POSTRETIREMENT BENEFIT PLANS - Effect on Operations of Pension Plans (Details) - Principal pension plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 49	$ 58	$ 98	$ 122
Prior service cost amortization	1	7	3	14
Expected return on plan assets	(785)	(762)	(1,571)	(1,525)
Interest cost on benefit obligations	516	490	1,033	976
Net actuarial loss amortization	351	878	712	1,742
Benefit plans cost	$ 132	$ 671	$ 275	$ 1,329