Income Tax - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017
Income Tax [Line Items]
Income tax benefit (expense)	$ 0	$ (540,000)
Reduction of previously recorded valuation allowance	9,200,000
Income tax related to share based compensation windfall settled	600,000
Deferred tax benefit	$ 0	$ 540,000
Federal statutory rate	35.00%
Income taxes paid	$ 0
Scenario, Forecast [Member]
Income Tax [Line Items]
Percentage of annual effective income tax rate			0.00%