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Utility Rate Regulation (Regulatory Assets and Liabilities) (Details) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Dec. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 12 $ 59 $ (42)
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 2 (9) (101)
Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset and liability balances expected to be amortized into net periodic defined benefit costs in the next year   $ 68    
Regulatory Asset Amortization Period   15 years    
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 the following year   $ 16    
Unamortized Loss On Debt [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2044    
Power Purchase Agreement Ohio Valley Electric Corporation [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Mar. 31, 2026    
Tax Cuts And Jobs Act [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 2,185    
PPL Electric [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
Regulatory Assets and Liabilities - Storm Costs (Numeric) [Abstract]        
Period over which storm costs will be recovered (in years)   3 years    
PPL Electric [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   5 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   5 years    
PPL Electric [Member] | Storm Damage Expense Rider [Member]        
Regulatory Assets and Liabilities - Storm Damage Expense Rider (Numeric) [Abstract]        
Maximum reportable storm damage expenses to be recovered annually through base rates   $ 15    
Amount of amortized storm expense included in base rate component   5    
PPL Electric [Member] | Act 129 Compliance Rider [Member]        
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]        
Maximum recoverable cost   250    
Maximum recoverable cost Phase II   $ 185    
Period over which program costs can be recovered for Phase II (in years)   3 years    
Maximum amount of costs that can be recovered under the Act 129 Phase III plan   $ 313    
Period over which program costs can be recovered for Phase III (in years)   5 years    
LKE [Member] | Defined Benefit Plans [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   $ 33 20  
LGE [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
LGE [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
LGE [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2033    
LGE [Member] | Terminated Interest Rate Swap [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps $ 9      
LGE [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program   5 years    
LGE [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   18 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   18 months    
LGE [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
KU [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
KU [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
KU [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
PPL Electric Utilities Corp [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   5 years    
Increase (Decrease) in Regulatory Assets and Liabilities   $ 5 62 (35)
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   5 years    
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]        
Maximum amount of costs that can be recovered under the Act 129 Phase III plan   $ 313    
Period over which program costs can be recovered for Phase III (in years)   5 years    
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset and liability balances expected to be amortized into net periodic defined benefit costs in the next year   $ 30    
PPL Electric Utilities Corp [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
Regulatory Assets and Liabilities - Storm Costs (Numeric) [Abstract]        
Period over which storm costs will be recovered (in years)   3 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]        
Regulatory Asset Amortization Period   5 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   5 years    
PPL Electric Utilities Corp [Member] | Storm Damage Expense Rider [Member]        
Regulatory Assets and Liabilities - Storm Damage Expense Rider (Numeric) [Abstract]        
Maximum reportable storm damage expenses to be recovered annually through base rates   $ 15    
Amount of amortized storm expense included in base rate component   5    
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]        
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]        
Maximum recoverable cost   250    
Maximum recoverable cost Phase II   $ 185    
Period over which program costs can be recovered for Phase II (in years)   3 years    
Maximum amount of costs that can be recovered under the Act 129 Phase III plan   $ 313    
Period over which program costs can be recovered for Phase III (in years)   5 years    
PPL Electric Utilities Corp [Member] | Tax Cuts And Jobs Act [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 1,019    
LG And E And KU Energy LLC [Member]        
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 0 (9) (88)
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset and liability balances expected to be amortized into net periodic defined benefit costs in the next year   $ 38    
Regulatory Asset Amortization Period   15 years    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   $ 33 20  
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 the following year   $ 16    
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, 2044    
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] | Tax Cuts And Jobs Act [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 1,166    
LG And E And KU Energy LLC [Member] | LGE [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
LG And E And KU Energy LLC [Member] | LGE [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 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    
LG And E And KU Energy LLC [Member] | LGE [Member] | Terminated Interest Rate Swap [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps (9)      
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program   5 years    
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   18 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   18 months    
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
LG And E And KU Energy LLC [Member] | KU [Member] | Storm Costs [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2020    
LG And E And KU Energy LLC [Member] | KU [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Louisville Gas And Electric Co [Member]        
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 0 (9) (44)
Louisville Gas And Electric Co [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset and liability balances expected to be amortized into net periodic defined benefit costs in the next year   $ 26    
Regulatory Asset Amortization Period   15 years    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   $ 18 11  
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 the following year   $ 10    
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, 2044    
Louisville Gas And Electric Co [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Louisville Gas And Electric Co [Member] | Interest Rate Swaps [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Amortization end date   Dec. 31, 2033    
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    
Louisville Gas And Electric Co [Member] | Terminated Interest Rate Swap [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   17 years    
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps $ 9      
Louisville Gas And Electric Co [Member] | Gas Line Tracker [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Regulatory Assets and Liabilities - Gas Line Tracker (Numeric) [Abstract]        
Term, in years, of the gas service rider program   5 years    
Louisville Gas And Electric Co [Member] | Gas Supply Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   18 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   18 months    
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Louisville Gas And Electric Co [Member] | Tax Cuts And Jobs Act [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 532    
Kentucky Utilities Co [Member]        
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]        
Net cash settlements on terminated interest rate swaps   $ 0 0 $ (44)
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   15 years    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory asset and liability balances expected to be amortized into net periodic defined benefit costs in the next year   $ 12    
Regulatory Asset Amortization Period   15 years    
Deferred recovery of the difference between pension costs calculated with pension accounting policy and pension cost using 15 year amortization period   $ 15 $ 9  
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 the following year   $ 6    
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, 2042    
Kentucky Utilities Co [Member] | Fuel Adjustment Clause [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
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] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Regulatory Asset Amortization Period   12 months    
Return on equity   9.70%    
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]        
Regulatory Asset Amortization Period   12 months    
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]        
Return on equity   9.70%    
Kentucky Utilities Co [Member] | Tax Cuts And Jobs Act [Member]        
Regulatory Assets and Liabilities (Numeric) [Line Items]        
Increase (Decrease) in Regulatory Assets and Liabilities   $ 634