Commitments and Contingencies (Environmental Matter and Other) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 gal MW Integer	Apr. 30, 2013
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (formerly Clean Air Transport Rule) and Clean Air Interstate Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented	2
Environmental Matters - Domestic - Air - Mercury and Air Toxics (Numeric) [Abstract]
Period for compliance with final mercury and air toxics standards (in years)	3
Possible period of extension to comply with final mercury and air toxics standards (in years)	1
Carrying value of Corette plant in Montana that is being moved to long-term reserve status	$ 65,000,000
Environmental Matters - Domestic - Air - Greenhouse Gas Regulations and Tort Litigation (Numeric) [Abstract]
Number of northeastern states that signed a Memorandum of Understanding that established Regional Greenhouse Gas Initiative	10
Minimum capacity of electric power plants that are impacted by Regional Greenhouse Gas Initiative's emissions stabilization program (in MW)	25
Percentage reduction by 2019 in carbon dioxide emissions under Regional Greenhouse Gas Initiative	10.00%
Maximum percentage reduction in greenhouse gas emissions by implementing actions identified in a Pennsylvania 2009 report	30.00%
Proposed mandatory percentage improvement at power plants	5.00%
Number of western states that are members of the Western Climate Initiative	11
Western Climate Initiative's target percentage for reducing carbon dioxide emissions	15.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision	5
Number of companies cited in May 2011 Mississippi court filing	87
Number of indirect subsidaries cited in a May 2011 Mississippi court filing	3
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Proposed amount of funding for solar projects	25,000,000
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of approaches proposed by EPA in June 2010 to regulate CCRs	2
Period included in notice of intent to sue the Environmental Protection Agency (in days)	60
Number of companies that have issued an intent to sue against the EPA regarding CCRs	2
Environmental Matters - Domestic - Water/Waste - Martins Creek Fly Ash Release (Numeric) [Abstract]
Gallons of water released at the Martins Creek plant in 2005 that contained fly ash	100,000,000
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
Period for PPL Montana to provide financial assurance to Montana Department of Environmental Quality (in years)	5
Environmental Matters - Domestic - Water/Waste - Clean Water Act 316(b) (Numeric) [Abstract]
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms	2
Number of factors to make a site-specific determination	9
Other - Nuclear Insurance (Numeric) [Abstract]
Maximum amount of insured property damage losses at nuclear station		2,500,000,000
Maximum assessment for retroactive premiums for nuclear outage insurance coverage		46,000,000
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
PPL Energy Supply LLC [Member]
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (formerly Clean Air Transport Rule) and Clean Air Interstate Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented	2
Environmental Matters - Domestic - Air - Mercury and Air Toxics (Numeric) [Abstract]
Period for compliance with final mercury and air toxics standards (in years)	3
Possible period of extension to comply with final mercury and air toxics standards (in years)	1
Carrying value of Corette plant in Montana that is being moved to long-term reserve status	65,000,000
Environmental Matters - Domestic - Air - Greenhouse Gas Regulations and Tort Litigation (Numeric) [Abstract]
Number of northeastern states that signed a Memorandum of Understanding that established Regional Greenhouse Gas Initiative	10
Minimum capacity of electric power plants that are impacted by Regional Greenhouse Gas Initiative's emissions stabilization program (in MW)	25
Percentage reduction by 2019 in carbon dioxide emissions under Regional Greenhouse Gas Initiative	10.00%
Maximum percentage reduction in greenhouse gas emissions by implementing actions identified in a Pennsylvania 2009 report	30.00%
Proposed mandatory percentage improvement at power plants	5.00%
Number of western states that are members of the Western Climate Initiative	11
Western Climate Initiative's target percentage for reducing carbon dioxide emissions	15.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision	5
Number of companies cited in May 2011 Mississippi court filing	87
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Proposed amount of funding for solar projects	25,000,000
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of approaches proposed by EPA in June 2010 to regulate CCRs	2
Period included in notice of intent to sue the Environmental Protection Agency (in days)	60
Number of companies that have issued an intent to sue against the EPA regarding CCRs	2
Environmental Matters - Domestic - Water/Waste - Martins Creek Fly Ash Release (Numeric) [Abstract]
Gallons of water released at the Martins Creek plant in 2005 that contained fly ash	100,000,000
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
Period for PPL Montana to provide financial assurance to Montana Department of Environmental Quality (in years)	5
