Income Taxes - Income Tax Reconciliation from Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent									35.00%
(Loss) income from continuing operations before income taxes	$ 113,032	$ (38,774)	$ (39,728)	$ (152,826)	$ 114,007	$ 227,710	$ 62,228	$ 30,297	$ (118,296)	$ 434,242	$ (289,419)
Federal income taxes at 35%									(41,404)	151,985	(101,297)
State and local income taxes, net of federal tax benefit									(4,606)	17,474	3,195
Domestic production activities deduction									(5,539)	(6,807)	(6,554)
Non-deductible reorganization and transaction costs									7,598	497	622
Non-deductible goodwill									0	0	133,350
Impact of federal and state rate changes									(262,851)	0	0
Income tax settlements and other adjustments, net									634	179,558	(7,842)
Other, net									4,795	4,495	4,444
Income tax (benefit) expense from continuing operations	$ (219,767)	$ (20,087)	$ (9,905)	$ (51,614)	$ 43,280	$ 73,871	$ 214,856	$ 15,195	$ (301,373)	$ 347,202	$ 25,918
Effective tax rate									254.80%	80.00%	(9.00%)