Stockholders' equity - SARs Activity (Details) - Stock Appreciation Rights - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
RSUs Outstanding
Outstanding, beginning balance (in shares)	106,155
Granted (in shares)	0
Exercised (in shares)	(743)
Canceled (in shares)	(532)
Outstanding, ending balance (in shares)	104,880	106,155
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share)	$ 8.45
Granted (in USD per share)	0
Exercised (in USD per share)	3.63
Canceled (in USD per share)	10.02
Outstanding, ending balance (in USD per share)	$ 8.48	$ 8.45
Outstanding, Weighted Average Remaining Contractual Term (in years)	7 years 9 months 3 days	8 years 3 months
Outstanding, Aggregate Intrinsic Value	$ 392	$ 1,267
Vested and Expected to Vest, Awards Outstanding (in shares)	104,880
Vested and Expected to Vest, Weighted Average Exercise Price (in USD per shares)	$ 8.48
Vested and Expected to Vest, Weighted Average Remaining Contractual Term (in years)	7 years 9 months 3 days
Vested and Expected to Vest, Aggregate Intrinsic Value	$ 392
Exercisable, Awards Outstanding (in shares)	63,358
Exercisable, Weighted Average Exercise Price (in USD per share)	$ 6.49
Exercisable, Weighted Average Remaining Contractual Term (in years)	7 years 6 months 10 days
Exercisable, Aggregate Intrinsic Value	$ 283