Utility Rate Regulation (Regulatory Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2010	Dec. 31, 2011
Regulatory Assets [Line Items]
Current regulatory assets	$ 19			$ 9
Noncurrent regulatory assets	1,483			1,349
Regulatory Liabilities [Line Items]
Current regulatory liabilities	61			73
Noncurrent regulatory liabilities	1,010			1,010
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]
Maximum recoverable cost	250
Defined Benefit Plan Combined Asset And Liability [Member]
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year	60
Gas Supply Clause Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	18
Fuel Adjustments Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	12
LGE [Member]
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
KU [Member]
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
Generation Supply Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	27			42
Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			7
Gas Supply Clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			6
Transmission Service Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	6			2
Transmission Formula Rate [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities				5
Universal Service Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	17			1
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	679			651
Coal Contracts [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	141	[1]		180	[1]
Power Purchase Agreement Ohio Valley Electric Corporation [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	108	[1]		116	[1]
Net Deferred Tax Assets [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	34			39
Act 129 Compliance Rider [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	8			7
Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	17			9
Interest Rate Swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	14
Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	3			10
Noncurrent regulatory liabilities	9			8
Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	11			6
Fuel Adjustment Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6			3
Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	730			615
Taxes Recoverable Through Future Rates [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	293			289
Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	168			154
Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	96			110
Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	67			69
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	71			53
Coal Contracts [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	4	[1]		11	[1]
Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	26			18
Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2
Noncurrent regulatory assets	28			30
PPL Electric Utilities Corp [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	853			729
Regulatory Liabilities [Line Items]
Current regulatory liabilities	52			53
Noncurrent regulatory liabilities	8			7
Regulatory Assets and Liabilities - Act 129 Compliance Rider (Numeric) [Abstract]
Maximum recoverable cost	250
PPL Electric Utilities Corp [Member] | Defined Benefit Plan Combined Asset And Liability [Member]
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year	22
PPL Electric Utilities Corp [Member] | Generation Supply Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	27			42
PPL Electric Utilities Corp [Member] | Transmission Service Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	6			2
PPL Electric Utilities Corp [Member] | Transmission Formula Rate [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities				5
PPL Electric Utilities Corp [Member] | Universal Service Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	17			1
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	8			7
PPL Electric Utilities Corp [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	2			3
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	362			276
PPL Electric Utilities Corp [Member] | Taxes Recoverable Through Future Rates [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	293			289
PPL Electric Utilities Corp [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	59			31
PPL Electric Utilities Corp [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	65			77
PPL Electric Utilities Corp [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	71			53
PPL Electric Utilities Corp [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	3			3
LG And E And KU Energy LLC [Member]
Regulatory Assets [Line Items]
Current regulatory assets	19			9
Noncurrent regulatory assets	630			620
Regulatory Liabilities [Line Items]
Current regulatory liabilities	9			20
Noncurrent regulatory liabilities	1,002			1,003
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]
Reversal of previously recorded losses to reflect the reclassification of ineffective swaps			21
Reversal of previously recorded losses to reflect the reclassification of terminated swaps			9
LG And E And KU Energy LLC [Member] | Defined Benefit Plan Combined Asset And Liability [Member]
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year	38
LG And E And KU Energy LLC [Member] | Gas Supply Clause Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	18
LG And E And KU Energy LLC [Member] | Fuel Adjustments Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	12
LG And E And KU Energy LLC [Member] | LGE [Member]
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
LG And E And KU Energy LLC [Member] | KU [Member]
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
LG And E And KU Energy LLC [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			7
LG And E And KU Energy LLC [Member] | Gas Supply Clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			6
LG And E And KU Energy LLC [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	679			651
LG And E And KU Energy LLC [Member] | Coal Contracts [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	141	[1]		180	[1]
LG And E And KU Energy LLC [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	108	[1]		116	[1]
LG And E And KU Energy LLC [Member] | Net Deferred Tax Assets [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	34			39
