Loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Loss per share
Net loss	$ (4,995)	$ (6,346)	$ (14,206)	$ (15,093)
Charge to retained earnings for preferred share exchange				(32,039)
Loss attributable to common shareholders	$ (4,995)	$ (6,346)	$ (14,206)	$ (47,132)
Weighted average shares - basic (in shares)	979,946,407	978,494,076	979,915,419	948,664,410
Denominator for diluted loss per share (in shares)	979,946,407	978,494,076	979,915,419	948,664,410
Loss per share - basic (in dollars per share)	$ (0.005)	$ (0.006)	$ (0.014)	$ (0.050)
Loss per share - diluted (in dollars per share)	$ (0.005)	$ (0.006)	$ (0.014)	$ (0.050)