Summary of significant accounting policies - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($) segment	Jan. 01, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)
Summary of significant accounting policies
Number of operating segments | segment	1
Restricted cash	$ 100		$ 100	$ 100
Deferred offering costs	300		$ 300
Operating lease liability		$ 200
Operating right-of-use asset, net	$ 171	$ 200
Expected dividend yield	0.00%