Income Taxes - Income Tax (Benefit) Expense Attributable to (Loss) Income Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components Of Income Tax Expense Benefit Continuing Operations [Abstract]
U.S. federal, Current									$ 0	$ 0	$ 0
U.S. state and local, Current									6,147	0	17
Total, Current	$ 2,068	$ 4,079	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	6,147	0	17
U.S. federal, Deferred									(434,585)	(25,322)	(302,507)
U.S. state and local, Deferred									(71,853)	(5,167)	51,464
Total, Deferred	(500,927)	(51,298)	40,099	5,688	(68,784)	24,137	(28,518)	42,676	(506,438)	(30,489)	(251,043)
U.S. federal, Total									(434,585)	(25,322)	(302,507)
U.S. state and local, Total									(65,706)	(5,167)	51,481
Total (benefit) expense for income taxes	$ (498,859)	$ (47,219)	$ 40,099	$ 5,688	$ (68,784)	$ 24,137	$ (28,518)	$ 42,676	$ (500,291)	$ (30,489)	$ (251,026)