Liabilities, Commitments And Contingencies (Schedule Of Environmental Remediation Activity) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance - January 1	$ 570	$ 555
Reductions for payments made	(42)	(47)
Changes in estimates	37	62
Ending balance - December 31	$ 565	$ 570

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Amount of expense (reversal of expense) which increases (decreases) the accrual for environmental loss contingencies from revisions in estimates to existing obligations. Excludes changes related to business acquisitions, divestitures, or currency movement.

+ References

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Amount of cash outflow to settle environmental loss contingencies.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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