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Utility Rate Regulation (Regulatory Matters) (Details)
$ in Millions
1 Months Ended 9 Months Ended
Jul. 31, 2015
Sep. 30, 2015
USD ($)
Integer
Y
Sep. 30, 2014
USD ($)
Regulatory Matters - United Kingdom Activities - Ofgem Review of Line Loss Calculation (Numeric) [Abstract]      
Charge to income during period for line loss incentive/penalty liability   $ 0.0 $ 65.0
Liability at period end regarding line loss incentive/penalty   $ 75.0  
PPL Electric [Member]      
Regulatory Matters Pennsylvania Activities Numeric [Abstract]      
Number of ratemaking mechanisms authorized for PUC approval | Integer   2  
Regulatory Matters - Pennsylvania Activities - Distribution System Improvement Charge (Numeric) [Abstract]      
Current percentage of billed revenues allowable for the distribution system improvement charge   5.00%  
Requested percentage of billed revenues allowable for the distribution system improvement charge   7.50%  
Regulatory Matters - Pennsylvania Activities - Smart Meter Rider (Numeric) [Abstract]      
Maximum number of years the cost of smart meters can be depreciated | Y   15  
Projected cost of proposed smart meter replacement project   $ 450.0  
Portion of projected cost of proposed smart meters replacement project expected to be capital   328.0  
PPL Electric [Member] | Hurricane Sandy [Member]      
Regulatory Matters - Pennsylvania Activities - Storm Damage Expense Rider (Numeric) [Abstract]      
Amount of regulatory liability reversed   12.0  
Regulatory Matters - Storm Costs (Numeric) [Abstract]      
Amount of regulatory asset established   $ 29.0  
Period over which storm costs will be recovered (in years) | Y   3  
PPL Electric [Member] | Distribution Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 124.0  
Dollar amount requested increase in base rates with anticipated rate case filing   $ 167.5  
LGE [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which pension costs will be recovered   15 years  
LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 7.0  
KU [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which deferred costs associated with Green River Units 3 and 4 will be recovered   3 years  
Number of years over which pension costs will be recovered   15 years  
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 125.0  
KU [Member] | Federal Energy Regulatory Commission [Member]      
Regulatory Matters - Federal Matters - Federal Energy Regulatory Commission Wholesale Formula Rates (Numeric) [Abstract]      
Number of municipal customers impacted for Federal Energy Regulatory Commission formula rate request | Integer   12  
Number of municipalities that submitted termination notices, effective 2019 | Integer   9  
Number of municipalities that submitted termination notices, effective 2017 | Integer   1  
Number of municipalities that agreed to settlement terms of rate change request | Integer   2  
Return on equity authorized with respect to two municipalities   10.00%  
Return on equity in a settlement reached with respect to nine municipalities 10.25%    
Requested return on equity for certain wholesale customers   10.70%  
PPL Electric Utilities Corp [Member]      
Regulatory Matters Pennsylvania Activities Numeric [Abstract]      
Number of ratemaking mechanisms authorized for PUC approval | Integer   2  
Regulatory Matters - Pennsylvania Activities - Distribution System Improvement Charge (Numeric) [Abstract]      
Current percentage of billed revenues allowable for the distribution system improvement charge   5.00%  
Requested percentage of billed revenues allowable for the distribution system improvement charge   7.50%  
Regulatory Matters - Pennsylvania Activities - Smart Meter Rider (Numeric) [Abstract]      
Maximum number of years the cost of smart meters can be depreciated | Y   15  
Projected cost of proposed smart meter replacement project   $ 450.0  
Portion of projected cost of proposed smart meters replacement project expected to be capital   328.0  
PPL Electric Utilities Corp [Member] | Hurricane Sandy [Member]      
Regulatory Matters - Pennsylvania Activities - Storm Damage Expense Rider (Numeric) [Abstract]      
Amount of regulatory liability reversed   12.0  
Regulatory Matters - Storm Costs (Numeric) [Abstract]      
Amount of regulatory asset established   $ 29.0  
Period over which storm costs will be recovered (in years) | Y   3  
PPL Electric Utilities Corp [Member] | Distribution Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 124.0  
Dollar amount requested increase in base rates with anticipated rate case filing   $ 167.5  
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which pension costs will be recovered   15 years  
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 7.0  
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which deferred costs associated with Green River Units 3 and 4 will be recovered   3 years  
Number of years over which pension costs will be recovered   15 years  
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 125.0  
LG And E And KU Energy LLC [Member] | KU [Member] | Federal Energy Regulatory Commission [Member]      
Regulatory Matters - Federal Matters - Federal Energy Regulatory Commission Wholesale Formula Rates (Numeric) [Abstract]      
Number of municipal customers impacted for Federal Energy Regulatory Commission formula rate request | Integer   12  
Number of municipalities that submitted termination notices, effective 2019 | Integer   9  
Number of municipalities that submitted termination notices, effective 2017 | Integer   1  
Number of municipalities that agreed to settlement terms of rate change request | Integer   2  
Return on equity authorized with respect to two municipalities   10.00%  
Return on equity in a settlement reached with respect to nine municipalities 10.25%    
Requested return on equity for certain wholesale customers   10.70%  
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which pension costs will be recovered   15 years  
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 7.0  
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Approved return on equity   10.00%  
Number of years over which deferred costs associated with Green River Units 3 and 4 will be recovered   3 years  
Number of years over which pension costs will be recovered   15 years  
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]      
Regulatory Matters - Rate Case Proceeding / Federal Energy Regulatory Commission Formula Rates (Numeric) [Abstract]      
Increase in annual revenue requirements associated with base rates resulting from rate case   $ 125.0  
Kentucky Utilities Co [Member] | Federal Energy Regulatory Commission [Member]      
Regulatory Matters - Federal Matters - Federal Energy Regulatory Commission Wholesale Formula Rates (Numeric) [Abstract]      
Number of municipal customers impacted for Federal Energy Regulatory Commission formula rate request | Integer   12  
Number of municipalities that submitted termination notices, effective 2019 | Integer   9  
Number of municipalities that submitted termination notices, effective 2017 | Integer   1  
Number of municipalities that agreed to settlement terms of rate change request | Integer   2  
Return on equity authorized with respect to two municipalities   10.00%  
Return on equity in a settlement reached with respect to nine municipalities 10.25%    
Requested return on equity for certain wholesale customers   10.70%