Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) ft² Lease	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of operating leases | Lease	5
General office, laboratory, and research and development space leased | ft²	106,740
Deferred rent liability	$ 7.5	$ 4.3
Operating lease agreement rent expense	3.8	$ 3.2	$ 1.4
Non cancellable purchase obligations	$ 9.3