Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued clinical and preclinical costs	$ 11,134	$ 10,033
Accrued contract manufacturing costs	5,736	4,673
Accrued employee compensation costs	5,177	8,748
Accrued professional fees	3,759	2,799
Product revenue related reserve	875	305
Accrued research costs	441	1,186
Other	4,035	3,272
Total accrued expenses	$ 31,157	$ 31,016