Nature of the Business - Additional Information (Detail)	Apr. 03, 2017 USD ($)
Ipsen [Member] | Asset Sale Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received	$ 575,000,000
Working capital adjustment receivable	2,200,000
Ipsen [Member] | Asset Sale Agreement [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional payments receivable on achievement of certain milestone events	450,000,000
Baxalta [Member] | License and Collaboration Agreements [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Net milestone payments expected to be received	$ 33,000,000