Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 18,451	$ 23,604
Prepaid clinical expenses	1,822	1,163
Other prepaids	1,513	1,214
Other	956	914
Total other current assets	$ 22,742	$ 26,895