License Agreements - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended
	Dec. 31, 2013	Mar. 31, 2016	Jan. 31, 2014
License Agreement Terms [Member] | Takeda License Agreements [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization milestone payments payable			$ 9.2
Potential pre-commercialization payments receivable		$ 57.5
Biogen [Member] | Development Events [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment depending on development	$ 2.5