Financial Derivative Instruments - Schedule of Premium Expense (Benefit) for Fuel Derivative Contracts (Details) - Fuel derivative contracts - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Designated as Hedging Instrument | Fuel and oil | ||||
| Derivative [Line Items] | ||||
| Expense (benefit) recognized in income on derivatives | $ 36 | $ 34 | $ 110 | $ 114 |
| Not Designated as Hedging Instrument | Other (gains) losses, net | ||||
| Derivative [Line Items] | ||||
| Premium expense recognized in income on derivatives | $ 0 | $ 5 | $ 0 | $ 5 |