Revenue (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue
Revenue		$ 525	$ 847	$ 2,228	$ 8,398
Collaboration revenue
Revenue
Revenue				1,000	6,500
Collaboration revenue - upfront payment | License Agreement | Sinovant Sciences, LTD
Revenue
Revenue accounted for under Topic 606	$ 5,000				5,000
Collaboration revenue - upfront payment | License Agreement | Sunovion Pharmaceutics Canada, Inc.
Revenue
Revenue not accounted for under Topic 606				1,000
Collaboration revenue - Variable consideration | Clinical trial application submission
Revenue
Revenue accounted for under Topic 606				1,500
Collaboration revenue - Variable consideration | License Agreement | Clinical trial application submission | Sinovant Sciences, LTD
Revenue
Revenue accounted for under Topic 606					1,500
Research premium
Revenue
Revenue		351	709	744	1,479
Government grants
Revenue
Revenue		$ 174	$ 138	$ 484	$ 419