Commitments And Contingent Liabilities (Accrued Liability For Environmental Remediation Classified In The Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Loss Contingencies [Line Items]
Environmental remediation liability	$ 166	$ 110	$ 115	$ 115
Accrued Liabilities [Member]
Loss Contingencies [Line Items]
Environmental remediation liability	37	35
Other Deferred Credits And Liabilities [Member]
Loss Contingencies [Line Items]
Environmental remediation liability	$ 129	$ 75