Segments - Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information, Profit (Loss)
Operating revenue	$ 9,154	$ 3,062	$ 20,429	$ 13,122
Operating income (loss)	2,205	(6,386)	1,623	(11,611)
Interest expense, net	314	291	1,014	564
Depreciation and amortization	501	545	1,494	1,813
Restructuring charges	33	5,345	(3)	7,798
Total assets, end of period	72,783	79,076	72,783	79,076	$ 71,996
Net fair value obligations, end of period	(547)	(68)	(547)	(68)
Capital expenditures	830	133	2,029	1,351
Fair value of obligation	625	80	625	80
Fair value of asset component	78	12	78	12
Operating Segments | Airline
Segment Reporting Information, Profit (Loss)
Operating revenue	8,282	2,645	18,240	12,413
Operating income (loss)	2,108	(6,358)	1,809	(11,498)
Interest expense, net	312	288	1,009	564
Depreciation and amortization	501	545	1,494	1,813
Restructuring charges	33	5,345	(3)	7,798
Total assets, end of period	70,771	77,558	70,771	77,558
Net fair value obligations, end of period	0	0	0	0
Capital expenditures	818	130	1,994	1,336
Operating Segments | Refinery
Segment Reporting Information, Profit (Loss)
Operating revenue	1,696	669	4,177	2,366
Operating income (loss)	97	(28)	(186)	(113)
Interest expense, net	2	3	5	0
Depreciation and amortization	24	25	72	74
Restructuring charges	0	0	0	0
Total assets, end of period	2,012	1,518	2,012	1,518
Net fair value obligations, end of period	(547)	(68)	(547)	(68)
Capital expenditures	12	3	35	15
Intersegment Sales/Other
Segment Reporting Information, Profit (Loss)
Operating income (loss)	0	0	0	0
Interest expense, net	0	0	0	0
Depreciation and amortization	(24)	(25)	(72)	(74)
Restructuring charges	0	0	0	0
Total assets, end of period	0	0	0	0
Net fair value obligations, end of period	0	0	0	0
Capital expenditures	0	0	0	0
Intersegment Sales/Other | Sales to airline segment
Segment Reporting Information, Profit (Loss)
Operating revenue	(183)	0	(292)	(214)
Intersegment Sales/Other | Exchanged products
Segment Reporting Information, Profit (Loss)
Operating revenue	(629)	(249)	(1,667)	(1,144)
Intersegment Sales/Other | Sales of refined products
Segment Reporting Information, Profit (Loss)
Operating revenue	$ (12)	$ (3)	$ (29)	$ (299)