EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Unvested service-based restricted stock awards included in the calculation of earnings per share (in shares)									700	700	600
Numerator:
Net income	$ 9,958	$ 14,510	$ 14,460	$ 11,502	$ 9,848	$ 15,902	$ 17,011	$ 15,508	$ 50,430	$ 58,269	$ 51,614
Less: Income allocated to participating securities									(546)	(629)	(479)
Net income available to common stockholders									$ 49,884	$ 57,640	$ 51,135
Denominator:
Basic (in shares)	66,967	66,960	66,940	66,670	66,569	66,562	66,541	66,323	66,884	66,499	66,209
Shares issuable in lieu of dividend payments on performance-based restricted stock awards (in shares)									0	61	57
Weighted average shares - diluted (in shares)	66,967	66,960	66,940	66,670	66,641	66,598	66,561	66,323	66,884	66,560	66,266
Basic net income per share:
Basic net income per share (in usd per share)	$ 0.15	$ 0.21	$ 0.21	$ 0.17	$ 0.15	$ 0.24	$ 0.25	$ 0.23	$ 0.75	$ 0.87	$ 0.77
Diluted net income per share:
Diluted net income per share (in usd per share)	$ 0.15	$ 0.21	$ 0.21	$ 0.17	$ 0.15	$ 0.24	$ 0.25	$ 0.23	$ 0.75	$ 0.87	$ 0.77