Stockholders' equity (Accumulated Other Comprehensive Income (Loss), Textual) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Equity [Abstract] | |||
| Income tax expense or (benefit) for reclassification adjustments to income for available-for-sale securities | $ (14) | $ 3 | $ (8) |
| Income taxes expense or (benefit) for unrealized gains and losses for available-for-sale securities | 22 | (9) | 9 |
| Income taxes expense or (benefit) for unrealized gains and losses for cash flow hedges | 28 | 21 | 68 |
| Income tax expense or (benefit) reclassification adjustments to income for cash flow hedges | $ (46) | $ 55 | $ (226) |