Derivative Instruments and Hedging Activities (Risk Disclosures) (Details)	3 Months Ended				3 Months Ended
	Mar. 31, 2014 Cash Flow Hedges [Member] USD ($)	Mar. 31, 2013 Cash Flow Hedges [Member]	Mar. 31, 2014 Cash Flow Hedges [Member] Interest Rate Swap Contracts [Member] USD ($)	Mar. 31, 2014 Cash Flow Hedges [Member] Cross Currency Interest Rate Swaps [Member] USD ($)	Mar. 31, 2014 Economic Hedges [Member] Interest Rate Swap Contracts [Member] USD ($)	Mar. 31, 2014 Economic Hedges [Member] Foreign Currency Contracts [Member] USD ($)	Mar. 31, 2014 Economic Hedges [Member] Foreign Currency Contracts [Member] GBP (£)	Mar. 31, 2014 Net Investment Hedges [Member] Foreign Currency Contracts [Member] USD ($)	Mar. 31, 2014 Net Investment Hedges [Member] Foreign Currency Contracts [Member] GBP (£)	Mar. 31, 2014 Net Investment Hedges [Member] Intercompany Loans [Member]	Mar. 31, 2013 Net Investment Hedges [Member] Intercompany Loans [Member] USD ($)	Mar. 31, 2014 WPD [Member] Net Investment Hedges [Member] Intercompany Loans [Member] USD ($)	Mar. 31, 2014 WPD [Member] Net Investment Hedges [Member] Intercompany Loans [Member] GBP (£)	Mar. 31, 2014 LG And E And KU Energy LLC [Member] Economic Hedges [Member] Interest Rate Swap Contracts [Member] USD ($)	Mar. 31, 2014 Louisville Gas And Electric Co [Member] Economic Hedges [Member] Interest Rate Swap Contracts [Member] USD ($)
Interest Rate Risk And Foreign Currency Risk [Line Items]
Notional amount			$ 500,000,000	$ 1,300,000,000	$ 179,000,000			$ 549,000,000	£ 345,000,000					$ 179,000,000	$ 179,000,000
Notional amount of nonderivative instruments												67,000,000	40,000,000
Interest Rate Risk - Cash Flow Hedges (Numeric) [Abstract]
Year of expiration of the maximum maturity date of interest rate cash flow hedge contracts			2025
Latest maturity date of cross-currency cash flow hedge contracts				2028
Insignificant or no hedge ineffectiveness associated with interest rate cash flow hedges	insignificant	insignificant
No or insignificant after-tax gains (losses) previously recorded in AOCI reclassified to earnings related to interest rate cash flow hedge contracts	insignificant	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)
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
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]
Earliest settlement date of net investment hedge contracts								May 2014	May 2014
Latest settlement date of net investment hedge contracts								December 2015	December 2015
Net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI											5,000,000
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								(5,000,000)
Foreign Currency Risk - Economic Activity (Numeric) [Abstract]
Total exposure hedged related to foreign currency contracts for anticipated earnings hedges classified as economic activity						$ 3,000,000,000	£ 1,800,000,000
Earliest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity						April 2014	April 2014
Latest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity						October 2016	October 2016