Quarterly report pursuant to Section 13 or 15(d)

Concentration of credit risk and off-balance sheet risk (Details)

v3.20.2
Concentration of credit risk and off-balance sheet risk (Details) - Customer concentration risk
9 Months Ended
Sep. 30, 2020
Dec. 31, 2019
Sep. 30, 2020
Revenues | Two customers      
Concentration Risk [Line Items]      
Concentration risk, percentage     35.00%
Accounts receivable | Three customers      
Concentration Risk [Line Items]      
Concentration risk, percentage 70.00%    
Accounts receivable | One customer      
Concentration Risk [Line Items]      
Concentration risk, percentage   44.00%