Basis Of Presentation Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	[1],[2]	$ 1,116	$ 1,054
Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	850	799
Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	151	129
Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	71	70
Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	44	56
Realogy Franchise Group
Disaggregation of Revenue [Line Items]
Revenues	[1],[2]	168	179
Realogy Franchise Group | Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0
Realogy Franchise Group | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	13	16
Realogy Franchise Group | Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	127	123
Realogy Franchise Group | Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	28	40
Realogy Brokerage Group
Disaggregation of Revenue [Line Items]
Revenues	[1],[2]	869	816
Realogy Brokerage Group | Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	850	799
Realogy Brokerage Group | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	5	2
Realogy Brokerage Group | Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	0	0
Realogy Brokerage Group | Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	14	15
Realogy Title Group
Disaggregation of Revenue [Line Items]
Revenues	[1],[2]	137	114
Realogy Title Group | Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0
Realogy Title Group | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	133	111
Realogy Title Group | Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	0	0
Realogy Title Group | Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	4	3
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	[1],[2],[7]	(58)	(55)
Corporate and Other | Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0
Corporate and Other | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	0	0
Corporate and Other | Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	(56)	(53)
Corporate and Other | Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	$ (2)	$ (2)

[1] Revenues for Realogy Franchise Group include intercompany referral commissions related to Realogy Advantage Broker Network paid by Realogy Brokerage Group of $2 million and $3 million for the three months ended March 31, 2020 and 2019, respectively. Such amounts are recorded as contra-revenues by Realogy Brokerage Group. There are no other material intersegment transactions.

[2] Transactions between segments are eliminated in consolidation. Revenues for the Realogy Franchise Group include intercompany royalties and marketing fees paid by Realogy Brokerage Group of $58 million and $55 million for the three months ended March 31, 2020 and 2019, respectively. Such amounts are eliminated through the Corporate and Other line.

[3] Consists primarily of revenues related to gross commission income at Realogy Brokerage Group, which is recognized at a point in time at the closing of a homesale transaction.

[4] Service revenue primarily consists of title and escrow fees at Realogy Title Group, which are recognized at a point in time at the closing of a homesale transaction.

[5] Franchise fees at Realogy Franchise Group primarily include domestic royalties which are recognized at a point in time when the underlying franchisee revenue is earned (upon close of the homesale transaction).

[6] Other revenue is comprised of brand marketing funds received at Realogy Franchise Group from franchisees, third-party listing fees and other miscellaneous revenues across all of the business segments.

[7] Includes the elimination of transactions between segments.