Revenue Recognition - Other Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Operating revenue	$ 9,154	$ 3,062	$ 20,429	$ 13,122
Other
Disaggregation of Revenue [Line Items]
Operating revenue	1,701	982	4,423	2,534
Refinery
Disaggregation of Revenue [Line Items]
Operating revenue	872	417	2,189	709
Loyalty program
Disaggregation of Revenue [Line Items]
Operating revenue	453	343	1,260	1,086
Ancillary businesses
Disaggregation of Revenue [Line Items]
Operating revenue	215	155	586	476
Miscellaneous
Disaggregation of Revenue [Line Items]
Operating revenue	$ 161	$ 67	$ 388	$ 263