Asset Retirement Obligations (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	$ 397
Accretion	3
Effect of foreign exchange rates	1
Changes in estimated timing or cost	(10)
Obligations settled	(9)
Balance at End of Period	382
LG And E And KU Energy LLC [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	356
Accretion	3
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(10)
Obligations settled	(9)
Balance at End of Period	340
Louisville Gas And Electric Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	121
Accretion	0
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(5)
Obligations settled	(5)
Balance at End of Period	111
Kentucky Utilities Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	235
Accretion	3
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(5)
Obligations settled	(4)
Balance at End of Period	$ 229