Comprehensive Income - Schedule of AOCI Components (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 10,417	$ 10,414
Balance at end of period	11,120	11,120
Accumulated other comprehensive income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	891	388
Changes in fair value	147	804
Reclassification to earnings	(233)	(387)
Balance at end of period	805	805
Fuel and Interest Rate Derivatives | Fuel derivative contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	1,141	492
Changes in fair value	182	1,033
Reclassification to earnings	(306)	(508)
Balance at end of period	1,017	1,017
Fuel and Interest Rate Derivatives | Interest rate derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(50)	(57)
Changes in fair value	10	16
Reclassification to earnings	2	3
Balance at end of period	(38)	(38)
Defined benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	66	66
Balance at end of period	66	66
Deferred tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(266)	(113)
Changes in fair value	(45)	(245)
Reclassification to earnings	71	118
Balance at end of period	$ (240)	$ (240)