Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Statutory federal income tax rate (in hundredths)		35.00%	35.00%	35.00%
Percentage of effect for immediate expensing on costs of qualified property due to impact of U.S. tax rate		100.00%
Description for percentage of effect for immediate expensing on costs of qualified property due to impact of U.S. tax rate		The Act also provides for immediate expensing of 100% of the costs of qualified property that are incurred and placed in service during the period from September 27, 2017 to December 31, 2022. Beginning January 1, 2023, the immediate expensing provision is phased down by 20% per year until it is completely phased out as of January 1, 2027.
Valuation allowance for deferred tax assets		$ 2,155,000
Valuation allowance, deferred tax asset, increase (decrease), amount		2,200,000
Gross unrecognized tax benefits		23,258,000	$ 3,677,000	$ 3,677,000	$ 3,677,000
Accrued interest on unrecognized tax benefits		0	$ 0	$ 0
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		145,900,000
State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		579,400,000
VIEs [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance, deferred tax asset, increase (decrease), amount		500,000
SAB 118 [Member]
Operating Loss Carryforwards [Line Items]
Provisional reduction in net deferred tax liability		322,200,000
Deferred income tax expense (benefit)		$ 322,200,000
Scenario, Forecast [Member]
Operating Loss Carryforwards [Line Items]
Statutory federal income tax rate (in hundredths)	21.00%
January 1, 2023 to January 1, 2027 [Member]
Operating Loss Carryforwards [Line Items]
Percentage of effect for immediate expensing provision phase down per year		20.00%