Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Examination [Line Items]
Income tax expense (benefit)	$ 6,000	$ 0
Effective tax rate	(0.94%)
Federal and state Net Operating Losses	$ 143,000,000
Year of expiration of net operating loss carryforward expiration year	2027
Accruals related to uncertainties tax positions	$ 0	$ 0
Minimum [Member]
Income Tax Examination [Line Items]
Tax year remain subject to examination	2014
Maximum [Member]
Income Tax Examination [Line Items]
Tax year remain subject to examination	2016