New Accounting Pronouncements - Adoption of ASC 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services	$ 375,830	$ 375,800	$ 1,082,541	$ 1,111,032
Cost of services sold	238,690	249,418	735,110	754,803
Operating profit (loss)	2,618	37,220	18,757	72,000
Net loss attributable to MDC Partners, Inc. common shareholders	$ (18,234)	$ 14,137	$ (48,339)	$ 13,033
Loss per common share - basic and diluted (in USD per share)	$ (0.32)		$ (0.85)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services	$ 384,002		$ 1,121,717
Cost of services sold	252,812		783,193
Operating profit (loss)	(3,332)		9,850
Net loss attributable to MDC Partners, Inc. common shareholders	$ (22,934)		$ (54,424)
Loss per common share - basic and diluted (in USD per share)	$ (0.40)		$ (0.95)
Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services	$ 8,172		$ 39,176
Cost of services sold	14,122		48,083
Operating profit (loss)	(5,950)		(8,907)
Net loss attributable to MDC Partners, Inc. common shareholders	$ (4,700)		$ (6,085)
Loss per common share - basic and diluted (in USD per share)	$ (0.08)		$ (0.10)

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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