PENSION AND OTHER POST-EMPLOYMENT BENEFITS - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		$ 184	$ 195	$ 194
Interest cost		273	226	287
Expected return on plan assets		(657)	(652)	(618)
Amortization of prior service costs (credits)		2	3	12
One-time termination benefits		0	0	8
Pension & OPEB mark-to-market		(98)	(253)	463
Net periodic benefit costs (credits)		(296)	(481)	346
Net accelerated credits	$ 18
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		3	4	4
Interest cost		11	11	15
Expected return on plan assets		(39)	(36)	(33)
Amortization of prior service costs (credits)		(11)	(17)	(46)
One-time termination benefits		0	0	0
Pension & OPEB mark-to-market		26	(129)	14
Net periodic benefit costs (credits)		$ (10)	$ (167)	$ (46)