Derivative Instruments and Hedging Activities (Offseting Derivative Instruments and Credit Risk-Related Features) (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit risk-related contingent features		$ 42
Aggregate fair value of collateral posted on these derivative instruments		9
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	[1]	33
Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets		156	$ 159
Derivative instruments eligible for offset - assets		64	65
Net assets		92	94
Gross liabilities		124	161
Derivative instruments eligible for offset - liabilities		64	65
Cash collateral pledged eligible for offset - liabilities		9	21
Net liabilities		51	75
LG And E And KU Energy LLC [Member]
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit risk-related contingent features		28
Aggregate fair value of collateral posted on these derivative instruments		9
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	[1]	19
LG And E And KU Energy LLC [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets		0	0
Derivative instruments eligible for offset - assets		0	0
Cash collateral received eligible for offset - assets		0	0
Net assets		0	0
Gross liabilities		91	114
Derivative instruments eligible for offset - liabilities		0	0
Cash collateral pledged eligible for offset - liabilities		9	20
Net liabilities		82	94
Louisville Gas And Electric Co [Member]
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit risk-related contingent features		28
Aggregate fair value of collateral posted on these derivative instruments		9
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	[1]	19
Louisville Gas And Electric Co [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets		0	0
Derivative instruments eligible for offset - assets		0	0
Cash collateral received eligible for offset - assets		0	0
Net assets		0	0
Gross liabilities		68	81
Derivative instruments eligible for offset - liabilities		0	0
Cash collateral pledged eligible for offset - liabilities		9	20
Net liabilities		59	61
Kentucky Utilities Co [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets		0	0
Derivative instruments eligible for offset - assets		0	0
Cash collateral received eligible for offset - assets		0	0
Net assets		0	0
Gross liabilities		23	33
Derivative instruments eligible for offset - liabilities		0	0
Cash collateral pledged eligible for offset - liabilities		0	0
Net liabilities		$ 23	$ 33

[1] Includes the effect of net receivables and payables alread y recorded on the Balance Sheet.