QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
QUARTERLY FINANCIAL DATA (UNAUDITED)
Interest income	$ 47,484	$ 46,296	$ 45,850	$ 44,602	$ 44,320	$ 46,354	$ 46,352	$ 44,515	$ 184,232	$ 181,541	$ 168,984
Interest expense	4,492	5,589	5,418	7,952	8,672	9,639	10,835	10,192	23,451	39,338	32,204
Net interest income	42,992	40,707	40,432	36,650	35,648	36,715	35,517	34,323	160,781	142,203	136,780
Provision for credit losses	500	1,500	4,500	5,000	600	1,000	3,500	600	11,500	5,700	1,800
Net interest income after provision for credit losses	42,492	39,207	35,932	31,650	35,048	35,715	32,017	33,723	149,281	136,503	134,980
Non-interest income (loss)	5,444	6,790	2,252	5,217	8,426	6,244	5,499	5,218	19,703	25,387	11,568
Non-interest expense	35,078	28,937	24,399	24,843	25,332	24,204	24,004	22,599	113,257	96,139	98,180
Income before income taxes	12,858	17,060	13,785	12,024	18,142	17,755	13,512	16,342	55,727	65,751	48,368
Income tax expense	3,881	3,999	3,129	2,676	3,934	3,852	2,859	3,415	13,685	14,060	9,141
Net income	$ 8,977	$ 13,061	$ 10,656	$ 9,348	$ 14,208	$ 13,903	$ 10,653	$ 12,927	$ 42,042	$ 51,691	$ 39,227
Basic earnings per share (in dollars per share)	$ 0.45	$ 0.66	$ 0.54	$ 0.47	$ 0.71	$ 0.70	$ 0.53	$ 0.65	$ 2.11	$ 2.59	$ 1.97
Diluted earnings per share (in dollars per share)	$ 0.45	$ 0.66	$ 0.54	$ 0.47	$ 0.71	$ 0.70	$ 0.53	$ 0.65	$ 2.11	$ 2.59	$ 1.97