Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of the provision for income taxes
Federal	$ 4,607	$ 0	$ (2,832)	$ 0
State	2,439	(77)	(1,403)	(241)
Deferred portion of income tax (expense) benefit	64,015	95,975	30,790	291,014
Income tax (expense) benefit	$ 71,061	$ 95,898	$ 26,555	$ 290,773
Effective tax rate	37.20%	36.20%	36.90%	36.00%