Derivative Instruments and Hedging Activities (Fair Values) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Fair Values by Balance Sheet Location [Abstract]
Net pre-tax gains (losses) included in AOCI related to derivatives not designated as hedging instruments	$ 479		$ 237
Accumulated after-tax net gains (losses), excluding net investment hedges, included in AOCI	231		527		491	695
Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	120	[1]	948	[1]
Liability value	26	[1]	10	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	67	[1]	882	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			3	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			7	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	66	[1]	872	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	53	[1]	66	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	23	[1]	24	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	30	[1]	42	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	20	[1]	8	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	16	[1]	3	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	2	[1]	2	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	3	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	6	[1]	2	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	2	[1]
Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	2,508	[1],[2]	2,520	[1],[2]
Liability value	2,042	[1],[2]	2,400	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,701	[1],[2]	1,666	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			11	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,701	[1],[2]	1,655	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	807	[1],[2]	854	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	807	[1],[2]	854	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1,164	[1],[2]	1,562	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1],[2]	5	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	19	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1,140	[1],[2]	1,557	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	878	[1],[2]	838	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	57	[1],[2]	55	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	16	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	805	[1],[2]	783	[1],[2]
PPL Energy Supply LLC [Member]
Fair Values by Balance Sheet Location [Abstract]
Net pre-tax gains (losses) included in AOCI related to derivatives not designated as hedging instruments	479		237
Accumulated after-tax net gains (losses), excluding net investment hedges, included in AOCI	312		605		539	733
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	96	[1]	914	[1]
Liability value	2	[1]	5	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	66	[1]	872	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	66	[1]	872	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	30	[1]	42	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	30	[1]	42	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	3	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	3	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	2	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	2	[1]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	2,508	[1],[2]	2,509	[1],[2]
Liability value	1,945	[1],[2]	2,340	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,701	[1],[2]	1,655	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,701	[1],[2]	1,655	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	807	[1],[2]	854	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	807	[1],[2]	854	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1,140	[1],[2]	1,557	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1,140	[1],[2]	1,557	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	805	[1],[2]	783	[1],[2]
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	805	[1],[2]	783	[1],[2]
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Liability value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Liability value	62	[1]	60	[1]
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1]	5	[1]
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1]	5	[1]
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	57	[1]	55	[1]
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	57	[1]	55	[1]
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Liability value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Liability value	62	[1]	60	[1]
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1]	5	[1]
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	5	[1]	5	[1]
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	57	[1]	55	[1]
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	$ 57	[1]	$ 55	[1]

[1] Represents the location on the Balance Sheet.

[2] $479 million and $237 million of net gains associated with derivatives that were no longer designated as hedging instruments are recorded in AOCI at September 30, 2012 and December 31, 2011.