EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
EARNINGS 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
Diluted
Income available to common stockholders (in dollars)	$ 53,247	$ 48,595	$ 155,957	$ 150,060
Shares of common stock	62,886	64,886	62,627	65,225
Total average equivalent shares	64,454	66,845	64,609	67,761
Net income per share, diluted (in dollars per share)	$ 0.83	$ 0.73	$ 2.41	$ 2.21
Basic
Income available to common stockholders (in dollars)	$ 53,247	$ 48,595	$ 155,957	$ 150,060
Shares of common stock	62,886	64,886	62,627	65,225
Net income per share, basic (in dollars per share)	$ 0.85	$ 0.75	$ 2.49	$ 2.30
Stock options
Diluted
Effect of dilutive stock based compensation (in shares)	1,544	1,953	1,947	2,505
Restricted stock units
Diluted
Effect of dilutive stock based compensation (in shares)	24	6	35	31