INTANGIBLE ASSETS (Information Concerning Intangible Assets with Finite Life) (Details) - USD ($)  | 
Dec. 31, 2019  | 
Dec. 31, 2018  | 
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| Finite-Lived Intangible Assets [Line Items] | ||
| Total estimated amortization expense | $ 73,669,000 | |
| Core Deposits | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Value | 135,300,000 | $ 95,152,000 | 
| Accumulated Amortization | 73,336,000 | 57,293,000 | 
| Total estimated amortization expense | 61,964,000 | 37,859,000 | 
| Other Amortizable Intangibles | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Value | 15,349,000 | 12,695,000 | 
| Accumulated Amortization | 3,644,000 | 1,870,000 | 
| Total estimated amortization expense | $ 11,705,000 | $ 10,825,000 | 
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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- 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. No definition available. 
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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before accumulated amortization of finite-lived intangible assets classified as other. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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