Reconciliation of Revenue from Segments to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 1,354		$ 1,676		$ 1,820		$ 1,229		$ 1,444		$ 1,674		$ 1,793		$ 1,203		$ 6,079	[1],[2]	$ 6,114	[1],[2],[3]	$ 5,810	[1],[2],[3]
Real Estate Franchise Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	186		221		237		176		199		224		237		170		820	[1],[2]	830	[1],[2],[3]	781	[1],[2],[3]
Real Estate Franchise Services | Royalties and Marketing Fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues																	306		311		293
Company Owned Real Estate Brokerage Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	1,014		1,268		1,408		917		1,087		1,267		1,392		897		4,607	[1],[2]	4,643	[1],[2],[3]	4,344	[1],[2],[3]
Relocation Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	86		108		105		79		92		111		102		77		378	[1],[2]	382	[1],[2],[3]	405	[1],[2],[3]
Relocation Services | Referral and Relocation Fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues																	39		40		43
Title and Settlement Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	136		162		162		120		139		154		157		120		580	[1],[2]	570	[1],[2],[3]	573	[1],[2],[3]
Corporate and Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ (68)	[4]	$ (83)	[4]	$ (92)	[4]	$ (63)	[4]	$ (73)	[5]	$ (82)	[5]	$ (95)	[5]	$ (61)	[5]	$ (306)	[1],[2],[6]	$ (311)	[1],[2],[3],[6]	$ (293)	[1],[2],[3],[6]

[1] Revenues for the Relocation Services segment include intercompany referral commissions paid by the Company Owned Real Estate Brokerage Services segment of $39 million, $40 million and $43 million for the years ended December 31, 2018, 2017 and 2016, respectively. Such amounts are recorded as contra-revenues by the Company Owned Real Estate Brokerage Services segment. There are no other material intersegment transactions.

[2] Transactions between segments are eliminated in consolidation. Revenues for the Real Estate Franchise Services segment include intercompany royalties and marketing fees paid by the Company Owned Real Estate Brokerage Services segment of $306 million, $311 million and $293 million for the years ended December 31, 2018, 2017 and 2016, respectively. Such amounts are eliminated through the Corporate and Other line.

[3] Prior period amounts have not been adjusted under the modified retrospective method.

[4] Represents the elimination of transactions primarily between the Real Estate Franchise Services segment and the Company Owned Real Estate Brokerage Services segment.

[5] Represents the elimination of transactions primarily between the Real Estate Franchise Services segment and the Company Owned Real Estate Brokerage Services segment.

[6] Includes the elimination of transactions between segments.