Fair Value Measurements (Schedule Of The Carrying Amount And Estimated Fair Value Of The Company's Financial Instruments That Are Recorded At Fair Value On A Recurring Basis) (Details) - Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Quoted Prices In Active Markets (Level 1) [Member]
Financial Assets:
Deferred compensation trust	$ 13	$ 13
Total financial assets	13	13
Significant Other Observable Inputs (Level 2) [Member]
Financial Assets:
Total financial assets		5
Total financial liabilities	55	1
Significant Other Observable Inputs (Level 2) [Member] | Cross-Currency Interest Rate Swap [Member]
Financial Assets:
Derivative contracts	7
Significant Other Observable Inputs (Level 2) [Member] | Net Investment Hedge [Member]
Financial Assets:
Derivative contracts	10
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Swap Contract [Member]
Financial Assets:
Derivative asset, current		5
Derivative contracts	38	1
Significant Unobservable Inputs (Level 3) [Member]
Financial Assets:
Total financial assets	2	1
Total financial liabilities	2
Significant Unobservable Inputs (Level 3) [Member] | Fuel Swap Contracts [Member]
Financial Assets:
Derivative asset, current	2	1
Derivative contracts	2
Carrying Value [Member]
Financial Assets:
Deferred compensation trust	13	13
Total financial assets	15	19
Total financial liabilities	57	1
Carrying Value [Member] | Cross-Currency Interest Rate Swap [Member]
Financial Assets:
Derivative contracts	7
Carrying Value [Member] | Net Investment Hedge [Member]
Financial Assets:
Derivative contracts	10
Carrying Value [Member] | Fuel Swap Contracts [Member]
Financial Assets:
Derivative asset, current	2	1
Derivative contracts	2
Carrying Value [Member] | Interest Rate Swap Contract [Member]
Financial Assets:
Derivative asset, current		5
Derivative contracts	$ 38	$ 1