Retirement and Postemployment Benefits (Plan Assets and Expected Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Assumptions Used in Calculations (Numeric) [Abstract]
Weighted average coupon for debt securities held	3.96%
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Amount to be contributed to plan in the next fiscal year	$ 0
Pension Benefits - US [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	3,471		2,819
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	2,819		1,772
Acquisition of LKE	0		765	[1]
Balance at end of period	3,471		2,819
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Company contributions for 2012 already made	207
Expected amount of benefit payments in the next period for non-qualified plans	28
Estimated Future Benefit Payments (Details) [Abstract]
2012	205
2013	192
2014	203
2015	217
2016	229
2017 - 2021	1,384
Pension Benefits - US [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	1,213		869
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	1,213		869
Pension Benefits - US [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	2,155		1,856
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	2,155		1,856
Pension Benefits - US [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	103		94
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	94		28
Actual return on plan assets relating to assets still held at the reporting date	7		(3)
Actual return on plan assets relating to assets sold during the period			1
Acquisition of LKE			46
Purchases, sales and settlements	2		22
Balance at end of period	103		94
Pension Benefits - US [Member] | Residential - Commercial Backed Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	0		2
Actual return on plan assets relating to assets still held at the reporting date	0		(1)
Actual return on plan assets relating to assets sold during the period			0
Purchases, sales and settlements	0		(1)
Balance at end of period			0
Pension Benefits - US [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	6		10
Actual return on plan assets relating to assets still held at the reporting date	(4)		(1)
Actual return on plan assets relating to assets sold during the period			1
Purchases, sales and settlements	5		(4)
Balance at end of period			6
Pension Benefits - US [Member] | Private Equity Alternative Investments [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Actual return on plan assets relating to assets sold during the period			0
Balance at end of period			10
Pension Benefits - US [Member] | Private Equity Alternative Investments [Member] | Level 3 [Member]
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period			6
Actual return on plan assets relating to assets still held at the reporting date	8		(1)
Purchases, sales and settlements	27		5
Pension Benefits - US [Member] | TBA Debt Securities Derivatives [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			31
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	31
Actual return on plan assets relating to assets still held at the reporting date	0		0
Actual return on plan assets relating to assets sold during the period			0
Balance at end of period			31
Pension Benefits - US [Member] | TBA Debt Securities Derivatives [Member] | Level 3 [Member]
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period			10
Purchases, sales and settlements	(26)		21
Pension Benefits - US [Member] | Insurance Contracts [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	47
Actual return on plan assets relating to assets still held at the reporting date	3		0
Actual return on plan assets relating to assets sold during the period			0
Balance at end of period			47
Pension Benefits - US [Member] | Insurance Contracts [Member] | Level 3 [Member]
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period			0
Acquisition of LKE			46
Purchases, sales and settlements	(4)		1
Pension Benefits - US [Member] | Master Trust [Member]
Information About Plan Assets (Numeric) [Abstract]
Value of plan U.S. pension trust assets that relate to PPL subsidiary	133
Undivided interest percentage in each asset category that PPL Montana holds	5.00%
Assumptions Used in Calculations (Numeric) [Abstract]
Weighted average duration for debt securities held (in years)	25
The limited lives of two partnership of private equity investments (in years)	10
The limited life of a third partnership of private equity investments (in years)	15
The amount of potential liability that maybe required to be funded by the master trust during life of the partnership	83
The number of days notice required to redeem shares in hedge fund investments	90
Actual Allocation by Plan Asset (Details) [Abstract]
Total actual allocation	100.00%		100.00%
Target Allocations (Details ) [Abstract]
Total, target allocation	100.00%
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	2,527
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	2,041
Balance at end of period	2,527
Pension Benefits - US [Member] | Master Trust [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	963		863
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	963		863
Pension Benefits - US [Member] | Master Trust [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	1,507		1,131
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	1,507		1,131
Pension Benefits - US [Member] | Master Trust [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	57		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	57		47
Pension Benefits - US [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	78		87
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	78		87
Pension Benefits - US [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	78		87
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	78		87
Pension Benefits - US [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Large Cap Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	371		414
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	371		414
Pension Benefits - US [Member] | Master Trust [Member] | US Large Cap Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	247		293
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	247		293
Pension Benefits - US [Member] | Master Trust [Member] | US Large Cap Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	124		121
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	124		121
Pension Benefits - US [Member] | Master Trust [Member] | US Large Cap Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Small Cap Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	112		113
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	112		113
Pension Benefits - US [Member] | Master Trust [Member] | US Small Cap Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	112		113
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	112		113
Pension Benefits - US [Member] | Master Trust [Member] | US Small Cap Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Small Cap Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	458		249
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	458		249
Pension Benefits - US [Member] | Master Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	458		249
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	458		249
Pension Benefits - US [Member] | Master Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | International Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	299		343
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	299		343
Pension Benefits - US [Member] | Master Trust [Member] | International Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	102		121
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	102		121
Pension Benefits - US [Member] | Master Trust [Member] | International Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	197		222
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	197		222
