EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income (Numerator)
Income available to common stockholders (in dollars)	$ 53,098	$ 53,247	$ 156,009	$ 155,957
Shares (Denominator)
Basic (in shares)	62,858	62,886	62,878	62,627
Total average equivalent shares	64,690	64,454	64,989	64,609
Per Share Amount
Net income per share, basic (in dollars per share)	$ 0.84	$ 0.85	$ 2.48	$ 2.49
Net income per share, diluted (in dollars per share)	$ 0.82	$ 0.83	$ 2.40	$ 2.41
Stock options
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	1,791	1,544	2,059	1,947
Restricted stock units
Shares (Denominator)
Effect of dilutive stock based compensation (in shares)	41	24	52	35