Commitments And Contingencies (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Schedule Of Commitments And Contingencies [Line Items]
Liability net of recoverable insurance proceeds	$ 12
Range of possible loss (up to)	40
Purchase obligation over the next twelve months	6,400
Purchase commitment period decrease	2,300
Other receivables	195	$ 491
Realogy [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other receivables	25
Wyndham [Member]
Schedule Of Commitments And Contingencies [Line Items]
Other receivables	$ 15