Pension Benefits - US [Member] | Master Trust [Member] | International Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	515		331
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	515		331
Pension Benefits - US [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	443		295
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	443		295
Pension Benefits - US [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	72		36
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	72		36
Pension Benefits - US [Member] | Master Trust [Member] | US Treasury And US Government Sponsored Agency Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Residential - Commercial Backed Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	9		10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	9		10
Pension Benefits - US [Member] | Master Trust [Member] | Residential - Commercial Backed Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Residential - Commercial Backed Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	9		10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	9		10
Pension Benefits - US [Member] | Master Trust [Member] | Residential - Commercial Backed Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	446		319
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	446		319
Pension Benefits - US [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	439		313
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	439		313
Pension Benefits - US [Member] | Master Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	7		6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	7		6
Pension Benefits - US [Member] | Master Trust [Member] | International Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	6		3
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	6		3
Pension Benefits - US [Member] | Master Trust [Member] | International Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | International Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	6		3
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	6		3
Pension Benefits - US [Member] | Master Trust [Member] | International Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Other Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	10		12
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	10		12
Pension Benefits - US [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	10		12
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	10		12
Pension Benefits - US [Member] | Master Trust [Member] | Other Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	85		76
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	85		76
Pension Benefits - US [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	85		76
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	85		76
Pension Benefits - US [Member] | Master Trust [Member] | Real Estate Alternative Investments [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	45		10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	45		10
Pension Benefits - US [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Private Equity Alternative Investments [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	45		10
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	45		10
Pension Benefits - US [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	92		95
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	92		95
Pension Benefits - US [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	92		95
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	92		95
Pension Benefits - US [Member] | Master Trust [Member] | Hedge Fund Of Funds Alternative Investments [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | TBA Debt Securities Derivatives [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	5		31
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	5		31
Pension Benefits - US [Member] | Master Trust [Member] | TBA Debt Securities Derivatives [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | TBA Debt Securities Derivatives [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | TBA Debt Securities Derivatives [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	5		31
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	5		31
Pension Benefits - US [Member] | Master Trust [Member] | Interest Rate Swaps Derivatives [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	20		(4)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	20		(4)
Pension Benefits - US [Member] | Master Trust [Member] | Interest Rate Swaps Derivatives [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Interest Rate Swaps Derivatives [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	20		(4)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	20		(4)
Pension Benefits - US [Member] | Master Trust [Member] | Interest Rate Swaps Derivatives [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Receivables [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	50		24
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	50		24
Pension Benefits - US [Member] | Master Trust [Member] | Receivables [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	31		13
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	31		13
Pension Benefits - US [Member] | Master Trust [Member] | Receivables [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	19		11
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	19		11
Pension Benefits - US [Member] | Master Trust [Member] | Receivables [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Payables [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(48)		(54)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(48)		(54)
Pension Benefits - US [Member] | Master Trust [Member] | Payables [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(40)		(51)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(40)		(51)
Pension Benefits - US [Member] | Master Trust [Member] | Payables [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(8)		(3)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(8)		(3)
Pension Benefits - US [Member] | Master Trust [Member] | Payables [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Insurance Contracts [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	2,553		2,059
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	2,553		2,059
Pension Benefits - US [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	973		871
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	973		871
Pension Benefits - US [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	1,523		1,141
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	1,523		1,141
Pension Benefits - US [Member] | Master Trust [Member] | Insurance Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	57		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	57		47
Pension Benefits - US [Member] | Master Trust [Member] | 401 H Account [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(26)		(18)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(26)		(18)
Pension Benefits - US [Member] | Master Trust [Member] | 401 H Account [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(10)		(8)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(10)		(8)
Pension Benefits - US [Member] | Master Trust [Member] | 401 H Account [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(16)		(10)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(16)		(10)
Pension Benefits - US [Member] | Master Trust [Member] | 401 H Account [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Master Trust [Member] | Growth Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	57.00%		72.00%
Equity securities, actual allocation	31.00%		43.00%
Debt securities, actual allocation	17.00%	[2]	20.00%	[2]
Alternative investments, actual allocation	9.00%		9.00%
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	45.00%
