EARNINGS PER SHARE - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Basic, numerator:
Net income	$ 60,981	$ 23,361	$ 15,880	$ 1,902	$ 84,342	$ 17,782
Effect of unvested restricted stock unit awards			(17)			(18)
Adjusted net income	$ 60,981		$ 15,863		$ 84,342	$ 17,764
Basic, denominator:
Weighted-average shares	25,586,353		25,463,559		25,522,453	25,468,624
Earnings per common share (in dollars per share)	$ 2.38		$ 0.62		$ 3.30	$ 0.70
Diluted, numerator:
Net income	$ 60,981	$ 23,361	$ 15,880	$ 1,902	$ 84,342	$ 17,782
Effect of unvested restricted stock unit awards			(17)			(18)
Adjusted net income	$ 60,981		$ 15,863		$ 84,342	$ 17,764
Diluted, denominator:
Weighted-average shares	25,586,353		25,463,559		25,522,453	25,468,624
Effect of dilutive securities	1,324,443		754,398		1,403,680	783,862
Adjusted weighted-average shares and assumed conversions	26,910,796		26,217,957		26,926,133	26,252,486
Earnings per common share (in dollars per share)	$ 2.27		$ 0.61		$ 3.13	$ 0.68