Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts payable and accrued liabilities
Trade accounts payable	$ 4,376	$ 2,603
Accrued research and development liabilities	1,513	1,012
Other accrued liabilities	331	164
Accrued compensation and benefits payable	1,777	698
Accounts payable and accrued liabilities	$ 7,997	$ 4,477