Basis of Presentation and Significant Accounting Policies - Accrued Rebates and Other Accruals (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Schedule Of Accrued Liabilities [Line Items] | ||
| Total accrued rebates and other sales-related accruals | $ 4,712 | $ 4,098 |
| Trade accounts receivable, less allowance for doubtful accounts [Member] | ||
| Schedule Of Accrued Liabilities [Line Items] | ||
| Total accrued rebates and other sales-related accruals | 861 | 823 |
| Other current liabilities [Member] | ||
| Schedule Of Accrued Liabilities [Line Items] | ||
| Accrued rebates | 3,017 | 2,512 |
| Other accruals | 436 | 379 |
| Other noncurrent liabilities [Member] | ||
| Schedule Of Accrued Liabilities [Line Items] | ||
| Total accrued rebates and other sales-related accruals | $ 399 | $ 384 |