Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - Southern California Edison - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,817	$ 2,917
Fair Value	4,290	4,331
Stocks
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	311	304
Fair Value	1,464	1,460
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	736	691
Fair Value	894	840
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	1,002	1,070
Fair Value	1,092	1,128
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	662	708
Fair Value	731	755
Short-term investments and receivables/payables
Fair Value Disclosures:
Repurchase agreement	8	81
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	106	144
Fair Value	$ 109	$ 148

Amount, after the effects of master netting arrangements, of funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price. Includes purchases of participations in pools of securities that are subject to a resale agreement, assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.3)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226008-175313

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=49176635&loc=d3e9760-107771

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(2)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph m
-Subparagraph 1(i)
-Article 4

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