Segments - Schedule of Segment Reporting (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information, Profit (Loss)
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Operating income (loss)	(12,469)	6,618	5,264
Interest expense, net	929	301	311
Depreciation and amortization	2,312	2,581	2,329
Restructuring charges	8,219	0	0
Total assets	71,996	64,532	60,266
Capital expenditures	1,899	4,936	5,168
Operating Segments | Airline
Segment Reporting Information, Profit (Loss)
Operating revenue	15,945	46,910	43,890
Operating income (loss)	(12,253)	6,542	5,206
Interest expense, net	928	327	334
Depreciation and amortization	2,312	2,581	2,329
Restructuring charges	8,219
Total assets	70,548	62,793	58,561
Capital expenditures	1,879	4,880	5,005
Operating Segments | Refinery
Segment Reporting Information, Profit (Loss)
Operating revenue	3,143	5,558	5,458
Operating income (loss)	(216)	76	58
Interest expense, net	1	(26)	(23)
Depreciation and amortization	99	99	67
Restructuring charges	0
Total assets	1,448	1,739	1,705
Capital expenditures	20	56	163
Intersegment Sales/Other
Segment Reporting Information, Profit (Loss)
Depreciation and amortization	(99)	(99)	(67)
Intersegment Sales/Other | Sales to airline segment
Segment Reporting Information, Profit (Loss)
Operating revenue	(214)	(1,103)	(962)
Intersegment Sales/Other | Exchanged products
Segment Reporting Information, Profit (Loss)
Operating revenue	(1,472)	(3,963)	(3,596)
Intersegment Sales/Other | Sales of refined products
Segment Reporting Information, Profit (Loss)
Operating revenue	$ (307)	$ (395)	$ (352)