Pension, Other Postretirement Benefits (OPEB) And Savings Plans (Reconciliations Of The Beginning And Ending Balances Of Pension And OPEB Plans' Level 3 Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year	$ 4,042		$ 3,750
Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year	73		117
Temporary Investment Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year	32	[1]	118	[1]
Temporary Investment Funds [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	23	[1]	53
Purchases/(Sales)	0		(30)
Transfer In/ (Out)	(23)
Actual Return on Asset Sales	0		0
Actual Return on Assets Still Held	0		0
Fair Value of Assets at End of Year	0	[1]	23	[1]
Commingled Bonds - US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year			8	[2]
Commingled Bonds - US [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	8	[2]	17
Purchases/(Sales)	(8)		(11)
Transfer In/ (Out)	0
Actual Return on Asset Sales	0		1
Actual Return on Assets Still Held	0		1
Fair Value of Assets at End of Year	0		8	[2]
Commingled Bonds - International [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year			11
Purchases/(Sales)			0
Actual Return on Asset Sales			(11)
Actual Return on Assets Still Held			0
Fair Value of Assets at End of Year			0
Pooled Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year	36	[3]	48	[3]
Pooled Real Estate [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	48	[3]	102
Purchases/(Sales)	(18)		(53)
Transfer In/ (Out)	0
Actual Return on Asset Sales	1		(29)
Actual Return on Assets Still Held	5		28
Fair Value of Assets at End of Year	36	[3]	48	[3]
Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at End of Year	37	[4]	38	[4]
Private Equity [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	38	[4]	37
Purchases/(Sales)	(5)		(7)
Transfer In/ (Out)	0
Actual Return on Asset Sales	7		5
Actual Return on Assets Still Held	(3)		3
Fair Value of Assets at End of Year	$ 37	[4]	$ 38	[4]

[1] Certain temporary investment funds are valued using inputs such as time-to-maturity, coupon rate, quality rating and current yield (primarily Level 2), whereas certain other commingled temporary investment funds are measured with significant unobservable inputs and assumptions (primarily Level 3).

[2] Investments in fixed income securities including bond funds are priced using an evaluated pricing approach or the most recent exchange or quoted bid (primarily Level 2). Certain investments in privately held commingled bond funds are valued using broker quotations or using inputs that are not market observable or can not be derived principally from or corroborated by observable market data (primarily Level 3).

[3] The fair value of real estate investments is based on the annual independent appraisals. The investments are also valued internally every quarter by the investment managers based on significant changes in property operations and market conditions (primarily Level 3).

[4] Limited partnership interests in private equity funds are valued using significant unobservable inputs as there is little, if any, market activity. In addition, there may be transfer restrictions on private equity securities. The process for determining the fair value of such securities relied on commonly accepted valuation techniques, including the use of earnings multiples based on comparable public securities, industry-specific non-earnings-based multiples and discounted cash flow models. These inputs require significant management judgment or estimation (primarily Level 3).