Consolidated Statement of Stockholders' Equity - 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	165,016			165,016
Retirement of common stock (in shares)		(92)
Retirement of common stock	(3,052)	$ (1)	(3,051)
Dividend on common stock	(179,190)			(179,190)
Restricted stock compensation, net of forfeitures (in shares)		(14)
Restricted stock compensation, net of forfeitures	8,975		8,898	77
Income tax benefit of equity compensation	222		222
Stock option compensation expense, net of forfeitures	1,463		1,463
Restricted stock grants (in shares)		267
Restricted stock grants	3	$ 3
Stock options exercised (in shares)		392
Stock options exercised	6,349	$ 4	6,345
Ending Balance (in shares) at Sep. 30, 2014		116,476
Ending Balance at Sep. 30, 2014	1,502,293	$ 1,165	1,739,240	(238,112)
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	173,256			173,256
Retirement of common stock (in shares)		(237)
Retirement of common stock	(9,454)	$ (3)	(9,451)
Dividend on common stock	(191,023)			(191,023)
Restricted stock compensation, net of forfeitures (in shares)		(9)
Restricted stock compensation, net of forfeitures	10,937		10,876	61
Income tax benefit of equity compensation	529		529
Stock option compensation expense, net of forfeitures	579		579
Restricted stock grants (in shares)		303
Restricted stock grants	3	$ 3
Stock options exercised (in shares)		402
Stock options exercised	7,554	$ 4	7,550
Ending Balance (in shares) at Sep. 30, 2015		117,223
Ending Balance at Sep. 30, 2015	$ 1,473,881	$ 1,172	$ 1,758,386	$ (285,677)