EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Earning per share
Authorized common stock (in shares)	199,000		199,000		199,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Income (Numerator)
Income available to common stockholders, basic (in dollars)	$ 53,523	$ 53,098	$ 170,517	$ 156,009
Income available to common stockholders, diluted (in dollars)	$ 53,523	$ 53,098	$ 170,517	$ 156,009
Shares (Denominator)
Basic (in shares)	62,592	62,858	62,527	62,878
Total average equivalent shares	64,821	64,690	64,626	64,989
Per Share Amount
Net income per share, basic (in dollars per share)	$ 0.86	$ 0.84	$ 2.73	$ 2.48
Net income per share, diluted (in dollars per share)	$ 0.83	$ 0.82	$ 2.64	$ 2.40
Stock options
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	2,171	1,791	2,046	2,059
Restricted stock units
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	58	41	53	52