QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
QUARTERLY FINANCIAL DATA (UNAUDITED)
Interest income	$ 44,320	$ 46,354	$ 46,352	$ 44,515	$ 43,480	$ 42,589	$ 41,551	$ 41,364	$ 181,541	$ 168,984	$ 149,849
Interest expense	8,672	9,639	10,835	10,192	9,382	8,375	7,622	6,825	39,338	32,204	22,689
Net interest income	35,648	36,715	35,517	34,323	34,098	34,214	33,929	34,539	142,203	136,780	127,160
Provision for loan losses	600	1,000	3,500	600	400	200	400	800	5,700	1,800	14,050
Net interest income after provision for loan losses	35,048	35,715	32,017	33,723	33,698	34,014	33,529	33,739	136,503	134,980	113,110
Non-interest income (loss)	8,426	6,244	5,499	5,218	5,115	4,918	(2,578)	4,113	25,387	11,568	18,102
Non-interest expense	25,332	24,204	24,004	22,599	22,071	31,004	22,507	22,598	96,139	98,180	91,727
Income before income taxes	18,142	17,755	13,512	16,342	16,742	7,928	8,444	15,254	65,751	48,368	39,485
Income tax expense	3,934	3,852	2,859	3,415	2,878	1,381	1,701	3,181	14,060	9,141	18,946
Net income	$ 14,208	$ 13,903	$ 10,653	$ 12,927	$ 13,864	$ 6,547	$ 6,743	$ 12,073	$ 51,691	$ 39,227	$ 20,539
Basic earnings per share (in dollars per share)	$ 0.71	$ 0.70	$ 0.53	$ 0.65	$ 0.70	$ 0.33	$ 0.34	$ 0.61	$ 2.59	$ 1.97	$ 1.04
Diluted earnings per share (in dollars per share)	$ 0.71	$ 0.70	$ 0.53	$ 0.65	$ 0.70	$ 0.33	$ 0.34	$ 0.61	$ 2.59	$ 1.97	$ 1.04