Income taxes (Income Before Income Taxes) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Income Tax Examination [Line Items] | |||
| Income before income taxes | $ 9,138 | $ 9,545 | $ 9,597 |
| Domestic [Member] | |||
| Income Tax Examination [Line Items] | |||
| Income before income taxes | 4,371 | 4,856 | 4,436 |
| Foreign [Member] | |||
| Income Tax Examination [Line Items] | |||
| Income before income taxes | $ 4,767 | $ 4,689 | $ 5,161 |