v3.26.1
Derivative Instruments and Hedging Activities - Gains and Losses - BS (Details) - Not Designated As Hedging Instruments [Member] - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (loss) recognized as regulatory liabilities/assets $ (9) $ (14) $ (10) $ 4
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 1 (1) 1 (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 1 (1) 1 (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 $ (10) (1) $ (11) 0
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   $ (12)   $ 6