Basis of presentation and significant accounting policies (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Concentration Risk [Line Items]
Asset impairment charges			$ 0
Customer concentration | Total revenue | Customer one
Concentration Risk [Line Items]
Percentage of concentration of credit risk	10.00%	10.00%		10.00%	10.00%
Customer concentration | Total revenue | Customer two
Concentration Risk [Line Items]
Percentage of concentration of credit risk	10.00%	10.00%		10.00%	10.00%
Customer concentration | Total revenue | Customer three
Concentration Risk [Line Items]
Percentage of concentration of credit risk	10.00%	10.00%		10.00%
Customer concentration | Total revenue | Customer four
Concentration Risk [Line Items]
Percentage of concentration of credit risk				10.00%
Customer concentration | Total revenue | Three customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk	60.00%	71.00%
Customer concentration | Total revenue | Top five customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk	79.00%	82.00%		77.00%	82.00%
Customer concentration | Total revenue | Four customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk				67.00%
Customer concentration | Total revenue | Two customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk					67.00%
Customer concentration | Accounts receivable | Three customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk						65.00%
Customer concentration | Accounts receivable | Four customers
Concentration Risk [Line Items]
Percentage of concentration of credit risk				65.00%