CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - UNAUDITED (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Preferred Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Balance at Dec. 31, 2012	$ 1,806,680	$ 950	$ 54	$ 1,308,315	$ 413,385	$ 83,976
Balance (in Shares) at Dec. 31, 2012		95,006,729	5,415,794
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	125,506				156,543	(31,037)
Conversion of preferred shares to common shares (in Shares)		5,415,794	(5,415,794)
Conversion of preferred shares to common shares		54	(54)
Dividends	(65,226)				(65,226)
Equity based compensation (in Shares)		104,585
Equity based compensation	10,952	1		10,951
Forfeiture of unvested shares (in Shares)		(43,607)
Exercise of stock options (in Shares)		376,769
Exercise of stock options, value	6,738	4		6,734
Tax benefits from dividend equivalents and equity based compensation	1,164			1,164
Balance at Sep. 30, 2013	1,885,814	1,009	0	1,327,164	504,702	52,939
Balance (in Shares) at Sep. 30, 2013		100,860,270	0
Balance at Dec. 31, 2013	1,928,698	1,010		1,334,945	535,263	57,480
Balance (in Shares) at Dec. 31, 2013		101,013,014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	163,328				157,381	5,947
Dividends	(65,883)				(65,883)
Equity based compensation (in Shares)		692,029
Equity based compensation	11,629	7		11,622
Forfeiture of unvested shares (in Shares)		(93,951)
Stock Issued During Period, Value, Share-based Compensation, Forfeited		(1)		1
Exercise of stock options (in Shares)		54,883
Exercise of stock options, value	914	1		913
Tax benefits from dividend equivalents and equity based compensation	1,483			1,483
Balance at Sep. 30, 2014	$ 2,040,169	$ 1,017		$ 1,348,964	$ 626,761	$ 63,427
Balance (in Shares) at Sep. 30, 2014		101,665,975