EARNINGS PER SHARE (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator for basic and diluted earnings per share:
Net income	$ 30,747	$ 25,880	$ 18,116	$ 4,487
Denominator:
Basic shares outstanding (in shares)	56,410	57,190	56,304	57,226
Dilutive effect of equity-based compensation awards (in shares)	95	146	95	123
Dilutive shares outstanding (in shares)	56,505	57,336	56,399	57,349
Basic income per share (in USD per share)	$ 0.55	$ 0.45	$ 0.32	$ 0.08
Diluted income per share (in USD per share)	$ 0.54	$ 0.45	$ 0.32	$ 0.08