Other Long-Term Liablilities (Details 2) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	May. 31, 2014	Sep. 30, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
REVENUE
Contracts and Grants			$ 649	$ 817	$ 2,636	$ 1,591
Rockefeller Development Services Agreement
REVENUE
Upfront payment recognized as revenue over the term of the agreement		$ 1,300
Contracts and Grants			500	800	2,100	1,500
Bristol Meyers Collaborative Arrangement
REVENUE
Term of the agreement	5 years
Upfront payment recognized as revenue over the term of the agreement	$ 5,000
Contracts and Grants			$ 300	$ 300	$ 1,000	$ 400
Reimbursement of external costs incurred by the company (as a percent)	50.00%