Collaboration Agreement - Grifols License and Collaboration Agreement - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments received	$ 10,000,000
Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payments receivable upon the achievement of regulatory filing and approval milestones	$ 25,000,000
Grifols [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Minority interst percentage by other	48.00%
Unsatisfied performance obligations	$ 448,000