Commitments And Contingencies (Schedule Of Reconciliation Of Beginning And Ending Accrued Self-Insured Claims) (Details) - Accrued self-insured claims, net - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Commitments and Contingencies [Line Items]
Balance at the beginning of the period	$ 111	$ 111
Provision for self-insured claims	13	8
Cash payments	(8)	(6)
Balance at the end of the period	$ 116	$ 113