Fair Value Measurements and Credit Concentration (Net Assets and Liabilities Measured on Recurring and Nonrecurring Basis Level 3 Significant Unobservable Inputs) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Recurring [Member] | Energy Commodities, Net [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	2	[1]
Recurring [Member] | Energy Commodities, Net [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] | 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] | Retail Natural Gas Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	24	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	11
Recurring [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]
Recurring [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	21.00%	[2]
Recurring [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	75.00%	[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)	(4)	[4]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(4)
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 basis prices	24.00%	[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 basis prices	24.00%	[2]
Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	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	[5]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	23
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	74.00%	[2]
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	54.00%	[2]
Recurring [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	64.00%	[2]
Recurring [Member] | Cross Currency Swaps [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	1	[6]
Recurring [Member] | Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	22.00%	[2]
Recurring [Member] | Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	22.00%	[2]
Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)
Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%
Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	2	[1]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [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] | 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] | Retail Natural Gas Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	24	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	11
PPL Energy Supply LLC [Member] | Recurring [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]
PPL Energy Supply LLC [Member] | Recurring [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	21.00%	[2]
PPL Energy Supply LLC [Member] | Recurring [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	75.00%	[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)	(4)	[4]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(4)
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 basis prices	24.00%	[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 basis prices	24.00%	[2]
PPL Energy Supply LLC [Member] | Recurring [Member] | Energy Commodities, Net [Member] | Financial Transmission Rights Purchase Contracts [Member]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	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	[5]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	23
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	74.00%	[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	57.00%	[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	65.00%	[2]
LG And E And KU Energy LLC [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)
LG And E And KU Energy LLC [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%
LG And E And KU Energy LLC [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%
Kentucky Utilities Co [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)
Kentucky Utilities Co [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%
Kentucky Utilities Co [Member] | Nonrecurring [Member] | Equity Investment In Electric Energy Incorporated [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Long term forward price curves and capital expenditure projections	100.00%

[1] FTR purchase contracts extend into 2015. $2 million of the fair value is scheduled to deliver within the next 12 months. As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases).

[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] Retail natural gas sales contracts extend into 2017. $11 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.

[4] Power sales contracts extend into 2014. $(4) 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.

[5] 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).

[6] Cross-currency swaps extend into 2017. 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.