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Available-for-Sale Securities (Details) (USD $)
In Millions, unless otherwise specified
1 Months Ended 12 Months Ended
Apr. 30, 2009
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   $ 479 $ 624  
Gross unrealized gains   187 182  
Gross unrealized losses   2 0  
Fair value   664 806  
Available-for-sale securities scheduled maturity dates of debt securities (Details) [Abstract]        
Amortized cost - maturity less than 1 year   14    
Amortized cost - maturity between 1 and 5 years   69    
Amortized cost - maturity between 5 and 10 years   62    
Amortized cost - maturity in excess of 10 years   82    
Amortized cost total   227    
Fair value - maturity less than 1 year   14    
Fair value - maturity between 1 and 5 years   72    
Fair value - maturity between 5 and 10 years   67    
Fair value - maturity in excess of 10 years   90    
Fair value total   243    
Available-for-sale securities proceeds from and realized gains and losses (Details) [Abstract]        
Proceeds from sales of NDT securities   156 114 201
Other proceeds from sales   163 0 154
Gross realized gains   28 [1] 13 [1] 27 [1]
Gross realized losses   16 [1] 5 [1] 20 [1]
Short Term Investments (Numeric) [Abstract]        
Principal amount of tax-exempt revenue bonds held as short-term investment     163  
Principal amount of bonds issued by development authority on behalf of PPL Energy Supply   150    
Proceeds from the sale of short-term investments by PPL Energy Supply of PEDFA bonds 150      
Nuclear Decommissioning Trust Funds (Numeric) [Abstract]        
Term competitive transition charge was recovered from certain customers (in years)   11    
Percentage of shortfall PPL Susquehanna would be obligated to fund   90.00%    
Impairments recorded to NDT securities   6 3 18
Short Term Investments - Municipal Debt Securities [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   0 163 [2]  
Gross unrealized gains   0 0  
Gross unrealized losses   0 0  
Fair value   0 163 [2]  
Nuclear Decommissioning Trust Funds [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   454 436  
Gross unrealized gains   187 182  
Gross unrealized losses   1 0  
Fair value   640 618  
Nuclear Decommissioning Trust Funds [Member] | Cash And Cash Equivalents [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   12 10  
Gross unrealized gains   0 0  
Gross unrealized losses   0 0  
Fair value   12 10  
Nuclear Decommissioning Trust Funds [Member] | Equity Securities [Member] | US Large Cap [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   173 180  
Gross unrealized gains   119 123  
Gross unrealized losses   0 0  
Fair value   292 303  
Nuclear Decommissioning Trust Funds [Member] | Equity Securities [Member] | US Mid Small Cap [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   67 67  
Gross unrealized gains   50 52  
Gross unrealized losses   0 0  
Fair value   117 119  
Nuclear Decommissioning Trust Funds [Member] | Debt Securities [Member] | US Treasury [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   76 71  
Gross unrealized gains   10 4  
Gross unrealized losses   0 0  
Fair value   86 75  
Nuclear Decommissioning Trust Funds [Member] | Debt Securities [Member] | US Government Sponsored Agency [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   9 6  
Gross unrealized gains   1 1  
Gross unrealized losses   0 0  
Fair value   10 7  
Nuclear Decommissioning Trust Funds [Member] | Debt Securities [Member] | Municipalities Debt Securities [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   80 69  
Gross unrealized gains   4 0  
Gross unrealized losses   1 0  
Fair value   83 69  
Nuclear Decommissioning Trust Funds [Member] | Debt Securities [Member] | Corporate Debt Securities [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   35 31  
Gross unrealized gains   3 2  
Gross unrealized losses   0 0  
Fair value   38 33  
Nuclear Decommissioning Trust Funds [Member] | Debt Securities [Member] | Other [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   2 1  
Gross unrealized gains   0 0  
Gross unrealized losses   0 0  
Fair value   2 1  
Nuclear Decommissioning Trust Funds [Member] | Receivables Payables Net [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   0 1  
Gross unrealized gains   0 0  
Gross unrealized losses   0 0  
Fair value   0 1  
Auction Rate Securities [Member]
       
Available-for-sale securities balance sheet (Details) [Abstract]        
Amortized cost   25 25  
Gross unrealized gains   0 0  
Gross unrealized losses   1 0  
Fair value   $ 24 $ 25  
[1] Excludes the impact of other-than-temporary impairment charges recognized in the Statements of Income.
[2] Represents tax-exempt bonds issued by Louisville/Jefferson County, Kentucky, on behalf of LG&E that were subsequently purchased by LG&E. Such bonds were remarketed to unaffiliated investors in January 2011.