FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

Fair values of financial instruments on the unaudited Condensed Consolidated Balance Sheets:

	September 30, 2024
(in millions)	Level 1		Level 2		Level 3		Total
Assets
Marketable securities
U.S. government and agency securities	$	284	$	283	$	—	$	567
Equity mutual funds	7		—		—		7
Asset-backed securities	—		114		8		122
Mortgage-backed securities	—		93		—		93
Corporate notes and bonds	—		587		5		592
Municipal securities and other	—		25		6		31
Other fixed income securities	—		78		—		78
Total Marketable securities	291		1,180		19		1,490
Derivative instruments
Fuel hedge contracts - call options	—		1		—		1
Interest rate swap agreements	—		4		—		4
Total Assets	$	291	$	1,185	$	19	$	1,495

	December 31, 2023
(in millions)	Level 1		Level 2		Level 3		Total
Assets
Marketable securities
U.S. government and agency securities	$	387	$	—	$	—	$	387
Equity mutual funds	5		—		—		5
Foreign government bonds	—		10		—		10
Asset-backed securities	—		192		—		192
Mortgage-backed securities	—		115		—		115
Corporate notes and bonds	—		763		—		763
Municipal securities and other	—		38		—		38
Total Marketable securities	392		1,118		—		1,510
Derivative instruments
Fuel hedge contracts - call options	—		11		—		11
Interest rate swap agreements	—		8		—		8
Total Assets	$	392	$	1,137	$	—	$	1,529

Fixed-rate debt on the unaudited Condensed Consolidated Balance Sheets and the estimated fair value of long-term fixed-rate debt:

(in millions)	September 30, 2024		December 31, 2023
Fixed-rate debt	$	2,947	$	1,515
Estimated fair value	$	2,857	$	1,382