Derivative Instruments and Hedging Activities (Intro) (Details) (USD $) In Millions, except Per Share data	3 Months Ended			9 Months Ended		12 Months Ended		3 Months Ended					9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2009	Dec. 31, 2010	Sep. 30, 2010 Early July 2010 Monetization [Member]	Jun. 30, 2010 Early July 2010 Monetization [Member]	Sep. 30, 2010 Late July 2010 Monetization [Member]	Sep. 30, 2011 Unregulated Retail Electric and Gas [Member]	Sep. 30, 2010 Unregulated Retail Electric and Gas [Member]	Sep. 30, 2011 Unregulated Retail Electric and Gas [Member]	Sep. 30, 2010 Unregulated Retail Electric and Gas [Member]	Sep. 30, 2011 Wholesale Energy Marketing [Member]	Sep. 30, 2010 Wholesale Energy Marketing [Member]	Sep. 30, 2011 Wholesale Energy Marketing [Member]	Sep. 30, 2010 Wholesale Energy Marketing [Member]	Sep. 30, 2011 Energy Purchases [Member]	Sep. 30, 2010 Energy Purchases [Member]	Sep. 30, 2011 Energy Purchases [Member]	Sep. 30, 2010 Energy Purchases [Member]
Master Netting Arrangements (Numeric) [Abstract]
Obligation to return cash collateral obligation under master netting arrangement	$ 64			$ 64			$ 338
Cash collateral posted under master netting arrangements	30			30			19
Commodity Price Risk (Non-trading) - Monetization of Certain Full-Requirement Sales Contracts (Numeric) [Abstract]
Proceeds received from the monetization of certain full-requirement sales contracts		249						156		93
Fair value of NPNS contracts recorded due to the sale ofcertain full-requirements contracts									66
Realized pre-tax gains (losses) on NPNS contracts recorded due to sale of contracts										93
Portion of the fair value of NPNS contracts recorded that were not monetized									16
Dedesignation of cash flow hedges due to monetization of certain full-requirement sales contracts									(87)	(61)
Change in the fair value related to certain full-requirement sales contracts that were monetized									(23)
Pre-tax gain (loss) recorded on the monetization of certain full-requirement sales contracts									(60)	32
After-tax gain (loss) recorded on the monetization of certain full-requirement sales contracts									(36)	19
Commodity Price Risk (Non-trading) - Cash Flow Hedges (Numeric) [Abstract]
Year of expiration of the maximum maturity date of commodity price risk cash flow hedge contracts				2016
Net unrealized after-tax gains (losses) expected to be reclassified into earnings within 12 months related to commodity price risk cash flow hedge contracts	309			309
After-tax gains (losses) previously recorded in AOCI reclassified to earnings related to commodity price risk cash flow hedge contracts		(36)			(89)
No or insignificant amounts previously recorded in AOCI reclassified to earnings related to commodity price risk cash flow hedge contracts	insignificant			insignificant
Hedge ineffectiveness after-tax gains (losses) related to commodity price risk cash flow hedge contracts	(3)	8		(17)	(16)
After-tax gains (losses) resulting from hedge effectiveness testing failure reversals related to commodity price risk cash flow hedge contracts			(82)
Commodity Price Risk (Non-trading) - Economic Activity (Numeric) [Abstract]
Year of expiration of the maximum maturity date of economic activity derivative contracts				2017
Fair value of commodity contracts classified as economic activity, net (asset) liability	218			218			389
Pre-tax Gains (Losses) Of Economic Activity Details - Unregulated Business [Abstract]
Pre-tax gain (loss)											4	8	9	16	216	52	229	(190)	(176)	(300)	(49)	(418)	[1]
Pre-tax impact of correction of an error that was deemed to have an immaterial impact on prior periods			5			35
After-tax impact of correction of an error that was deemed to have an immaterial impact on prior periods			$ 3			$ 20
Per share impact of correction of an error that was deemed to have an immaterial impact on prior periods (in dollars per share)			$ 0.01			$ 0.05
Commodity Price Risk (Non-trading) - Economic Activity - Regulated Business (Numeric) [Abstract]
Year of expiration of the maximum maturity date of economic activity derivative contracts specific to regulated business				2012

[1] During the second quarter of 2010, PPL Energy Supply corrected an error relating to the fair value of a capacity contract (classified as economic activity) due to the use of an incorrect forward capacity curve. PPL Energy Supply's energy purchases were understated for the year ended December 31, 2009 and the first quarter of 2010 by an unrealized amount of $35 million ($20 million after tax or $0.05 per share, basic and diluted, for PPL) and $5 million ($3 million after tax or $0.01 per share, basic and diluted, for PPL). Management concluded that the impacts were not material to first quarter 2010 financial statements of PPL and PPL Energy Supply, and were not material to the financial statements for the full year 2010.