Accrued Liabilities - Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Accrued R&D agreements and study expenses	$ 7,898	$ 5,383
Other accrued liabilities	254	242
Total accrued liabilities	$ 8,152	$ 5,625