Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Carrying amount of total other intangibles		$ 645	$ 647
Accumulated Amortization		376	363
Net carrying amount of finite-lived and indefinite-lived intangible assets		269	284
Indefinite life—Trademarks (b)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of indefinite-lived intangible assets	[1]	749	749
Indefinite life—Title plant shares (e)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of indefinite-lived intangible assets	[2]	18	18
Amortizable—Franchise agreements (a)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of finite-lived intangible assets	[3]	2,019	2,019
Accumulated Amortization	[3]	759	725
Net carrying amount of finite-lived intangible assets	[3]	1,260	1,294
Amortizable—License agreements (c)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of finite-lived intangible assets	[4]	45	45
Accumulated Amortization	[4]	10	10
Net carrying amount of finite-lived intangible assets	[4]	$ 35	35
Amortization period		50 years
Amortizable—Customer relationships (d)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of finite-lived intangible assets	[5]	$ 549	549
Accumulated Amortization	[5]	347	335
Net carrying amount of finite-lived intangible assets	[5]	$ 202	214
Amortizable—Customer relationships (d) | Minimum
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization period		2 years
Amortizable—Customer relationships (d) | Maximum
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization period		20 years
Amortizable—Pendings and listings (f)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of finite-lived intangible assets	[6]	$ 0	2
Accumulated Amortization	[6]	0	1
Net carrying amount of finite-lived intangible assets	[6]	$ 0	1
Amortization period		5 months
Amortizable—Other (g)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount of finite-lived intangible assets	[7]	$ 33	33
Accumulated Amortization	[7]	19	17
Net carrying amount of finite-lived intangible assets	[7]	$ 14	$ 16
Amortizable—Other (g) | Minimum
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization period		5 years
Amortizable—Other (g) | Maximum
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization period		10 years
Real Estate Franchise Services | Amortizable—Franchise agreements (a)
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization period		30 years

[1] Primarily relates to the Century 21®, Coldwell Banker®, ERA®, Corcoran®, Coldwell Banker Commercial® and Cartus tradenames, which are expected to generate future cash flows for an indefinite period of time.

[2] Ownership in a title plant is required to transact title insurance in certain states. The Company expects to generate future cash flows for an indefinite period of time.

[3] Generally amortized over a period of 30 years.

[4] Relates to the Sotheby’s International Realty® and Better Homes and Gardens® Real Estate agreements which are being amortized over 50 years (the contractual term of the license agreements).

[5] Relates to the customer relationships at the Relocation Services segment, the Title and Settlement Services segment and our Company Owned Real Estate Brokerage Services segment. These relationships are being amortized over a period of 2 to 20 years.

[6] Generally amortized over a period of 5 months.

[7] Consists of covenants not to compete which are amortized over their contract lives and other intangibles which are generally amortized over periods ranging from 5 to 10 years.