Derivative Instruments and Hedging Activities (Fair Values) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 1,882		$ 2,097
Liability value	1,505		1,694
Net pre-tax gains (losses) included in AOCI related to derivatives not designated as hedging instruments	324		300
Accumulated after-tax net gains (losses), excluding net investment hedges, included in AOCI	114		132		471	527
Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	125	[1]	115	[1]
Liability value	16	[1]	28	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	41	[1]	73	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	24	[1]	14	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	2	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	15	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			59	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	84	[1]	42	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	3	[1]	1	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	81	[1]	14	[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			27	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	16	[1]	27	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	15	[1]	22	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	1	[1]	3	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value			2	[1]
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value			1	[1]
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value			1	[1]
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
Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,757	[1],[2]	1,982	[1],[2]
Liability value	1,489	[1],[2]	1,666	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,243	[1],[2]	1,452	[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	49	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,194	[1],[2]	1,452	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	514	[1],[2]	530	[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	32	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	482	[1],[2]	530	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	956	[1],[2]	1,038	[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			23	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	951	[1],[2]	1,010	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	533	[1],[2]	628	[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	49	[1],[2]	53	[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	3	[1],[2]	19	[1],[2]
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	481	[1],[2]	556	[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	324		300
Accumulated after-tax net gains (losses), excluding net investment hedges, included in AOCI	181		211		522	605
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			86	[1]
Liability value
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			59	[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			59	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value			27	[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			27	[1]
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
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
PPL Energy Supply LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value
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
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	1,676	[1],[2]	1,982	[1],[2]
Liability value	1,432	[1],[2]	1,566	[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	1,194	[1],[2]	1,452	[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	1,194	[1],[2]	1,452	[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	482	[1],[2]	530	[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	482	[1],[2]	530	[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	951	[1],[2]	1,010	[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	951	[1],[2]	1,010	[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	481	[1],[2]	556	[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	481	[1],[2]	556	[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	24	[1]	14	[1]
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	24	[1]	14	[1]
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	24	[1]	14	[1]
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	54	[1]	58	[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	49	[1]	53	[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	49	[1]	53	[1]
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	12	[1]	7	[1]
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	12	[1]	7	[1]
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	12	[1]	7	[1]
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	54	[1]	58	[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	49	[1]	53	[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	49	[1]	53	[1]
Kentucky Utilities Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 12		$ 7

[1] Represents the location on the Balance Sheets.

[2] $324 million and $300 million of net gains associated with derivatives that were no longer designated as hedging instruments are recorded in AOCI at March 31, 2013 and December 31, 2012.