FAIR VALUE MEASUREMENTS - Fair Values and Carrying Amounts (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Assets
Securities available for sale	$ 626,341	$ 663,230
Financial Liabilities
Borrowings with the FRB	265,644	348,118
Level 1
Financial Assets
Cash and cash equivalents	85,655	56,910
Securities available for sale	0
FHLB stock	0
Net loans	0
Accrued interest receivable	0
Cash surrender value of bank-owned life insurance policies	0
Derivative assets	0
Financial Liabilities
Short-term other borrowings	0
FHLB advances	0
Derivative liabilities	0
Level 1 | Bank Non-maturity Deposits [Member]
Financial Liabilities
Deposits	0
Level 1 | Bank Time Deposits [Member]
Financial Liabilities
Deposits	0
Level 1 | Federal Reserve Bank Advances
Financial Liabilities
Borrowings with the FRB	0
Level 1 | Subordinated borrowings
Financial Liabilities
Subordinated borrowings	0
Level 2
Financial Assets
Cash and cash equivalents	0
Securities available for sale	626,341	663,230
FHLB stock	19,897	20,679
Net loans	0
Accrued interest receivable	3,268	3,294
Cash surrender value of bank-owned life insurance policies	76,400	75,863
Derivative assets	24,933	6,791
Financial Liabilities
Short-term other borrowings	31,000	44,831
FHLB advances	410,065	425,989
Derivative liabilities	28,032	8,102
Level 2 | Bank Non-maturity Deposits [Member]
Financial Liabilities
Deposits	1,861,960	1,751,481
Level 2 | Bank Time Deposits [Member]
Financial Liabilities
Deposits	852,346	932,886
Level 2 | Federal Reserve Bank Advances
Financial Liabilities
Borrowings with the FRB	62,000
Level 2 | Subordinated borrowings
Financial Liabilities
Subordinated borrowings	59,849	59,920
Level 3
Financial Assets
Cash and cash equivalents	0
Securities available for sale	0
FHLB stock	0
Net loans	2,604,406	2,634,147
Accrued interest receivable	0
Cash surrender value of bank-owned life insurance policies	0
Derivative assets	93	59
Financial Liabilities
Short-term other borrowings	0
FHLB advances	0
Derivative liabilities	73	84
Level 3 | Bank Non-maturity Deposits [Member]
Financial Liabilities
Deposits	0
Level 3 | Bank Time Deposits [Member]
Financial Liabilities
Deposits	0
Level 3 | Federal Reserve Bank Advances
Financial Liabilities
Borrowings with the FRB	0
Level 3 | Subordinated borrowings
Financial Liabilities
Subordinated borrowings	0
Carrying Amount
Financial Assets
Cash and cash equivalents	85,655	56,910
Securities available for sale	626,341	663,230
FHLB stock	19,897	20,679
Net loans	2,619,686	2,625,739
Accrued interest receivable	3,268	3,294
Cash surrender value of bank-owned life insurance policies	76,400	75,863
Derivative assets	25,026	6,850
Financial Liabilities
Short-term other borrowings	31,001	44,832
FHLB advances	404,579	426,564
Derivative liabilities	28,105	8,186
Carrying Amount | Bank Non-maturity Deposits [Member]
Financial Liabilities
Deposits	1,806,460	1,763,116
Carrying Amount | Bank Time Deposits [Member]
Financial Liabilities
Deposits	844,097	932,635
Carrying Amount | Federal Reserve Bank Advances
Financial Liabilities
Borrowings with the FRB	62,000
Carrying Amount | Subordinated borrowings
Financial Liabilities
Subordinated borrowings	59,849	59,920
Fair Value
Financial Assets
Cash and cash equivalents	85,655	56,910
Securities available for sale	626,341	663,230
FHLB stock	19,897	20,679
Net loans	2,604,406	2,634,147
Accrued interest receivable	3,268	3,294
Cash surrender value of bank-owned life insurance policies	76,400	75,863
Derivative assets	25,026	6,850
Financial Liabilities
Short-term other borrowings	31,000	44,831
FHLB advances	410,065	425,989
Derivative liabilities	28,105	8,186
Fair Value | Bank Non-maturity Deposits [Member]
Financial Liabilities
Deposits	1,861,960	1,751,481
Fair Value | Bank Time Deposits [Member]
Financial Liabilities
Deposits	852,346	932,886
Fair Value | Federal Reserve Bank Advances
Financial Liabilities
Borrowings with the FRB	62,000
Fair Value | Subordinated borrowings
Financial Liabilities
Subordinated borrowings	$ 59,849	$ 59,920