Derivative Instruments and Hedging Activities (Offseting Derivative Instruments and Credit Risk-Related Features) (Details) - USD ($) $ in Millions		Dec. 31, 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		$ 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
Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets		295	$ 159
Derivative instruments eligible for offset - assets		25	65
Net assets		270	94
Gross liabilities		72	161
Derivative instruments eligible for offset - liabilities		25	65
Cash collateral pledged eligible for offset - liabilities		9	21
Net liabilities		38	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 liabilities		47	114
Cash collateral pledged eligible for offset - liabilities		9	20
Net liabilities		38	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 liabilities		47	81
Cash collateral pledged eligible for offset - liabilities		9	20
Net liabilities		$ 38	61
Kentucky Utilities Co [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross liabilities			33
Cash collateral pledged eligible for offset - liabilities			0
Net liabilities			$ 33

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