Summary of Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company’s condensed consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and include the assets, liabilities, revenues and expenses of all controlled subsidiaries. The condensed consolidated statements of operations include the results of entities acquired from the date of each respective acquisition. Interests held by third parties in consolidated subsidiaries are presented as non-controlling interests, which represents the non-controlling stockholders’ interests in the underlying net assets of the Company’s consolidated subsidiaries. For entities where the Company does not have a controlling interest (financial or operating), the investments in such entities are accounted for using the equity method. The Company applies the equity method of accounting when it has the ability to exercise significant influence over the operating and financial policies of an investee. The Company measures all other investments at fair value with changes in fair value recognized in net income or in the case that an equity investment does not have readily determinable fair values, at cost minus impairment (if any) plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment. The unaudited interim condensed consolidated financial statements and related disclosures have been prepared by management on a basis consistent with the annual consolidated financial statements and, in the opinion of management, include all adjustments necessary for a fair statement of the interim periods presented. The results of the interim periods presented are not necessarily indicative of the results expected for the full year. Certain information and notes normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted under the SEC’s rules and regulations. Accordingly, the unaudited condensed consolidated financial statements and notes included herein should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2021, included in the 2021 Form 10-K.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and reported amounts of revenue and expenses during the reporting periods covered by the condensed consolidated financial statements and accompanying notes. These judgments, estimates and assumptions are used for, but not limited to (i) valuation of the Company’s common stock and stock awards, (ii) fair value of acquired intangible assets and goodwill, (iii) fair value of contingent consideration arrangements in connection with business combinations, (iv) incremental borrowing rate used for the Company’s operating leases, (v) useful lives of long-lived assets, (vi) impairment of intangible assets and goodwill, (vii) allowance for Compass Concierge receivables and (viii) income taxes and certain deferred tax assets. The Company determines its estimates and judgments based on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates and these differences may be material. There are many uncertainties regarding the ongoing coronavirus (“COVID-19”) pandemic, and the Company is closely monitoring the impact of the pandemic on all aspects of its business, including how it has impacted and may continue to impact the Company’s operations and its customers for an indefinite period of time. The extent and duration of the ongoing COVID-19 pandemic over the longer term and the extent to which it will impact the global economy, U.S. residential market and the Company’s financial condition, results of operations, or cash flows remain uncertain and depend on future developments that are highly uncertain and difficult to predict. Such developments include, but are not limited to, the emergence of new variants, severity and transmission rate of the virus, the duration and extent of the spread of the virus (including new variants), the timing, availability, and effectiveness of vaccines (including booster shots) and the vaccination rates, the prevalence of local, regional and national restrictions and regulatory orders in response to the ongoing COVID-19 pandemic and the extent and effectiveness of containment actions taken, as well as the impact of these and other factors on residential real estate values, real estate transaction behavior in general, and on the Company’s business in particular. The Company will continue to assess the impacts of the ongoing COVID-19 pandemic and will adjust its operations as necessary.
Business Combinations	Business Combinations Business combinations are accounted for under the acquisition method of accounting. This method requires, among other things, allocation of the fair value of purchase consideration to the tangible and intangible assets acquired and liabilities assumed at their estimated fair values on the acquisition date. The excess of the fair value of purchase consideration over the values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed, with a corresponding offset to goodwill if new information is obtained related to facts and circumstances that existed as of the acquisition date. After the measurement period, any subsequent adjustments are reflected in the condensed consolidated statements of operations. Acquisition costs, consisting primarily of third-party legal and consulting fees, are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation The Company measures compensation expense for all stock-based awards based on the estimated fair value of the awards on the date of grant. Compensation expense is generally recognized as expense on a straight-line basis over the service period based on the vesting requirements. The Company recognizes forfeitures as they occur. For stock options, which the Company issues to employees, affiliated agents and board members, the Company generally estimates the fair value using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (1) the fair value of common stock, (2) the expected stock price volatility, (3) the expected term of the award, (4) the risk-free interest rate and (5) expected dividends. The Company also issues RSUs to employees, affiliated agents, service providers and board members. In addition to the issuance of RSUs to agents as equity compensation for the provision of services, the Company offers RSUs to affiliated agents through its Agent Equity Program. The Agent Equity Program offers affiliated agents the ability to elect to have a portion of their commissions earned during a calendar year to be paid in the form of RSUs. RSUs issued in connection with the Agent Equity Program are granted at the beginning of the year following the calendar year in which the commissions were earned and are subject to the terms and conditions of the 2012 Stock Incentive Plan and the 2021 Equity Incentive Plan, as applicable. The Company’s RSUs granted prior to December 2020 generally vest based upon the satisfaction of both a service-based condition and a liquidity event-based condition. The service-based vesting condition for these awards is generally satisfied over four years, except for the RSUs granted since 2020 associated with the Agent Equity Program, which vested immediately on the date of issuance. The liquidity event-based vesting condition is satisfied on the occurrence of a qualifying event, generally defined as a change in control or the effective date of the registration statement for the Company’s IPO. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will begin to be recognized as expense when both the required service-based vesting condition and the liquidity event-based vesting condition has been achieved using the accelerated attribution method. The liquidity event-based vesting requirement was met on March 31, 2021, the effective date of the Company’s registration statement, see Note 1—“Business and Basis of Presentation—Initial Public Offering.” Beginning in December 2020, the Company began issuing RSUs that vest upon the satisfaction of only a service-based vesting condition that generally ranges from four to five years. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will be recognized as expense on a straight-line basis as the required service-based vesting condition is satisfied. Any vested RSUs that require only a service-based vesting condition will convert to common stock following vesting and their prescribed delayed settlement periods. For RSUs to be granted in connection with the Agent Equity Program, the Company determines the value of the stock-based compensation expense at the time the underlying commission is earned and begins to recognize the associated expense on a straight-line basis over the requisite service periods beginning on the closing date of the underlying real estate commission transactions. The stock-based compensation expense is recorded as a liability and will be reclassified to Additional paid-in capital at the end of the vesting period when the underlying RSUs are issued. On a limited basis, the Company has issued stock options and RSUs that contain service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. Such awards are valued using a Monte Carlo simulation and the underlying expense will be recognized as the associated vesting conditions are met.
New Accounting Pronouncements	New Accounting Pronouncements In March 2020, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. An update was also issued expanding the scope of this guidance. The guidance provides optional expedients and exceptions for applying GAAP to contract modifications, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The guidance became effective starting March 12, 2020 and may be applied prospectively through December 31, 2022. The Company is evaluating applicable contracts and transactions to determine whether to elect the optional guidance. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. The guidance amends ASC 805 to require acquiring entities to apply Topic 606 to recognize and measure contract assets and contract liabilities in a business combination. The amendment is effective for public companies with fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendment should be applied prospectively to business combinations occurring on or after the effective date. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements. In March 2022, the FASB issued ASU 2022-02, Financial Instruments - Credit Losses (Topic 326) - Troubled Debt Restructurings and Vintage Disclosures, which requires enhanced disclosure of certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty while eliminating certain current recognition and measurement accounting guidance. This ASU also requires the disclosure of current-period gross write-offs by year of origination for financing receivables and net investments in leases. The amendments in this update are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The adoption of this standard is currently being evaluated and is not expected to have a material impact on the Company’s consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

