Leases - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2009 ft²
Leases [Line Items]
Book value of assets, gross	$ 8.2	$ 5.1
Net book value of assets	$ 7.4	3.2
San Carlos facility capital leases, end date	Oct. 05, 2016
Operating Sublease term commenced start date	2010-08
Operating Sublease term commenced period	114 months
Operating Sublease term commenced end date	Jan. 31, 2020
Rent expense	$ 3.2	3.2	$ 3.2
Deferred rent	$ 6.6	$ 8.5
Pfizer, Inc. [Member]
Leases [Line Items]
Operating sublease | ft²				126,285