Fair Value Measurements and Credit Concentration (Net Assets and Liabilities Measured on Recurring Basis Level 3 Significant Unobservable Inputs) (Details) (Recurring [Member], Level 3 [Member], USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	$ 36	[1]	$ 24	[1]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	16
Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	100.00%	[2]	100.00%	[2]
Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	17.00%	[2]	21.00%	[2]
Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	82.00%	[2]	75.00%	[2]
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)	(5)	[3]	(4)	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(5)
Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	100.00%	[2]	24.00%	[2]
Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	11.00%	[2]	24.00%	[2]
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 basis prices	39.00%	[2]	24.00%	[2]
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)			2	[4]
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]
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]
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]
Energy Commodities, Net [Member] | Heat Rate Call Option [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	9	[5]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	6
Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
Auction Rate Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	19	[6]	16	[6]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	23
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	78.00%	[2]	74.00%	[2]
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	11.00%	[2]	54.00%	[2]
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	63.00%	[2]	64.00%	[2]
Cross Currency Swaps [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	3	[7]	1	[7]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	11.00%	[2]	22.00%	[2]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	11.00%	[2]	22.00%	[2]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	11.00%	[2]	22.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	36	[1]	24	[1]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	16
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	100.00%	[2]	100.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	17.00%	[2]	21.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	82.00%	[2]	75.00%	[2]
PPL Energy Supply LLC [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)	(5)	[3]	(4)	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(5)
PPL Energy Supply LLC [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 basis prices	100.00%	[2]	24.00%	[2]
PPL Energy Supply LLC [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 basis prices	11.00%	[2]	24.00%	[2]
PPL Energy Supply LLC [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 basis prices	39.00%	[2]	24.00%	[2]
PPL Energy Supply LLC [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)			2	[4]
PPL Energy Supply LLC [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] | 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] | 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] | Energy Commodities, Net [Member] | Heat Rate Call Option [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	9	[5]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	6
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Heat Rate Call Option [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward basis prices	18.00%	[2]
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	$ 16	[6]	$ 13	[6]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	23
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	78.00%	[2]	74.00%	[2]
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	11.00%	[2]	57.00%	[2]
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	62.00%	[2]	65.00%	[2]

[1] At June 30, 2013, retail natural gas sales contracts extend through 2018, and $16 million of the fair value is scheduled to deliver within the next 12 months. 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. For cross-currency swaps, the range and weighted average represent the percentage decrease in fair value due to the unobservable inputs used in the model to calculate the credit valuation adjustment.

[3] At June 30, 2013, power sales contracts extend into 2018, and $(5) million of the fair value is scheduled to deliver within the next 12 months. As the forward price of basis increases/(decreases), 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] At June 30, 2013, the heat rate call option extends through 2014, and $6 million of the fair value is scheduled to deliver within the next 12 months. As the market implied heat rate increases/(decreases), the fair value of the contracts increases/(decreases).

[6] At June 30, 2013, auction rate securities have a weighted average contractual maturity of 23 years. 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] At June 30, 2013, cross-currency swaps extend into 2021. The credit valuation adjustment incorporates projected probabilities of default and estimated recovery rates. As the credit valuation adjustment increases/(decreases), the fair value of the swaps (decreases)/increases.