Annual report [Section 13 and 15(d), not S-K Item 405]

PENSION AND POST RETIREMENT BENEFITS - Components of Accumulated Other Comprehensive Loss (Income) (Details)

v3.25.4
PENSION AND POST RETIREMENT BENEFITS - Components of Accumulated Other Comprehensive Loss (Income) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation $ (89) $ (113)
Actual returns on assets under (over) expected (158) 67
Amortization of net actuarial gain (loss) 8 1
Amortization of prior service credits (costs) (17) (18)
Settlements 0 2
Plan amendments 0 0
OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 311 335
Actual returns on assets under (over) expected (20) (3)
Amortization of net actuarial gain (loss) 134 154
Amortization of prior service credits (costs) 13 15
Settlements 0 0
Plan amendments 3 7
Discount rates | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 109 (146)
Discount rates | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 34 (43)
Demographic updates | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 22 (14)
Demographic updates | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 23 26
Mortality | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation (50) 0
Mortality | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 0 0
Per capita healthcare costs | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 0 0
Per capita healthcare costs | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 124 179
Other | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation (3) (5)
Other | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 0 0
Actuarial loss (gain) on benefit obligation | Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation 78 (165)
Actuarial loss (gain) on benefit obligation | OPEB    
Defined Benefit Plan Disclosure [Line Items]    
Actuarial loss (gain) on benefit obligation $ 181 $ 162