PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Pension and Other Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit costs (credits)	$ (64)	$ (57)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	7	7
Interest cost	45	53
Expected return on plan assets	(81)	(79)
Prior service credits	4	4
Net actuarial loss (gain)	(4)	(2)
Net periodic benefit costs (credits)	(29)	(17)
Defined benefit pension contributions	13	15
Defined benefit plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	2	2
Interest cost	14	14
Expected return on plan assets	(11)	(11)
Prior service credits	(3)	(3)
Net actuarial loss (gain)	(28)	(33)
Net periodic benefit costs (credits)	(26)	(31)
OPEB contributions	$ 0	$ 0