Prepaid Expenses - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 4,820	$ 1,729
Prepaid R&D clinical costs	4,363	1,500
Prepaid insurance	327	98
Other prepaid costs	$ 130	35
Prepaid rent		$ 96