The statutory corporate income tax rate for a foreign jurisdiction.

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the tax effect of certain temporary differences due to state utility rate regulation.

+ References

No definition available.

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- Definition

The carrying amount as of the balance sheet date of income taxes receivable from (payable to) related parties (typically the parent company) that are due within one year of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes with taxing authorities.

+ References

No definition available.

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- Definition

The number of years from its in-service date that each wind-powered generating facility is eligible for federal renewable energy production tax credits.

+ References

No definition available.

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- Definition

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 2

-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 13

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(2))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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- Definition

The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

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-Name Accounting Standards Codification

-Topic 740

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 6.I)

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the difference between statutory income tax rates in foreign jurisdictions and the domestic federal statutory income tax rate recorded during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

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-Name Accounting Standards Codification

-Topic 740

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-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 6.I)

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

+ References

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to revisions in previously reported amounts of income tax provision.

+ References

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense or benefit, net of the federal tax benefit (expense) thereon, recorded during the period.

+ References

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- Definition

The sum of the differences between the effective income tax rate and domestic federal statutory income tax rate that can be explained by all tax credits generated or utilized under enacted tax laws during the period.

+ References

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- Definition

The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to changes in the income tax rates under enacted tax laws in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 27

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

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-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32059-109318

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the current period and the expected income tax expense or benefit computed attributable to revisions of previously reported income tax expense.

+ References

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Income Taxes Reconciliation of Effective Income Tax Rate (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			1 Months Ended									12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jul. 31, 2012 United Kingdom	Jul. 31, 2011 United Kingdom	Jul. 31, 2010 United Kingdom	Jul. 31, 2011 Corporate Income Tax Rate Enacted July 2011, Effective April 1, 2012 [Member] United Kingdom	Jul. 31, 2012 Corporate Income Tax Rate Enacted July 2012, Effective April 1, 2012 [Member] United Kingdom	Jul. 31, 2012 Corporate Income Tax Rate Enacted July 2012, Effective April 1, 2013 [Member] United Kingdom	Jul. 31, 2010 Corporate Income Tax Rate Enacted July 2010, Effective April 1, 2011 [Member] United Kingdom	Jul. 31, 2009 Corporate Income Tax Rate Enacted July 2009, Effective April 1, 2011 [Member] [Member] United Kingdom	Jul. 31, 2011 Corporate Income Tax Rate Enacted July 2011, Effective April 1, 2011 [Member] United Kingdom	Dec. 31, 2012 Repairs deduction [Member]	Dec. 31, 2010 Repairs deduction [Member]	Dec. 31, 2010 A&G deduction [Member]	Dec. 31, 2011 Tax method Changes, Issue Resolutions [Member]
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
Income tax credits	(14.00%)	(11.00%)	(10.00%)
State income tax, net of federal income tax benefit	(3.00%)	0.00%	0.00%
Income tax effect of foreign income	(7.00%)	(5.00%)	(7.00%)
Income tax method changes	(1.00%)	(2.00%)	(4.00%)
Effects of ratemaking	(1.00%)	0.00%	(2.00%)
Other, net	0.00%	1.00%	2.00%
Effective income tax rate	9.00%	18.00%	14.00%
Related Party Tax Expense [Abstract]
Income taxes receivable from Berkshire Hathaway	$ 336	$ 456
Production Tax Credit Carryforwards [Abstract]
Years Eligible For Renewable Energy Production Tax Credit	10 years
United Kingdom Corporate Income Tax Rate Change [Abstract]
Income Tax Reconciliation, Change in Enacted Tax Rate				38	40	25
Corporate Income Tax Rate, Foreign							25.00%	24.00%	23.00%	27.00%	28.00%	26.00%
Income tax method change [Abstract]
Income tax benefits from tax method change													$ 16	$ 17	$ 44	$ 35