Derivative Instruments and Hedging Activities (Gains and Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Credit Risk-Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position with credit contingent provisions	211				211
Aggregate fair value of collateral posted on these derivative instruments	34				34
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	186	[1]			186	[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		1		1		2
Gain (loss) recognized in income on related item	1		8		2		18
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(5)		(51)		123		18
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	224		144		433		264
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(4)		(26)		(4)		(34)
Cash Flow Hedges [Member] | Interest Rate Swaps [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(25)		(9)		(22)		1
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)	(5)		(3)		(9)		(6)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0		(12)		0		(13)
Cash Flow Hedges [Member] | Cross Currency Swaps [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	34		(8)		46		(33)
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)	0		0		(1)		3
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0		0		0		0
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)	47		30		28		17
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0		0		0		0
Cash Flow Hedges [Member] | Commodity Contracts [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(14)		(34)		99		50
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)	227		164		499		367
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(5)		(14)		(1)		(22)
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)	0				1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0				0
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)	(45)		(47)		(85)		(117)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1		0		(3)		1
Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	47		79		337		90
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			(3)				(1)
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)		(4)
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	33		(71)		1,376		(26)
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	(12)		(8)		(6)		15
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	(11)		91		(1,081)		36
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	1		4		23		5
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	13	[2]	4	[2]	22	[2]	11	[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	0		(3)		0		(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	25		64		7		55
Net Investment Hedges [Member] | Foreign Currency Contracts [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	2		0		(1)		(1)
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	167				167
Aggregate fair value of collateral posted on these derivative instruments	3				3
Aggregate fair value of additional collateral requirements in the event of a credit downgrade below investment grade	172	[1]			172	[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			0				0
Gain (loss) recognized in income on related item			1				1
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(14)		(34)		99		50
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	183		117		415		250
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(4)		(14)		(4)		(21)
PPL Energy Supply LLC [Member] | Cash Flow Hedges [Member] | Commodity Contracts [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(14)		(34)		99		50
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)	227		164		499		367
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(5)		(14)		(1)		(22)
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
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0				0
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)	(45)		(47)		(85)		(117)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	1		0		(3)		1
PPL Energy Supply LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative	24		20		334		41
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	33		(71)		1,376		(26)
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	(12)		(8)		(6)		15
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	(11)		91		(1,081)		36
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	1		4		23		5
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	13	[2]	4	[3]	22	[2]	11	[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	31				31
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			(5)				(6)
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	(9)		(3)		(3)		(1)
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)		(4)		(4)
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Operating Revenues Retail And Wholesale [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			(3)	[4]			(2)	[4]
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	31				31
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] | Interest Rate Swaps [Member] | Regulatory Assets [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gains (losses) recognized as regulatory asset on derivative	(9)				(3)
Louisville Gas And Electric Co [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)				(4)
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			(5)				(6)
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			(3)				(1)
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)				(4)
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member] | Operating Revenues Retail And Wholesale [Member]
Amounts Included in Income, OCI or Regulatory Assets [Abstract]
Gain (loss) recognized in income on derivative			(3)	[4]			(2)	[4]

[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.

[4] Amounts are included in "Operating Revenues" for LKE.