EARNINGS (LOSS) 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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator for basic and diluted (loss) earnings per share:
Net income (loss)	$ 16,431	$ 31,089	$ 30,747	$ (12,631)	$ 84,194	$ 12,058	$ 25,880	$ (21,393)	$ 65,636	$ 100,739	$ (39,873)
Denominator:
Weighted basic shares outstanding (in shares)									56,148	57,072	57,532
Dilutive effect of equity-based compensation awards (in shares)									192	128	0
Weighted dilutive shares outstanding (in shares)									56,340	57,200	57,532
Basic earnings (loss) per share (in dollars per share)									$ 1.17	$ 1.77	$ (0.69)
Diluted earnings (loss) per share (in dollars per share)									$ 1.16	$ 1.76	$ (0.69)