Derivative Instruments and Hedging Activities (Offseting Derivative Instruments and Credit Risk-Related Features) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Offsetting Assets And Liabilities [Line Items]
Gross assets	$ 1,431		$ 1,279
Derivative instruments eligible for offset - assets	1,282		973
Cash collateral received eligible for offset - assets	8		7
Net assets	141		299
Gross liabilities	1,752		1,244
Derivative instruments eligible for offset - liabilities	1,282		973
Cash collateral pledged eligible for offset - liabilities	118		24
Net liabilities	352		247
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit risk-related contingent features	339
Aggregate fair value of collateral posted on these derivative instruments	57
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	363	[1]
Energy Commodities [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	1,417		1,188
Derivative instruments eligible for offset - assets	1,268		912
Cash collateral received eligible for offset - assets	8		7
Net assets	141		269
Gross liabilities	1,527		1,070
Derivative instruments eligible for offset - liabilities	1,268		912
Cash collateral pledged eligible for offset - liabilities	94		1
Net liabilities	165		157
Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	14		91
Derivative instruments eligible for offset - assets	14		61
Cash collateral received eligible for offset - assets
Net assets			30
Gross liabilities	225		174
Derivative instruments eligible for offset - liabilities	14		61
Cash collateral pledged eligible for offset - liabilities	24		23
Net liabilities	187		90
PPL Energy Supply 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	168
Aggregate fair value of collateral posted on these derivative instruments	36
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	209	[1]
PPL Energy Supply LLC [Member] | Energy Commodities [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	1,417		1,188
Derivative instruments eligible for offset - assets	1,268		912
Cash collateral received eligible for offset - assets	8		7
Net assets	141		269
Gross liabilities	1,527		1,070
Derivative instruments eligible for offset - liabilities	1,268		912
Cash collateral pledged eligible for offset - liabilities	94		1
Net liabilities	165		157
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	27
Aggregate fair value of collateral posted on these derivative instruments	21
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	7	[1]
LG And E And KU Energy LLC [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets
Derivative instruments eligible for offset - assets
Cash collateral received eligible for offset - assets
Net assets
Gross liabilities	40		36
Derivative instruments eligible for offset - liabilities
Cash collateral pledged eligible for offset - liabilities	20		20
Net liabilities	20		16
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	27
Aggregate fair value of collateral posted on these derivative instruments	21
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	7	[1]
Louisville Gas And Electric Co [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets
Derivative instruments eligible for offset - assets
Cash collateral received eligible for offset - assets
Net assets
Gross liabilities	40		36
Derivative instruments eligible for offset - liabilities
Cash collateral pledged eligible for offset - liabilities	20		20
Net liabilities	$ 20		$ 16

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