Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended					3 Months Ended
	Jan. 31, 2017	Oct. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Jan. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Carna License Agreement [Member]
Loss Contingencies [Line Items]
Upfront payment paid				$ 900,000
Aggregate milestone payment						$ 270,000,000
CPF License Agreements [Member]
Loss Contingencies [Line Items]
Upfront payment paid		$ 7,000,000
Aggregate milestone payment	$ 2,000,000
Additional milestone payment payable			$ 319,500,000
Operating Lease Agreement To Sublease Office Space [Member] | Vancouver [Member]
Loss Contingencies [Line Items]
Operating lease agreement expiration date						Feb. 27, 2018
Collateralized restricted deposit						$ 13,000
Operating Lease Agreement To Lease Office Space [Member] | San Francisco [Member]
Loss Contingencies [Line Items]
Operating lease agreement expiration date					Apr. 30, 2019
Lease Agreements [Member]
Loss Contingencies [Line Items]
Total rent expense						$ 100,000	$ 100,000