INVESTMENT SECURITIES - Classified (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Investment securities available for sale
Amortized cost	$ 596,027		$ 639,168
Gross unrealized gains	15,901		11,139
Gross unrealized losses	1,789		874
Allowance for credit losses on investments	308
Fair value	609,831		649,433
U.S. government sponsored entities and U.S. agency securities
Investment securities available for sale
Amortized cost	32,276		59,600
Gross unrealized gains	461		442
Gross unrealized losses	20		22
Allowance for credit losses on investments	0
Fair value	32,717		60,020
Mortgage-backed securities - agency
Investment securities available for sale
Amortized cost	282,389		321,840
Gross unrealized gains	6,796		3,368
Gross unrealized losses	6		234
Allowance for credit losses on investments	0
Fair value	289,179		324,974
Mortgage-backed securities - non-agency
Investment securities available for sale
Amortized cost	23,712		17,198
Gross unrealized gains	260		3
Gross unrealized losses	0		53
Allowance for credit losses on investments	0
Fair value	23,972		17,148
State and municipal securities
Investment securities available for sale
Amortized cost	120,998		119,371
Gross unrealized gains	7,009		5,195
Gross unrealized losses	3		11
Allowance for credit losses on investments	2	$ 1	0
Fair value	128,002		124,555
Corporate securities
Investment securities available for sale
Amortized cost	136,652		121,159
Gross unrealized gains	1,375		2,131
Gross unrealized losses	1,760		554
Allowance for credit losses on investments	306	$ 126	0
Fair value	$ 135,961		$ 122,736

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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