Long-term debt - Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Long-term debt
Term loan payable	$ 30,000	$ 30,000
End of term charge	470	376
Unamortized debt issuance costs	(462)	(503)
Carrying value of term loan	$ 30,008	$ 29,873