v3.26.3
Derivative Instruments and Hedging Activities - Gains and Losses - BS (Details) - Not Designated As Hedging Instruments [Member] - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets $ (2) $ (9) $ (12) $ (5)
Interest Rate Swaps [Member] | Regulatory Assets Noncurrent [Member] | Louisville Gas And Electric Co [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets 2 0 3 (2)
Interest Rate Swaps [Member] | Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets 2 0 3 (2)
Gas Contracts | Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryAssetsNoncurrent        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets $ (4) (6) $ (15) (6)
Gas Contracts | Location, Statement of Financial Position, Activity, Accrual [Axis]: us-gaap:RegulatoryLiabilityCurrent        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets   $ (3)   $ 0