Basis of Presentation and Recent Developments	9 Months Ended
Basis of Presentation and Recent Developments	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Recent Developments	Business and Basis of Presentation Stagwell Inc. (the “Company” or “Stagwell”), incorporated under the laws of Delaware, conducts its business through its networks and their Brands ("Brands"), which provide marketing and business solutions that realize the potential of combining data and creativity. Stagwell’s strategy is to build, grow and acquire market-leading businesses that deliver the modern suite of services that marketers need to thrive in a rapidly evolving business environment. The accompanying consolidated financial statements include the accounts of Stagwell and its subsidiaries. Stagwell has prepared the unaudited condensed consolidated interim financial statements included herein in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for reporting interim financial information on Form 10-Q. Accordingly, the financial statements have been condensed and do not include certain information and disclosures pursuant to these rules. The preparation of financial statements in conformity with GAAP requires us to make judgments, assumptions and estimates about current and future results of operations and cash flows that affect the amounts reported and disclosed. Actual results could differ from these estimates and assumptions. The consolidated results for interim periods are not necessarily indicative of results for the full year and should be read in conjunction with the Company’s other SEC filings. On December 21, 2020, MDC Partners Inc. (“MDC”) and Stagwell Media LP (“Stagwell Media”) announced that they had entered into the Transaction Agreement, providing for the combination of MDC with the operating businesses and subsidiaries of Stagwell Media (the “Stagwell Subject Entities”). The Stagwell Subject Entities comprised Stagwell Marketing Group LLC (“Stagwell Marketing”) and its direct and indirect subsidiaries. On August 2, 2021, we completed the previously announced combination of MDC Partners Inc. (“MDC”) and the operating businesses and subsidiaries of Stagwell Media LP. (“Stagwell Media”) and a series related transactions (such combination and transactions, the “Transactions”). The Transactions were treated as a reverse acquisition for financial reporting purposes, with MDC treated as the legal acquirer and Stagwell Marketing Group LLC (“Stagwell Marketing or SMG”) treated as the accounting acquirer. The results of MDC are included within the Unaudited Condensed Consolidated Statements of Operations for the period beginning on the date of the acquisition through the end of the respective period presented and the results of SMG are included for the entire period presented. See Note 4 for information in connection with the acquisition of MDC. While a recovery from the COVID-19 pandemic is underway, economic conditions will be volatile as long as COVID-19 remains a public health threat. The Company continues to monitor developments. We will continue to monitor the worldwide public health threat, government actions to combat COVID-19 and the impact such developments may have on the overall economy, our clients and operations. The impact of the pandemic and the corresponding actions are reflected in our judgments, assumptions and estimates in the preparation of the financial statements. The judgments, assumptions and estimates will be updated and could result in different results in the future depending on the continued impact of the COVID-19 pandemic. The accompanying financial statements reflect all adjustments, consisting of normally recurring accruals, which in the opinion of management are necessary for a fair presentation, in all material respects, of the information contained therein. Intercompany balances and transactions have been eliminated in consolidation. Certain reclassifications have been made to the prior year financial information to conform to the current year presentation. Recent Developments On September 23, 2021, the Company provided notices of conversion to each holder of record of each of the Company’s Series 6 and Series 8 Preferred Stock. See Note 12 for additional information in connection with the conversion of the Preferred Stock to Class A Common Stock. On October 1, 2021 (the "closing date"), the Company entered into an agreement to purchase the remaining 26.7% interest in Targeted Victory it did not previously own for a combination of cash and Class A Common Stock, up to 50% with certain exceptions, determined at the option of the Company. The agreement provides for the purchase of half of the remaining interest on the closing date and the other half on July 31, 2023 ("second purchase"). The total purchase price, which is capped at $135,000 with certain exceptions, is based on a formula taking a multiple of the two-year average of earnings that includes the year of and the year subsequent to the year of the purchase. The seller has the option to extend the measurement period for two years in connection with the second purchase.