| LOANS AND ALLOWANCE FOR LOAN LOSSES (Allowance for Loan Loss Activity, by Portfolio Segment, Balances for Allowance for Credit Losses, and Loans Based on Impairment Methodology) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | |
| Allowance for loan losses: | ||||
| Balance, beginning of period | $ 142,911 | $ 141,043 | $ 160,540 | $ 42,294 | 
| Impact of ASC 326 adoption on non-PCD loans | 45,098 | |||
| Impact of ASC 326 adoption on PCD loans | 2,386 | |||
| Impact of ASC 326 adoption | 47,484 | |||
| Loans charged off | (1,945) | (4,677) | (5,586) | (11,828) | 
| Recoveries credited to allowance | 1,876 | 1,411 | 4,345 | 3,571 | 
| Provision charged to operations | (24,581) | 32,200 | (41,038) | 88,456 | 
| Balance, end of period | 118,261 | 169,977 | 118,261 | 169,977 | 
| Commercial Portfolio | ||||
| Allowance for loan losses: | ||||
| Balance, beginning of period | 106,432 | 77,843 | 117,403 | 30,941 | 
| Impact of ASC 326 adoption on non-PCD loans | 4,432 | |||
| Impact of ASC 326 adoption on PCD loans | 1,752 | |||
| Impact of ASC 326 adoption | 6,184 | |||
| Loans charged off | (891) | (1,590) | (2,865) | (4,558) | 
| Recoveries credited to allowance | 1,042 | 708 | 2,648 | 1,862 | 
| Provision charged to operations | (16,746) | 34,993 | (27,349) | 77,525 | 
| Balance, end of period | 89,837 | 111,954 | 89,837 | 111,954 | 
| Consumer Portfolio | ||||
| Allowance for loan losses: | ||||
| Balance, beginning of period | 36,479 | 63,200 | 43,137 | 11,353 | 
| Impact of ASC 326 adoption on non-PCD loans | 40,666 | |||
| Impact of ASC 326 adoption on PCD loans | 634 | |||
| Impact of ASC 326 adoption | 41,300 | |||
| Loans charged off | (1,054) | (3,087) | (2,721) | (7,270) | 
| Recoveries credited to allowance | 834 | 703 | 1,697 | 1,709 | 
| Provision charged to operations | (7,835) | (2,793) | (13,689) | 10,931 | 
| Balance, end of period | $ 28,424 | $ 58,023 | $ 28,424 | $ 58,023 | 
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- Definition Financing Receivable Allowance For Credit Loss Purchased Without Credit Deterioration No definition available. 
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- Definition Financing Receivable Allowance For Credit Losses, impact of adopting new accounting standard No definition available. 
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- Definition Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of increase in allowance for credit loss on financing receivable from recovery. Reference 1: http://www.xbrl.org/2003/role/exampleRef 
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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. No definition available. 
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- Definition Amount of writeoff of financing receivable, charged against allowance for credit loss. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of expense related to estimated loss from loan and lease transactions. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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