Collaboration Agreement - Grifols License and Collaboration Agreement - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract revenue-related party	$ 40,000	$ 4,671,000	$ 40,000	$ 23,337,000
Long-term deferred revenue-related party	5,000,000		5,000,000		$ 5,000,000
Long term deferred revenue-related party, milestone payment received			5,000,000
Research and development	5,836,000	8,880,000	18,522,000	26,995,000
General and administrative	1,460,000	1,320,000	4,489,000	4,201,000
Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additional payments receivable upon the achievement of regulatory filing and approval milestones	20,000,000		20,000,000
License Agreement with Grifols [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Fully utilized reimbursable research and development expenses		65,000,000		65,000,000
Reimbursable costs incurred under the Grifols License Agreement	$ 0	4,700,000	$ 0	23,300,000
Research and development		4,700,000		22,100,000
General and administrative		$ 0		$ 1,200,000