| **BUSINESS SEGMENT INFORMATION (As Restated) (Tables)** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              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| **Segment Reporting [Abstract]**                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         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| Schedule of Segment Reporting Information, by Segment   | The following tables present certain information regarding the Company’s segments.             For the Year EndedSHUSA excluding SC SC(4)  December 31, 2015Consumer and Business BankingCommercial BankingCommercial Real Estate Global Corporate BankingOther(2) SC(3)SC Purchase Price AdjustmentsEliminations Total (in thousands)Net interest income/(loss)$845,192$276,407$272,999$218,917$(47,122) $4,614,402$407,139$347 $6,588,281Total non-interest income700,64552,30244,17089,20894,996 1,303,643285,882(46,091) 2,524,755Gain on change in control————— ——— —Provision for credit losses42,90717,39825,71940,8818,228 2,785,8711,091,952— 4,012,956Total expenses1,788,418184,36572,095108,718320,642 1,842,5624,644,576(51,957) 8,909,419Income/(loss) before income taxes(285,488)126,946219,355158,526(280,996) 1,289,612(5,043,507)6,213 (3,809,339)            Intersegment revenue/(expense)(1)1,2074,1462,814(9,601)1,434 ——— —Total assets21,627,86916,581,17515,085,97112,092,98626,615,618 35,567,663—— 127,571,282(1)Intersegment revenue/(expense) represents charges or credits for funds used or provided by each of the segments and is included in net interest income.(2)Other is not considered a segment and includes earnings from non-strategic assets, the investment portfolio, interest expense on the Bank’s and Holding Company's borrowings and other debt obligations, amortization of intangible assets and certain unallocated corporate income and indirect expenses.(3)Management of SHUSA manages SC by analyzing the pre-Change in Control results of SC as disclosed in this column.(4)Purchase Price Adjustments represents the impact that SC purchase marks had on the results of SC included within the consolidated operations of SHUSA, while eliminations eliminate intercompany transactions.            For the Year EndedSHUSA excluding SC SC(4)  December 31, 2014Consumer and Business BankingCommercial BankingCommercial Real Estate Global Corporate BankingOther(2) SC(3)SC Purchase Price AdjustmentsEliminations Total (in thousands)Net interest income$823,403$242,413$249,949$180,244$81,440 $4,155,446$517,393$(333,155) $5,917,133Total non-interest income619,13548,60636,74583,715187,510 1,048,386345,821(107,575) 2,262,343Gain on Change in Control————— —2,417,563— 2,417,563Provision for/(release of) credit losses67,54726,702(98,192)6921,252 2,518,366111,927(215,051) 2,413,243Total expenses1,547,621150,27280,317101,223344,057 1,564,332155,786(270,230) 3,673,378Income/(loss) before income taxes(172,630)114,045304,569162,044(76,359) 1,121,1343,013,06444,551 4,510,418            Intersegment revenue/(expense)(1)8845,1021,317(8,487)1,184 ——— —Total assets22,284,61815,074,83414,046,70110,207,96625,301,604 31,905,157—— 118,820,880(1)Intersegment revenue/(expense) represents charges or credits for funds used or provided by each of the segments and is included in net interest income.(2)Other is not considered a segment and includes earnings from non-strategic assets, the investment portfolio, interest expense on the Bank’s and Holding Company's borrowings and other debt obligations, amortization of intangible assets and certain unallocated corporate income and indirect expenses.(3)Management of SHUSA manages SC by analyzing the pre-Change in Control results of SC as disclosed in this column.(4)Purchase Price Adjustments represent the impact that SC purchase marks had on the results of SC included within the consolidated operations of SHUSA, while eliminations adjust for the one month that SHUSA accounted for SC as an equity method investment and eliminate intercompany transactions.NOTE 24. BUSINESS SEGMENT INFORMATION (As Restated) (continued)For the Year Ended       December 31, 2013Consumer and Business BankingCommercial BankingCommercial Real Estate Global Corporate BankingOther(2)Equity Method Investment in SCTotal (in thousands)Net interest income$836,098$228,937$210,963$167,643$70,130$—$1,513,771Total non-interest income408,84146,16362,29180,86236,769464,4911,099,417Provision for/(release of) credit losses152,191(27,733)(83,204)(893)6,489—46,850Total expenses1,392,849202,07656,62977,45098,058—1,827,062Income/(loss) before income taxes(300,101)100,757299,829171,9482,352464,491739,276        Intersegment revenue/(expense)(1)5,4983,0073,659(12,164)———Total assets21,679,47113,072,58613,583,0898,104,24520,759,535—77,198,926(1)Intersegment revenue/(expense) represents charges or credits for funds used or provided by each of the segments and is included in net interest income.(2)Other is not considered a segment and includes earnings from non-strategic assets, the investment portfolio, interest expense on the Bank’s and Holding Company's borrowings and other debt obligations, amortization of intangible assets and certain unallocated corporate income and indirect expenses. |

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| - Definition
Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.
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