Convertible notes payable (Details) - Convertible unsecured redeemable note	Jun. 04, 2019
0-30 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	105.00%
31-60 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	110.00%
61-90 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	115.00%
91-120 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	120.00%
121-150 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	125.00%
151-180 days
Debt Instrument, Redemption [Line Items]
Percentage of principal and interest amount redeemed as redemption price	130.00%