| Cover | Aug. 20, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 20, 2021 |
| Entity File Number | 001-13718 |
| Entity Registrant Name | STAGWELL INC. |
| Entity Central Index Key | 0000876883 |
| Entity Tax Identification Number | 86-1390679 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | One World Trade Center |
| Entity Address, Address Line Two | Floor 65 |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10007 |
| City Area Code | 646 |
| Local Phone Number | 429-1800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Subordinate Voting Shares, $0.001 par value |
| Trading Symbol | STGW |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
