Condensed Consolidated Statements of Shareholders Equity - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2016-09 cumulative effect on retained earnings	$ 5,150				5,150
Net income (unaudited)	(63,088)				(63,088)
Other comprehensive income, net of tax (unaudited)	327			327
Stock-based compensation (unaudited)	20,561		20,561
Restricted stock:
Granted (unaudited)	$ 14	$ 14
Granted (unaudited), shares	1,464,944	1,464,944
Repurchased and canceled (unaudited)	$ (10,620)	$ (2)	(10,618)
Repurchased and canceled (unaudited), shares	(230,377)	(230,377)
Forfeited (unaudited), shares	(520,002)	(520,002)
Forfeitures (unaudited)	$ (5)	$ (5)
Balance at Jun. 30, 2017	$ 4,254,335	$ 3,752	$ 1,385,233	$ 67	$ 2,865,283
Balance, shares at Jun. 30, 2017	375,206,922	375,206,922