| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Troubled Debt Restructuring Activity) (Details) $ in Thousands** | 3 Months Ended |               |
|-----------------------------------------------------------------------------------------------------------|----------------|---------------|
||
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Troubled debt restructurings                                                                              | $ 4,702,984    | $ 3,257,394   | $ 4,411,247 |
| Number of Contracts | contract                                                                            | 59,471         | 80,142        |   |
| Pre-TDR Recorded Investment                                                                               | $ 793,141      | $ 1,156,958   |   |
| Post-TDR Recorded Investment                                                                              | (781,451)      | $ (1,152,222) |   |
| Number of Contracts | contract                                                                            |           | 9,782         |   |
| Recorded Investment                                                                                       |           | $ 144,305     |   |
| Performing                                                                                                |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Troubled debt restructurings                                                                              | 4,192,307      | 2,875,546     | 3,807,751 |
| Non-performing                                                                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Troubled debt restructurings                                                                              | $ 510,677      | $ 381,848     | $ 603,496 |
| Commercial | Corporate banking                                                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 9              | 2             |   |
| Pre-TDR Recorded Investment                                                                               | $ 47,776       | $ 1,448       |   |
| Post-TDR Recorded Investment                                                                              | $ (37,166)     | $ (1,439)     |   |
| Commercial | Middle market commercial real estate                                                         |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 3              | 1             |   |
| Pre-TDR Recorded Investment                                                                               | $ 10,454       | $ 14,439      |   |
| Post-TDR Recorded Investment                                                                              | $ (10,385)     | $ (14,439)    |   |
| Commercial | Commercial and industrial                                                                    |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts                                                                                       | 223            | 81            |   |
| Pre-TDR Recorded Investment                                                                               | $ 7,281        | $ 10,880      |   |
| Post-TDR Recorded Investment                                                                              | $ (7,280)      | $ (8,166)     |   |
| Number of Contracts | contract                                                                            | 55             | 10            |   |
| Recorded Investment                                                                                       | $ 2,000        | $ 276         |   |
| Consumer                                                                                                  |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 14,796         | 9,782         |   |
| Recorded Investment                                                                                       | $ 220,706      | $ 144,305     |   |
| Consumer | Residential mortgages                                                                          |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 49             | 46            |   |
| Pre-TDR Recorded Investment                                                                               | $ 6,648        | $ 7,588       |   |
| Post-TDR Recorded Investment                                                                              | $ (6,853)      | $ (7,866)     |   |
| Number of Contracts | contract                                                                            | 11             | 8             |   |
| Recorded Investment                                                                                       | $ 1,812        | $ 931         |   |
| Consumer | Home equity loans and lines of credit                                                          |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 67             | 40            |   |
| Pre-TDR Recorded Investment                                                                               | $ 4,539        | $ 3,671       |   |
| Post-TDR Recorded Investment                                                                              | $ (4,434)      | $ (3,671)     |   |
| Number of Contracts | contract                                                                            | 5              | 5             |   |
| Recorded Investment                                                                                       | $ 341          | $ 262         |   |
| Consumer | Retail installment contracts and auto loans                                                    |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 42,039         | 75,489        |   |
| Pre-TDR Recorded Investment                                                                               | $ 694,175      | $ 1,112,626   |   |
| Post-TDR Recorded Investment                                                                              | $ (693,372)    | $ (1,110,365) |   |
| Number of Contracts | contract                                                                            | 13,124         | 9,693         |   |
| Recorded Investment                                                                                       | $ 214,702      | $ 142,534     |   |
| Consumer | Personal unsecured loans                                                                       |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 17,055         | 4,468         |   |
| Pre-TDR Recorded Investment                                                                               | $ 21,345       | $ 5,394       |   |
| Post-TDR Recorded Investment                                                                              | $ (21,216)     | $ (5,356)     |   |
| Number of Contracts | contract                                                                            | 1,599          | 64            |   |
| Recorded Investment                                                                                       | $ 1,827        | $ 58          |   |
| Consumer | Other consumer                                                                                 |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Number of Contracts | contract                                                                            | 26             | 15            |   |
| Pre-TDR Recorded Investment                                                                               | $ 923          | $ 912         |   |
| Post-TDR Recorded Investment                                                                              | $ (745)        | $ (920)       |   |
| Number of Contracts | contract                                                                            | 2              | 2             |   |
| Recorded Investment                                                                                       | $ 24           | $ 244         |   |
| Term Extension                                                                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (568)          | (1,829)       |   |
| Term Extension | Commercial | Corporate banking                                                           |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (16)           | 0             |   |
| Term Extension | Commercial | Middle market commercial real estate                                        |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Term Extension | Commercial | Commercial and industrial                                                   |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (1)            | (34)          |   |
| Term Extension | Consumer | Residential mortgages                                                         |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (1)            | 0             |   |
| Term Extension | Consumer | Home equity loans and lines of credit                                         |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 132            | 0             |   |
| Term Extension | Consumer | Retail installment contracts and auto loans                                   |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (682)          | (1,795)       |   |
| Term Extension | Consumer | Personal unsecured loans                                                      |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Term Extension | Consumer | Other consumer                                                                |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Principal Forbearance                                                                                     |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (10,583)       | (2,705)       |   |
| Principal Forbearance | Commercial | Corporate banking                                                    |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (10,583)       | 0             |   |
| Principal Forbearance | Commercial | Middle market commercial real estate                                 |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Principal Forbearance | Commercial | Commercial and industrial                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | (2,680)       |   |
| Principal Forbearance | Consumer | Residential mortgages                                                  |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | (25)          |   |
| Principal Forbearance | Consumer | Home equity loans and lines of credit                                  |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Principal Forbearance | Consumer | Retail installment contracts and auto loans                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Principal Forbearance | Consumer | Personal unsecured loans                                               |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Principal Forbearance | Consumer | Other consumer                                                         |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Other                                                                                                     |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (539)          | (202)         |   |
| Other | Commercial | Corporate banking                                                                    |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (11)           | (9)           |   |
| Other | Commercial | Middle market commercial real estate                                                 |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (69)           | 0             |   |
| Other | Commercial | Commercial and industrial                                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 0              | 0             |   |
| Other | Consumer | Residential mortgages                                                                  |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | 206            | 303           |   |
| Other | Consumer | Home equity loans and lines of credit                                                  |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (237)          | 0             |   |
| Other | Consumer | Retail installment contracts and auto loans                                            |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (121)          | (466)         |   |
| Other | Consumer | Personal unsecured loans                                                               |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | (129)          | (38)          |   |
| Other | Consumer | Other consumer                                                                         |           |          |   |
| **Financing Receivable, Modifications [Line Items]**                                                      |           |          |   |
| Post-TDR Recorded Investment                                                                              | $ (178)        | $ 8           |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of financing receivables that have been modified by troubled debt restructurings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Post-modification amount of investment in financing receivables modified by troubled debt restructurings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953682-111524
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953682-111524
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