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Commitments and Contingencies - Collective Bargaining Agreements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Multiemployer Plan [Line Items]
Amount of employees represented by unions	87.00%
Accrued liabilities for health care claims	$ 6	$ 5
Pilots
Multiemployer Plan [Line Items]
Amount of employees represented by unions	28.00%
Flight Attendants
Multiemployer Plan [Line Items]
Amount of employees represented by unions	51.00%
Aircraft Technicians
Multiemployer Plan [Line Items]
Amount of employees represented by unions	6.00%
Aircraft Appearance Agents
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Dispatchers
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Material Specialists
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Maintenance Controllers
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%