PARENT COMPANY ONLY CONDENSED FINANCIAL INFORMATION - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed financial information
Interest expense	$ 9,382	$ 8,375	$ 7,622	$ 6,825	$ 6,399	$ 6,093	$ 5,441	$ 4,756	$ 32,204	$ 22,689	$ 16,845
Non-interest expense	22,071	31,004	22,507	22,598	29,154	21,271	21,006	20,296	98,180	91,727	77,081
Income tax benefit	2,878	1,381	1,701	3,181	5,422	4,703	4,505	4,316	9,141	18,946	18,795
Net income	$ 13,864	$ 6,547	$ 6,743	$ 12,073	$ (6,916)	$ 9,443	$ 8,841	$ 9,171	39,227	20,539	35,491
Parent Company
Condensed financial information
Dividends from the Bank									15,000	0	14,800
Interest expense									4,539	4,588	5,903
Non-interest expense									135	147	260
Income (loss) before income taxes and equity in undistributed earnings of the Bank									10,326	(4,735)	8,637
Income tax benefit									(1,005)	(1,774)	(2,126)
Income (loss) before equity in undistributed earnings of the Bank									11,331	(2,961)	10,763
Equity in undistributed earnings of the Bank									27,896	23,500	24,728
Net income									$ 39,227	$ 20,539	$ 35,491