Derivative Instruments and Hedging Activities (Offseting Derivative Instruments and Credit Risk-Related Features) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Offsetting Assets And Liabilities [Line Items]
Gross assets	$ 1,595		$ 2,097
Derivative instruments eligible for offset - assets	1,169		1,432
Cash collateral received eligible for offset - assets	14		111
Net assets	412		554
Gross liabilities	1,361		1,694
Derivative instruments eligible for offset - liabilities	1,169		1,432
Cash collateral pledged eligible for offset - liabilities	22		39
Net liabilities	170		223
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit risk-related contingent features	178
Aggregate fair value of collateral posted on these derivative instruments	39
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	167	[1]
Energy Commodities [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	1,480		2,068
Derivative instruments eligible for offset - assets	1,122		1,413
Cash collateral received eligible for offset - assets	14		111
Net assets	344		544
Gross liabilities	1,235		1,566
Derivative instruments eligible for offset - liabilities	1,122		1,413
Cash collateral pledged eligible for offset - liabilities			9
Net liabilities	113		144
Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	115		29
Derivative instruments eligible for offset - assets	47		19
Cash collateral received eligible for offset - assets
Net assets	68		10
Gross liabilities	126		128
Derivative instruments eligible for offset - liabilities	47		19
Cash collateral pledged eligible for offset - liabilities	22		30
Net liabilities	57		79
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	115
Aggregate fair value of collateral posted on these derivative instruments	17
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	127	[1]
PPL Energy Supply LLC [Member] | Energy Commodities [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets	1,480		2,068
Derivative instruments eligible for offset - assets	1,122		1,413
Cash collateral received eligible for offset - assets	14		111
Net assets	344		544
Gross liabilities	1,235		1,566
Derivative instruments eligible for offset - liabilities	1,122		1,413
Cash collateral pledged eligible for offset - liabilities			9
Net liabilities	113		144
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	29
Aggregate fair value of collateral posted on these derivative instruments	22
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			14
Derivative instruments eligible for offset - assets
Cash collateral received eligible for offset - assets
Net assets			14
Gross liabilities	55		58
Derivative instruments eligible for offset - liabilities
Cash collateral pledged eligible for offset - liabilities	22		30
Net liabilities	33		28
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	29
Aggregate fair value of collateral posted on these derivative instruments	22
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			7
Derivative instruments eligible for offset - assets
Cash collateral received eligible for offset - assets
Net assets			7
Gross liabilities	48		58
Derivative instruments eligible for offset - liabilities
Cash collateral pledged eligible for offset - liabilities	22		30
Net liabilities	26		28
Kentucky Utilities Co [Member] | Treasury Derivatives [Member]
Offsetting Assets And Liabilities [Line Items]
Gross assets			7
Derivative instruments eligible for offset - assets
Cash collateral received eligible for offset - assets
Net assets			7
Gross liabilities	7
Derivative instruments eligible for offset - liabilities
Cash collateral pledged eligible for offset - liabilities
Net liabilities	$ 7

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