Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Gain Loss Included in Earnings and Other Recurring Numeric Data) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Recurring Fair Value Measurements Valuation Techniques - NDT Funds (Numeric) [Abstract]
Weighted average coupon of NDT funds debt securities	4.19%		4.19%
Weighted average maturity for debt securities held by NDT funds (in years)	8.3		8.3
Energy Commodities, Net [Member] | Wholesale Energy Marketing [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	$ (4)	$ (1)	$ (7)	$ (5)
Change in unrealized gains (losses) relating to positions still held at the reporting date	(1)			(6)
Energy Commodities, Net [Member] | Unregulated Retail Electric And Gas [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(3)	6	16	11
Change in unrealized gains (losses) relating to positions still held at the reporting date	(2)	3	29	6
Energy Commodities, Net [Member] | Net Energy Trading Margins [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(8)	1	(9)	(2)
Change in unrealized gains (losses) relating to positions still held at the reporting date	2	1	2	1
Energy Commodities, Net [Member] | Energy Purchases [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(2)		(1)	(2)
Change in unrealized gains (losses) relating to positions still held at the reporting date		1	1	20
Cross Currency Swaps [Member] | Interest Expense [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings			(1)
Change in unrealized gains (losses) relating to positions still held at the reporting date
PPL Energy Supply LLC [Member]
Recurring Fair Value Measurements Valuation Techniques - NDT Funds (Numeric) [Abstract]
Weighted average coupon of NDT funds debt securities	4.19%		4.19%
Weighted average maturity for debt securities held by NDT funds (in years)	8.3		8.3
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Wholesale Energy Marketing [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(4)	(1)	(7)	(5)
Change in unrealized gains (losses) relating to positions still held at the reporting date	(1)			(6)
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Unregulated Retail Electric And Gas [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(3)	6	16	11
Change in unrealized gains (losses) relating to positions still held at the reporting date	(2)	3	29	6
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Net Energy Trading Margins [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(8)	1	(9)	(2)
Change in unrealized gains (losses) relating to positions still held at the reporting date	2	1	2	1
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member] | Energy Purchases [Member]
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(2)		(1)	(2)
Change in unrealized gains (losses) relating to positions still held at the reporting date		$ 1	$ 1	$ 20