Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Flight credits, expiration period			18 months
Flight credits (as a percent)	5.00%		5.00%		8.00%
Total operating revenues	$ 6,949	$ 6,870	$ 20,621	$ 20,553
Chase Bank USA Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total operating revenues	$ 723	$ 538	$ 1,900	$ 1,600

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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+ Details