Commitments And Contingencies (Narrative) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Commitments And Contingencies [Line Items]
Loss Contingency Accrual	$ 12
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 50
Document Period End Date	Jun. 30, 2018
Purchase obligation over the next twelve months	$ 2,800
Other Receivables	248	$ 235
Realogy [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other Receivables	23
Wyndham [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other Receivables	$ 14