STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Basic
Net income	$ 107,516	$ 100,027
Less: Earnings allocated to participating securities	0	3
Net income allocated to common stockholders	$ 107,516	$ 100,024
Basic weighted-average common shares outstanding (in shares)	143,958	143,655
Basic EPS (in dollars per share)	$ 0.75	$ 0.70
Diluted
Net income allocated to diluted common stockholders	$ 107,516	$ 100,024
Basic weighted-average common shares outstanding (in shares)	143,958	143,655
Diluted potential common shares (in shares)	845	694
Diluted weighted-average common shares outstanding (in shares)	144,803	144,349
Diluted EPS (in dollars per share)	$ 0.74	$ 0.69