Commitments and contingencies (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Commitments and Contingencies Disclosure [Line Items]
2020	$ 19,260
2021	9,642
Thereafter	0
Total	28,902
Obligations for investment contracts [Member]
Commitments and Contingencies Disclosure [Line Items]
2020	2,144
2021	441
Thereafter	0
Total	2,585
Obligations for purchasing and service agreements
Commitments and Contingencies Disclosure [Line Items]
2020	17,116
2021	9,201
Thereafter	0
Total	$ 26,317