Income Taxes - Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax benefit at U.S. statutory rate	$ 121,320	$ 205,777	$ 139,657
State taxes, net of federal income tax	21,576	24,891	11,788
Valuation allowance	5,713	(246,037)	(142,862)
Tax credits	688	1,908	6,163
Goodwill impairment	(88,265)	(78,515)	(10,789)
Impact of the Tax Act	(6,042)	114,716	0
Stock compensation	(4,717)	(4,093)	(5,716)
Meals and entertainment	(493)	(726)	(868)
Other, net	(324)	(1,406)	(2,751)
Total	$ 49,456	$ 16,515	$ (5,378)