not have a material effect on its Condensed Consolidated Financial Statements. •The Company adopted FASB ASU 2014-14, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure. This ASU requires that a government-guaranteed mortgage loan be de-recognized, and that a separate other receivable be recognized, upon foreclosure if the three criteria identified in the ASU are met. Upon foreclosure and meeting the three criteria, the separate other receivable should be measured based on the amount of the loan balance (principal and interest) that is expected to be recovered from the guarantor. The Company’s adoption of this ASU did not have a material effect on its Condensed Consolidated Financial Statements. •During the third quarter of 2015, the Company early adopted FASB ASU 2015-03, Interest- Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, on a retrospective basis. This ASU simplifies the presentation of debt issuance costs and requires that debt issuance costs be presented as a deduction from the recognized debt liability, and eliminates prior guidance which required that debt issuance costs be recorded as a deferred charge. The Company’s adoption of this ASU resulted in the re-classification of $59.0 million and $30.3 million in debt issuance costs from Other assets to Borrowings as of September 30, 2015 and December 31, 2014, respectively. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The most significant estimates pertain to consolidation, fair value measurements, allowance for loan and lease losses and reserve for unfunded lending commitments, estimates of expected residual values of leased vehicles subject to operating leases, goodwill, derivatives and hedge activities, and income taxes. Actual results may differ from the estimates, and the differences may be material to the Condensed Consolidated Financial Statements. Subsequent Events The Company evaluated events from the date of the Condensed Consolidated Financial Statements on September 30, 2015 through the issuance of these Condensed Consolidated Financial Statements and has determined that there have been no material events that would require recognition in its Condensed Consolidated Financial Statements or disclosure in the Notes to the Condensed Consolidated Financial Statements for the quarter ended September 30, 2015 other than the transactions disclosed within Note 5 of these Condensed Consolidated Financial Statements. |

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The entire disclosure for the basis of presentation and significant accounting policies concepts. Basis of presentation describes the underlying basis used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS).  Accounting policies describe all significant accounting policies of the reporting entity.
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