Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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Unrecognized cost of unvested options awarded to employees as compensation.

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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.

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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Description of pertinent provisions of equity-based compensation awards that have actual or potential impact upon the company's financial statements.

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Percentage of vesting of share-based compensation awards.

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Date of first vesting.

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Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Aggregate Grant Date Fair Value

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Share-Based Awards - Restricted Stock Units - Additional Information (Detail) - Restricted Stock Units - USD ($) $ in Millions		1 Months Ended		12 Months Ended
	Apr. 30, 2015	Aug. 31, 2015	Feb. 28, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			82,077	1,354,185
Accelerated vesting period received by employee				12 months
Terms of restricted stock unit award				In the event of termination of service or employment by Zillow Group without cause or upon the resignation by such employee for good reason, the employee will receive an additional 12 months’ accelerated vesting of the then outstanding restricted stock units, except that in the event of such a termination in connection with a change in control, the employee will receive 50% accelerated vesting of the then outstanding restricted stock units. The employee will be entitled to receive one share of Class A common stock and two shares of Class C capital stock for each then outstanding restricted stock unit that becomes vested. The grant date fair value of the restricted stock units
Fair value of restricted shares issued				$ 3.0
Total fair value of restricted stock vested				67.3	$ 5.1	$ 10.5
Total unrecognized compensation cost				$ 69.0
Unrecognized compensation cost expected recognition period				2 years 7 months 6 days
Retention Plan \| Trulia
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting commencement date of restricted shares				Feb. 18, 2015
Options vesting rights				12.5% of the retention restricted stock units vested approximately 6 months after the vesting commencement date of February 18, 2015, and the remaining retention restricted stock units vest quarterly thereafter for approximately 3.5 years, subject to the recipient's continued full-time employment or service to Zillow Group
Total fair value of restricted stock vested	$ 10.2
Retention Plan \| Trulia \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	6 months
Retention Plan \| Trulia \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years 6 months
Retention Plan \| Class A Common Stock and Class C Capital Stock \| Trulia
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	316,074
Retention Bonus Plan Member \| DotLoop Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock vested				$ 4.5
Vesting After 12 Months
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			50,202
Vesting percentage			25.00%	50.00%
Vesting period			3 years
Vesting commencement date of restricted shares			Feb. 17, 2016
Vesting After 6 Months
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			31,875
Vesting percentage			12.50%
Vesting period			3 years 6 months
Vesting commencement date of restricted shares			Aug. 17, 2015
Vesting After 6 Months \| Retention Plan \| Trulia
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	12.50%
For 178,428 of Restricted Stock Units \| Retention Bonus Plan Member \| DotLoop Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		178,428
Vesting percentage		25.00%
Vesting period		3 years
Vesting commencement date of restricted shares				Aug. 20, 2016
Options vesting rights				25% of the restricted stock units vest on August 20, 2016, and the remaining restricted stock units vest quarterly thereafter over the next three years.
For 173,761 of Restricted Stock Units \| Retention Bonus Plan Member \| DotLoop Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		173,761
Vesting percentage		50.00%
Vesting period		3 years
Vesting commencement date of restricted shares				Aug. 20, 2016
Options vesting rights				50% of the restricted stock units vest on August 21, 2016, and the remaining restricted stock units vest quarterly thereafter for the next three years.
Total fair value of restricted stock vested				$ 4.4