| **GOODWILL AND OTHER INTANGIBLES (As Restated) (Goodwill) (Details) $ in Thousands**                          | 3 Months Ended |
|---------------------------------------------------------------------------------------------------------------|----------------|
||
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | $ 8,951,484    |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 8,951,484      |
| SCUSA [Member]                                                                                                |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | 5,527,055      |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 5,527,055      |
| Retail Banking [Member]                                                                                       |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | 1,815,729      |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 1,815,729      |
| Auto Finance & Alliances [Member]                                                                         |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | 71,522         |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 71,522         |
| Real Estate and Commercial Banking [Member]                                                                   |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | 1,406,048      |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 1,406,048      |
| Global Banking & Markets and Large Corporate [Member]                                                     |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | 131,130        |
| Additions / disposals during the period                                                                       | 0              |
| Goodwill, Ending balance                                                                                      | 131,130        |
| Increased Value of the SC Business at Acquisition [Member] | Restatement Adjustment [Member] | SCUSA [Member] |           |
| **Goodwill [Roll Forward]**                                                                                   |           |
| Goodwill, Beginning balance                                                                                   | $ 59,500       |

| X                                                                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Goodwill, Acquired or Written off During Period
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266
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| X                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
+ References
No definition available.
+ Details**Name:**us-gaap_GoodwillRollForward**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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