Financial Derivative Instruments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Current unrealized net loss in OCI	$ 179
Designated as Hedging Instrument
Derivative [Line Items]
Gross amounts offset in the balance sheet	0	$ 4
Fuel derivative contracts
Derivative [Line Items]
Collateral deposits	106	175
Fuel derivative contracts \| Other assets
Derivative [Line Items]
Gross amounts offset in the balance sheet	0	95
Fuel derivative contracts \| Not Designated as Hedging Instrument
Derivative [Line Items]
Loss from AOCI into other (gains) losses	6	39
Interest rate derivatives \| Other noncurrent liabilities
Derivative [Line Items]
Collateral deposits	0
Gross amounts offset in the balance sheet	0	4
Interest rate derivatives \| Designated as Hedging Instrument \| Other noncurrent liabilities
Derivative [Line Items]
Gross amounts offset in the balance sheet	$ 0	$ 4

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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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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The amount of loss reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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The estimated net amount of unrealized gains or losses on price risk cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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