Commitments And Contingencies (Schedule Of Reconciliation Of Beginning And Ending Accrued Self-Insured Claims) (Details) - Accrued Self-Insured Claims, Net [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Commitments and Contingencies [Line Items]
Balance at the beginning of the period	$ 126	$ 111
Provision for self-insured claims	29	35
Cash payments	(21)	(21)
Balance at the end of the period	$ 134	$ 125