Derivative Instruments and Hedging Activities (Risk Disclosures) (Details)	1 Months Ended	3 Months Ended	12 Months Ended					12 Months Ended					12 Months Ended
	Jul. 31, 2012 USD ($)	Jun. 30, 2011 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 GBP (£)	Dec. 31, 2011 GBP (£)	Dec. 31, 2012 WPD [Member] USD ($)	Dec. 31, 2012 WPD [Member] GBP (£)	Dec. 31, 2010 PPL Energy Supply LLC [Member]	Dec. 31, 2012 LG And E And KU Energy LLC [Member] USD ($)	Dec. 31, 2011 LG And E And KU Energy LLC [Member] USD ($)	Dec. 31, 2012 LG And E And KU Energy LLC [Member] LGE [Member] USD ($)	Dec. 31, 2012 LG And E And KU Energy LLC [Member] KU [Member] USD ($)	Dec. 31, 2012 Louisville Gas And Electric Co [Member] USD ($)	Dec. 31, 2011 Louisville Gas And Electric Co [Member] USD ($)	Dec. 31, 2012 Kentucky Utilities Co [Member] USD ($)
Interest Rate Risk - Cash Flow Hedges (Numeric) [Abstract]
Year of expiration of the maximum maturity date of interest rate cash flow hedge contracts			2043					2024	2024				2043	2043
Notional value of interest rate cash flow hedge contracts (excludes cross-currency contracts)			$ 1,200,000,000					$ 465,000,000	£ 290,000,000				$ 150,000,000	$ 150,000,000	$ 150,000,000		$ 150,000,000
Net notional value of cross-currency cash flow hedge contracts			1,300,000,000
Latest maturity date of cross-currency cash flow hedge contracts			2028
Insignificant or no hedge ineffectiveness associated with interest rate cash flow hedges			insignificant
Hedge ineffectiveness associated with interest rate cash flow hedges		(4,000,000)		(9,000,000)	(9,000,000)
No or insignificant hedge ineffectiveness associated with cross-currency cash flow hedge contracts										insignificant
No or insignificant after-tax gains (losses) previously recorded in AOCI reclassified to earnings related to interest rate cash flow hedge contracts			no such reclassifications	no such reclassifications						no reclassifications
After-tax gains (losses) previously recorded in AOCI reclassified to earnings related to interest rate cash flow hedge contracts					(19,000,000)
Net unrealized after-tax gains (losses) on interest rate cash flow hedge contracts expected to be reclassified into earnings during next 12 months			(13,000,000)
Interest Rate Risk - Fair Value Hedges (Numeric) [Abstract]
Year of expiration of the maximum maturity date of interest rate fair value hedge contracts	2047
Notional value of interest rate fair value hedges	99,000,000
No or insignificant hedge ineffectiveness associated with interest rate fair value hedges			did not recognize	did not recognize	did not recognize					did not recognize
No or insignificant gains (losses) associated with interest rate fair value hedges being excluded from the assessment of hedge effectiveness			did not recognize	did not recognize	did not recognize					did not recognize
No or insignificant gain (loss) resulting from firm commitments that no longer qualified as interest rate fair value hedges			did not recognize	did not recognize	did not recognize					did not recognize
Principal amount of debt related to discontinuance of fair value hedge				400,000,000
Gain (loss) resulting from firm commitments no longer qualifying as interest rate fair value hedges, pre-tax				22,000,000
Gain (loss) resulting from firm commitments that no longer qualified as interest rate fair value hedges, after-tax				14,000,000
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount of interest rate swaps classified as economic activity			179,000,000								179,000,000				179,000,000
Year of expiration of the maximum maturity date of interest rate economic activity contracts			2033								2033				2033
The fair value, net (asset) or liability, of interest rate swap contracts classified as economic activity			58,000,000	60,000,000							58,000,000	60,000,000			58,000,000	60,000,000
Foreign Currency Risk - Cash Flow Hedges (Numeric) [Abstract]
No or insignificant after-tax gains (losses) previously recorded in AOCI reclassified to earnings related to foreign currency cash flow hedge contracts			no cash flow hedges were discontinued	no cash flow hedges were discontinued	no cash flow hedges were discontinued
No or insignificant unrealized after-tax gains (losses) on foreign currency cash flow hedge contracts expected to be reclassified into earnings during next 12 months			Insignificant
Foreign Currency Risk - Fair Value Hedges (Numeric) [Abstract]
No or insignificant hedge ineffectiveness associated with foreign currency fair value hedges			no gains or losses	no gains or losses	no gains or losses
No or insignificant gains (losses) associated with foreign currency fair value hedges being excluded from the assessment of hedge effectiveness			no gains or losses	no gains or losses	no gains or losses
No or insignificant gain (loss) resulting from firm commitments that no longer qualified as foreign currency fair value hedges			no gains or losses	no gains or losses	no gains or losses
Foreign Currency Risk - Net Investment Hedges (Numeric) [Abstract]
Notional amount of net investment hedge contracts			261,000,000			162,000,000
Earliest settlement date of net investment hedge contracts			May 2013
Latest settlement date of net investment hedge contracts			December 2013
Fair value of net asset (liability) position of net investment hedge contracts			(2,000,000)	7,000,000
Notional amount outstanding on intercompany loan qualified as a net investment hedge			76,000,000			47,000,000
Net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI			(5,000,000)	4,000,000	4,000,000
Insignificant or no net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI										insignificant
Net after tax gains (losses) on net investment hedges included in the foreign currency translation adjustment component of AOCI			14,000,000	19,000,000
Foreign Currency Risk - Economic Activity (Numeric) [Abstract]
Total exposure hedged related to foreign currency contracts for anticipated earnings hedges classified as economic activity			2,000,000,000			1,300,000,000	288,000,000
Fair value of net asset or (liability) position of foreign currency contracts for anticipated earnings hedges classified as economic activity			(42,000,000)	11,000,000
Earliest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			January 2013
Latest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			February 2015
Gains (losses) on foreign currency contracts for anticipated earnings hedges classified as economic activity			(52,000,000)	10,000,000
Insignificant or no gains (losses) on foreign currency contracts for anticipated earnings hedges classified as economic activity					insignificant
Gains (losses) on foreign currency contracts related to debt or commitments hedged with foreign currency contracts classified as economic activity				$ 55,000,000
Insignificant or no gains (losses) on foreign currency contracts related to debt or commitments hedged with foreign currency contracts classified as economic activity										insignificant