Share based compensation - Share Option Activity (Details) - $ / shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021
Number of share options outstanding
Beginning balance outstanding	12,928,952	12,128,952	13,125,672
Forfeited	(638,112)		(996,720)
Granted	576,000	800,000
Ending balance outstanding	12,866,840	12,928,952	12,128,952
Weighted average exercise price
Outstanding, Beginning Balance, Weighted average exercise price (in dollars per share)	$ 1.38	$ 1.43	$ 1.41
Forfeited, Weight average exercise price (in dollars per share)	0.75		1.17
Granted, Weight average exercise price (in dollars per share)	0.78	0.73
Outstanding, Ending Balance, Weighted average exercise price (in dollars per share)	$ 1.39	$ 1.38	$ 1.43