Revenue Recognition - Narrative (Details) - USD ($) $ in Billions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Revenue from Contract with Customer [Abstract] | ||
| Revenue recognized that was previously deferred | $ 3.9 | $ 1.8 |
| Cash sales of mileage credits | $ 4.1 | $ 2.9 |
| Redemption period for majority of new miles (in years) | 2 years | |