Derivative Instruments and Hedging Activities (Fair Values) (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Derivatives Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		$ 200	$ 96
Liability value		42	24
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	83	45
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1],[2]	71	35
Derivatives Designated As Hedging Instruments [Member] | Current Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	12	10
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	117	51
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1],[2]	117	51
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1]	42	24
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1],[2]	42	24
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		237	199
Liability value		56	48
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	100	94
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Current Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	100	94
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	137	105
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Assets [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value	[1]	137	105
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1]	9	6
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1],[2]	6	5
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Current Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1]	3	1
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1]	47	42
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Interest Rate Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value	[1],[2]	47	42
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Cross Currency Swaps [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
Derivatives Not Designated As Hedging Instruments [Member] | Noncurrent Liabilities [Member] | Foreign Currency Contracts [Member]
Fair Values by Balance Sheet Location [Abstract]
Liability value		0	0
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Liability value		53	47
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		0	0
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		0	0
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		0	0
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		0	0
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		6	5
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	[3]	6	5
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		47	42
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	[3]	47	42
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Fair Values by Balance Sheet Location [Abstract]
Asset value		0	0
Liability value		53	47
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		0	0
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		0	0
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		0	0
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		0	0
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		6	5
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	[3]	6	5
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		47	42
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	[3]	$ 47	$ 42

[1] Current portion is included in " Price risk management assets " and "Other current liabilities" and noncurrent portion is included in " Price risk management assets " and "Other deferred credits and noncurrent liabilities" on the B alance S heets .

[2] Excludes accrued interest, if applicable.

[3] Represents the location on the Balance Sheet s .