Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2017
Tax Credit Carryforward [Line Items]
Loss before income tax expense (benefit) less loss attributable to non-controlling interest	$ (153,200)	$ (150,200)	$ (2,200)
Effect of tax rate change	53,048	0	$ 0
Valuation allowance	140,623	$ 75,308
Federal
Tax Credit Carryforward [Line Items]
Operating loss carryforward	342,500
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforward	323,800
Research and development tax credit carry forward	2,300
Research and Development | Federal
Tax Credit Carryforward [Line Items]
Research and development tax credit carry forward	6,200
Research and Development | State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Research and development tax credit carry forward	$ 5,800
Accounting Standards Update 2016-09
Tax Credit Carryforward [Line Items]
Deferred tax assets				$ 56,700