| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Rollforward of Allowance for Credit Losses) (Details) - USD ($) $ in Thousands** | 3 Months Ended |
|---------------------------------------------------------------------------------------------------------------------------|----------------|
||
| **Allowance for Loan Losses [Roll Forward]**                                                                              |           |   |
| Allowance for loan and lease losses, beginning of period                                                                  | $ 3,203,759    | $ 1,750,643 |
| Provision for loan and lease losses                                                                                       | 895,828        | 1,049,213 |
| Other                                                                                                                     |           | (27,117) |
| Charge-offs                                                                                                               | (1,197,600)    | (981,978) |
| Recoveries                                                                                                                | 631,953        | 510,477 |
| Charge-offs, net of recoveries                                                                                            | (565,647)      | (471,501) |
| Allowance for loan and lease losses, end of period                                                                        | 3,533,940      | 2,301,238 |
| Reserve for unfunded lending commitments, beginning of period                                                             | 147,397        | 132,641 |
| Provision for unfunded lending commitments                                                                                | 24,611         | (5,000) |
| Loss on unfunded lending commitments                                                                                      | 0              | 0 |
| Reserve for unfunded lending commitments, end of period                                                                   | 172,008        | 127,641 |
| Total allowance for credit losses, end of period                                                                          | 3,705,948      | 2,428,879 |
| Ending balance, individually evaluated for impairment                                                                     | 1,098,166      | 337,146 |
| Ending balance, collectively evaluated for impairment                                                                     | 2,435,774      | 1,964,092 |
| **Financing receivables:**                                                                                                |           |   |
| Ending balance                                                                                                            | 83,756,948     | 79,874,854 |
| Ending balance, evaluated under the fair value option or lower of cost or fair value                                      | 2,910,653      | 2,037,992 |
| Ending balance, individually evaluated for impairment                                                                     | 4,992,157      | 3,352,234 |
| Ending balance, collectively evaluated for impairment                                                                     | 75,854,138     | 74,484,628 |
| Sale of TDRs and NPLs classified as held-for-sale                                                                         |           | 1,000,000 |
| Commercial                                                                                                                |           |   |
| **Allowance for Loan Losses [Roll Forward]**                                                                              |           |   |
| Allowance for loan and lease losses, beginning of period                                                                  | 433,514        | 386,837 |
| Provision for loan and lease losses                                                                                       | 107,210        | 24,908 |
| Charge-offs                                                                                                               | (39,973)       | (19,310) |
| Recoveries                                                                                                                | 25,414         | 5,999 |
| Charge-offs, net of recoveries                                                                                            | (14,559)       | (13,311) |
| Allowance for loan and lease losses, end of period                                                                        | 526,165        | 398,434 |
| Reserve for unfunded lending commitments, beginning of period                                                             | 147,397        | 132,641 |
| Provision for unfunded lending commitments                                                                                | 24,611         | (5,000) |
| Loss on unfunded lending commitments                                                                                      | 0              | 0 |
| Reserve for unfunded lending commitments, end of period                                                                   | 172,008        | 127,641 |
| Total allowance for credit losses, end of period                                                                          | 698,173        | 526,075 |
| Ending balance, individually evaluated for impairment                                                                     | 129,304        | 79,032 |
| Ending balance, collectively evaluated for impairment                                                                     | 396,861        | 319,402 |
| **Financing receivables:**                                                                                                |           |   |
| Ending balance                                                                                                            | 41,719,535     | 38,334,686 |
| Ending balance, evaluated under the fair value option or lower of cost or fair value                                      | 0              | 44,325 |
| Ending balance, individually evaluated for impairment                                                                     | 638,728        | 476,861 |
| Ending balance, collectively evaluated for impairment                                                                     | 41,080,807     | 37,813,500 |
| Consumer                                                                                                                  |           |   |
| **Allowance for Loan Losses [Roll Forward]**                                                                              |           |   |
| Allowance for loan and lease losses, beginning of period                                                                  | 2,724,917      | 1,330,782 |
| Provision for loan and lease losses                                                                                       | 788,618        | 986,030 |
| Other                                                                                                                     |           | (27,117) |
| Charge-offs                                                                                                               | (1,157,627)    | (962,668) |
| Recoveries                                                                                                                | 606,539        | 504,478 |
| Charge-offs, net of recoveries                                                                                            | (551,088)      | (458,190) |
| Allowance for loan and lease losses, end of period                                                                        | 2,962,447      | 1,831,505 |
| Reserve for unfunded lending commitments, beginning of period                                                             | 0              | 0 |
