Asset Retirement Obligations (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	$ 397
Accretion	10
Effect of foreign exchange rates	(1)
Changes in estimated timing or cost	1
Obligations settled	(26)
Balance at End of Period	381
LG And E And KU Energy LLC [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	356
Accretion	9
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(7)
Obligations settled	(26)
Balance at End of Period	332
Louisville Gas And Electric Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	121
Accretion	3
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(2)
Obligations settled	(10)
Balance at End of Period	112
Kentucky Utilities Co [Member]
Asset Retirement Obligation [Roll Forward]
Balance at Beginning of Period	235
Accretion	6
Effect of foreign exchange rates	0
Changes in estimated timing or cost	(5)
Obligations settled	(16)
Balance at End of Period	$ 220