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