Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated Other Comprehensive Loss	Retained earnings
Balance at Dec. 31, 2013	$ 3,953,118	$ 3,713	$ 1,250,178		$ 2,699,227
Balance, shares at Dec. 31, 2013		371,317,318
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	977,341				977,341
Other Comprehensive Income (Loss), Net of Tax	(385)			$ (385)
Stock-based compensation	54,343		54,343
Restricted stock:
Issued	14	$ 14	0
Issued, shares		1,424,764
Repurchased and canceled	(16,583)	$ (3)	(16,580)
Repurchased and canceled, shares		(283,434)
Forfeited	(4)	$ (4)
Forfeited, shares		(453,146)
Balance at Dec. 31, 2014	4,967,844	$ 3,720	1,287,941	(385)	3,676,568
Balance, shares at Dec. 31, 2014		372,005,502
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(353,668)				(353,668)
Other Comprehensive Income (Loss), Net of Tax	(2,969)			(2,969)
Stock-based compensation	51,817		51,817
Excess Tax Benefit from Share-based Compensation	13,177		13,177
Restricted stock:
Issued	15	$ 15	0
Issued, shares		1,462,534
Repurchased and canceled	(7,313)	$ (2)	(7,311)
Repurchased and canceled, shares		(172,786)
Forfeited	(3)	$ (3)
Forfeited, shares		(336,170)
Balance at Dec. 31, 2015	$ 4,668,900	$ 3,730	1,345,624	(3,354)	3,322,900
Balance, shares at Dec. 31, 2015	372,959,080	372,959,080
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (399,679)				(399,679)
Other Comprehensive Income (Loss), Net of Tax	3,094			3,094
Stock-based compensation	48,084		48,084
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(9,828)		(9,828)
Restricted stock:
Issued	20	$ 20	0
Issued, shares		2,064,508
Repurchased and canceled	(8,593)	$ (3)	(8,590)
Repurchased and canceled, shares		(337,981)
Forfeited	(2)	$ (2)
Forfeited, shares		(193,250)
Balance at Dec. 31, 2016	$ 4,301,996	$ 3,745	$ 1,375,290	$ (260)	$ 2,923,221
Balance, shares at Dec. 31, 2016	374,492,357	374,492,357