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Asset Retirement Obligations (Details)
$ in Millions
3 Months Ended
Mar. 31, 2017
USD ($)
Asset Retirement Obligation [Roll Forward]  
Balance at Beginning of Period $ 488
Accretion 5
Obligations settled (6)
Balance at End of Period $ 487
Minimum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 10 years
Maximum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 25 years
LG And E And KU Energy LLC [Member]  
Asset Retirement Obligation [Roll Forward]  
Balance at Beginning of Period $ 433
Accretion 5
Obligations settled (6)
Balance at End of Period $ 432
LG And E And KU Energy LLC [Member] | Minimum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 10 years
LG And E And KU Energy LLC [Member] | Maximum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 25 years
Louisville Gas And Electric Co [Member]  
Asset Retirement Obligation [Roll Forward]  
Balance at Beginning of Period $ 145
Accretion 2
Obligations settled (4)
Balance at End of Period $ 143
Louisville Gas And Electric Co [Member] | Minimum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 10 years
Louisville Gas And Electric Co [Member] | Maximum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 25 years
Kentucky Utilities Co [Member]  
Asset Retirement Obligation [Roll Forward]  
Balance at Beginning of Period $ 288
Accretion 3
Obligations settled (2)
Balance at End of Period $ 289
Kentucky Utilities Co [Member] | Minimum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 10 years
Kentucky Utilities Co [Member] | Maximum [Member]  
Asset Retirement Obligation [Line Items]  
Regulatory Asset Amortization Period 25 years