Asset Retirement Obligations (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	$ 182
Accretion	12
Changes in estimated timing or cost	50
Obligations settled	(43)
Balance at End of Period	201
Louisville Gas And Electric Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	67
Accretion	4
Changes in estimated timing or cost	34
Obligations settled	(16)
Balance at End of Period	89
Kentucky Utilities Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	115
Accretion	8
Changes in estimated timing or cost	16
Obligations settled	(27)
Balance at End of Period	$ 112