Derivative Instruments and Hedging Activities (Risk Disclosures) (Details)	3 Months Ended		6 Months Ended				6 Months Ended
	Jun. 30, 2013 USD ($)	Jun. 30, 2012	Jun. 30, 2013 USD ($)	Jun. 30, 2012	Jun. 30, 2013 GBP (£)	Dec. 31, 2012 USD ($)	Jun. 30, 2013 WPD [Member] USD ($)	Jun. 30, 2013 WPD [Member] GBP (£)	Jun. 30, 2013 LG And E And KU Energy LLC [Member] USD ($)	Jun. 30, 2013 LG And E And KU Energy LLC [Member] LGE [Member] USD ($)	Jun. 30, 2013 LG And E And KU Energy LLC [Member] KU [Member] USD ($)	Jun. 30, 2013 Louisville Gas And Electric Co [Member] USD ($)	Jun. 30, 2013 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			2044				2024	2024		2043	2043	2043	2043
Notional value of interest rate cash flow hedge contracts (excludes cross-currency contracts)	$ 1,900,000,000		$ 1,900,000,000				$ 455,000,000	£ 300,000,000		$ 250,000,000	$ 250,000,000	$ 250,000,000	$ 250,000,000
Net notional value of cross-currency cash flow hedge contracts	1,300,000,000		1,300,000,000
Latest maturity date of cross-currency cash flow hedge contracts	2028		2028
Insignificant or no hedge ineffectiveness associated with interest rate cash flow hedges	insignificant	insignificant	insignificant	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 such reclassifications	no such reclassifications
Net unrealized after-tax gains (losses) on interest rate cash flow hedge contracts expected to be reclassified into earnings during next 12 months	(12,000,000)		(12,000,000)
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			179,000,000
Year of expiration of the maximum maturity date of interest rate economic activity contracts			2033						2033			2033
Foreign Currency Risk - Net Investment Hedges (Numeric) [Abstract]
Notional amount of net investment hedge contracts	263,000,000		263,000,000		166,000,000
Earliest settlement date of net investment hedge contracts			November 2013
Latest settlement date of net investment hedge contracts			June 2014
Notional amount outstanding on intercompany loan qualified as a net investment hedge	142,000,000		142,000,000		94,000,000
Net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI	2,000,000		6,000,000
Insignificant or no net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI		insignificant		insignificant
Net after tax gains (losses) on net investment hedges included in the foreign currency translation adjustment component of AOCI	29,000,000		29,000,000			14,000,000
Foreign Currency Risk - Economic Activity (Numeric) [Abstract]
Total exposure hedged related to foreign currency contracts for anticipated earnings hedges classified as economic activity	$ 1,900,000,000		$ 1,900,000,000		£ 1,200,000,000
Earliest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			July 2013
Latest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			June 2015