Income Taxes - Components of Income before Taxes, Less Net Income (Loss) Attributable to Noncontrolling Interests (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Components Of Income Before Tax Less Noncontrolling Interest [Line Items] | |||
| Income tax expense based on components of income before taxes, net income (loss) attributable to non-controlling interests | $ 6,170 | $ 5,737 | $ 5,381 |
| Domestic [Member] | |||
| Components Of Income Before Tax Less Noncontrolling Interest [Line Items] | |||
| Income tax expense based on components of income before taxes, net income (loss) attributable to non-controlling interests | 3,805 | 3,766 | 3,536 |
| Foreign [Member] | |||
| Components Of Income Before Tax Less Noncontrolling Interest [Line Items] | |||
| Income tax expense based on components of income before taxes, net income (loss) attributable to non-controlling interests | $ 2,365 | $ 1,971 | $ 1,845 |