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Utility Rate Regulation (Regulatory Assets and Liabilities) (Details)
$ in Millions
 1 Months Ended 12 Months Ended
Jun. 30, 2015
Dec. 31, 2015
USD ($)
Integer
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 101 $ 0 $ 0
Net cash settlements on terminated interest rate swaps   $ 0 0 104
Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period for the deferred recovery of a regulatory asset   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year   $ 46    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   10    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period to be recorded as a regulatory asset in 2016   $ 10    
Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2040    
Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity for approved projects remaining from earlier ECR plans   10.00%    
Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date for the deferred recovery of a regulatory liability   Dec. 31, 2043    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 88    
Net cash settlements on terminated interest rate swaps       86
Coal Contracts [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2016    
Power Purchase Agreement Ohio Valley Electric Corporation [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Mar. 31, 2026    
Plant Retirement Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   3 years    
PPL Electric [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   five-year    
PPL Electric [Member] | Act 129 Compliance Rider [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   three-year    
Amortization end date   May 31, 2016    
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]        
Maximum recoverable cost   $ 250    
Maximum recoverable cost Phase II   $ 185    
LGE [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 18 months    
LGE [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2033    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Amortization end date for 2008 terminated swap contract   Dec. 31, 2035    
LGE [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   10.00%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program | Integer   5    
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year   $ 18    
PPL Electric Utilities Corp [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   three years    
PPL Electric Utilities Corp [Member] | Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2029    
PPL Electric Utilities Corp [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   five-year    
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   three-year    
Amortization end date   May 31, 2016    
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]        
Maximum recoverable cost   $ 250    
Maximum recoverable cost Phase II   185    
LG And E And KU Energy LLC [Member]        
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   (9)    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   88 0 0
Net cash settlements on terminated interest rate swaps   $ 0 0 86
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period for the deferred recovery of a regulatory asset   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year   $ 28    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   10    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period to be recorded as a regulatory asset in 2016   $ 10    
LG And E And KU Energy LLC [Member] | Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2040    
LG And E And KU Energy LLC [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity for approved projects remaining from earlier ECR plans   10.00%    
LG And E And KU Energy LLC [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
LG And E And KU Energy LLC [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date for the deferred recovery of a regulatory liability   Dec. 31, 2043    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 88    
Net cash settlements on terminated interest rate swaps       86
LG And E And KU Energy LLC [Member] | Coal Contracts [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2016    
LG And E And KU Energy LLC [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Mar. 31, 2026    
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 18 months    
LG And E And KU Energy LLC [Member] | LGE [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2033    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Amortization end date for 2008 terminated swap contract   Dec. 31, 2035    
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   10.00%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program | Integer   5    
LG And E And KU Energy LLC [Member] | KU [Member] | Plant Retirement Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   3 years    
Louisville Gas And Electric Co [Member]        
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   $ (3)    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   44 0 0
Net cash settlements on terminated interest rate swaps   $ 0 0 43
Louisville Gas And Electric Co [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period for the deferred recovery of a regulatory asset   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year   $ 19    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   6    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period to be recorded as a regulatory asset in 2016   $ 6    
Louisville Gas And Electric Co [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
Louisville Gas And Electric Co [Member] | Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2035    
Louisville Gas And Electric Co [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Return on equity 10.00%      
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity for approved projects remaining from earlier ECR plans   10.00%    
Louisville Gas And Electric Co [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 18 months    
Louisville Gas And Electric Co [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Louisville Gas And Electric Co [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2033    
Amortization end date for the deferred recovery of a regulatory liability   Dec. 31, 2043    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 44    
Net cash settlements on terminated interest rate swaps       43
Amortization end date for 2008 terminated swap contract   Dec. 31, 2035    
Louisville Gas And Electric Co [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   10.00%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program | Integer   5    
Louisville Gas And Electric Co [Member] | Coal Contracts [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2016    
Louisville Gas And Electric Co [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Mar. 31, 2026    
Kentucky Utilities Co [Member]        
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 44 0 0
Net cash settlements on terminated interest rate swaps   $ 0 $ 0 43
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period for the deferred recovery of a regulatory asset   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year   $ 9    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   4    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period to be recorded as a regulatory asset in 2016   $ 4    
Kentucky Utilities Co [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
Kentucky Utilities Co [Member] | Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2040    
Kentucky Utilities Co [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Return on equity 10.00%      
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity for approved projects remaining from earlier ECR plans   10.00%    
Kentucky Utilities Co [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   within 12 months    
Period of recurring reviews of activity   six-month and two-year    
Kentucky Utilities Co [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date for the deferred recovery of a regulatory liability   Dec. 31, 2043    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 44    
Net cash settlements on terminated interest rate swaps       $ 43
Kentucky Utilities Co [Member] | Coal Contracts [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2016    
Kentucky Utilities Co [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Mar. 31, 2026    
Kentucky Utilities Co [Member] | Plant Retirement Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization period   3 years