Basis of Presentation	3 Months Ended
Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation and Recent Developments The accompanying consolidated financial statements include the accounts of MDC Partners Inc. (the “Company” or “MDC”), its subsidiaries and variable interest entities for which the Company is the primary beneficiary. References herein to “Partner Firms” generally refer to the Company’s subsidiary agencies. MDC Partners Inc. 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 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 Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”). 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. Due to changes in the composition of certain business and the Company’s internal management and reporting structure during 2019, reportable segment results for the 2018 periods presented have been recast to reflect the reclassification of certain businesses between segments. See Note 12 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information. Recent Developments Issuance of Shares and Appointment of Chief Executive Officer On March 14, 2019, the Company entered into a securities purchase agreement with Stagwell Agency Holdings LLC (“Stagwell Holdings”), an affiliate of Stagwell Group LLC (“Stagwell”). See Note 8 of the Notes to the Unaudited Condensed Consolidated Financial Statements for additional information regarding the issuance of the Class A and Series 6 convertible preference shares. Effective March 18, 2019, the Company’s Board of Directors (the “Board”) appointed Mark Penn as the Chief Executive Officer and as a director of the Board. Mr. Penn is manager of Stagwell. Effective April 18, 2019, Mr. Penn was also appointed as Chairman of the Board. Amendment to Credit Agreement On March 12, 2019 , the Company, Maxxcom Inc. (a subsidiary of the Company) (“Maxxcom”) and each of their subsidiaries party thereto entered into an amendment (the “Amendment”) to the existing senior secured revolving credit facility, dated as of May 3, 2016 (as amended, the “Credit Agreement”), among the Company, Maxxcom Inc., a Delaware corporation, each of their subsidiaries party thereto, Wells Fargo Capital Finance, LLC, as agent (“Wells Fargo”), and the lenders from time to time party thereto. See Note 7 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the amendments to the Credit Agreement. Sale of Kingsdale On March 8, 2019, the Company consummated the sale of its equity interest in Kingsdale. See Note 4 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the sale of Kingsdale.

Basis of Presentation and Recent Developments

The accompanying consolidated financial statements include the accounts of MDC Partners Inc. (the “Company” or “MDC”), its subsidiaries and variable interest entities for which the Company is the primary beneficiary. References herein to “Partner Firms” generally refer to the Company’s subsidiary agencies.

MDC Partners Inc. 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 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 Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”).

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.

Due to changes in the composition of certain business and the Company’s internal management and reporting structure during 2019, reportable segment results for the 2018 periods presented have been recast to reflect the reclassification of certain businesses between segments. See Note 12 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information.

Recent Developments

Issuance of Shares and Appointment of Chief Executive Officer

On March 14, 2019, the Company entered into a securities purchase agreement with Stagwell Agency Holdings LLC (“Stagwell Holdings”), an affiliate of Stagwell Group LLC (“Stagwell”). See Note 8 of the Notes to the Unaudited Condensed Consolidated Financial Statements for additional information regarding the issuance of the Class A and Series 6 convertible preference shares.

Effective March 18, 2019, the Company’s Board of Directors (the “Board”) appointed Mark Penn as the Chief Executive Officer and as a director of the Board. Mr. Penn is manager of Stagwell. Effective April 18, 2019, Mr. Penn was also appointed as Chairman of the Board.

Amendment to Credit Agreement

On March 12, 2019 , the Company, Maxxcom Inc. (a subsidiary of the Company) (“Maxxcom”) and each of their subsidiaries party thereto entered into an amendment (the “Amendment”) to the existing senior secured revolving credit facility, dated as of May 3, 2016 (as amended, the “Credit Agreement”), among the Company, Maxxcom Inc., a Delaware corporation, each of their subsidiaries party thereto, Wells Fargo Capital Finance, LLC, as agent (“Wells Fargo”), and the lenders from time to time party thereto. See Note 7 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the amendments to the Credit Agreement.

Sale of Kingsdale

On March 8, 2019, the Company consummated the sale of its equity interest in Kingsdale. See Note 4 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the sale of Kingsdale.