Disaggregation of Revenue - Contract balances (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Liabilities
Contract liabilities	$ 333,500	$ 235,000
Contract liabilities
Opening	235,000	180,200
Additions	98,500	79,000
Transfer to revenue		(24,200)
Ending	$ 333,500	$ 235,000