Retirement Benefits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined benefit contributions percentage	11.00%
Maximum percentage of employees' before-tax contribution on a dollar-for-dollar basis	5.50%
Estimated net gain and prior service of other postretirement plans	$ 9	$ 29
Estimate long-term rate of return on plan assets	8.25%
Annualized ten-year rate of return on plan assets	8.58%
Net management fee excess of expected rate of return period	10
Percentage of investments in non-U.S. common stocks	27.00%	27.00%
Receivables and payables for foreign currency forward contracts and futures contracts		2
Define benefit plan obligation to return collateral on loaned securities		0
Contribution estimates on defined benefit pension plans	6.5
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	143	264
The estimated net loss and prior service cost for the defined benefit pension plans	250	13
Estimate long-term rate of return on plan assets	8.50%	8.50%
Retiree Medical And Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	$ 203	$ 232
Estimate long-term rate of return on plan assets	8.50%	8.50%