Revenue Recognition - Other 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 |
| Other | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 3,977 | 3,818 | 3,447 | ||||||||
| Ancillary businesses and refinery | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 1,297 | 1,801 | 1,591 | ||||||||
| Loyalty program | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | 1,962 | 1,459 | 1,269 | ||||||||
| Miscellaneous | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Operating revenue | $ 718 | $ 558 | $ 587 | ||||||||