Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0	$ 0
Deferred tax assets	0	0
Deferred tax liabilities	$ 0	$ 0