Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.	$ 1,003	$ (113)
Numerator
Net loss attributable to MDC Partners Inc. common shareholders	(2,437)	(2,496)
Net loss attributable to MDC Partners Inc. common shareholders	$ (2,437)	$ (2,496)
Denominator
Denominator for basic income (loss) per common share - weighted average common shares	72,397,661	60,258,102
Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions	72,397,661	60,258,102
Earnings per share, basic	$ (0.03)	$ (0.04)
Earnings per share, diluted	$ (0.03)	$ (0.04)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,835,770,000
MDC Partners Inc. Shareholders' Deficit
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.	$ 1,003	$ (113)
Series 4 Convertible Preferred Stock | Convertible Preferred Stock
Numerator
Accretion on and net income allocated to convertible preference shares	3,440	$ 2,383
Denominator
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,633,464,000
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock
Numerator
Accretion on and net income allocated to convertible preference shares	$ (3,440)	$ (2,383)