EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Numerator:
Net income	$ 17,844	$ 25,091	$ 13,796	$ 11,863	$ 9,958	$ 14,510	$ 14,460	$ 11,502	$ 68,594	$ 50,430	$ 58,269
Less: Income allocated to participating securities									(736)	(546)	(629)
Net income available to common stockholders									$ 67,858	$ 49,884	$ 57,640
Denominator:
Basic (in shares)	67,030	67,025	66,999	66,987	66,967	66,960	66,940	66,670	67,010	66,884	66,499
Shares issuable in lieu of dividend payments on performance-based restricted stock awards (in shares)									107	0	61
Weighted average shares - diluted (in shares)	67,166	67,025	66,999	66,987	66,967	66,960	66,940	66,670	67,117	66,884	66,560
Basic net income per share:
Basic net income per share (in usd per share)	$ 0.26	$ 0.37	$ 0.20	$ 0.18	$ 0.15	$ 0.21	$ 0.21	$ 0.17	$ 1.01	$ 0.75	$ 0.87
Diluted net income per share:
Diluted net income per share (in usd per share)	$ 0.26	$ 0.37	$ 0.20	$ 0.18	$ 0.15	$ 0.21	$ 0.21	$ 0.17	$ 1.01	$ 0.75	$ 0.87