Portfolio Category, maximum range	60.00%
Portfolio Category, target allocations	55.00%
Pension Benefits - US [Member] | Master Trust [Member] | Immunizing Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	41.00%		27.00%
Debt securities, actual allocation	40.00%	[2]	27.00%	[2]
Derivatives, actual allocations	1.00%		0.00%
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	35.00%
Portfolio Category, maximum range	55.00%
Portfolio Category, target allocations	43.00%
Pension Benefits - US [Member] | Master Trust [Member] | Liquidity Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	2.00%		1.00%
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	0.00%
Portfolio Category, maximum range	9.00%
Portfolio Category, target allocations	2.00%
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	100.00%
Equity securities, actual allocation			56.00%
Debt securities, actual allocation			37.00%	[3]
Other - actual allocation			7.00%
Total actual allocation			100.00%
Target Allocations (Details ) [Abstract]
U.S. equity securities, minimum range			45.00%
U.S. equity securities, maximum range			75.00%
Debt securities, minimum range			30.00%	[3]
Debt securities, maximum range			50.00%	[3]
Other, minimum range			0.00%
Other, maximum range			10.00%
Total, target allocation	100.00%
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	944		778
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	778
Balance at end of period	944		778
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	250		6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	250		6
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	648		725
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	648		725
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	46		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	46		47
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	122		6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	122		6
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	122		6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	122		6
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Large Cap Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	220		293
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	220		293
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Large Cap Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Large Cap Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	220		293
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	220		293
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Large Cap Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Small Cap Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		67
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		67
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Small Cap Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Small Cap Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		67
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		67
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Small Cap Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	65		307
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	65		307
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	65		307
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	65		307
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | International Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	106		105
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	106		105
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | International Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	44		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	44		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | International Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	62		105
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	62		105
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | International Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Treasury Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	97		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	97		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Treasury Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	97		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	97		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Treasury Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | US Treasury Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	342		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	342		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	342		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	342		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Return Swaps Derivatives [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	4		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	4		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Return Swaps Derivatives [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Return Swaps Derivatives [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	4		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	4		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Return Swaps Derivatives [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Insurance Contracts [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	46		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	46		47
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Insurance Contracts [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Insurance Contracts [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Insurance Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	46		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	46		47
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Trust Assets Not Including 401 H Assets [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	1,002		825
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	1,002		825
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	263		6
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	263		6
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	693		772
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	693		772
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	46		47
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	46		47
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | 401 H Account [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(58)		(47)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(58)		(47)
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | 401 H Account [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(13)		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(13)		0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | 401 H Account [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	(45)		(47)
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	(45)		(47)
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | 401 H Account [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period			0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period			0
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Growth Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	54.00%
Equity securities, actual allocation	33.00%
Debt securities, actual allocation	21.00%	[4]
Alternative investments, actual allocation	0.00%
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	45.00%
Portfolio Category, maximum range	60.00%
Portfolio Category, target allocations	59.00%
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Immunizing Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	34.00%
Debt securities, actual allocation	34.00%	[4],[5]
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	35.00%
Portfolio Category, maximum range	55.00%
Portfolio Category, target allocations	38.00%
