STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details 3) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic
Net income	$ 110,734	$ 110,143	$ 103,284	$ 107,516	$ 91,805	$ 94,097	$ 98,748	$ 100,027	$ 431,677	$ 384,677	$ 345,878
Less: Earnings allocated to participating securities									0	3	506
Net income allocated to common stockholders									$ 431,677	$ 384,674	$ 345,372
Basic weighted average common shares outstanding (in shares)	144,166	144,122	144,101	143,958	143,900	143,861	143,846	143,655	144,087	143,818	142,952
Basic EPS (in dollars per share)	$ 0.77	$ 0.76	$ 0.72	$ 0.75	$ 0.64	$ 0.65	$ 0.69	$ 0.70	$ 3.00	$ 2.67	$ 2.42
Diluted
Net income allocated to common stockholders									$ 431,677	$ 384,674	$ 345,372
Basic weighted average common shares outstanding (in shares)	144,166	144,122	144,101	143,958	143,900	143,861	143,846	143,655	144,087	143,818	142,952
Diluted potential common shares (in shares)									1,085	694	611
Diluted weighted average common shares outstanding (in shares)	145,428	145,238	145,078	144,803	144,686	144,590	144,480	144,349	145,172	144,512	143,563
Diluted EPS (in dollars per share)	$ 0.76	$ 0.76	$ 0.71	$ 0.74	$ 0.63	$ 0.65	$ 0.68	$ 0.69	$ 2.97	$ 2.66	$ 2.41