License agreements (Details) - USD ($) $ in Thousands				1 Months Ended	3 Months Ended
	Oct. 23, 2018	Oct. 31, 2017	Feb. 29, 2016	Apr. 30, 2020	Mar. 31, 2020
Shire LLC | NDA 204326 | Maximum
License agreements
Payment of non-refundable license fee			$ 1,000
Shire LLC | NDA 204325 | Maximum
License agreements
Payment of non-refundable license fee		$ 1,000
NeuRx License
License agreements
Upfront payment to be paid	$ 200
Milestone payment				$ 300	$ 200