EARNINGS PER SHARE - Reconciliation of Basic and Diluted Earnings Per Share Computations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Numerator for basic and diluted earnings per share:
Net income	$ 67,075	$ 21,736	$ 29,023	$ 11,572	$ 88,811	$ 40,595
Denominator:
Basic shares outstanding (in shares)	54,529		55,590		54,625	55,673
Dilutive effect of outstanding stock awards (in shares)	325		158		320	209
Dilutive shares outstanding (in shares)	54,854		55,748		54,945	55,882
Basic earnings per share (in dollars per share)	$ 1.23		$ 0.52		$ 1.63	$ 0.73
Diluted earnings per share (in dollars per share)	$ 1.22		$ 0.52		$ 1.62	$ 0.73