Derivative Instruments and Hedging Activities (Gains and Losses) (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
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit contingent provisions	225				225
Aggregate fair value of collateral posted on these derivative instruments	33				33
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	201	[1]			201	[1]
Fair Value Hedges [Member] | Interest Rate Swaps [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Hedged items in fair value hedging relationships	Fixed rate debt		Fixed rate debt		Fixed rate debt		Fixed rate debt
Fair Value Hedges [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(1)						2
Gain (loss) recognized in income on related item	1		5		3		23
Fair Value Hedges [Member] | Interest Rate Swaps [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative
Gain (loss) recognized in income on related item			22				22
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	112		151		545		415
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1		(9)		(3)		(43)
Cash Flow Hedges [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(55)		60		68		78
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(6)		(52)		(28)		(51)
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	(4)		(4)		(13)		(10)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)							(13)
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	1				1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(49)		46		(3)		13
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)					(1)		3
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	(40)		32		(12)		49
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)			66		99		116
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Wholesale Energy Marketing [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	174		163		673		530
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)			(9)		(1)		(31)
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Fuel [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)			1				1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Depreciation [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	1		1		2		1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Energy Purchases [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	(20)		(42)		(105)		(159)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1				(2)		1
Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(168)		(12)		171		77
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gains (losses) recognized as regulatory asset on derivative			(22)				(23)
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gains (losses) recognized as regulatory asset on derivative	(9)				(3)
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)		(2)		(4)		(6)
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Wholesale Energy Marketing [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(476)		193		900		167
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Fuel [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	6		(27)				(12)
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Energy Purchases [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	364		(192)		(717)		(156)
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Unregulated Retail Electric And Gas [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(3)		6		20		11
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Net Energy Trading Margins [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(10)	[2]	(2)	[2]	12	[2]	9	[2]
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Utility [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			1				(2)
Derivatives Not Designated As Hedging Instruments [Member] | Foreign Currency Contracts [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(47)		11		(40)		66
Net Investment Hedges [Member] | Foreign Currency Contracts [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(4)		5		(5)		4
PPL Energy Supply LLC [Member]
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit contingent provisions	127				127
Aggregate fair value of collateral posted on these derivative instruments	1				1
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	134	[1]			134	[1]
PPL Energy Supply LLC [Member] | Fair Value Hedges [Member] | Interest Rate Swaps [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Hedged items in fair value hedging relationships			Fixed rate debt				Fixed rate debt
PPL Energy Supply LLC [Member] | Fair Value Hedges [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative
Gain (loss) recognized in income on related item							1
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	154		123		569		373
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1		(9)		(3)		(30)
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)			66		99		116
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)			66		99		116
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member] | Wholesale Energy Marketing [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	174		163		673		530
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)			(9)		(1)		(31)
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member] | Fuel [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)			1				1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member] | Depreciation [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)			1		1		1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member] | Energy Purchases [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	(20)		(42)		(105)		(159)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1				(2)		1
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(119)		(22)		215		19
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Wholesale Energy Marketing [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(476)		193		900		167
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Fuel [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	6		(27)				(12)
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Energy Purchases [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	364		(192)		(717)		(156)
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Unregulated Retail Electric And Gas [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(3)		6		20		11
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Net Energy Trading Margins [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(10)	[3]	(2)	[3]	12	[3]	9	[3]
LG And E And KU Energy LLC [Member]
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit contingent provisions	40				40
Aggregate fair value of collateral posted on these derivative instruments	32				32
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	9	[1]			9	[1]
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			(1)				(8)
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gains (losses) recognized as regulatory asset on derivative	1		(22)		(2)		(23)
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)		(2)		(6)		(6)
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Operating Revenues [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			1				(2)
Louisville Gas And Electric Co [Member]
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit contingent provisions	40				40
Aggregate fair value of collateral posted on these derivative instruments	32				32
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	9	[1]			9	[1]
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			(1)				(8)
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gains (losses) recognized as regulatory asset on derivative	1		(22)		(2)		(23)
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)		(2)		(6)		(6)
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Operating Revenues [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			1				(2)

[1] Includes the effect of net receivables and payables already recorded on the Balance Sheet.

[2] Differs from the Statement of Income due to intra-month transactions that PPL defines as spot activity, which is not accounted for as a derivative.

[3] Differs from the Statement of Income due to intra-month transactions that PPL Energy Supply defines as spot activity, which is not accounted for as a derivative.