Basis Of Presentation Revenue Recognition - Deferred Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Jan. 01, 2019
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue		$ 86	$ 85
Deferred Revenue, Additions		30
Deferred Revenue, Revenue Recognized		(29)
Realogy Franchise Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue		73	72
Deferred Revenue, Additions		28
Deferred Revenue, Revenue Recognized		(27)
Realogy Brokerage Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue		13	13
Deferred Revenue, Additions		2
Deferred Revenue, Revenue Recognized		$ (2)
Minimum | Realogy Brokerage Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
New Development Period		18 months
Maximum | Realogy Brokerage Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
New Development Period		24 months
International Franchise Rights | Realogy Franchise Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Finite-Lived Intangible Asset, Useful Life		25 years
Area Development Fees | Realogy Franchise Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	[1]	$ 47	48
Deferred Revenue, Additions	[1]	0
Deferred Revenue, Revenue Recognized	[1]	(1)
Brand Marketing Fees | Realogy Franchise Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	[2]	14	13
Deferred Revenue, Additions	[2]	20
Deferred Revenue, Revenue Recognized	[2]	(19)
Deferred Income, Other | Realogy Franchise Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue		12	11
Deferred Revenue, Additions		8
Deferred Revenue, Revenue Recognized		(7)
Deferred Income, Other | Realogy Brokerage Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue		4	4
Deferred Revenue, Additions		1
Deferred Revenue, Revenue Recognized		(1)
New Development Business | Realogy Brokerage Group
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	[3]	9	$ 9
Deferred Revenue, Additions	[3]	1
Deferred Revenue, Revenue Recognized	[3]	$ (1)

[1] The Company collects initial area development fees ("ADF") for international territory transactions, which are recorded as deferred revenue when received and recognized into franchise revenue over the average 25 year life of the related franchise agreement as consideration for the right to access and benefit from Realogy’s brands.

[2] consideration for the right to access and benefit from Realogy’s brands. In the event an ADF agreement is terminated prior to the end of its term, the unamortized deferred revenue balance will be recognized into revenue immediately upon termination. (b)Revenues recognized include intercompany marketing fees paid by Realogy Brokerage Group.

[3] New development closings generally have a development period of between 18 and 24 months from contracted date to closing.