Accrued Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Accrued Liabilities [Line Items]
Legal and accounting fees	$ 14	$ 123
Accrued compensation	614	626
Accrued research and development costs and other	2,174	96
Total	$ 2,802	$ 845