Income Taxes - Schedule of Reconciliation of Income Tax Expense to Amount Computed at the Federal Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ (646,261)	$ 69,515	$ (312,992)
Federal tax reform	5,288	(1,205,140)	0
State income taxes	(251,780)	(57,414)	(76,043)
Valuation allowance	88,785	10,680	23,808
Regulatory liability/asset	(276)	10,488	0
Federal tax credits	(2,400)	(34,956)	(4,539)
Goodwill impairment	111,470	0	0
Other	(1,337)	18,411	6,997
Total income taxes	$ (696,511)	$ (1,188,416)	$ (362,769)
Effective tax rate	22.60%	(598.40%)	40.60%