Supplemental Information - Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Revenues	$ 307,585	$ 327,742
Asset Impairment Charges	875	161
Costs and Expenses	279,918	298,415
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	11,296	15,293
Income Tax Expense (Benefit)	1,302	13,500
Net income (loss) attributable to MDC Partners Inc. common shareholders	$ 921	$ (2,438)
Weighted Average Number of Shares Outstanding, Basic	73,392,824	72,397,661,000
Weighted Average Number of Shares Outstanding, Diluted	75,439,066	72,397,661,000
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.01	$ (0.03)
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.01	$ (0.03)

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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