Revenue - Passenger Revenue Breakout (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total passenger revenues	$ 6,949	$ 6,870	$ 20,621	$ 20,553
Passenger
Disaggregation of Revenue [Line Items]
Total passenger revenues	6,313	6,250	18,751	18,673
Passenger non-loyalty
Disaggregation of Revenue [Line Items]
Total passenger revenues	4,896	5,092	15,110	15,316
Passenger loyalty - air transportation
Disaggregation of Revenue [Line Items]
Total passenger revenues	805	896	2,475	2,589
Passenger ancillary sold separately
Disaggregation of Revenue [Line Items]
Total passenger revenues	$ 612	$ 262	$ 1,166	$ 768

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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- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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