| **BUSINESS COMBINATIONS (Tables)**                                                             | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
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| **Business Combinations [Abstract]**                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Schedule of Recognized Identified Assets Acquired and Liabilities Assumed                      | The following table summarizes these equity related interests in SCUSA which constitute the purchase price and the identified assets acquired and liabilities assumed:  January 28, 2014  (dollars in thousands)Fair value of noncontrolling interest in SCUSA $3,273,265Fair value of SCUSA employee vested stock options  210,181Fair value of SHUSA remaining ownership interest in SCUSA 5,063,881Fair value of equity-related interests in SCUSA $8,547,327   Recognized amounts of identifiable assets acquired and liabilities assumed:  Cash and cash equivalents $11,075Restricted cash 1,704,906Loan receivables - held for sale 990,137Loan receivables - retail installment contracts 19,870,790Loan receivables from dealers 102,689Loan receivables - personal 1,009,896Premises and equipment 74,998Leased vehicles, net 2,486,929Intangibles 768,750Miscellaneous receivables and other assets 1,061,351Deferred tax asset 16,399Borrowings and other debt obligations (24,497,607)Accounts payable and accrued liabilities (520,568)Total identifiable net assets 3,079,745   Goodwill $5,467,582                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period |   January 28, 2014  (dollars in thousands)Fair value of loan receivables (1) $19,870,790Gross contractual amount of loan receivables (1) $31,410,699Estimate of contractual cash flows not expected to be collected at acquisition (1) $4,301,586   (1) - Fair value of receivables excludes certain amounts related to the personal loan receivables and loan receivables from dealers due to the short-term and revolving nature of the receivables.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination   | Intangibles identified in connection with the Change in Control were:  January 28, 2014  Fair ValueWeighted Average Amortization Period  (dollars in thousands)Intangibles subject to amortization: Dealer networks $580,00017.5 years (a)Chrysler relationship 138,7509.2 years    Intangibles not subject to amortization: Trade name 50,000indefinite livedTotal Intangibles $768,750    (a) - The amortization periods of the dealer network range between 7 and 20 years.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Schedule of Business Acquisition, Gain on Change in Control                                    | The Company recognized a pre-tax gain of $2.4 billion in connection with the Change in Control in Non-interest income in the Consolidated Statement of Operations.  January 28, 2014  (in thousands)   Gain attributable to SCUSA shares sold $137,536Gain attributable to the remaining equity interest 2,291,003Total pre-tax gain $2,428,539                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Business Acquisition, Actual Financial Information and Pro Forma Information of Acquiree       | The following table summarizes the actual amounts of Total revenue, net of Total interest expense and Net income including Noncontrolling Interest of SCUSA included in our Consolidated Financial Statements for the year ended December 31, 2014 and the supplemental pro forma consolidated Total revenue, net of total interest expense and Net income including noncontrolling interest of SHUSA entity for years ended December 31, 2014 and 2013, respectively, as if the Change in Control had occurred on January 1, 2013. These results include the impact of amortizing certain purchase accounting adjustments such as intangible assets as well as fair value adjustments to loans and issued debt. These pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual consolidated results of operations of SHUSA that would have been achieved had the Change in Control occurred at January 1, 2013, nor are they intended to represent or be indicative of future results of operations.   SCUSA Amounts Included in Results for Year Ended Supplemental Pro Forma - Combined for the Year Ended December 31,  December 31, 2014 2014 (b) 2013 (b)(c)  (in thousands)       Total Revenue, Net of Total Interest Expense (a) $5,883,682 $8,402,844 $9,132,721Net Income including Noncontrolling Interest 893,884 947,745 2,314,589       (a) - Total Revenue, Net of Total Interest Expense is calculated as the sum of Total Interest Income and Total Non-Interest Income, less Total Interest Expense.(b) - Includes the impact of recording provision for loan losses necessary to bring the retail installment contracts and personal unsecured loans to their expected carrying values considering the required allowance for loan losses on their recorded investment amounts. See Note 1 for a related discussion of the Company's accounting policy specific to these loans. (c) - Included within the Supplemental Pro Forma - Combined Total Revenue, Net of Total Interest Expense and Net Income including Noncontrolling Interest for the year ended December 31, 2013 are non-recurring gains of $2.43 billion and $1.53 billion, respectively, that arose on the re-measurement of SHUSA's equity method investment in SCUSA to fair value. |

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Tabular disclosure of the reconciliation of contractual cash flows to the carrying amount relating to certain loans acquired in a transfer.
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Tabular disclosure of finite-lived and indefinite-lived intangible assets acquired as part of a business combination.
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Tabular disclosure of the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed. May include but not limited to the following: (a) acquired receivables; (b) contingencies recognized at the acquisition date; and (c) the fair value of noncontrolling interests in the acquiree.
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