Fair Value Measures and Disclosures (Policies)	9 Months Ended
Sep. 30, 2026
Fair Value Disclosures [Abstract]
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 that 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 MBSs that are utilized as economic hedging instruments is calculated by reference to quoted prices for similar assets (Level 2). Contingent consideration — In December 2023, Zillow Group acquired Follow Up Boss for $399 million in cash, net of cash acquired, and contingent consideration of up to $100 million, payable over a three-year period upon achievement of certain performance metrics. During the nine months ended September 30, 2026 and 2025, we paid $33 million in cash each period to settle the first and second earn out payments, most of which represented settlement of the acquisition date fair value. The fair value of the contingent consideration is estimated using a Monte Carlo simulation which considers the probabilities of the achievement of certain performance metrics (Level 3). The discount rates used in our valuation of contingent consideration are based on our estimated cost of debt and are directly related to the fair value of contingent consideration. An increase in the discount rate, in isolation, would result in a decrease in the fair value measurement. Conversely, a decrease in the discount rate, in isolation, would result in an increase in the fair value measurement. The probabilities of achieving the relevant performance metrics used in our valuation of contingent consideration are directly related to the fair value of contingent consideration, as an increase in the probability, in isolation, would result in an increase in the fair value measurement. Conversely, a decrease in the probability, in isolation, would result in a decrease in the fair value measurement. During the three and nine months ended September 30, 2026, there were no material changes in the unobservable inputs used in determining the fair value of contingent consideration included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025. IRLCs — The fair value of 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 canceled or expire, any recorded gain or loss is reversed at the end of the commitment period (Level 3). The pull-through rate is based on estimated changes in market conditions, loan stage and historical borrower behavior. Pull-through rates are directly related to the fair value of IRLCs as an increase in the pull-through rate, in isolation, would result in an increase in the fair value measurement. Conversely, a decrease in the pull-through rate, in isolation, would result in a decrease in the fair value measurement. Changes in the fair value of IRLCs are included within revenue in our condensed consolidated statements of operations.

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).

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 MBSs that are utilized as economic hedging instruments is calculated by reference to quoted prices for similar assets (Level 2).

Contingent consideration — In December 2023, Zillow Group acquired Follow Up Boss for $399 million in cash, net of cash acquired, and contingent consideration of up to $100 million, payable over a three-year period upon achievement of certain performance metrics. During the nine months ended September 30, 2026 and 2025, we paid $33 million in cash each period to settle the first and second earn out payments, most of which represented settlement of the acquisition date fair value. The fair value of the contingent consideration is estimated using a Monte Carlo simulation which considers the probabilities of the achievement of certain performance metrics (Level 3).

The discount rates used in our valuation of contingent consideration are based on our estimated cost of debt and are directly related to the fair value of contingent consideration. An increase in the discount rate, in isolation, would result in a decrease in the fair value measurement. Conversely, a decrease in the discount rate, in isolation, would result in an increase in the fair value measurement. The probabilities of achieving the relevant performance metrics used in our valuation of contingent consideration are directly related to the fair value of contingent consideration, as an increase in the probability, in isolation, would result in an increase in the fair value measurement. Conversely, a decrease in the probability, in isolation, would result in a decrease in the fair value measurement.

During the three and nine months ended September 30, 2026, there were no material changes in the unobservable inputs used in determining the fair value of contingent consideration included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

IRLCs — The fair value of 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