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	6 Months Ended
	Jun. 30, 2012
Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	30	[1]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	14
Energy Commodities, Net [Member] | Retail Natural Gas 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]
Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	20.00%	[2]
Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	69.00%	[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)	(7)	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(4)
Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Basis price between delivery points	61.00%	[2]
Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Basis price between delivery points	24.00%	[2]
Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Basis price between delivery points	25.00%	[2]
Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	11	[4]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	11
Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Customer migration	80.00%	[2]
Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Customer migration	13.00%	[2]
Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Customer migration	34.00%	[2]
Auction Rate Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	15	[5]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	26
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	80.00%	[2]
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	54.00%	[2]
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	65.00%	[2]
Cross Currency Swaps [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	10	[6]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	37.00%	[2]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	25.00%	[2]
Cross Currency Swaps [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Credit valuation adjustment	32.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	30	[1]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	14
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas 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] | Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	20.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Retail Natural Gas Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Observable wholesale prices used as proxy for retail delivery points	69.00%	[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)	(7)	[3]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	(4)
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Basis price between delivery points	61.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Power Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Basis price between delivery points	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]
Basis price between delivery points	25.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	11	[4]
Fair Value Inputs [Abstract]
Fair value scheduled to deliver within next 12 months	11
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Customer migration	80.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Customer migration	13.00%	[2]
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Full Requirement Sales Contracts [Member] | Discounted Cash Flow [Member] | Weighted Average [Member]
Fair Value Inputs [Abstract]
Customer migration	34.00%	[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)	12	[5]
Fair Value Inputs [Abstract]
Weighted average contractual maturity of auction rate securites (in years)	26
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	80.00%	[2]
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	61.00%	[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	66.00%	[2]

[1] Retail natural gas sales contracts extend through 2017. $14 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] Power sales contracts extend through 2017. $(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.

[4] Full-requirement sales contracts extend through 2013. $11 million of the fair value is scheduled to deliver within the next 12 months. As customer migration increases/(decreases), the fair value of the contracts decreases/(increases).

[5] Auction rate securities have a weighted average contractual maturity of 26 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 through 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.