Revenue Recognition - Loyalty Program Deferred Revenue (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2020 |
Sep. 30, 2019 |
|
| Frequent Flyer Liability Activity [Roll Forward] | ||
| Miles earned | $ 1,132 | $ 2,352 |
| Travel miles redeemed | (731) | (2,175) |
| Non-travel miles redeemed | (40) | (122) |
| Loyalty program | ||
| Frequent Flyer Liability Activity [Roll Forward] | ||
| Deferred revenue (current and noncurrent), beginning | 6,728 | 6,641 |
| Deferred revenue (current and noncurrent), ending | $ 7,089 | $ 6,696 |