Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	$ 552
Accretion expense	9
Effect of foreign currency exchange rates	(2)
Obligations settled	(3)
Balance at End of Period	556
Susquehanna Nuclear Station ARO (Numeric) [Abstract]
Susquehanna accrued nuclear decommissioning obligation	322	316
Susquehanna NDT funds	764	712
PPL Energy Supply LLC [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	375
Accretion expense	7
Obligations settled	(2)
Balance at End of Period	380
Susquehanna Nuclear Station ARO (Numeric) [Abstract]
Susquehanna accrued nuclear decommissioning obligation	322	316
Susquehanna NDT funds	764	712
LG And E And KU Energy LLC [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	131
Accretion expense	2
Obligations settled	(1)
Balance at End of Period	132
Louisville Gas And Electric Co [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	62
Accretion expense	1
Obligations settled	(1)
Balance at End of Period	62
Kentucky Utilities Co [Member]
Asset Retirement Obligation [Rollforward]
Balance at Beginning of Period	69
Accretion expense	1
Balance at End of Period	$ 70