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	17			9
LG And E And KU Energy LLC [Member] | Interest Rate Swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	14
LG And E And KU Energy LLC [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1			7
Noncurrent regulatory liabilities	9			8
LG And E And KU Energy LLC [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	11			6
LG And E And KU Energy LLC [Member] | Fuel Adjustment Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6			3
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	368			339
LG And E And KU Energy LLC [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	109			123
LG And E And KU Energy LLC [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	31			33
LG And E And KU Energy LLC [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	67			69
LG And E And KU Energy LLC [Member] | Coal Contracts [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	4	[1]		11	[1]
LG And E And KU Energy LLC [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	26			18
LG And E And KU Energy LLC [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2
Noncurrent regulatory assets	25			27
Louisville Gas And Electric Co [Member]
Regulatory Assets [Line Items]
Current regulatory assets	19			9
Noncurrent regulatory assets	400			403
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			10
Noncurrent regulatory liabilities	471			478
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
Regulatory Assets and Liabilities - Interest Rate Swaps (Numeric) [Abstract]
Reversal of previously recorded losses to reflect the reclassification of terminated swaps			9
Louisville Gas And Electric Co [Member] | Defined Benefit Plan Combined Asset And Liability [Member]
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year	24
Louisville Gas And Electric Co [Member] | Gas Supply Clause Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	18
Louisville Gas And Electric Co [Member] | Fuel Adjustments Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	12
Louisville Gas And Electric Co [Member] | Gas Supply Clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			6
Louisville Gas And Electric Co [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	297			286
Louisville Gas And Electric Co [Member] | Coal Contracts [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	61	[1]		78	[1]
Louisville Gas And Electric Co [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	75	[1]		80	[1]
Louisville Gas And Electric Co [Member] | Net Deferred Tax Assets [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	28			31
Louisville Gas And Electric Co [Member] | Interest Rate Swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	7
Louisville Gas And Electric Co [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities				4
Noncurrent regulatory liabilities	3			3
Louisville Gas And Electric Co [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	11			6
Louisville Gas And Electric Co [Member] | Fuel Adjustment Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6			3
Louisville Gas And Electric Co [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	232			225
Louisville Gas And Electric Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	59			66
Louisville Gas And Electric Co [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	20			21
Louisville Gas And Electric Co [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	67			69
Louisville Gas And Electric Co [Member] | Coal Contracts [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	2	[1]		5	[1]
Louisville Gas And Electric Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	15			11
Louisville Gas And Electric Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2
Noncurrent regulatory assets	5			6
Kentucky Utilities Co [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	230			217
Regulatory Liabilities [Line Items]
Current regulatory liabilities	5			10
Noncurrent regulatory liabilities	531			525
Regulatory Assets and Liabilities - Environmental Cost Recovery (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans	10.63%
Return on equity for approved projects in the 2011 ECR proceedings	10.10%
Kentucky Utilities Co [Member] | Defined Benefit Plan Combined Asset And Liability [Member]
Regulatory Assets and Liabilities - Defined Benefit Plans (Numeric) [Abstract]
Regulatory asset costs expected to be amortized into net periodic defined benefit costs in the next year	14
Kentucky Utilities Co [Member] | Fuel Adjustments Combined Asset And Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Amortization period	12
Kentucky Utilities Co [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4			7
Kentucky Utilities Co [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	382			365
Kentucky Utilities Co [Member] | Coal Contracts [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	80	[1]		102	[1]
Kentucky Utilities Co [Member] | Power Purchase Agreement Ohio Valley Electric Corporation [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	33	[1]		36	[1]
Kentucky Utilities Co [Member] | Net Deferred Tax Assets [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	6			8
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	17			9
Kentucky Utilities Co [Member] | Interest Rate Swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	7
Kentucky Utilities Co [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1			3
Noncurrent regulatory liabilities	6			5
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	136			114
Kentucky Utilities Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	50			57
Kentucky Utilities Co [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	11			12
Kentucky Utilities Co [Member] | Coal Contracts [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	2	[1]		6	[1]
Kentucky Utilities Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	11			7
Kentucky Utilities Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	$ 20			$ 21

[1] (a)        These regulatory assets and liabilities were recorded as offsets to certain intangible assets and liabilities that were recorded at fair value upon the acquisition of LKE.