| **GOODWILL AND OTHER INTANGIBLES**                       | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              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| **Goodwill and Intangible Assets Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| GOODWILL AND OTHER INTANGIBLES                           | GOODWILL AND OTHER INTANGIBLESGoodwillThe following table presents activity in the Company's goodwill by its reportable segments for the three-month period endedMarch 31, 2016:  Consumer and Business Banking (1) Auto Finance & Business Banking Commercial Real Estate(2)  Commercial Banking(2) Global Corporate Banking SC Total  (in thousands)Goodwill at December 31, 2015 $1,550,321 $445,923 $— $1,297,055 $131,130 $1,019,960 $4,444,389Disposals during the period — — —   — — —Additions during the period — — —   — — —Impairment during the period — — —   — — —Re-allocations during the period 329,983 (445,923) 870,411 (754,471) — — —Goodwill at March 31, 2016 $1,880,304 $— $870,411 $542,584 $131,130 $1,019,960 $4,444,389 (1)  Consumer and Business Banking was formerly designated as the Retail Banking segment and was renamed during the first quarter of 2016.(2)  Commercial Real Estate and Commercial Banking were formerly disclosed as the combined Real Estate and Commercial Banking segment.As more fully described in Note 17 to the Condensed Consolidated Financial Statements, during the first quarter of 2016, certain management and line of business changes became effective as the Company reorganized its management reporting in order to improve its structure and focus to better align management teams and resources with the business goals of the Company and provide enhanced customer service to its clients. Accordingly, the following changes were made within the Company's reportable segments and reporting units to provide greater focus on each of its core businesses: •The small business banking, commercial business banking, and auto leasing lines of business formerly included in the Auto Finance and Business Banking reportable segment were combined with the Consumer and Business Banking reportable segment. The combined impact of these organizational changes resulted in the re-allocation of $330.0 million of goodwill from Auto Finance & Business Banking to Consumer and Business Banking. •The Real Estate and Commercial Banking reportable segment was split into the Commercial Real Estate reportable segment and the Commercial Banking reportable segment, resulting in the re-allocation of $870.4 million of goodwill from Commercial Banking to Commercial Real Estate.  •The commercial equipment vehicle financing and dealer floor plan lines of business, formerly included in the Auto Finance & Business Banking reportable segment were moved to the Commercial Banking business unit, resulting in the re-allocation of $115.9 million of goodwill from Auto Finance & Business Banking to Commercial Banking. NOTE 7. GOODWILL AND OTHER INTANGIBLES (continued)Previously, the Company reorganized its management reporting in the third quarter of 2015 in order to improve its structure and focus by better aligning management teams and resources with the business goals of the Company and to provide enhanced customer service to its clients. As a result of the change in segment reporting, the Company re-evaluated its conclusions related to goodwill reporting units, including the following:•The small business banking business unit, formerly included in the Retail Banking reportable segment, was combined with the Auto Finance and Business Banking business unit, resulting in re-allocation of goodwill in the amount of $265.4 million from Retail Banking to Auto Finance and Business Banking. •The commercial business banking business unit, formerly included in the Real Estate and Commercial Banking reportable segment, was combined with the Auto Finance and Business Banking business unit resulting in the re-allocation of goodwill in the amount of $109.0 million from Real Estate and Commercial Banking to Auto Finance and Business Banking. The Company conducted its annual goodwill impairment test as of October 1, 2015 using generally accepted valuation methods. After conducting an analysis of the fair value of each reporting unit as of October 1, 2015, the Company determined that there was no impairment of goodwill identified as a result of the annual impairment analysis. During the fourth quarter of 2015, due to a decline in SC's share price, the Company concluded that the fair value of our SC reporting unit was more likely than not less than its carrying value including goodwill. As a result, the Company performed an interim goodwill impairment analysis as of December 31, 2015, the results of which required the Company to record an impairment of $4.4 billion. During the first quarter of 2016, the Company continued to evaluate SC's share price. The Company performed an interim goodwill impairment analysis as of March 31, 2016, the results of which determined that there was no impairment to goodwill.Other Intangible AssetsThe following table details amounts related to the Company's finite-lived and indefinite-lived intangible assets for the dates indicated.  March 31, 2016 December 31, 2015 NetCarryingAmount AccumulatedAmortization NetCarryingAmount AccumulatedAmortization (in thousands)Intangibles subject to amortization:       Dealer networks$495,036 $(84,964) $504,839 $(75,161)Chrysler relationship106,250 (32,500) 110,000 (28,750)Core deposit intangibles152 (295,690) 763 (295,079)Other intangibles4,679 (25,230) 5,453 (24,455)Total intangibles subject to amortization606,117 (438,384) 621,055 (423,445)Intangibles not subject to amortization:       Trade name18,000 — 38,300 —Total Intangibles$624,117 $(438,384) $659,355 $(423,445)Amortization expense on intangible assets for the three-month periods endedMarch 31, 2016 and March 31, 2015 was $35.2 million and $16.8 million, respectively.As part of the Step 2 goodwill impairment analysis, the Company performed a valuation of the intangible assets allocated to the SC reporting unit as of December 31, 2015. As the fair value analysis was not complete at the time of the filing of the Company’s Form 10-K, the Company recorded an estimated provisional impairment charge of $11.7 million related to the indefinite-lived trade name. Subsequent to the filing of the Company's Form10-K for 2015, the Company's fair value analysis, and consequently the impairment analysis, was updated and the Company concluded that an additional impairment charge of $20.3 million relating to the trade name was necessary. The additional impairment was recorded within amortization expense of intangible assets for the three-month period ended March 31, 2016. NOTE 7. GOODWILL AND OTHER INTANGIBLES (continued)The estimated aggregate amortization expense related to intangibles, excluding any impairment charges, for each of the five succeeding calendar years ending December 31 is:Year Calendar Year Amount Recorded To Date Remaining Amount To Record  (in thousands)2016 $57,162 $14,938 $42,2252017 55,055 — 55,0552018 54,702 — 54,7022019 54,501 — 54,5012020 54,441 — 54,441Thereafter 345,194 — 345,194 |

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| - Definition
The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final.  May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.
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