Basis Of Presentation Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	[1]	$ 1,535	$ 1,584	$ 4,330	$ 4,386
Corporate, Non-Segment
Disaggregation of Revenue [Line Items]
Revenues	[1],[2]	(86)	(89)	(242)	(245)
Gross commission income
Disaggregation of Revenue [Line Items]
Revenues	[3]	1,242	1,293	3,525	3,559
Gross commission income | Corporate, Non-Segment
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0	0	0
Service revenue
Disaggregation of Revenue [Line Items]
Revenues	[4]	156	155	434	445
Service revenue | Corporate, Non-Segment
Disaggregation of Revenue [Line Items]
Revenues	[4]	0	0	0	0
Franchise fees
Disaggregation of Revenue [Line Items]
Revenues	[5]	98	99	269	270
Franchise fees | Corporate, Non-Segment
Disaggregation of Revenue [Line Items]
Revenues	[5]	(81)	(84)	(231)	(233)
Other
Disaggregation of Revenue [Line Items]
Revenues	[6]	39	37	102	112
Other | Corporate, Non-Segment
Disaggregation of Revenue [Line Items]
Revenues	[6]	(5)	(5)	(11)	(12)
Franchise Group | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[1]	267	271	732	762
Franchise Group | Gross commission income | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0	0	0
Franchise Group | Service revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[4]	57	60	158	177
Franchise Group | Franchise fees | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[5]	179	183	500	503
Franchise Group | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[6]	31	28	74	82
Owned Brokerage Group | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[1]	1,258	1,309	3,570	3,604
Owned Brokerage Group | Gross commission income | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[3]	1,242	1,293	3,525	3,559
Owned Brokerage Group | Service revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[4]	7	6	18	16
Owned Brokerage Group | Franchise fees | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[5]	0	0	0	0
Owned Brokerage Group | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[6]	9	10	27	29
Title Group | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[1]	96	93	270	265
Title Group | Gross commission income | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[3]	0	0	0	0
Title Group | Service revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[4]	92	89	258	252
Title Group | Franchise fees | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[5]	0	0	0	0
Title Group | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[6]	$ 4	$ 4	$ 12	$ 13

[1] Transactions between segments are eliminated in consolidation. Revenues for Franchise Group include intercompany royalties and marketing fees paid by Owned Brokerage Group of $86 million and $242 million for the three and nine months ended September 30, 2024, respectively, and $89 million and $245 million for the three and nine months ended September 30, 2023, respectively. Such amounts are eliminated through the Corporate and Other line.

[2] Includes the elimination of transactions between segments.

[3] Gross commission income at Owned Brokerage Group 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 Title Group and are recognized at a point in time at the closing of a homesale transaction. Service revenue at Franchise Group includes relocation fees, which are recognized as revenue when or as the related performance obligation is satisfied dependent on the type of service performed, and fees related to leads and related services, which are recognized at a point in time at the closing of a homesale transaction or at the completion of the related service.

[5] Franchise fees at 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 from franchisees at Franchise Group and other miscellaneous revenues across all of the business segments.