STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011
STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE
Common stock, shares outstanding	137,630,896				140,294,092				137,630,896	140,294,092
Earnings per share calculations
Net income									$ 295,045	$ 281,650		$ 245,234
Less: Preferred stock dividends			(1,714)	(1,714)	(1,715)	(1,714)	(1,714)	(1,714)	(3,428)	(6,857)		(6,857)
Less: Earnings allocated to participating securities									(1,692)	(3,279)
Basic EPS - income allocated to common stockholders									289,925	271,514	[1]	238,377
Effect of dilutive securities:
Restricted stock units									196	47		115
Convertible preferred stock									3,428	6,857		6,857
Diluted EPS - income allocated to common stockholders									$ 293,549	$ 278,418	[1]	$ 245,349
Number of Shares
Weighted average shares outstanding									137,342,000	141,457,000	[1]	147,093,000
Effect of dilutive securities on weighted average shares outstanding
Stock options (in shares)									71,000	29,000		62,000
Restricted stock units (in shares)									327,000	118,000		718,000
Convertible preferred stock (in shares)									1,834,000	5,571,000		5,571,000
Stock warrants (in shares)												23,000
Total weighted average diluted shares outstanding									139,574,000	147,175,000	[1]	153,467,000
Per Share Amounts
Basic EPS - income allocated to common stockholders (in dollars per share)	$ 0.55	$ 0.53	$ 0.52	$ 0.51	$ 0.50	$ 0.49	$ 0.48	$ 0.46	$ 2.11	$ 1.92	[1]	$ 1.62
Diluted EPS - Income available to common stockholders (in dollars per share)	$ 0.55	$ 0.53	$ 0.52	$ 0.50	$ 0.49	$ 0.48	$ 0.47	$ 0.45	$ 2.10	$ 1.89	[1]	$ 1.60

[1] On April 1, 2012, the Company revised its calculation of earnings per share to account for participating securities under the two-class method. This revision to the earnings per share calculation does not have an impact to previous periods as the amounts are immaterial.