Loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator:
Net loss	$ (13,388)	$ (12,978)	$ (16,182)	$ (13,399)	$ (26,366)	$ (29,581)
Denominator:
Weighted average shares used in calculating net loss per share - basic	43,459		35,707		43,442	34,899
Weighted average shares used in calculating net loss per share - diluted	43,459		35,707		43,442	34,899
Net loss per share - basic	$ (0.31)		$ (0.45)		$ (0.61)	$ (0.85)
Net loss per share - diluted	$ (0.31)		$ (0.45)		$ (0.61)	$ (0.85)