License and Research Collaboration Agreements (Details) - USD ($)	1 Months Ended		12 Months Ended
	Feb. 28, 2015	Dec. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Deferred Revenue Arrangement [Line Items]
Licensing and collaboration revenue			$ 1,206,000	$ 390,000	$ 3,526,000
Genentech Inc. | Collaborative Arrangement
Deferred Revenue Arrangement [Line Items]
Upfront cash payments						$ 150,000,000.0
Licensing and collaboration revenue			56,000	335,000	2,700,000
Alliance manager			56,000	335,000	670,000
Deferred revenue			$ 0	$ 56,000	391,000
JRC revenue					180,000
Employee labor revenue					1,900,000
Merck, Sharpe and Dohme Corp | Collaborative Arrangement
Deferred Revenue Arrangement [Line Items]
Upfront cash payments	$ 20,000,000.0	$ 30,000,000.0
Licensing and collaboration revenue					815,300
Revenue allocated to other deliverables					53,800
Ebola costs revenue recognition					$ 761,500