| Provision for unfunded lending commitments                                                                                | 0              | 0 |
| Loss on unfunded lending commitments                                                                                      | 0              | 0 |
| Reserve for unfunded lending commitments, end of period                                                                   | 0              | 0 |
| Total allowance for credit losses, end of period                                                                          | 2,962,447      | 1,831,505 |
| Ending balance, individually evaluated for impairment                                                                     | 968,862        | 258,114 |
| Ending balance, collectively evaluated for impairment                                                                     | 1,993,585      | 1,573,391 |
| **Financing receivables:**                                                                                                |           |   |
| Ending balance                                                                                                            | 42,037,413     | 41,540,168 |
| Ending balance, evaluated under the fair value option or lower of cost or fair value                                      | 2,910,653      | 1,993,667 |
| Ending balance, individually evaluated for impairment                                                                     | 4,353,429      | 2,875,373 |
| Ending balance, collectively evaluated for impairment                                                                     | 34,773,331     | 36,671,128 |
| Unallocated                                                                                                               |           |   |
| **Allowance for Loan Losses [Roll Forward]**                                                                              |           |   |
| Allowance for loan and lease losses, beginning of period                                                                  | 45,328         | 33,024 |
| Provision for loan and lease losses                                                                                       | 0              | 38,275 |
| Charge-offs                                                                                                               | 0              | 0 |
| Recoveries                                                                                                                | 0              | 0 |
| Charge-offs, net of recoveries                                                                                            | 0              | 0 |
| Allowance for loan and lease losses, end of period                                                                        | 45,328         | 71,299 |
| Reserve for unfunded lending commitments, beginning of period                                                             | 0              | 0 |
| Provision for unfunded lending commitments                                                                                | 0              | 0 |
| Loss on unfunded lending commitments                                                                                      | 0              | 0 |
| Reserve for unfunded lending commitments, end of period                                                                   | 0              | 0 |
| Total allowance for credit losses, end of period                                                                          | 45,328         | 71,299 |
| Ending balance, individually evaluated for impairment                                                                     | 0              | 0 |
| Ending balance, collectively evaluated for impairment                                                                     | 45,328         | 71,299 |
| **Financing receivables:**                                                                                                |           |   |
| Ending balance                                                                                                            | 0              | 0 |
| Ending balance, evaluated under the fair value option or lower of cost or fair value                                      | 0              | 0 |
| Ending balance, individually evaluated for impairment                                                                     | 0              | 0 |
| Ending balance, collectively evaluated for impairment                                                                     | $ 0            | $ 0 |

| X                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
A valuation allowance for financing receivables that are expected to be uncollectible and reserve for unfunded lending commitments.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                    |
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| - Definition
Net amount of direct write-downs and recoveries of financing receivables charged against the allowance.
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No definition available.
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| X                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Gain (Loss) on Unfunded Commitments
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No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Increase (Decrease) in Allowance for Credit Losses from Sale of Troubled Debt Restructuring and Non-performing Loans Held-for-sale
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Loans Receivable Held-for-sale, Net, Fair Value Option
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| X                                                                                                                                                                                                                                                                                                                                  |
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| - Definition
Net change in reserve for unfunded commitments which is included in the provision for credit losses.
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No definition available.
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| X                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reserve for unfunded loan commitments and letters of credit.
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No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of reduction of allowance reserve for credit loss arising from sale of loan and lease portfolios.
+ References
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| - Definition
A valuation allowance for financing receivables that are expected to be uncollectible.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| - Definition
Amount of recovery of financing receivables doubtful of collection that were previously charged off.
+ References
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| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
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No definition available.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of direct write-downs of financing receivables charged against the allowance.
+ References
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| - Definition
The balance of financing receivables that were collectively evaluated for impairment.
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| - Definition
The balance of financing receivables that were individually evaluated for impairment.
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| - Definition
Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.
+ References
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No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expense related to estimated loss from loan and lease transactions.
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