Income Taxes - Income Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
U.S. Federal	$ (55,799)	$ (51,243)	$ (130,003)
U.S. State	12	(113)	0
Current income tax (benefit)	(55,787)	(51,356)	(130,003)
Deferred:
U.S. Federal	(83,080)	47,717	319,813
U.S. State	(35,220)	31,375	25,747
Deferred income tax (benefit)	(118,300)	79,092	345,560
Income Tax (Benefit) Expense / Effective Rate	$ (174,087)	$ 27,736	$ 215,557

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

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