Noncontrolling and Redeemable Noncontrolling Interests - Changes in Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ 4,290	$ 3,406	$ 3,406	$ 4,177	$ (26,010)
Change from net loss attributable to MDC Partners Inc. and transfers to noncontrolling interests	(4,193)	(3,406)		(4,080)	27,176
MDC Partners Inc. Shareholders' Deficit
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.			$ 3,406		(26,010)
Decrease in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of redeemable noncontrolling interests and noncontrolling interests	$ 97	$ 0		$ 97	$ 1,166

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

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