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								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
Numerator for basic and diluted (loss) earnings per share:
Net income	$ 24,151	$ 36,369	$ 36,244	$ 976	$ 16,431	$ 31,089	$ 30,747	$ (12,631)	$ 97,740	$ 65,636	$ 100,739
Denominator:
Weighted basic shares outstanding (in shares)									55,845	56,148	57,072
Dilutive effect of equity-based compensation awards (in shares)									284	192	128
Weighted dilutive shares outstanding (in shares)									56,129	56,340	57,200
Basic earnings (loss) per share (in dollars per share)									$ 1.75	$ 1.17	$ 1.77
Diluted earnings (loss) per share (in dollars per share)									$ 1.74	$ 1.16	$ 1.76