Consolidated Statement of Stockholders' Equity (USD $) In Thousands	Total	Regular Dividend	Special Dividend	Common Stock	Common Stock Special Dividend	Additional Paid-in Capital	Additional Paid-in Capital Special Dividend	(Accumulated Deficit) Retained Earnings	(Accumulated Deficit) Retained Earnings Regular Dividend	(Accumulated Deficit) Retained Earnings Special Dividend
Beginning Balance at Dec. 31, 2012	$ 1,521,620			$ 1,001		$ 1,146,488		$ 374,131
Beginning Balance (in shares) at Dec. 31, 2012				100,105
Net income	201,521							201,521
Issuance of common stock (in shares)				19
Issuance of common stock	13					13
Retirement of common stock (in shares)				(144)
Retirement of common stock	(5,454)			(1)		(5,453)
Dividend on common stock (in shares)					13,878
Dividend on common stock		(109,488)	(135,546)		139		542,541		(109,488)	(678,226)
Restricted stock compensation, net of forfeitures (in shares)				(12)
Restricted stock compensation, net of forfeitures	4,721					4,445		276
Income tax benefit of equity compensation	31					31
Stock option compensation expense, net of forfeitures	1,677					1,677
Restricted stock grant (in shares)				300
Restricted stock grant				3		(3)
Stock options exercised (in shares)				1,272
Stock options exercised	22,094			12		22,082
Ending Balance at Jun. 30, 2013	1,501,189			1,154		1,711,821		(211,786)
Ending Balance (in shares) at Jun. 30, 2013				115,418
Beginning Balance at Dec. 31, 2013	1,502,507			1,159		1,725,363		(224,015)
Beginning Balance (in shares) at Dec. 31, 2013				115,923
Net income	107,470							107,470
Retirement of common stock (in shares)				(85)
Retirement of common stock	(2,803)			(1)		(2,802)
Dividend on common stock		(119,440)							(119,440)
Restricted stock compensation, net of forfeitures (in shares)				(8)
Restricted stock compensation, net of forfeitures	5,880					5,833		47
Income tax benefit of equity compensation	117					117
Stock option compensation expense, net of forfeitures	1,044					1,044
Restricted stock grant (in shares)				265
Restricted stock grant	3			3
Stock options exercised (in shares)				318
Stock options exercised	4,852			3		4,849
Ending Balance at Jun. 30, 2014	$ 1,499,630			$ 1,164		$ 1,734,404		$ (235,938)
Ending Balance (in shares) at Jun. 30, 2014				116,413