Compensation and Benefit Plans (Pension Plan Assets - Fair Value Levels) (Details) - Pension Plans - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		$ 3,368	$ 3,459
Receivables and payables, net		(70)	(5)
Fair Value of Plan Assets		3,298	3,454	$ 3,477
Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		971	984
Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		2,183	2,186
Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		214	289
Fair Value of Plan Assets		214	289	390
U.S. government and agency securities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[1]	425	469
U.S. government and agency securities | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[1]	127	140
U.S. government and agency securities | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[1]	298	329
U.S. government and agency securities | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[1]	0	0
Corporate stocks
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[2]	736	730
Corporate stocks | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[2]	720	716
Corporate stocks | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[2]	16	14
Corporate stocks | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[2]	0	0
Corporate bonds
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[3]	755	801
Corporate bonds | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[3]	0	0
Corporate bonds | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[3]	755	801
Corporate bonds | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[3]	0	0
Common/collective funds
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[4]	640	524
Common/collective funds | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[4]	0	0
Common/collective funds | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[4]	640	524
Common/collective funds | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[4]	0	0
Partnerships/joint ventures
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[5]	325	399
Partnerships/joint ventures | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[5]	0	0
Partnerships/joint ventures | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[5]	111	110
Partnerships/joint ventures | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[5]	214	289
Other investment entities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[6]	263	278
Other investment entities | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[6]	0	0
Other investment entities | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[6]	263	278
Other investment entities | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[6]	0	0
Registered investment companies
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[7]	121	143
Registered investment companies | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[7]	117	113
Registered investment companies | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[7]	4	30
Registered investment companies | Level 3
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross	[7]	0	0
Interest-bearing cash
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		6	10
Interest-bearing cash | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		6	10
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		97	105
Other | Level 1
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		1	5
Other | Level 2
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		96	100
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, percentage		22.00%	55.00%
Non-index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		22.00%	27.00%
Collateralized mortgage obligations and other asset backed securities
Pension and Other Postretirement Benefits
Fair Value of Plan Assets, Gross		$ 123	$ 102
Defined Benefit Plan, Fair Value of Plan Assets below Investment Grade		$ 25	$ 15
Private Equity Funds Including Branded Consumer Products, Clean Technology and California Geographic Focus Companies | Level 3
Pension and Other Postretirement Benefits
Actual plan asset allocations, percentage		78.00%	45.00%
Russell 200 and Russell 1000 indexes | Corporate stocks
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		59.00%
Russell 200 and Russell 1000 indexes | Undervalued Securities
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		14.00%	18.00%
Morgan Stanley Capital International | Corporate stocks
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		41.00%
Standard And Poors 500 Index | Equity index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		46.00%	32.00%
Morgan Stanley Capital International Europe Australasia And Far East Index | Equity index fund
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage		16.00%	20.00%
Southern California Edison
Pension and Other Postretirement Benefits
Fair Value of Plan Assets		$ 3,080	$ 3,217	$ 3,236

[1] 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.

[2] Corporate stocks are diversified. For both 2015 and 2014, performance for actively managed separate accounts is primarily benchmarked against the Russell Indexes (59%) and Morgan Stanley Capital International (MSCI) index (41%).

[3] Corporate bonds are diversified. At December 31, 2015 and 2014, respectively, this category includes $123 million and $102 million for collateralized mortgage obligations and other asset backed securities of which $25 million and $15 million are below investment grade.

[4] At December 31, 2015 and 2014, 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 (46% and 32%), Russell 1000 indexes (14% and 18%) and the MSCI Europe, Australasia and Far East (EAFE) Index (16% and 20%). A non-index U.S. equity fund representing 22% and 27% of this category for 2015 and 2014, respectively, is actively managed.

[5] Partnerships/joint venture Level 2 investments consist primarily of a partnership which invests in publicly traded fixed income securities. At December 31, 2015 and 2014, respectively, 22% 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. At December 31, 2015 and 2014, respectively, 78% and 45% of the Level 3 partnerships are invested in private equity funds with investment strategies that include branded consumer products, clean technology and California geographic focus companies.

[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 securities.

[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 a short-term bond fund.