RETIREMENT BENEFITS - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Plan asset amortization period	5 years
Pension plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 52,000,000	$ 61,000,000
Expected future employer contributions, next fiscal year	0
Actuarial losses	$ 493,000,000	$ (3,908,000,000)
Change in discount rate	(1800.00%)	2.16%
Pension plans | Qualified pension plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0
Other postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	73,000,000	$ 73,000,000
Expected future employer contributions, next fiscal year	0
Actuarial losses	$ (33,000,000)	$ (365,000,000)