INCOME TAXES - Components (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
Current:
Federal									$ 5,270	$ 8,762	$ 14,730
State									1,023	937	780
Total current									6,293	9,699	15,510
Deferred:
Federal									3,299	10,251	2,388
State									(451)	(1,004)	897
Total deferred									2,848	9,247	3,285
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