EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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 (in dollars)	$ 65,174	$ 59,048	$ 116,994	$ 102,911
Shares (Denominator)
Basic (in shares)	62,631	63,053	62,494	62,888
Total average equivalent shares	64,828	64,785	64,519	65,063
Per Share Amount
Net income per share, basic (in dollars per share)	$ 1.04	$ 0.94	$ 1.87	$ 1.64
Net income per share, diluted (in dollars per share)	$ 1.01	$ 0.91	$ 1.81	$ 1.58
Stock options
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	2,144	1,693	1,973	2,128
Restricted stock units
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	53	39	52	47