Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of the provision for income taxes
Federal	$ 2,832	$ 0	$ 0	$ 0
State	(230)	(24)	(1,633)	(265)
Deferred portion of income tax benefit	36,668	23,756	67,458	314,770
Income tax benefit	$ 39,270	$ 23,732	$ 65,825	$ 314,505
Effective tax rate	30.60%	36.70%	32.80%	36.10%
Income Tax Deficiency From Share-Based Awards Settlements	$ 8,200
Proceeds from Income Tax Refunds	$ 5,500