Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts payable and accrued liabilities
Trade accounts payable	$ 2,226	$ 4,376
Accrued research and development liabilities	1,924	1,513
Other accrued liabilities	526	331
Accrued compensation and benefits payable	494	1,777
Accounts payable and accrued liabilities	$ 5,170	$ 7,997