Commitments and Contingencies (Environmental Matter and Other) (Details) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended
	Jul. 31, 2011	Sep. 30, 2011 MW Kilovolts Gallons	Dec. 31, 2010 Tons	Dec. 31, 2009 Tons
Environmental Matters - Domestic - Air (Numeric) [Abstract]
Period over which capital expenditures are projected (in years)		5
Projected costs to comply with air matters for regulated subsidiaries		$ 3,100,000,000
Projected costs to comply with air matters for subsidiary that have been approved by state regulator		600,000,000
Projected costs to comply with air matters for subsidiary that are pending approval by state regulator		2,500,000,000
Projected costs to comply with air matters for unregulated subsidiary		400,000,000
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule formerly Clean Air Transport Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented		2
Environmental Matters - Domestic - Air - National Ambient Air Quality Standards [Abstract]
Standard for sulfur dioxide emissions (in hours)		1
Environmental Matters - Domestic - Air - Mercury and other Hazardous Air Pollutants (Numeric) [Abstract]
Period for compliance with final MACT standards (in years)		3
Possible period of extension to comply with final MACT standards (in years)		1
Environmental Matters - Domestic - AIR - Greenhouse Gas Regulations and Tort Litigation (Numeric) [Abstract]
Number of northeastern states that signed a Memorandum of Understanding that established RGGI		10
Minimum capacity of electric power plants that are impacted by RGGI's emissions stabilization program (in MW)		25
Percentage reduction by 2019 in carbon dioxide emissions under RGGI (in hundredths)		10.00%
Maximum percentage reduction in greenhouse gas emissions by implementing actions identified in a Pennsylvania 2009 report (in hundredths)		30.00%
Proposed mandatory percentage improvement at power plants (in hundredths)		5.00%
Number of western states that are members of the WCI		11
Number of companies cited in May 2011 Mississippi court filing		87
WCI's target percentage for reducing carbon dioxide emissions (in hundredths)		15.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision		5
Carbon dioxide emitted from PPL power plants during the reporting period (in millions of tons)			37	29
Carbon dioxide emitted from LKE power plants during the reporting period (in millions of tons)			6
Number of pounds in a ton of carbon dioxide emissions		2,000
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Minimum percentage of renewable energy supply and energy efficiency required by 2020 (in hundredths)		15.00%
Maximum percentage of renewable energy supply and energy efficiency required by 2020 (in hundredths)		20.00%
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of non-affiliated plants asked to respond to EPA regarding CCRs		18
Environmental Matters - Domestic - Water/Waste - Martins Creek Fly Ash Release (Numeric) [Abstract]
Millions of gallons of water released at the Martins Creek plant in 2005 that contained fly ash		100
Number of coal-fired generating units at the Martins Creek plant at the time of fly ash release		2
Capacity of each coal-fired generating unit at the Martins Creek plant (in MW)		150
Amounts incurred through period end for remediation and related costs related to 2005 Martins Creek fly ash release		28,000,000
Environmental Matters - Domestic - Water/Waste - Seepages and Groundwater Infiltration - Pennsylvania, Montana and Kentucky (Numeric) [Abstract]
Number of plaintiffs that filed a lawsuit against the Colstrip plant owners in 2007 for seepage issues		6
Period to complete a settlement (in days)		60
Environmental Matters - Domestic - Water/Waste - Conemaugh River Discharges (Numeric) [Abstract]
Percentage ownership, in hundreths, in generation station		16.25%
Environmental Matters - Domestic - Water/Waste - Other Issues (Numeric) [Abstract]
EPA's current drinking water standard relating to arsenic (in parts per billion)		10
Increase in cancer risk related to arsenic in drinking water		20 times
The EPA's proposed drinking water standard relating to arsenic (in parts per billion)		0.1
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms		2
Number of factors to make a site-specific determination		9
Estimated cost to construct a debris barrier at Brunner Island's river water intake area		4,000,000
Number of alternatives provided to the DEP to address fish kill issues at Brunner Island		3
Environmental Matters - Domestic - Superfund and Other Remediation (Numeric) [Abstract]
Number of PPL Generation subsidiaries that are pumping mine water at two mine sites		1
Number of mine sites where mine water is being pumped by a PPL Generation subsidiary		2
Number of mine sites where mine water is being treated by a PPL Generation subsidiary		1
Period end recorded discounted liability for the cost of pumping and treating groundwater, and operating and maintaining a passive wetlands treatment center		26,000,000
Period of years used to calculate discounted environmental liability		50
Weighted average discount rate applied to calculate the liability (in hundredths)		8.16%
Expected undiscounted payments per year related to pumping and treating groundwater, and operating and maintaining a passive wetlands treatment center for 2011		2,000,000
Expected undiscounted payments per year related to pumping and treating groundwater, and operating and maintaining a passive wetlands treatment center for each of the years 2012 through 2014		1,000,000
Expected undiscounted payments per year related to pumping and treating groundwater, and operating and maintaining a passive wetlands treatment center for 2015		2,000,000
Expected undiscounted payments per year related to pumping and treating groundwater, and operating and maintaining a passive wetlands treatment center after 2015		137,000,000
Environmental Matters - Domestic - Superfund and Other Remediation - Electric and Magnetic Fields (Numeric) [Abstract]
Number of reports issued by The Stakeholder Group on Extremely Low Frequency EMF		2
Kilovolt capacity of overhead lines proposed in the U.K. be phased out to reduce exposure to EMFs		132
Environmental Matters - WPD (Numeric) [Abstract]
Amount WPD committed to Ofgem to spend on flood prevention		46,000,000
Period over which WPD can recover costs spent on flood prevention (in years)		5
Number of distribution operators in the U.K.		4
Other - Nuclear Insurance (Numeric) [Abstract]
Maximum amount of insured property damage losses at nuclear station		2,750,000,000
Maximum assessment for retroactive premiums for nuclear outage insurance coverage		44,000,000
Maximum public liability for claims resulting an incident at nuclear station		12,600,000,000
Maximum amount that could be assessed resulting from an incident at nuclear station		235,000,000
Maximum amount payable per year resulting from an incident at nuclear station		$ 35,000,000
Other - Employee Relations (Numeric) [Abstract]
Period, in months, of extension to labor contract with certain KU employees	6
Percentage, in hundreths, increase to wages as part of extension to labor contract with certain KU employees	3.00%