Comprehensive Income (Loss) - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Fuel and oil	$ 1,750	$ 990	$ 4,390	$ 2,261
Less: Tax expense	76	154	254	339
Interest expense	86	115	272	343
Net income	277	$ 446	759	$ 909
Reclassification to earnings
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income	(148)		(535)
Fuel derivative contracts | Fuel and Interest Rate Derivatives | Reclassification to earnings
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Fuel and oil	(195)		(703)
Less: Tax expense	(45)		(164)
Net income	(150)		(539)
Interest rate derivatives | Fuel and Interest Rate Derivatives | Reclassification to earnings
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Less: Tax expense	0		1
Interest expense	2		5
Net income	$ 2		$ 4