Environmental Matters - Domestic - Water/Waste - Clean Water Act 316(b) (Numeric) [Abstract]
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms	2
Number of factors to make a site-specific determination	9
Other - Nuclear Insurance (Numeric) [Abstract]
Maximum amount of insured property damage losses at nuclear station		2,500,000,000
Maximum assessment for retroactive premiums for nuclear outage insurance coverage		46,000,000
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
LG And E And KU Energy LLC [Member]
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (formerly Clean Air Transport Rule) and Clean Air Interstate Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented	2
Environmental Matters - Domestic - Air - Mercury and Air Toxics (Numeric) [Abstract]
Period for compliance with final mercury and air toxics standards (in years)	3
Possible period of extension to comply with final mercury and air toxics 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 Regional Greenhouse Gas Initiative	10
Minimum capacity of electric power plants that are impacted by Regional Greenhouse Gas Initiative's emissions stabilization program (in MW)	25
Percentage reduction by 2019 in carbon dioxide emissions under Regional Greenhouse Gas Initiative	10.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision	5
Number of companies cited in May 2011 Mississippi court filing	87
Number of indirect subsidaries cited in a May 2011 Mississippi court filing	3
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Proposed amount of funding for solar projects	25,000,000
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of approaches proposed by EPA in June 2010 to regulate CCRs	2
Period included in notice of intent to sue the Environmental Protection Agency (in days)	60
Number of companies that have issued an intent to sue against the EPA regarding CCRs	2
Environmental Matters - Domestic - Water/Waste - Clean Water Act 316(b) (Numeric) [Abstract]
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms	2
Number of factors to make a site-specific determination	9
Louisville Gas And Electric Co [Member]
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (formerly Clean Air Transport Rule) and Clean Air Interstate Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented	2
Environmental Matters - Domestic - Air - Mercury and Air Toxics (Numeric) [Abstract]
Period for compliance with final mercury and air toxics standards (in years)	3
Possible period of extension to comply with final mercury and air toxics 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 Regional Greenhouse Gas Initiative	10
Minimum capacity of electric power plants that are impacted by Regional Greenhouse Gas Initiative's emissions stabilization program (in MW)	25
Percentage reduction by 2019 in carbon dioxide emissions under Regional Greenhouse Gas Initiative	10.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision	5
Number of companies cited in May 2011 Mississippi court filing	87
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Proposed amount of funding for solar projects	25,000,000
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of approaches proposed by EPA in June 2010 to regulate CCRs	2
Period included in notice of intent to sue the Environmental Protection Agency (in days)	60
Number of companies that have issued an intent to sue against the EPA regarding CCRs	2
Environmental Matters - Domestic - Water/Waste - Clean Water Act 316(b) (Numeric) [Abstract]
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms	2
Number of factors to make a site-specific determination	9
Kentucky Utilities Co [Member]
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (formerly Clean Air Transport Rule) and Clean Air Interstate Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented	2
Environmental Matters - Domestic - Air - Mercury and Air Toxics (Numeric) [Abstract]
Period for compliance with final mercury and air toxics standards (in years)	3
Possible period of extension to comply with final mercury and air toxics 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 Regional Greenhouse Gas Initiative	10
Minimum capacity of electric power plants that are impacted by Regional Greenhouse Gas Initiative's emissions stabilization program (in MW)	25
Percentage reduction by 2019 in carbon dioxide emissions under Regional Greenhouse Gas Initiative	10.00%
Number of electric utility companies affected by a September 2009 U.S. Court of Appeals for the Second Circuit decision	5
Number of companies cited in May 2011 Mississippi court filing	87
Environmental Matters - Domestic - Air - Renewable Energy Legislation (Numeric) [Abstract]
Proposed amount of funding for solar projects	$ 25,000,000
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (Numeric) [Abstract]
Number of approaches proposed by EPA in June 2010 to regulate CCRs	2
Period included in notice of intent to sue the Environmental Protection Agency (in days)	60
Number of companies that have issued an intent to sue against the EPA regarding CCRs	2
Environmental Matters - Domestic - Water/Waste - Clean Water Act 316(b) (Numeric) [Abstract]
Number of requirements under proposed EPA rule regarding reducing impact to aquatic organisms	2
Number of factors to make a site-specific determination	9