Regulatory Matters - General Disclosures (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014
Public Utilities Commission, Nevada [Member] \| Energy Efficiency Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Customer refund liability, current	$ 3
Public Utilities Commission, Nevada [Member] \| General Rate Case Companion [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	10
Public Utilities, Property, Plant and Equipment, Amount of Disallowed Costs for Recently Completed Plant	7
Utilities Operating Expense, Impairments	1
Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	17
Public Utilities, Approved Rate Increase (Decrease), Amount	4
Federal Energy Regulatory Commission [Member] \| Customer Deposits and Other [Member]
Public Utilities, General Disclosures [Line Items]
Customer refund liability, current	$ 2
MEHC Merger \| Public Utilities Commission, Nevada [Member] \| Energy Efficiency Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Recovery of loss on revenues	50.00%

Regulatory stipulation that limits the amount of lost revenues that can be requested.

No definition available.

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- Definition

Current regulatory liabilities generally represent obligations to make refunds to customers for various reasons including overpayment.

+ References

No definition available.

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- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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- Definition

The amount of disallowed costs for rate making purposes for recently completed plants in regulated industries when this becomes probable. Such charges do not meet the requirements of an extraordinary item.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section 35

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6500292&loc=d3e45799-110387

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section E

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 10.E)

-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e660019-123033

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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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- Definition

Amount of operating expense for impairments of regulated operation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2(b))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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