v3.25.1
PENSION AND OTHER POST-EMPLOYMENT BENEFITS - Schedule of Components of Net Periodic Benefit Costs (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pension    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Service costs $ 33 $ 35
Interest costs 93 99
Expected return on plan assets (115) (133)
Amortization of prior service costs (credits) 0 1
Net periodic benefit costs (credits) 11 2
Net periodic benefit credits, net of amounts capitalized (6) (15)
Pension | JERSEY CENTRAL POWER & LIGHT COMPANY    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Net periodic benefit costs (credits) (1) (1)
OPEB    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Service costs 1 1
Interest costs 5 5
Expected return on plan assets (10) (8)
Amortization of prior service costs (credits) 0 (1)
Net periodic benefit costs (credits) (4) (3)
Net periodic benefit credits, net of amounts capitalized (4) (4)
OPEB | JERSEY CENTRAL POWER & LIGHT COMPANY    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Net periodic benefit costs (credits) $ (4) $ (3)