INCOME TAXES - Components of Income Tax Expense (Details) - USD ($) $ 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
Current expense:
Federal									$ 10,468	$ 8,592	$ 20,165
State									8,861	8,576	12,152
Total current expense									19,329	17,168	32,317
Deferred expense (benefit):
Federal									(6,467)	5,033	2,857
State									(3,974)	390	2,363
Total deferred expense/(benefit)									(10,441)	5,423	5,220
Income tax expense	$ 6,124	$ 1,821	$ 841	$ 102	$ 6,788	$ 5,517	$ 5,369	$ 4,917	$ 8,888	$ 22,591	$ 37,537