Collaborations - Additional Information (Detail)				12 Months Ended
	Apr. 02, 2015	Aug. 20, 2013 USD ($) Payment	Jun. 16, 2013 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract revenue				$ 399,000	$ 1,750,000
Pfizer Inc
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Number of Non-refundable annual license maintenance payments | Payment		2
Non-refundable annual license maintenance payments		$ 1,500,000
License maintenance payable period one		Aug. 01, 2014
License maintenance payable period two		Aug. 01, 2013
Effective termination notice period	60 days
Contract revenue				0	1,300,000
Deferred revenue				0	0
Pfizer Inc | Collaboration Agreement | Maximum
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contingent cash payments upon achievement of clinical, regulatory and commercial milestones				17,500,000
ISU Abxis
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract revenue				400,000	400,000
Deferred revenue				$ 300,000	$ 700,000
Deferred revenue recognition period				4 years
ISU Abxis | Up Front Payment
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Amount received for research and development process			$ 1,750,000