Derivative Instruments and Hedging Activities - Fair Values (Details) - Not Designated As Hedging Instruments [Member] - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 4	$ 9
Liability value	16	16
Louisville Gas And Electric Co [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	0	0
Liability value	$ 5	$ 3

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References + Details