Pension Benefits - US [Member] | Louisville Gas Electric And Kentucky Energy Pension Trust [Member] | Liquidity Portfolio [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
Portfolio Category, actual allocations	12.00%	[5]
Target Allocations (Details ) [Abstract]
Portfolio Category, minimum range	0.00%	[5]
Portfolio Category, maximum range	9.00%	[5]
Portfolio Category, target allocations	3.00%	[5]
Pension Benefits - UK [Member]
Assumptions Used in Calculations (Numeric) [Abstract]
Fund management expects to outperform this percentage of ex-Japan Index returns	50.00%
Fund management expects to outperform this percentage of Japan Index returns	50.00%
Actual Allocation by Plan Asset (Details) [Abstract]
U.K. equity securities, actual allocation	14.00%		18.00%
European equity securities (excluding the U.K.), actual allocation	5.00%		11.00%
Asian-Pacific equity securities, actual allocation	5.00%		11.00%
North American equity securities, actual allocation	5.00%		6.00%
Emerging market equity securities, actual allocation	2.00%		5.00%
Currency equity securities, actual allocation	1.00%		2.00%
Global Tactical Assets Allocation equity securities, actual allocation	0.00%		1.00%
Debt securities, actual allocation	56.00%	[3]	38.00%	[3]
Alternative investments, actual allocation	7.00%		6.00%
Cash and cash equivalents, actual allocation	5.00%		2.00%
Total actual allocation	100.00%		100.00%
Target Allocations (Details ) [Abstract]
U.K. equity securities, target allocation	14.00%
European equity securities (excluding the U.K.), target allocation	6.00%
Asian-Pacific equity securities, target allocation	5.00%
North American equity securities, target allocation	4.00%
Emerging markets equity securities, target allocation	2.00%
Currency, target allocation	2.00%
Global Tactical Assets Allocation, target allocation	1.00%
Debt securities, target allocation	57.00%	[3]
Alternative investments, target allocation	9.00%
Cash and cash equivalents, target allocation	0.00%
Total, target allocation	100.00%
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	6,351		2,524
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	2,524		2,331
Acquisition of LKE	3,567	[1]	0
Balance at end of period	6,351		2,524
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Amount to be contributed to plan in the next fiscal year	161
Percentage of deficit funding requirements permitted to recover in rates	75.00%
Estimated Future Benefit Payments (Details) [Abstract]
2012	354
2013	357
2014	363
2015	371
2016	375
2017 - 2021	1,987
Pension Benefits - UK [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	313		46
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	313		46
Pension Benefits - UK [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	6,038		2,478
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	6,038		2,478
Pension Benefits - UK [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	313		46
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	313		46
Pension Benefits - UK [Member] | Cash And Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	313		46
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	313		46
Pension Benefits - UK [Member] | Cash And Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Cash And Cash Equivalents [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Companies Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	921		455
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	921		455
Pension Benefits - UK [Member] | UK Companies Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Companies Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	921		455
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	921		455
Pension Benefits - UK [Member] | UK Companies Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | European Companies Excluding UK Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	313		273
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	313		273
Pension Benefits - UK [Member] | European Companies Excluding UK Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | European Companies Excluding UK Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	313		273
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	313		273
Pension Benefits - UK [Member] | European Companies Excluding UK Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Asian Pacific Companies Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	312		279
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	312		279
Pension Benefits - UK [Member] | Asian Pacific Companies Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Asian Pacific Companies Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	312		279
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	312		279
Pension Benefits - UK [Member] | Asian Pacific Companies Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | North American Companies Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	335		162
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	335		162
Pension Benefits - UK [Member] | North American Companies Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | North American Companies Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	335		162
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	335		162
Pension Benefits - UK [Member] | North American Companies Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Emerging Markets Companies Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	116		127
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	116		127
Pension Benefits - UK [Member] | Emerging Markets Companies Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Emerging Markets Companies Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	116		127
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	116		127
Pension Benefits - UK [Member] | Emerging Markets Companies Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Currency Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	31		51
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	31		51
Pension Benefits - UK [Member] | Currency Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Currency Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	31		51
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	31		51
Pension Benefits - UK [Member] | Currency Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Global Tactical Asset Allocation Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	25		23
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	25		23
Pension Benefits - UK [Member] | Global Tactical Asset Allocation Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Global Tactical Asset Allocation Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	25		23
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	25		23
Pension Benefits - UK [Member] | Global Tactical Asset Allocation Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Corporate Bonds Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	699		321
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	699		321
Pension Benefits - UK [Member] | UK Corporate Bonds Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Corporate Bonds Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	699		321
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	699		321
Pension Benefits - UK [Member] | UK Corporate Bonds Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Gilts Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	2,109		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	2,109		0
Pension Benefits - UK [Member] | UK Gilts Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Gilts Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	2,109		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	2,109		0
Pension Benefits - UK [Member] | UK Gilts Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Index Linked Gilts Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	744		629
