Comprehensive Income (Loss) - Schedule of AOCI Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 10,414	$ 8,876
Changes in fair value	590	547
Reclassification to earnings	(634)	(34)
Balance at end of period	$ 10,687	$ 10,414
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2016-01 [Member]	Accounting Standards Update 2016-01 [Member]
Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ (245)	$ 0
Balance at end of period		(245)
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	388	(105)
Balance at end of period	344	388
Accumulated other comprehensive income (loss) | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(20)
Fuel derivatives | Fuel derivative contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	492	(119)
Changes in fair value	645	601
Reclassification to earnings	(832)	10
Balance at end of period	305	492
Fuel derivatives | Interest rate derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(57)	(66)
Changes in fair value	18	3
Reclassification to earnings	7	6
Balance at end of period	(32)	(57)
Defined benefit plan items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	66	(43)
Changes in fair value	106	109
Reclassification to earnings	(2)
Balance at end of period	170	66
Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	0	91
Reclassification to earnings		(60)
Balance at end of period	0	0
Other | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(31)
Deferred tax impact
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(113)	32
Changes in fair value	(179)	(166)
Reclassification to earnings	193	10
Balance at end of period	$ (99)	(113)
Deferred tax impact | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		$ 11