Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Balance | $ 31,848 | $ 29,140 |
| Other comprehensive income (loss) | 137 | 39 |
| Balance | 32,022 | 29,193 |
| Foreign Currency Translation Adjustments [Member] | ||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Balance | (436) | (721) |
| Other comprehensive income (loss) | 137 | 40 |
| Reclassification as a result of adoption of ASU 2018-02 | (6) | |
| Balance | (305) | (681) |
| Other [Member] | ||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Balance | 4 | 5 |
| Other comprehensive income (loss) | (1) | |
| Balance | 4 | 4 |
| Accumulated Other Comprehensive Income (Loss) [Member] | ||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Balance | (432) | (716) |
| Other comprehensive income (loss) | 137 | 39 |
| Reclassification as a result of adoption of ASU 2018-02 | (6) | |
| Balance | $ (301) | $ (677) |