| Cover | Jan. 05, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 05, 2023 |
| Entity Registrant Name | Compass, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-40291 |
| Entity Tax Identification Number | 30-0751604 |
| Entity Address, Address Line One | 90 Fifth Avenue, 3rd Floor |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10011 |
| Local Phone Number | 913-9058 |
| City Area Code | (212) |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, $0.00001 par value per share |
| Trading Symbol | COMP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001563190 |
| Amendment Flag | false |
