Note 12. Stock-Based Compensation Introduction Narrative (Details) shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) Performance_metrics shares
Retirement Eligibility Age	65 years
Retirement Eligibility Age with Ten Years of Service	55 years
Retirement Eligibility Years Tenure	10 years
Retirement Eligibility Service Requirement	1 year
Shares available for future grant under the plan (in shares) \| shares	3.0
Maximum
Shares authorized for issuance under the plan (in shares) \| shares	16.6
Restricted Stock Units
Stock options vesting period	3 years
Annual Vesting Percentage	33.33%
Performance Share Units
Stock options vesting period	3 years
Annual Vesting Percentage	33.33%
Number of performance metrics \| Performance_metrics	2
The first performance metric \| Performance_metrics	1
Performance Share Units \| RTSR \| Minimum
Award Vesting Percentage	0.00%
Performance Share Units \| RTSR \| Maximum
Award Vesting Percentage	175.00%
Performance Share Units \| Cumulative Free Cash Flow \| Minimum
Award Vesting Percentage	0.00%
Performance Share Units \| Cumulative Free Cash Flow \| Maximum
Award Vesting Percentage	200.00%
Options
Stock options vesting period	4 years
Annual Vesting Percentage	25.00%
Contractual Term	10 years
New CEO Inducement Award [Member]
Share-based Payment Award Granted Amount	$ 5.0
New CEO Inducement Award [Member] \| Restricted Stock Units
Share-based Payment Award Granted Amount	2.5
New CEO Inducement Award [Member] \| Options
Share-based Payment Award Granted Amount	$ 2.5

Number of performance metrics

No definition available.

Name:	rlgy_Numberofperformancemetrics
Namespace Prefix:	rlgy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Age attained for which the retirement provision for equity grants provides for continued vesting of awards provided they have been employed or provided services to the Company for one year following the date of grant.

+ References

No definition available.

+ Details

Name:	rlgy_RetirementEligibilityAge
Namespace Prefix:	rlgy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Age attained for which the retirement provision for equity grants provides for continued vesting of awards if the employee has at least ten years of tenure with the Company and provided they have been employed or provided services to the Company for one year following the date of grant.

+ References

No definition available.

+ Details

Name:	rlgy_RetirementEligibilityAgewithTenYearsofService
Namespace Prefix:	rlgy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of years of service required following the grant date or start of the performance period in order to qualify for the retirement provision for equity grants.

+ References

No definition available.

+ Details

Name:	rlgy_RetirementEligibilityServiceRequirement
Namespace Prefix:	rlgy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of years of tenure with the Company required for employees aged 55 to qualify for the retirement provision for equity grants.

+ References

No definition available.

+ Details

Name:	rlgy_RetirementEligibilityYearsTenure
Namespace Prefix:	rlgy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual percentage of vesting of share-based compensation awards.

+ References

No definition available.

+ Details

Name:	rlgy_SharebasedCompensationArrangementbySharebasedPaymentAwardAnnualVestingPercentage
Namespace Prefix:	rlgy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The first performance metric

+ References

No definition available.

+ Details

Name:	rlgy_Thefirstperformancemetric
Namespace Prefix:	rlgy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of vesting of share-based compensation awards.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardCompensationCost1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rlgy_PerformanceShareUnitAwardNameAxis=rlgy_RTSRMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rlgy_PerformanceShareUnitAwardNameAxis=rlgy_CumulativeFreeCashFlowMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rlgy_AwardNameAxis=rlgy_NewCEOInducementAwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: