Noncontrolling and Redeemable Noncontrolling Interests - Changes in Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ 1,003	$ (113)
Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests	(503)	0
Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests	(500)	113
MDC Partners Inc. Shareholders' Deficit
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	1,003	(113)
Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests	$ (503)	$ 0

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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