NET INCOME PER COMMON SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income	$ 46,109	$ 40,500	$ 138,337	$ 79,470
Adjustment for Basic EPS:
Earnings allocated to unvested shareholders	(255)	(277)	(857)	(613)
Adjusted net income	$ 45,854	$ 40,223	$ 137,480	$ 78,857
Denominator:
Weighted average common shares outstanding – Basic	47,291,192	47,227,061	47,286,927	47,182,625
Effect of dilutive shares:
Common stock equivalents arising from stock options and ESPP	400	339	769	1,263
Restricted stock awards and units and performance units	70,983	32,931	67,887	28,772
Weighted average common shares outstanding – Diluted	47,362,575	47,260,331	47,355,583	47,212,660
Basic	$ 0.97	$ 0.85	$ 2.91	$ 1.67
Diluted	$ 0.97	$ 0.85	$ 2.90	$ 1.67