FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Schedule of assets (liabilities) measured at fair value on a recurring basis

Assets/(Liabilities) Measured at Fair Value on a Recurring Basis

(in millions)	March 31, 2024		Level 1		Level 2		Level 3
Cash equivalents	$	2,495	$	2,495	$	—	$	—
Restricted cash equivalents	501		501		—		—
Short-term investments
U.S. Government securities	473		101		372		—
Corporate obligations	86		—		86		—
Other fixed income securities	30		—		30		—
Long-term investments and related	2,641		2,387		139		115
Fuel hedge contracts	(22)		—		(22)		—

(in millions)	December 31, 2023		Level 1		Level 2		Level 3
Cash equivalents	$	1,545	$	1,545	$	—	$	—
Restricted cash equivalents	653		653		—		—
Short-term investments
U.S. Government securities	859		204		655		—
Corporate obligations	218		—		218		—
Other fixed income securities	50		—		50		—
Long-term investments and related	2,867		2,614		134		119
Fuel hedge contracts	5		—		5		—