Commitments and Contingencies (Schedule Of Reconciliation Of Beginning And Ending Accrued Self-Insured Claims) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015
Commitments and Contingencies [Line Items]
Increase (Decrease) in Self Insurance Reserve	[1]	$ 23
Accrued Self-Insured Claims, Net [Member]
Commitments and Contingencies [Line Items]
Balance at the beginning of the period		114		$ 104
Provision for self-insured claims		50	[2]	28
Cash payments		(34)		(22)
Balance at the end of the period		$ 129		$ 110

[1] Represents an adjustment to the Company's accrued self-insured claims related to automobile, general liability and workers' compensation risks. The adjustment is based on the Company's detailed annual assessment of this actuarially determined accrual, which the Company completes in the second quarter of each year. This adjustment relates to coverage periods of 2015 and prior. We have excluded this discrete second quarter adjustment from Adjusted EBITDA because we believe it does not reflect our ongoing operations and because we believe doing so is useful to investors in aiding period-to-period comparability. Adjustments to accrued self-insured claims related to this insurance program of $2 million in the three months ended September 30, 2015 and $4 million and $6 million in the nine months ended September 30, 2016 and 2015, respectively, were recorded as charges in total Adjusted EBITDA. There were no similar adjustments recorded as charges in total Adjusted EBITDA in the three months ended September 30, 2016.

[2] Includes a charge of $23 million recorded in the nine months ended September 30, 2016 for an adjustment to the Company's accrued self-insured claims related to automobile, general liability and workers' compensation risks. The adjustment is based on the Company's detailed annual assessment of this actuarially determined accrual, which the Company completes in the second quarter of each year. This adjustment relates to coverage periods of 2015 and prior.