Geographic areas - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 1,371	$ 1,137	$ 3,083	$ 2,546
Total long-lived assets	10,890		10,890		$ 11,827
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	10,463		10,463		11,251
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	655	622	1,439	1,325
Total long-lived assets	427		427		$ 576
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	282	354	709	921
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	257	65	520	127
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 177	$ 96	$ 415	$ 173