Commitments And Contingencies (Schedule Of Reconciliation Of Beginning And Ending Accrued Self-Insured Claims) (Details) - Accrued Self-Insured Claims, Net [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies [Line Items]
Balance at the beginning of the period	$ 111	$ 115
Provision for self-insured claims	36	29
Cash payments	(35)	(33)
Balance at the end of the period	$ 111	$ 111