Tax Matters - Deferred Taxes - Footnotes (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Income Tax Examination [Line Items] | ||
| Reduction for unrecognized tax benefit | $ 2,900 | $ 3,300 |
| Net deferred tax liability | 4,700 | 2,948 |
| Noncurrent Deferred Tax Assets And Other Noncurrent Tax Assets [Member] | ||
| Income Tax Examination [Line Items] | ||
| Net deferred tax liability | 900 | 800 |
| Noncurrent Deferred Tax Liabilities [Member] | ||
| Income Tax Examination [Line Items] | ||
| Net deferred tax liability | $ 5,600 | $ 3,700 |