Utility Rate Regulation (Details) (USD $)	1 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2011	Apr. 30, 2011	Jun. 30, 2011	Jun. 30, 2011 Tons Kilovolts MW Gallons	Dec. 31, 2010
Regulatory Asset [Line Items]
Current regulatory assets	$ 25,000,000		$ 25,000,000	$ 25,000,000	$ 85,000,000
Noncurrent regulatory assets	1,200,000,000		1,200,000,000	1,200,000,000	1,180,000,000
Regulatory Liabilities [Line Items]
Current regulatory liabilities	77,000,000		77,000,000	77,000,000	109,000,000
Noncurrent regulatory liabilities	1,023,000,000		1,023,000,000	1,023,000,000	1,031,000,000
Regulatory Matters - Kentucky Activities - Environmental Upgrades (Numeric)
June 2011 request to KPSC of amount for environmental upgrades	2,500,000,000
LG&E portion of total cost of request to KPSC	1,400,000,000
Projected percentage, in hundreths, impact on LG&E's customers rates in 2012	2.30%
Projected percentage, in hundreths, impact on LG&E's customers rates in 2016	19.20%
KU portion of total cost of request to KPSC	1,100,000,000
Projected percentage, in hundreths, impact on KU's customers rates in 2012	1.50%
Projected percentage, in hundreths, impact on KU's customers rates in 2016	12.20%
Regulatory Matters - Kentucky Activities - Integrated Resource Planning (Numeric)
IRP regulation assumption of capacity, in MW, of retirements of coal-fired generation in 2016				800
IRP regulation assumption of reductions, in MW, of peak demand by 2017				500
Regulatory Matters - Virginia Activities - Rate Case (Numeric)
Dollar amount of requested increase (decrease) to electric base rates in Virginia for KU		9,000,000
Percentage increase (decrease) to electric base rates in Virginia for KU		14.00%
Return on rate base of increase (decrease) of requested increase to electric base rates in Virginia for KU		8.00%
Return on equity of increase (decrease) of requested increase to electric base rates in Virginia for KU		11.00%
Regulatory Matters - Virginia Activities - Storm Costs (Numeric)
Amount requested for deferral related to storm costs				6,000,000
Regulatory Matters - Pennsylvania Activities (Numeric)
Under Act 129, percentage reduction in electricity consumption by 2011				1.00%
Under Act 129, percentage reduction in electricity consumption by 2013				3.00%
Number of hours that are the benchmark for demand reductions by 2013				100
Under Act 129, percentage reduction in peak demand electricity consumption by 2013			4.50%
Under Act 129, percentage cap on costs that can be recovered for implementation of EE and C plan				2.00%
Number of programs included in EE and C plan				14
Number of components of EE and C Plan company requested permission to modify				2
Maximum number of years the cost of smart meters can be depreciated				15
Estimated cost for studies on smart meter capabilities	38,000,000		38,000,000	38,000,000
The time period covered by cost projection for studies on smart meter capabilities (in years)				5
Minimum term of long term supply contract under Act 129 (in years)				4
Maximum term of long term supply contract under Act 129 (in years)				20
Maximum percentage of long-term contracts that can be included in the mix of PLR supply contracts under Act 129				25.00%
Regulatory Matters - International Activities - U.K. Overhead Electricity Networks (Numeric)
Horizontal clearance that requires insulation or relocation of overhead lines in the U.K. (in meters)				3
WPD's projected cost for compliance with overhead electricity standards	126,000,000		126,000,000	126,000,000
Period over which WPD's projected costs to comply with overhead electricity standards are allowed to be recovered in rates (in years)				5
Number of years WPD has to implement vegetation management program				25
Projected costs to implement program for vegetation management	208,000,000		208,000,000	208,000,000
Period over which WPD's projected costs for vegetation management program are allowed to be recovered in rates (in years)				5
Regulatory Matters - New U.K. Pricing Model (Numeric)
Period, in years, in which the price control formula is normally reviewed			5
Generation Supply Charge [Member]
Regulatory Asset [Line Items]
Current regulatory assets	0		0	0	45,000,000
Generation Supply Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	16,000,000		16,000,000	16,000,000	0
Universal Service Rider [Member]
Regulatory Asset [Line Items]
Current regulatory assets	6,000,000		6,000,000	6,000,000	10,000,000
Defined Benefit Plans [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	588,000,000		588,000,000	588,000,000	592,000,000
Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	10,000,000		10,000,000	10,000,000	10,000,000
Taxes Recoverable Through Future Rates [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	268,000,000		268,000,000	268,000,000	254,000,000
Storm Costs [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	128,000,000		128,000,000	128,000,000	129,000,000
Unamortized Loss Reacquired Debt [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	58,000,000		58,000,000	58,000,000	61,000,000
Interest Rate Swaps [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	44,000,000		44,000,000	44,000,000	43,000,000
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	40,000,000		40,000,000	40,000,000	35,000,000
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	638,000,000		638,000,000	638,000,000	623,000,000
Coal Contracts [Member]
Regulatory Asset [Line Items]
Noncurrent regulatory assets	16,000,000		16,000,000	16,000,000	22,000,000
Coal Contracts [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	23,000,000		23,000,000	23,000,000	46,000,000
Noncurrent regulatory liabilities	197,000,000		197,000,000	197,000,000	213,000,000
ECR [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	9,000,000		9,000,000	9,000,000	12,000,000
Other Regulatory Asset [Member]
Regulatory Asset [Line Items]
Current regulatory assets	19,000,000		19,000,000	19,000,000	30,000,000
Noncurrent regulatory assets	58,000,000		58,000,000	58,000,000	44,000,000
PURTA Tax [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	5,000,000		5,000,000	5,000,000	10,000,000
Transmission Service Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0		0	0	8,000,000
Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	120,000,000		120,000,000	120,000,000	124,000,000
Act 129 Compliance Rider [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	15,000,000		15,000,000	15,000,000	14,000,000
Net Deferred Tax Assets [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	36,000,000		36,000,000	36,000,000	40,000,000
Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	24,000,000		24,000,000	24,000,000	33,000,000
Noncurrent regulatory liabilities	$ 7,000,000		$ 7,000,000	$ 7,000,000	$ 7,000,000