Fair Value Measurements (Level 3 Rollforward) (Details) - Southern California Edison - Level 3 - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net liabilities at beginning of period	$ (1,148)	$ (902)
Total realized/unrealized gains (losses):
Included in regulatory assets and liabilities	(65)	(74)
Fair value of net liabilities at end of period	(1,213)	(976)
Change during the period in unrealized losses related to assets and liabilities held at the end of the period	$ (84)	$ (96)

Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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)(1)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19279-110258

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