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	744		629
Pension Benefits - UK [Member] | UK Index Linked Gilts Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | UK Index Linked Gilts Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	744		629
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	744		629
Pension Benefits - UK [Member] | UK Index Linked Gilts Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Real Estate Alternative Investments [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	433		158
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	433		158
Pension Benefits - UK [Member] | Real Estate Alternative Investments [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Pension Benefits - UK [Member] | Real Estate Alternative Investments [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	433		158
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	433		158
Pension Benefits - UK [Member] | Real Estate Alternative Investments [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member]
Actual Allocation by Plan Asset (Details) [Abstract]
U.S. equity securities, actual allocation	53.00%		55.00%
Debt securities, actual allocation	41.00%	[6]	39.00%	[6]
Cash and cash equivalents, actual allocation	6.00%	[7]	6.00%	[7]
Total actual allocation	100.00%		100.00%
Target Allocations (Details ) [Abstract]
U.S. equity securities, minimum range	45.00%
U.S. equity securities, maximum range	65.00%
U.S. equity securities, target allocation	55.00%
Debt securities, minimum range	30.00%	[6]
Debt securities, maximum range	50.00%	[6]
Debt securities, target allocation	40.00%	[6]
Cash and cash equivalents, minimum range	0.00%	[7]
Cash and cash equivalents, maximum range	15.00%	[7]
Cash and cash equivalents, target allocation	5.00%	[7]
Total, target allocation	100.00%
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	391		360
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at beginning of period	360		301
Acquisition of LKE	0		42	[1]
Balance at end of period	391		360
Defined Benefit Plan Estimated Future Employer Contributions (Numeric) [Abstract]
Amount to be contributed to plan in the next fiscal year	28
Estimated Future Benefit Payments (Details) [Abstract]
2012	50
2013	53
2014	57
2015	59
2016	62
2017 - 2021	348
Expected Federal Subsidy (Details) [Abstract]
Federal subsidy 2012	1
Federal subsidy 2013	1
Federal subsidy 2014	1
Federal subsidy 2015	1
Federal subsidy 2016	1
Federal subsidy 2017-2021	4
Other Postretirement Benefits - US [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	23		8
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	23		8
Other Postretirement Benefits - US [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	368		352
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	368		352
Other Postretirement Benefits - US [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Large Cap Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	126		163
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	126		163
Other Postretirement Benefits - US [Member] | US Large Cap Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Large Cap Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	126		163
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	126		163
Other Postretirement Benefits - US [Member] | US Large Cap Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Commingled Debt Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	121		69
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	121		69
Other Postretirement Benefits - US [Member] | US Commingled Debt Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Commingled Debt Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	121		69
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	121		69
Other Postretirement Benefits - US [Member] | US Commingled Debt Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Commingled Money Market Funds Equity Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	20		18
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	20		18
Other Postretirement Benefits - US [Member] | US Commingled Money Market Funds Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | US Commingled Money Market Funds Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	20		18
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	20		18
Other Postretirement Benefits - US [Member] | US Commingled Money Market Funds Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Municipalities Debt Securities [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	40		44
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	40		44
Other Postretirement Benefits - US [Member] | Municipalities Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Municipalities Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	40		44
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	40		44
Other Postretirement Benefits - US [Member] | Municipalities Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Receivables [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		1
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		1
Other Postretirement Benefits - US [Member] | Receivables [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Receivables [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		1
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		1
Other Postretirement Benefits - US [Member] | Receivables [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Total Trust Assets Not Including 401 H Assets [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	307		295
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	307		295
Other Postretirement Benefits - US [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	307		295
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	307		295
Other Postretirement Benefits - US [Member] | Total Trust Assets Not Including 401 H Assets [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	0		0
Other Postretirement Benefits - US [Member] | 401 H Account [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	84		65
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	84		65
Other Postretirement Benefits - US [Member] | 401 H Account [Member] | Level 1 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	23		8
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	23		8
Other Postretirement Benefits - US [Member] | 401 H Account [Member] | Level 2 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	61		57
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	61		57
Other Postretirement Benefits - US [Member] | 401 H Account [Member] | Level 3 [Member]
Defined Benefit Plan Fair Value of Plan Assets (Details) [Abstract]
End of period	0		0
Change in Fair Value of Level 3 Plan Assets [Roll Forward]
Balance at end of period	$ 0		$ 0
Other Postretirement Benefits - US [Member] | Master Trust [Member]
Assumptions Used in Calculations (Numeric) [Abstract]
Number of months from date of purchase that investment must mature	13

[1] Includes the pension and other postretirement medical plans of LKE, which were acquired in 2010, and the pension plan of WPD Midlands, which was acquired in 2011. See Note 10 for additional information.

[2] Includes commingled debt funds, which PPL treats as debt securities for asset allocation purposes.

[3] Includes commingled debt funds.

[4] Includes commingled debt funds, which LKE treats as debt securities for asset allocation purposes.

[5] The asset allocation for this portfolio is not within the established target range due to the transition of assets at the end of 2011 in anticipation of transfer into the PPL Services Corporation Master Trust in January 2012.

[6] Includes commingled debt funds and debt securities.

[7] Includes commingled money market fund.