Revenue Recognition (Deferred Contract Acquisition and Fulfillment Costs) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Deferred Acquisition Costs | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | $ 6,285 | $ 5,453 |
| Deferred cost amortization | 2,755 | 2,174 |
| Deferred Acquisition Costs | Other current assets | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | 3,087 | 2,462 |
| Deferred Acquisition Costs | Other Assets | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | 3,198 | 2,991 |
| Deferred Fulfillment Costs | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | 9,752 | 10,958 |
| Deferred cost amortization | 5,110 | 4,947 |
| Deferred Fulfillment Costs | Other current assets | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | 4,118 | 4,519 |
| Deferred Fulfillment Costs | Other Assets | ||
| Capitalized Contract Cost, Net [Abstract] | ||
| Total deferred costs | $ 5,634 | $ 6,439 |