Stock-based compensation - Option activity (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Stock-based compensation
Options Outstanding, beginning balance (in shares)			50,717,724
Stock options granted (in shares)	7,075,000	2,900,000	28,075,000	12,100,000
Stock options forfeited (in shares)			2,687,500
Vested stock options expired (in shares)			9,110,000
Options Outstanding, ending balance (in shares)	66,995,224		66,995,224
Vested (in shares)	15,875,099		15,875,099
Weighted Avg Exercise Price Options Outstanding (in dollars per share)			$ 0.4466
Weighted Avg Exercise Price, Stock options granted (in dollars per share)			0.3082
Weighted Avg Exercise Price Stock options forfeited (in dollars per share)			0.5351
Weighted Avg Exercise Price Stock options expired (in dollars per share)			0.2404
Weighted Avg Exercise Price Options Outstanding (in dollars per share)	$ 0.4135		0.4135
Weighted Avg Exercise Price Vested (in dollars per share)	$ 0.3537		$ 0.3537