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Employee Benefit Plan - Additional Information (Detail) - Zillow Merger - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Contribution Plan Disclosure [Line Items]
Company's contribution based on employee contribution (up to)			4.00%
Company's expense related to its defined contribution 401(k) retirement plans	$ 8.0	$ 6.4	$ 15.7	$ 12.8

X

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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- Definition

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.

+ References

No definition available.

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- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

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- Details

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