Revenue (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2017	Mar. 31, 2016
Revenue
Collaboration revenue		$ 0	$ 1,875
Allergan
Revenue
Collaboration revenue			$ 1,900
Nonrefundable upfront fee	$ 10,000