Pension, Retiree Medical And Savings Plans (Estimated Future Benefit Payments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	$ 560
2013	560
2014	560
2015	600
2016	645
2017-21	4,050
Retiree Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2012	135	[1]
2013	135	[1]
2014	140	[1]
2015	145	[1]
2016	145	[1]
2017-21	730	[1]
2012 Through 2016 [Member]
Defined Benefit Plan Disclosure [Line Items]
Subsidies expected to be received under the 2003 Medicare Act	13
2017 Through 2021 [Member]
Defined Benefit Plan Disclosure [Line Items]
Subsidies expected to be received under the 2003 Medicare Act	$ 100

[1] Expected future benefit payments for our retiree medical plans do not reflect any estimated subsidies expected to be received under the 2003 Medicare Act. Subsidies are expected to be approximately $13 million for each of the years from 2012 through 2016 and approximately $100 million in total for 2017 through 2021.