v3.26.3
Derivative Instruments and Hedging Activities - Fair Values (Details) - Not Designated As Hedging Instruments [Member] - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Fair Values by Balance Sheet Location [Abstract]    
Asset value $ 3 $ 6
Liability value 22 15
Balance Sheet Location [Axis]: us-gaap:OtherAssetsCurrent    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 3 6
Balance Sheet Location [Axis]: us-gaap:OtherAssetsCurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 19 6
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 0 1
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 3 9
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 1 4
Louisville Gas And Electric Co [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Liability value 1 5
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherAssetsCurrent    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherAssetsCurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Asset value 0 0
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 0 1
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 0 1
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent    
Fair Values by Balance Sheet Location [Abstract]    
Liability value 1 4
Louisville Gas And Electric Co [Member] | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent | Interest Rate Swaps [Member]    
Fair Values by Balance Sheet Location [Abstract]    
Liability value $ 1 $ 4