Commitments and Contingencies - Narrative (Details) $ in Millions			12 Months Ended
	Feb. 17, 2012	Apr. 06, 2005	Dec. 31, 2016 USD ($) agreement	Dec. 31, 2015 USD ($)
Lease agreement term (years)		8 years
Additional lease term (years)			5 years
Rental expense | $			$ 1.6	$ 1.6
Number of collaboration agreements | agreement			2
Amended Lease
Lease agreement term (years)	10 years