Supplemental Financial Information - Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Extended Emergency Time Off	$ 0	$ 57
Voluntary Separation Program	276	321
Postretirement obligation	432	428
Other deferred compensation	338	353
Other	74	88
Other noncurrent liabilities	1,120	1,247
Unusual or Infrequent Item, or Both [Line Items]
Taxes receivable	696	740
Vendor prepayment	0	600
CARES Act
Unusual or Infrequent Item, or Both [Line Items]
Taxes receivable	$ 470	$ 470

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Voluntary Separation Program 2020 Other Noncurrent Liability

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Carrying amount due within one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

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Amount of the liabilities, classified as other, for deferred compensation arrangements payable after one year or the operating cycle, if longer.

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Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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