INVESTMENT SECURITIES - Classified (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Investment securities available for sale
Amortized cost	$ 644,668	$ 639,168
Gross unrealized gains	15,411	11,139
Gross unrealized losses	3,750	874
Allowance for credit losses on investments	75
Fair value	656,254	649,433
Equity securities recorded at fair value	5,640	5,621
U.S. government sponsored entities and U.S. agency securities
Investment securities available for sale
Amortized cost	46,428	59,600
Gross unrealized gains	929	442
Gross unrealized losses		22
Fair value	47,357	60,020
Agency mortgage-backed securities
Investment securities available for sale
Amortized cost	317,332	321,840
Gross unrealized gains	9,417	3,368
Gross unrealized losses	49	234
Fair value	326,700	324,974
Non-agency mortgage-backed securities
Investment securities available for sale
Amortized cost	28,121	17,198
Gross unrealized gains		3
Gross unrealized losses	840	53
Fair value	27,281	17,148
State and municipal securities
Investment securities available for sale
Amortized cost	112,500	119,371
Gross unrealized gains	3,897	5,195
Gross unrealized losses	284	11
Allowance for credit losses on investments	19
Fair value	116,094	124,555
Corporate Securities
Investment securities available for sale
Amortized cost	140,287	121,159
Gross unrealized gains	1,168	2,131
Gross unrealized losses	2,577	554
Allowance for credit losses on investments	56
Fair value	$ 138,822	$ 122,736

Amortized cost of 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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