EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income (loss)	$ 85,452	$ 68,864	$ 156,932	$ 129,688
Denominator (shares in 000's):
Basic weighted average shares outstanding (in shares)	62,305,000	65,337,000	62,733,000	65,458,000
Effect of dilutive securities - Stock options and awards (in shares)	665,000	784,000	686,000	799,000
Diluted weighted average shares outstanding (in shares)	62,970,000	66,121,000	63,419,000	66,257,000
Earnings (loss) per share
Basic earnings (loss) per share (in dollars per share)	$ 1.37	$ 1.05	$ 2.50	$ 1.98
Diluted earnings (loss) per share (in dollars per share)	$ 1.36	$ 1.04	$ 2.47	$ 1.96
Anti-dilutive shares excluded from the computation of diluted earnings per share	548,049	346,168	346,168	303,207