Commitments and Contingencies - Additional Information (Detail)		12 Months Ended
	Aug. 12, 2016 USD ($)	Dec. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Other Commitments [Line Items]
Potential loss on matter or to estimate | $		$ 0
Potential loss on derivative action or to estimate | $		0
Security deposit | $		1,482,000
Rental expense paid | $		$ 2,054,000	$ 1,630,000	$ 513,000
San Diego, California [Member]
Other Commitments [Line Items]
Lease beginning year		2017
Corporate office and laboratory space [Member] | San Diego, California [Member]
Other Commitments [Line Items]
Leased office space		43,000
Non-cancelable operating lease amended, expiration date		Dec. 31, 2026
Additional, leased office space		76,700
Corporate office and laboratory space [Member] | Suzhou, China [Member]
Other Commitments [Line Items]
Leased office space		25,381
Non-cancelable operating lease amended, expiration date		Jun. 30, 2018
Laboratory and office space [Member] | San Diego, California [Member]
Other Commitments [Line Items]
Leased office space		6,350
Non-cancelable operating lease amended, expiration date		Nov. 30, 2025
Office space [Member] | San Diego, California [Member]
Other Commitments [Line Items]
Leased office space		1,405
Non-cancelable operating lease amended, expiration date		Sep. 30, 2020
Office space [Member] | Cary, North Carolina [Member]
Other Commitments [Line Items]
Leased office space		1,800
Non-cancelable operating lease amended, expiration date		Mar. 31, 2016
Offices, facilities for cGMP fill and finish and storage space [Member] | San Diego, California [Member]
Other Commitments [Line Items]
Additional, leased office space		36,400
Yuhan agreement claim [Member]
Other Commitments [Line Items]
Aggregate purchase price of common stock warrants | $	$ 10,000,000