Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	$ 488	$ 586
Accretion	21	24
Changes in estimated cash flow or settlement date	(73)	(84)
Effect of foreign currency exchange rates	4	(9)
Obligations settled	(43)	(29)
Balance at End of Period	397	488
LG And E And KU Energy LLC [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	433	535
Accretion	20	22
Changes in estimated cash flow or settlement date	(54)	(95)
Obligations settled	(43)	(29)
Balance at End of Period	356	433
Increase (Decrease) to the asset retirement obligation due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments	(60)	114
Louisville Gas And Electric Co [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	145	175
Accretion	7	7
Changes in estimated cash flow or settlement date	(8)	(19)
Obligations settled	(23)	(18)
Balance at End of Period	121	145
Increase (Decrease) to the asset retirement obligation due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments	(8)	(24)
Kentucky Utilities Co [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	288	360
Accretion	13	15
Changes in estimated cash flow or settlement date	(46)	(76)
Obligations settled	(20)	(11)
Balance at End of Period	235	288
Increase (Decrease) to the asset retirement obligation due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments	$ (52)	$ (90)