Derivative Instruments and Hedging Activities - Fair Values (Details) - Not Designated As Hedging Instruments [Member] - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 1	$ 1
Liability value	39	67
Louisville Gas And Electric Co [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	0	0
Liability value	$ 5	$ 7

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.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant