Consolidated Statement of Stockholders' Equity - Entity [Domain] - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	(Accumulated Deficit) Retained Earnings
Beginning Balance (in shares) at Dec. 31, 2013		115,923
Beginning Balance at Dec. 31, 2013	$ 1,502,507	$ 1,159	$ 1,725,363	$ (224,015)
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 grants (in shares)		265
Restricted stock grants	3	$ 3
Stock options exercised (in shares)		318
Stock options exercised	4,852	$ 3	4,849
Ending Balance (in shares) at Jun. 30, 2014		116,413
Ending Balance at Jun. 30, 2014	1,499,630	$ 1,164	1,734,404	(235,938)
Beginning Balance (in shares) at Dec. 31, 2014		116,764
Beginning Balance at Dec. 31, 2014	1,481,500	$ 1,168	1,748,303	(267,971)
Net income	122,580			122,580
Retirement of common stock (in shares)		(235)
Retirement of common stock	(9,432)	$ (3)	(9,429)
Dividend on common stock	(127,310)			(127,310)
Restricted stock compensation, net of forfeitures (in shares)		(6)
Restricted stock compensation, net of forfeitures	7,233		7,188	45
Income tax benefit of equity compensation	475		475
Stock option compensation expense, net of forfeitures	475		475
Restricted stock grants (in shares)		296
Restricted stock grants	3	$ 3
Stock options exercised (in shares)		300
Stock options exercised	5,637	$ 3	5,634
Ending Balance (in shares) at Jun. 30, 2015		117,119
Ending Balance at Jun. 30, 2015	$ 1,481,161	$ 1,171	$ 1,752,646	$ (272,656)