POSTRETIREMENT BENEFIT PLANS - Effect on Operations of Pension Plans (Details) - Principal pension - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 21	$ 21
Expected return on plan assets	(578)	(594)
Interest cost on benefit obligations	453	474
Net actuarial loss amortization and other	(152)	(172)
Benefit plans expense (income)	$ (256)	$ (271)