Collaborations and License Agreements - Additional Information (Detail) - USD ($) $ in Millions			12 Months Ended
	Nov. 30, 2015	Nov. 16, 2015	Dec. 31, 2015
Duke University [Member]
License Agreement [Line Items]
Additional payment under license agreement to release financial obligation	$ 0.1	$ 0.1
Duke University [Member] | Maximum [Member]
License Agreement [Line Items]
Issued and pending patents right expiration year	2023
Duke University [Member] | Minimum [Member]
License Agreement [Line Items]
Issued and pending patents right expiration year	2036
Takeda License Agreement [Member]
License Agreement [Line Items]
Aggregate license fee payable			$ 102.0
Payments for Royalties			0.0
Takeda License Agreement [Member] | Research and Development [Member]
License Agreement [Line Items]
Upfront license fee			$ 3.0