Income Taxes (Income Tax Provision (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current income tax expense (benefit)
Federal	$ (8,515)	$ (42,500)	$ 393
State	160	(407)	9,864
Total current income tax expense (benefit)	(8,355)	(42,907)	10,257
Deferred income tax expense (benefit)
Federal	(1,853,517)	400,544	222,559
State	(78,662)	29,429	(33)
Total deferred income tax expense (benefit)	(1,932,179)	429,973	222,526
Total income tax expense (benefit)	$ (1,940,534)	$ 387,066	$ 232,783