RETIREMENT BENEFITS PLANS - Change in Plan Level 3 Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	$ 4,121
Ending balance	4,237	$ 4,121
Unobservable inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	559
Ending balance	569	559
Unobservable inputs (Level 3) | Real estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	199
Ending balance	199	199
Unobservable inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	360
Ending balance	370	360
Pension plans | Unobservable inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	559	535
Gains (losses) relating to assets still held at year-end	26	(2)
Purchases, sales, settlements - net	(7)	26
Transfers into or out of Level 3	(9)	0
Ending balance	569	559
Pension plans | Unobservable inputs (Level 3) | Real estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	199	216
Gains (losses) relating to assets still held at year-end	7	1
Purchases, sales, settlements - net	(7)	(18)
Transfers into or out of Level 3	0	0
Ending balance	199	199
Pension plans | Unobservable inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance	360	319
Gains (losses) relating to assets still held at year-end	19	(3)
Purchases, sales, settlements - net	0	44
Transfers into or out of Level 3	(9)	0
Ending balance	$ 370	$ 360