Schedule Of Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Presented in Consolidated Statements of Financial Position [Abstract]
Allowance for doubtful accounts - current	$ 4	$ 3
Allowance for doubtful accounts - long-term	35	27
Accrued casualty costs, current	190	211
Accrued Casualty Costs [Member]
Schedule Of Valuation And Qualifying Accounts [Line Items]
Balance, beginning of period	709	684	$ 716
Charges/(reduction) to expense	215	202	167
Net recoveries/(write-offs), cash payments and other reductions	(267)	(177)	(199)
Balance, end of period	657	709	684
Presented in Consolidated Statements of Financial Position [Abstract]
Accrued casualty costs, current	190	211	194
Accrued casualty costs, long-term	467	498	490
Balance, end of period	$ 657	$ 709	$ 684