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ACCOUNTING POLICIES (Details) $ in Thousands |  | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
Jul. 31, 2018 USD ($) | Jun. 30, 2018 USD ($) Type | Jun. 30, 2017 USD ($) | Jun. 30, 2018 USD ($) Type | Jun. 30, 2017 USD ($) | Dec. 31, 2017 USD ($)
Wealth Management Services [Abstract] |  |  |  |  |  |
Number of types of performance obligations | Type |  | 2 |  | 2 |  |
Contract Balances [Abstract] |  |  |  |  |  |
Accounts receivable |  | $ 25,700 |  | $ 25,700 |  | $ 29,800
Unbilled fee revenue |  | 7,400 |  | 7,400 |  | 6,500
Unearned revenue |  | 3,000 |  | 3,000 |  | $ 3,900
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Reclassification of other comprehensive income to retained earnings |  | 0 |  | 0 |  |
Salaries and employee benefits |  | 52,402 | $ 46,564 | 104,261 | $ 89,471 |
Other expenses |  | 4,036 | 5,054 | 9,605 | 10,026 |
Retained Earnings [Member] |  |  |  |  |  |
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Reclassification of other comprehensive income to retained earnings |  | 208 |  | 208 |  |
Accumulated Other Comprehensive Loss [Member] |  |  |  |  |  |
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Reclassification of other comprehensive income to retained earnings |  | (208) |  | (208) |  |
Subsequent Event [Member] | Community Statutory Trust III [Member] |  |  |  |  |  |
Subsequent Event [Abstract] |  |  |  |  |  |
Redemption of debentures and associated preferred securities | $ 25,200 |  |  |  |  |
ASU 2017-07 [Member] |  |  |  |  |  |
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Salaries and employee benefits |  |  | (1,800) |  | (3,300) |
Other expenses |  |  | $ 1,800 |  | $ 3,300 |
ASU 2016-01 [Member] | Retained Earnings [Member] |  |  |  |  |  |
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Reclassification of other comprehensive income to retained earnings |  | 208 |  | 208 |  |
ASU 2016-01 [Member] | Accumulated Other Comprehensive Loss [Member] |  |  |  |  |  |
Recently Adopted Accounting Pronouncements [Abstract] |  |  |  |  |  |
Reclassification of other comprehensive income to retained earnings |  | $ (208) |  | $ (208) |  |

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