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Asset Retirement Obligations (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2017
Asset Retirement Obligation [Roll Forward]    
Balance at Beginning of Period   $ 488
Accretion   11
Effect of foreign exchange rates   2
Changes in estimated timing or cost   (73)
Obligations settled   (12)
Balance at End of Period $ 416 $ 416
Minimum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   10 years
Maximum [Member]    
Asset Retirement Obligation [Roll Forward]    
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   10
Effect of foreign exchange rates   0
Changes in estimated timing or cost   (66)
Obligations settled   (12)
Balance at End of Period 365 365
Increase (Decrease) to the asset retirement obligations due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments (66) $ (66)
LG And E And KU Energy LLC [Member] | Minimum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   10 years
LG And E And KU Energy LLC [Member] | Maximum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   25 years
Louisville Gas And Electric Co [Member]    
Asset Retirement Obligation [Roll Forward]    
Balance at Beginning of Period   $ 145
Accretion   4
Effect of foreign exchange rates   0
Changes in estimated timing or cost   (10)
Obligations settled   (7)
Balance at End of Period 132 132
Increase (Decrease) to the asset retirement obligations due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments (56) $ (10)
Louisville Gas And Electric Co [Member] | Minimum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   10 years
Louisville Gas And Electric Co [Member] | Maximum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   25 years
Kentucky Utilities Co [Member]    
Asset Retirement Obligation [Roll Forward]    
Balance at Beginning of Period   $ 288
Accretion   6
Effect of foreign exchange rates   0
Changes in estimated timing or cost   (56)
Obligations settled   (5)
Balance at End of Period 233 233
Increase (Decrease) to the asset retirement obligations due to revisions in the amounts and timing of future expected costs related to the closure of CCR impoundments $ (10) $ (56)
Kentucky Utilities Co [Member] | Minimum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   10 years
Kentucky Utilities Co [Member] | Maximum [Member]    
Asset Retirement Obligation [Roll Forward]    
Regulatory Asset Amortization Period   25 years