Income taxes (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
May 31, 2021 |
|
| Income Tax Disclosure [Abstract] | |||||
| Effective income tax rate | 12.60% | 8.40% | 12.60% | 9.70% | |
| Increase in unrecognized tax benefits resulting from tax positions taken during the current period | $ 70 | $ 180 | |||
| Proposed additional income tax | $ 3,600 | ||||
| Repatriation tax on proposed additional tax | $ 900 | ||||