Compensation and Benefit Plans (Pension Plan Assets - Fair Value Levels) (Details) (Pension Plans, USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	$ 3,580		$ 3,192
Receivables and payables, net	(38)		(39)
Fair Value of Plan Assets	3,542		3,153		3,235
Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	1,108		829
Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	2,058		1,915
Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	414		448
Fair Value of Plan Assets	414		448		345
Corporate stocks
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	743	[1]	642	[1]
Corporate stocks | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	743	[1]	642	[1]
Corporate stocks | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[1]	0	[1]
Corporate stocks | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[1]	0	[1]
Partnerships/joint ventures
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	580		588	[2]
Partnerships/joint ventures | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0		0	[2]
Partnerships/joint ventures | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	166		140	[2]
Partnerships/joint ventures | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	414		448	[2]
Common/collective funds
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	635	[3]	582	[3]
Common/collective funds | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[3]	0	[3]
Common/collective funds | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	635	[3]	582	[3]
Common/collective funds | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[3]	0	[3]
Corporate bonds
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	508	[4]	497	[4]
Corporate bonds | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[4]	0	[4]
Corporate bonds | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	508	[4]	497	[4]
Corporate bonds | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[4]	0	[4]
U.S. government and agency securities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	592	[5]	455	[5]
U.S. government and agency securities | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	242	[5]	104	[5]
U.S. government and agency securities | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	350	[5]	351	[5]
U.S. government and agency securities | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[5]	0	[5]
Other investment entities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	271	[6]	247	[6]
Other investment entities | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[6]	0	[6]
Other investment entities | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	271	[6]	247	[6]
Other investment entities | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[6]	0	[6]
Registered investment companies
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	126	[7]	108	[7]
Registered investment companies | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	98	[7]	79	[7]
Registered investment companies | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	28	[7]	29	[7]
Registered investment companies | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0	[7]	0	[7]
Interest-bearing cash
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	24		5
Interest-bearing cash | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	24		5
Interest-bearing cash | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0		0
Interest-bearing cash | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0		0
Other
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	101		68
Other | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	1		(1)
Other | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	100		69
Other | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	0		0
Asset backed securities including distressed mortgages | Level 3
Pension and Other Postretirement Benefits
Actual plan asset allocations	56.00%		55.00%
Non-index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark	25.00%		23.00%
Global asset allocation fund
Pension and Other Postretirement Benefits
Actual plan asset allocations	6.00%		8.00%
Collateralized mortgage obligations and other asset backed securities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	65		53
Defined Benefit Plan, Fair Value of Plan Assets below Investment Grade	7		10
Russell 200 and Russell 1000 indexes | Corporate stocks
Pension and Other Postretirement Benefits
Performance percentage benchmark	60.00%		60.00%
Russell 200 and Russell 1000 indexes | Undervalued Securities
Pension and Other Postretirement Benefits
Performance percentage benchmark	28.00%		27.00%
Morgan Stanley Capital International | Corporate stocks
Pension and Other Postretirement Benefits
Performance percentage benchmark	40.00%		40.00%
Standard And Poors 500 Index | Equity index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark	29.00%		29.00%
Morgan Stanley Capital International Europe Australasia And Far East Index | Equity index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark	11.00%		10.00%
Southern California Edison
Pension and Other Postretirement Benefits
Fair Value of Plan Assets	3,320		2,971		3,066
Edison Mission Energy
Pension and Other Postretirement Benefits
Fair Value of Plan Assets	215		177
Edison International Parent and Other
Pension and Other Postretirement Benefits
Fair Value of Plan Assets	$ 7		$ 5

[1] Corporate stocks are diversified. For 2012 and 2011, respectively, performance is primarily benchmarked against the Russell Indexes (60% and 60%) and Morgan Stanley Capital International (MSCI) index (40% and 40%).

[2] Partnerships/joint venture Level 2 investments consist primarily of a partnership which invests in publicly traded fixed income securities, primarily from the banking and finance industry and U.S. government agencies. At December 31, 2012 and 2011, respectively, approximately 56% and 55% of the Level 3 partnerships are invested in (1) asset backed securities, including distressed mortgages and (2) commercial and residential loans and debt and equity of banks. The remaining Level 3 partnerships are invested in small private equity and venture capital funds. Investment strategies for these funds include branded consumer products, early stage technology, California geographic focus, and diversified US and non-US fund-of-funds.

[3] At December 31, 2012 and 2011, respectively, the common/collective assets were invested in equity index funds that seek to track performance of the Standard and Poor's (S&P 500) Index (29% and 29%), Russell 200 and Russell 1000 indexes (28% and 27%) and the MSCI Europe, Australasia and Far East (EAFE) Index (11% and 10%). A non-index U.S. equity fund representing 25% and 23% of this category for 2012 and 2011, respectively, is actively managed. Another fund representing 6% and 8% of this category for 2012 and 2011, respectively, is a global asset allocation fund

[4] Corporate bonds are diversified. At December 31, 2012 and 2011, respectively, this category includes $65 million and $53 million for collateralized mortgage obligations and other asset backed securities of which $7 million and $10 million are below investment grade.

[5] Level 1 U.S. government and agency securities are U.S. treasury bonds and notes. Level 2 primarily relates to the Federal National Mortgage Association and the Federal Home Loan Mortgage Corporation

[6] Other investment entities were primarily invested in (1) emerging market equity securities, (2) a hedge fund that invests through liquid instruments in a global diversified portfolio of equity, fixed income, interest rate, foreign currency and commodities markets, and (3) domestic mortgage backed securitie

[7] Level 1 of registered investment companies primarily consisted of a global equity mutual fund which seeks to outperform the MSCI World Total Return Index. Level 2 primarily consisted of government inflation-indexed bonds and a short-term bond fund.