Employee Benefit Plan	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanWe have a defined contribution 401(k) retirement plan covering Zillow Group employees who have met certain eligibility requirements (the “Zillow Group 401(k) Plan”). Eligible employees may contribute pretax compensation up to a maximum amount allowable under the Internal Revenue Service limitations. Employee contributions and earnings thereon vest immediately. We currently match up to 4% of employee contributions under the Zillow Group 401(k) Plan. The total expense related to the Zillow Group 401(k) Plan was $6.1 million and $5.6 million, respectively, for the three months ended September 30, 2020 and 2019, and $18.9 million and $15.7 million, respectively, for the nine months ended September 30, 2020 and 2019.