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Commitments And Contingencies (Commitments And Contingencies Activity) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies [Line Items]
Current portion, ending balance at December 31	$ 177	$ 190
Environmental [Abstract]
Beginning balance.	227	223	$ 196
Accruals	76	67	84
Payments	(70)	(63)	(57)
Ending balance at December 31	233	227	223
Current portion, ending balance at December 31	65	62	59
Personal Injury [Member]
Commitments and Contingencies [Line Items]
Beginning balance	265	271	285
Current year accruals	72	78	74
Changes in estimates for prior years	(3)	(11)	(16)
Payments	(64)	(73)	(72)
Ending balance at December 31	270	265	271
Current portion, ending balance at December 31	$ 60	$ 63	$ 72

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The charge against earnings in the period to change the loss contingency reserves for change in estimates from prior years.

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

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Amount of cash outflow to settle environmental loss contingencies.

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