The condensed consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company’s condensed consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and include the assets, liabilities, revenues and expenses of all controlled subsidiaries. The condensed consolidated statements of operations include the results of entities acquired from the date of each respective acquisition. Interests held by third parties in consolidated subsidiaries are presented as non-controlling interests, which represents the non-controlling stockholders’ interests in the underlying net assets of the Company’s consolidated subsidiaries. For entities where the Company does not have a controlling interest (financial or operating), the investments in such entities are accounted for using the equity method. The Company applies the equity method of accounting when it has the ability to exercise significant influence over the operating and financial policies of an investee. The Company measures all other investments at fair value with changes in fair value recognized in net income or in the case that an equity

investment does not have readily determinable fair values, at cost minus impairment (if any) plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment.

The unaudited interim condensed consolidated financial statements and related disclosures have been prepared by management on a basis consistent with the annual consolidated financial statements and, in the opinion of management, include all adjustments necessary for a fair statement of the interim periods presented.

The results of the interim periods presented are not necessarily indicative of the results expected for the full year. Certain information and notes normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted under the SEC’s rules and regulations. Accordingly, the unaudited condensed consolidated financial statements and notes included herein should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2021, included in the 2021 Form 10-K.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and reported amounts of revenue and expenses during the reporting periods covered by the condensed consolidated financial statements and accompanying notes. These judgments, estimates and assumptions are used for, but not limited to (i) valuation of the Company’s common stock and stock awards, (ii) fair value of acquired intangible assets and goodwill, (iii) fair value of contingent consideration arrangements in connection with business combinations, (iv) incremental borrowing rate used for the Company’s operating leases, (v) useful lives of long-lived assets, (vi) impairment of intangible assets and goodwill, (vii) allowance for Compass Concierge receivables and (viii) income taxes and certain deferred tax assets. The Company determines its estimates and judgments based on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates and these differences may be material.

There are many uncertainties regarding the ongoing coronavirus (“COVID-19”) pandemic, and the Company is closely monitoring the impact of the pandemic on all aspects of its business, including how it has impacted and may continue to impact the Company’s operations and its customers for an indefinite period of time. The extent and duration of the ongoing COVID-19 pandemic over the longer term and the extent to which it will impact the global economy, U.S. residential market and the Company’s financial condition, results of operations, or cash flows remain uncertain and depend on future developments that are highly uncertain and difficult to predict. Such developments include, but are not limited to, the emergence of new variants, severity and transmission rate of the virus, the duration and extent of the spread of the virus (including new variants), the timing, availability, and effectiveness of vaccines (including booster shots) and the vaccination rates, the prevalence of local, regional and national restrictions and regulatory orders in response to the ongoing COVID-19 pandemic and the extent and effectiveness of containment actions taken, as well as the impact of these and other factors on residential real estate values, real estate transaction behavior in general, and on the Company’s business in particular. The Company will continue to assess the impacts of the ongoing COVID-19 pandemic and will adjust its operations as necessary.

