Fair Value Measurements and Derivative Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Millions		Jun. 30, 2024	Dec. 31, 2023
Derivative financial instruments
Asset Derivatives
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Derivative financial instruments	Derivative financial instruments
Liability Derivatives
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Derivative financial instruments	Derivative financial instruments
Other assets
Asset Derivatives
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other assets, net of allowances of $42 and $43 at June 30, 2024 and December 31, 2023, respectively	Other assets, net of allowances of $42 and $43 at June 30, 2024 and December 31, 2023, respectively
Other long-term liabilities
Liability Derivatives
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other long-term liabilities	Other long-term liabilities
Designated as Hedging Instrument
Asset Derivatives
Asset Derivatives	[1]	$ 148	$ 144
Liability Derivatives
Liability Derivatives	[1]	29	66
Interest rate swaps | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives		0	1
Liability Derivatives
Liability Derivatives		0	0
Interest rate swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	78	75
Interest rate swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	0	0
Foreign currency forward contracts | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	13	20
Liability Derivatives
Liability Derivatives	[1]	19	9
Foreign currency forward contracts | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	1	44
Foreign currency forward contracts | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	5	4
Fuel swaps | Designated as Hedging Instrument | Derivative financial instruments
Asset Derivatives
Asset Derivatives	[1]	38	4
Liability Derivatives
Liability Derivatives	[1]	3	26
Fuel swaps | Designated as Hedging Instrument | Other assets
Asset Derivatives
Asset Derivatives	[1]	18	0
Fuel swaps | Designated as Hedging Instrument | Other long-term liabilities
Liability Derivatives
Liability Derivatives	[1]	$ 2	$ 27

[1] Subtopic 815-20 “Hedging-General” under ASC 815.