Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, which was filed with the SEC on February 10, 2022. The condensed consolidated balance sheet as of December 31, 2021, included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date, adjusted for the reclassification of discontinued operations discussed in Note 3. The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2022 and our results of operations, comprehensive loss, and shareholders’ equity for the three and nine month periods ended September 30, 2022 and 2021, and our cash flows for the nine month periods ended September 30, 2022 and 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any interim period, or for any other future year. Unless indicated otherwise, the information in the Notes to Condensed Consolidated Financial Statements relates to the Company’s continuing operations and does not include the results of discontinued operations.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the accounting for certain revenue offerings, restructuring costs, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets, share-based compensation, income taxes, the presentation of discontinued and continuing operations, business combinations and the recoverability of goodwill, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The health of the residential housing market, interest rate environment and the COVID-19 pandemic have introduced significant additional uncertainty with respect to estimates, judgments and assumptions, which may materially impact the estimates previously listed, among others.
Recently Issued Accounting Standards Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted In June 2022, the Financial Accounting Standards Board issued guidance to improve existing measurement and disclosure requirements for equity securities that are subject to a contractual sale restriction. This guidance is effective for interim and annual periods beginning after December 15, 2023 on a prospective basis, with early adoption permitted. We expect to adopt this guidance on January 1, 2024. We have not yet determined the impact the adoption of this guidance will have on our financial position, results of operations and cash flows.
Fair Value Measurements	We apply the following methods and assumptions in estimating our fair value measurements: Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets (Level 1). The fair value measurement of other cash equivalents is based on observable market-based inputs principally derived from or corroborated by observable market data (Level 2). Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means (Level 2). Restricted cash — The carrying value of restricted cash approximates fair value due to the short period of time amounts are held in escrow (Level 1). Mortgage loans held for sale — The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics (Level 2). Forward contracts — The fair value of mandatory loan sales commitments and derivative instruments such as forward sales of mortgage-backed securities that are utilized as economic hedging instruments is calculated by reference to quoted prices for similar assets (Level 2). Interest rate lock commitments — The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. This adjustment is effected through the pull-through rate, which represents the probability that an IRLC will ultimately result in a closed loan. For IRLCs that are cancelled or expire, any recorded gain or loss is reversed at the end of the commitment period (Level 3).
Segment Reporting	We have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Mortgages and Homes segments. The IMT segment includes the financial results for the Premier Agent, rentals and new construction marketplaces, as well as display, StreetEasy, ShowingTime+, which houses ShowingTime, Bridge Interactive, dotloop and interactive floor plans, and other advertising and business software solutions. In the first quarter of 2022, we began reporting rentals revenue as a separate revenue category within the IMT segment and prior period amounts have been recast to conform to this presentation. In the fourth quarter of 2021, we began to include the financial results of ShowingTime in the IMT segment. The Mortgages segment primarily includes the financial results for mortgage originations and the sale of mortgages on the secondary market through Zillow Home Loans and advertising sold to mortgage lenders and other mortgage professionals. The Homes segment includes the financial results from title and escrow services performed by Zillow Closing Services and certain indirect costs of the Homes segment which do not qualify as discontinued operations. As discussed in Note 3, as of September 30, 2022, the wind down of Zillow Offers was complete and we have presented the financial results of Zillow Offers as discontinued operations in our condensed consolidated financial statements, and prior period amounts have been recast to conform to this presentation. Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses, general and administrative expenses including executive, finance, accounting, legal, human resources, recruiting and facilities costs, product development and data acquisition costs, costs related to operating our mobile applications and websites and marketing and advertising costs. These costs are allocated to each segment based on the estimated benefit each segment receives from such expenditures. The chief executive officer reviews information about our revenue categories as well as statement of operations data inclusive of income (loss) from continuing operations before income taxes by segment.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2022

The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, which was filed with the SEC on February 10, 2022. The condensed consolidated balance sheet as of December 31, 2021, included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date, adjusted for the reclassification of discontinued operations discussed in Note 3.

The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2022 and our results of operations, comprehensive loss, and shareholders’ equity for the three and nine month periods ended September 30, 2022 and 2021, and our cash flows for the nine month periods ended September 30, 2022 and 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any interim period, or for any other future year. Unless indicated otherwise, the information in the Notes to Condensed Consolidated Financial Statements relates to the Company’s continuing operations and does not include the results of discontinued operations.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the accounting for certain revenue offerings, restructuring costs, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets, share-based compensation, income taxes, the presentation of discontinued and continuing operations, business combinations and the recoverability of goodwill, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The health of the residential housing market, interest rate environment and the COVID-19 pandemic have introduced significant additional uncertainty with respect to estimates, judgments and assumptions, which may materially impact the estimates previously listed, among others.

Recently Issued Accounting Standards Not Yet Adopted

In June 2022, the Financial Accounting Standards Board issued guidance to improve existing measurement and disclosure requirements for equity securities that are subject to a contractual sale restriction. This guidance is effective for interim and annual periods beginning after December 15, 2023 on a prospective basis, with early adoption permitted. We expect to adopt this guidance on January 1, 2024. We have not yet determined the impact the adoption of this guidance will have on our financial position, results of operations and cash flows.

Fair Value Measurements

We apply the following methods and assumptions in estimating our fair value measurements:

Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets (Level 1). The fair value measurement of other cash equivalents is based on observable market-based inputs principally derived from or corroborated by observable market data (Level 2).

Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means (Level 2).

Restricted cash — The carrying value of restricted cash approximates fair value due to the short period of time amounts are held in escrow (Level 1).

Mortgage loans held for sale — The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics (Level 2).

Forward contracts — The fair value of mandatory loan sales commitments and derivative instruments such as forward sales of mortgage-backed securities that are utilized as economic hedging instruments is calculated by reference to quoted prices for similar assets (Level 2).

Interest rate lock commitments — The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. This adjustment is effected through the pull-through rate, which represents the probability that an IRLC will ultimately result in a closed loan. For IRLCs that are cancelled or expire, any recorded gain or loss is reversed at the end of the commitment period (Level 3).

Segment Reporting

We have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Mortgages and Homes segments.

The IMT segment includes the financial results for the Premier Agent, rentals and new construction marketplaces, as well as display, StreetEasy, ShowingTime+, which houses ShowingTime, Bridge Interactive, dotloop and interactive floor plans, and other advertising and business software solutions. In the first quarter of 2022, we began reporting rentals revenue as a separate revenue category within the IMT segment and prior period amounts have been recast to conform to this presentation. In the fourth quarter of 2021, we began to include the financial results of ShowingTime in the IMT segment. The Mortgages segment primarily includes the financial results for mortgage originations and the sale of mortgages on the secondary market through Zillow Home Loans and advertising sold to mortgage lenders and other mortgage professionals. The Homes segment includes the financial results from title and escrow services performed by Zillow Closing Services and certain indirect costs of the Homes segment which do not qualify as discontinued operations. As discussed in Note 3, as of September 30, 2022, the wind down of Zillow Offers was complete and we have presented the financial results of Zillow Offers as discontinued operations in our condensed consolidated financial statements, and prior period amounts have been recast to conform to this presentation.

Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses, general and administrative expenses including executive, finance, accounting, legal, human resources, recruiting and facilities costs, product development and data acquisition costs, costs related to operating our mobile applications and websites and marketing and advertising costs. These costs are allocated to each segment based on the estimated benefit each segment receives from such expenditures.

The chief executive officer reviews information about our revenue categories as well as statement of operations data inclusive of income (loss) from continuing operations before income taxes by segment.