Fair Value Measurements (Level 3 Rollforward) (Details) (Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Level 3
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net asset (liabilities) at beginning of period	$ (791)	$ (754)
Total realized/unrealized gains (losses):
Included in regulatory assets and liabilities	(82)	(356)
Purchases	18	21
Settlements	(27)	(8)
Fair value of net liabilities at end of period	(882)	(1,097)
Change during the period in unrealized losses related to assets and liabilities held at the end of the period	$ (66)	$ (351)

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This element represents total gains or losses for the period (realized and unrealized), included in regulatory assets and liabilities measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

No definition available.

+ Details

Name:	eix_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInRegulatoryAssetsAndLiabilities
Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the change during the period in unrealized gains (losses) for financial instruments, held at the end of the period, with unobservable inputs (level 3).

+ References

No definition available.

+ Details

Name:	eix_IncreaseDecreaseDuringPeriodInUnrealizedGainsLossesRelatedToLevel3FinancialInstrumentsHeldAtPeriodEnd
Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	eix_NetRealizedOrUnrealizedGainLossAbstract
Namespace Prefix:	eix_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-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.

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant