Pension, Other Postretirement Benefits (OPEB) And Savings Plans (Estimated Future Benefit Payments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	$ 247
2013	251
2014	257
2015	264
2016	272
2017-2021	1,514
Total Estimated Future Benefit Payments	2,805
Gross OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	81
2013	77
2014	78
2015	78
2016	79
2017-2021	407
Total Estimated Future Benefit Payments	800
Medicare Subsidy [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	(6)
2013	0
2014	0
2015	0
2016	0
2017-2021	0
Total Estimated Future Benefit Payments	(6)
Net OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	75
2013	77
2014	78
2015	78
2016	79
2017-2021	407
Total Estimated Future Benefit Payments	$ 794