Derivative Instruments and Hedging Activities (Risk Disclosures) (Details) $ in Millions, £ in Billions	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 GBP (£)	Sep. 30, 2016 GBP (£)
Cash Flow Hedges [Member] | Interest Rate Swaps [Member]
Interest Rate Risk - Cash Flow Hedges (Numeric) [Abstract]
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness			$ 0	$ 0
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net			$ 0		$ 0
Cash Flow Hedges [Member] | Cross Currency Interest Rate Swaps [Member]
Interest Rate Risk - Cash Flow Hedges (Numeric) [Abstract]
Earliest maturity date of cross-currency cash flow hedge contracts			2021
Latest maturity date of cross-currency cash flow hedge contracts			2028
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness			$ 0	0	0
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount			702
Economic Hedges [Member] | Foreign Currency Contracts [Member]
Foreign Currency Risk - Economic Activity (Numeric) [Abstract]
Total exposure hedged related to foreign currency contracts for anticipated earnings hedges classified as economic activity			$ 2,200			£ 1.5
Earliest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			Jan. 31, 2019
Latest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity			Oct. 30, 2020
Economic Hedges [Member] | Foreign Currency Contracts [Member] | Hedges 2017 and 2018 [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount		$ 2,000					£ 1.3
Foreign Currency Risk - Economic Activity (Numeric) [Abstract]
Earliest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity		Jan. 31, 2017
Latest termination date of foreign currency contracts for anticipated earnings hedges classified as economic activity		Nov. 30, 2018
Derivative Cash Received On Hedge		$ 310
Net Investment Hedges [Member] | Foreign Currency Contracts [Member]
Foreign Currency Risk - Net Investment Hedges (Numeric) [Abstract]
Net after tax gains (losses) on net investment hedges recognized in the foreign currency translation adjustment component of AOCI			$ 31	22
LGE [Member] | Economic Hedges [Member] | Interest Rate Swaps [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount			147
Notional amount of terminated swaps	$ 32
Net cash settlements on terminated interest rate swaps			$ 9
Year of expiration of the maximum maturity date of interest rate economic activity contracts			2033
LG And E And KU Energy LLC [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Net cash settlements on terminated interest rate swaps			$ 0	0	9
LG And E And KU Energy LLC [Member] | LGE [Member] | Economic Hedges [Member] | Interest Rate Swaps [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount			147
Notional amount of terminated swaps	32
Net cash settlements on terminated interest rate swaps			$ 9
Year of expiration of the maximum maturity date of interest rate economic activity contracts			2033
Louisville Gas And Electric Co [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Net cash settlements on terminated interest rate swaps			$ 0	$ 0	$ 9
Louisville Gas And Electric Co [Member] | Economic Hedges [Member] | Interest Rate Swaps [Member]
Interest Rate Risk - Economic Activity (Numeric) [Abstract]
Notional amount			147
Notional amount of terminated swaps	$ 32
Net cash settlements on terminated interest rate swaps			$ 9
Year of expiration of the maximum maturity date of interest rate economic activity contracts			2033