Financial instruments (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Recurring
Fair value, Assets	$ 128,000	$ 0
Net liability arising from put/call options	0	(690,000)
Fair Value, Inputs, Level 3 [Member]
Recurring
Fair value, Assets	128,000
Net liability arising from put/call options		$ (690,000)
Certificate of deposit [Member]
Recurring
Fair value, Assets	2,500,000
Certificate of deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring
Fair value, Assets	$ 2,500,000