INCOME TAXES - Reconciliation (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
Amount
Federal income tax expense computed by applying the statutory rate to income before income taxes									$ 10,157	$ 13,820	$ 19,000
Tax exempt interest									(1,002)	(1,808)	(1,661)
State taxes, net of federal income tax benefit									1,999	725	1,090
Deferred tax asset remeasurement										7,572
Other									(2,013)	(1,363)	366
Total income tax expense	$ 2,878	$ 1,381	$ 1,701	$ 3,181	$ 5,422	$ 4,703	$ 4,505	$ 4,316	$ 9,141	$ 18,946	$ 18,795
Percentage of Pre-tax Earnings
Federal income tax expense computed by applying the statutory rate to income before income taxes (as a percent)									21.00%	35.00%	35.00%
Tax exempt interest (as a percent)									(2.00%)	(5.00%)	(3.00%)
State taxes, net of federal income tax benefit (as a percent)									4.00%	2.00%	2.00%
Deferred tax asset remeasurement (as a percent)										19.00%
Other (as a percent)									(4.00%)	(3.00%)	1.00%
Income tax expense (as a percent)									19.00%	48.00%	35.00%