Operating Leases - Aircraft (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) lease transaction aircraft	Sep. 30, 2023 USD ($) aircraft transaction lease	Sep. 30, 2024 USD ($) lease aircraft engine transaction	Sep. 30, 2023 USD ($) lease transaction aircraft
Lessee, Lease, Description [Line Items]
Gains recognized on sale-leaseback transactions | $			$ 218	$ 97
Aircraft
Lessee, Lease, Description [Line Items]
Number of leases	153		153
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	5 months		5 months
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	12 years		12 years
Engines
Lessee, Lease, Description [Line Items]
Number of leases	30		30
Number of engines dependent on usage-based metrics | engine			6
Engines | Aircraft Sale Leaseback
Lessee, Lease, Description [Line Items]
Number of sale-leaseback transactions | transaction	1	3	1	3
Engines | Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 month		1 month
Engines | Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	12 years		12 years
Aircraft and Aircraft Engines
Lessee, Lease, Description [Line Items]
Gains recognized on sale-leaseback transactions | $	$ 70	$ 40	$ 218	$ 97
A320neo
Lessee, Lease, Description [Line Items]
Number of leases in period	0	5	0	10
A320neo | Aircraft | Aircraft Sale Leaseback
Lessee, Lease, Description [Line Items]
Number of sale-leaseback transactions | aircraft	5	3	17	7