EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator for common earnings per share:
Net income	$ 23,899	$ 14,714
Numerator for basic and diluted earnings per share	$ 23,899	$ 14,714
Denominator for basic earnings per share:
Weighted average common shares outstanding (in shares)	49,714	47,886
Effect of dilutive securities (in shares):
Stock options, RSUs and performance-based awards (in shares)	3,169	3,114
Denominator for diluted earnings per share (in shares)	52,883	51,000
Net income per share:
Basic (in dollars per share)	$ 0.48	$ 0.31
Diluted (in dollars per share)	$ 0.45	$ 0.29
Anti-dilutive options not included in the calculation (in shares)	2,218	121