Business Combinations

Business Combinations Business combinations are accounted for under the acquisition method of accounting. This method requires, among other things, allocation of the fair value of purchase consideration to the tangible and intangible assets acquired and liabilities assumed at their estimated fair values on the acquisition date. The excess of the fair value of purchase consideration over the values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed, with a corresponding offset to goodwill if new information is obtained related to facts and circumstances that existed as of the acquisition date. After the measurement period, any subsequent adjustments are reflected in the condensed consolidated statements of operations. Acquisition costs, consisting primarily of third-party legal and consulting fees, are expensed as incurred.

Stock-Based Compensation

The Company measures compensation expense for all stock-based awards based on the estimated fair value of the awards on the date of grant. Compensation expense is generally recognized as expense on a straight-line basis over the service period based on the vesting requirements. The Company recognizes forfeitures as they occur.

For stock options, which the Company issues to employees, affiliated agents and board members, the Company generally estimates the fair value using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (1) the fair value of common stock, (2) the expected stock price volatility, (3) the expected term of the award, (4) the risk-free interest rate and (5) expected dividends.

The Company also issues RSUs to employees, affiliated agents, service providers and board members. In addition to the issuance of RSUs to agents as equity compensation for the provision of services, the Company offers RSUs to affiliated agents through its Agent Equity Program. The Agent Equity Program offers affiliated agents the ability to elect to have a portion of their commissions earned during a calendar year to be paid in the form of RSUs. RSUs issued in connection with the Agent Equity Program are granted at the beginning of the year following the calendar year in which the commissions were earned and are subject to the terms and conditions of the 2012 Stock Incentive Plan and the 2021 Equity Incentive Plan, as applicable.

The Company’s RSUs granted prior to December 2020 generally vest based upon the satisfaction of both a service-based condition and a liquidity event-based condition. The service-based vesting condition for these awards is generally satisfied over four years, except for the RSUs granted since 2020 associated with the Agent Equity Program, which vested immediately on the date of issuance. The liquidity event-based vesting condition is satisfied on the occurrence of a qualifying event, generally defined as a change in control or the effective date of the registration statement for the Company’s IPO. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will begin to be recognized as expense when both the required service-based vesting condition and the liquidity event-based vesting condition has been achieved using the accelerated attribution method. The liquidity event-based vesting requirement was met on March 31, 2021, the effective date of the Company’s registration statement, see Note 1—“Business and Basis of Presentation—Initial Public Offering.”

Beginning in December 2020, the Company began issuing RSUs that vest upon the satisfaction of only a service-based vesting condition that generally ranges from four to five years. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will be recognized as expense on a straight-line basis as the required service-based vesting condition is satisfied. Any vested RSUs that require only a service-based vesting condition will convert to common stock following vesting and their prescribed delayed settlement periods.

For RSUs to be granted in connection with the Agent Equity Program, the Company determines the value of the stock-based compensation expense at the time the underlying commission is earned and begins to recognize the associated expense on a straight-line basis over the requisite service periods beginning on the closing date of the underlying real estate commission transactions. The stock-based compensation expense is recorded as a liability and will be reclassified to Additional paid-in capital at the end of the vesting period when the underlying RSUs are issued.

On a limited basis, the Company has issued stock options and RSUs that contain service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. Such awards are valued using a Monte Carlo simulation and the underlying expense will be recognized as the associated vesting conditions are met.

New Accounting Pronouncements

In March 2020, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. An update was also issued expanding the scope of this guidance. The guidance provides optional expedients and exceptions for applying GAAP to contract modifications, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The guidance became effective starting March 12, 2020 and may be applied prospectively through December 31, 2022. The Company is evaluating applicable contracts and transactions to determine whether to elect the optional guidance. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements.

In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. The guidance amends ASC 805 to require acquiring entities to apply Topic 606 to recognize and measure contract assets and contract liabilities in a business combination. The amendment is effective for public companies with fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendment should be applied prospectively to business combinations occurring on or after the effective date. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements.

In March 2022, the FASB issued ASU 2022-02, Financial Instruments - Credit Losses (Topic 326) - Troubled Debt Restructurings and Vintage Disclosures, which requires enhanced disclosure of certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty while eliminating certain current recognition and measurement accounting guidance. This ASU also requires the disclosure of current-period gross write-offs by year of origination for financing receivables and net investments in leases. The amendments in this update are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The adoption of this standard is currently being evaluated and is not expected to have a material impact on the Company’s consolidated financial statements.