NET INCOME PER COMMON SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income	$ 51,687	$ 38,155
Adjustment for Basic EPS:
Earnings allocated to unvested shareholders	(358)	(339)
Adjusted net income	$ 51,329	$ 37,816
Denominator:
Weighted average common shares outstanding – Basic	47,267,921	47,093,033
Effect of dilutive shares:
Common stock equivalents arising from stock options and ESPP	165	441
Restricted stock awards and units and performance units	61,618	29,355
Weighted average common shares outstanding – Diluted	47,329,704	47,122,829
Basic	$ 1.09	$ 0.80
Diluted	$ 1.08	$ 0.80