EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income	$ 31,317	$ 70,898	$ 84,955	$ 139,252
Denominator (shares in 000's):
Basic weighted average shares outstanding (in shares)	68,181,000	75,000,000	68,883,000	75,621,000
Effect of dilutive securities - Stock options and awards (in shares)	709,000	773,000	686,000	795,000
Diluted weighted average shares outstanding (in shares)	68,890,000	75,773,000	69,569,000	76,416,000
Earnings (loss) per share
Basic earnings (loss) per share (in dollars per share)	$ 0.46	$ 0.95	$ 1.23	$ 1.84
Diluted earnings (loss) per share (in dollars per share)	$ 0.45	$ 0.94	$ 1.22	$ 1.82
Anti-dilutive shares excluded from the computation of diluted earnings per share	810,200	556,371	750,209	481,831