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Fair Value Measurements and Credit Concentration (Net Assets and Liabilities Measured on Recurring Basis Level 3 Significant Unobservable Inputs) (Details) (Level 3 [Member], USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) $ 13 [1] $ 36 [1]
Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 100.00% [2] 100.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 11.00% [2] 10.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 73.00% [2] 86.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) (43) [3] (12) [3]
Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 100.00% [2] 100.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 11.00% [2] 100.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 83.00% [2] 100.00% [2]
Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 3 [4]  
Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 44 [5]  
Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 59.00% [2]  
Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 23.00% [2]  
Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 44.00% [2]  
Recurring [Member] | Auction Rate Securities [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 16 [6] 19 [6]
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 78.00% [2] 80.00% [2]
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 61.00% [2] 10.00% [2]
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 70.00% [2] 63.00% [2]
Nonrecurring [Member] | Kerr Dam Project [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 29  
Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 13 [1] 36 [1]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 100.00% [2] 100.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 11.00% [2] 10.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 73.00% [2] 86.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) (43) [3] (12) [3]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 100.00% [2] 100.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 11.00% [2] 100.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 83.00% [2] 100.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 3 [4]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Historical settled prices used to model forward prices 100.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 44 [5]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 59.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 23.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Heat Rate Option [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary model used to calculate forward prices 44.00% [2]  
PPL Energy Supply LLC [Member] | Recurring [Member] | Auction Rate Securities [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) 13 [6] 16 [6]
PPL Energy Supply LLC [Member] | Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 78.00% [2] 80.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 63.00% [2] 10.00% [2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Modeled from SIFMA Index 71.00% [2] 63.00% [2]
PPL Energy Supply LLC [Member] | Nonrecurring [Member] | Kerr Dam Project [Member]
    
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Fair value of net asset and (liability) $ 29  
PPL Energy Supply LLC [Member] | Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Maximum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
PPL Energy Supply LLC [Member] | Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Minimum [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
PPL Energy Supply LLC [Member] | Nonrecurring [Member] | Kerr Dam Project [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
    
Fair Value Inputs [Abstract]    
Proprietary Model Used To Calculate Plant Value 38.00% [7]  
[1] As the forward price of natural gas increases/(decreases), the fair value of the contracts (decreases)/increases.
[2] For energy commodities and auction rate securities, the range and weighted average represent the percentage of fair value derived from the unobservable inputs.
[3] As forward market prices increase/(decrease), the fair value of contracts (decreases)/increases. As volumetric assumptions for contracts in a gain position increase/(decrease), the fair value of contracts increases/(decreases). As volumetric assumptions for contracts in a loss position increase/(decrease), the fair value of the contracts (decreases)/increases.
[4] As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases).
[5] The proprietary model used to calculate fair value incorporates market heat rates, correlations and volatilities. As the market implied heat rate increases/(decreases), the fair value of the contracts increases/(decreases).
[6] The model used to calculate fair value incorporates an assumption that the auctions will continue to fail. As the modeled forward rates of the SIFMA Index increase/(decrease), the fair value of the securities increases/(decreases).
[7] The range and weighted average represent the percentage of fair value derived from the unobservable inputs.