Commitments And Contingencies (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	Mar. 31, 2018
Purchase obligation over the next twelve months	$ 5,400
Other Receivables	329	$ 277
Realogy [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other Receivables	23
Wyndham [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other Receivables	$ 14