Income Taxes - Additional Information (Detail) - USD ($)			12 Months Ended
	Dec. 31, 2017	Dec. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Federal statutory income tax rate				34.00%	34.00%	34.00%
Tax Cuts and Jobs Act, Accounting Complete				false
Income tax benefit				$ 33,100,000
State and local income taxes				2.01%	2.88%	3.45%
Income tax expense (benefit)				$ (15,972,000)	$ 0	$ 0
Minimum percentage of likelihood of realization of deferred tax assets				50.00%
Change in valuation allowance (independent of the impact of the 2017 Tax Act)				$ 4,400,000
Uncertain income tax positions	$ 0			0
State and Local Jurisdiction [Member]
Income Tax [Line Items]
Operating Loss carry forward	292,000,000			$ 292,000,000
Operating loss carry forward expiration term				Dec. 31, 2030
State and Local Jurisdiction [Member] | North Carolina [Member]
Income Tax [Line Items]
State and local income taxes		4.00%		3.00%
Income tax benefit				$ 1,700,000
Domestic Country [Member]
Income Tax [Line Items]
Operating Loss carry forward	263,000,000			263,000,000
Net operating loss used to offset taxable income	$ 1,500,000			$ 1,500,000
Domestic Country [Member] | Minimum [Member]
Income Tax [Line Items]
Operating loss carry forward expiration term	Dec. 31, 2024
Domestic Country [Member] | Maximum [Member]
Income Tax [Line Items]
Operating loss carry forward expiration term	Dec. 31, 2037
Scenario, Plan [Member]
Income Tax [Line Items]
Federal statutory income tax rate			21.00%