Special Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Restructuring Cost and Reserve [Line Items]
Labor contract ratification bonuses	$ 813	$ 0	$ 813	$ 0
(Gains) losses on sale of assets and other special charges	(46)	(112)	(60)	(104)
Nonoperating unrealized gains (losses)	84	(40)	108	(40)
Deferred debt issuance cost, writeoff	11		11	7
Loss contingency, loss in period				94
Unsecured Debt
Restructuring Cost and Reserve [Line Items]
Repayments of debt	$ 1,000		$ 1,000
Long-term debt		$ 400		$ 400
Stated interest rate		4.25%		4.25%

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Amount of gain (loss) on sale of other assets and other miscellaneous charges.

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Labor Contract Ratification Bonus

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Amount of cash outflow for short-term and long-term debt. Excludes payment of lease obligation.

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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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