Revenue Recognition - Passenger Revenue (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | $ 11,439 | $ 12,560 | $ 12,536 | $ 10,472 | $ 10,742 | $ 11,953 | $ 11,775 | $ 9,968 | $ 47,007 | $ 44,438 | $ 41,138 |
| Passenger | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 42,277 | 39,755 | 36,947 | ||||||||
| Ticket | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 36,908 | 34,950 | 32,467 | ||||||||
| Loyalty travel awards | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 2,900 | 2,651 | 2,403 | ||||||||
| Travel-related services | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | $ 2,469 | $ 2,154 | $ 2,077 | ||||||||