CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Services	$ 1,513,779,000	$ 1,385,785,000	$ 1,326,256,000
Operating Expenses:
Cost of services sold	1,023,476,000	936,133,000	879,716,000
Office and general expenses	310,455,000	306,251,000	322,207,000
Depreciation and amortization	43,474,000	46,446,000	52,223,000
Asset Impairment Charges	4,415,000	48,524,000	0
Costs and Expenses, Total	1,381,820,000	1,337,354,000	1,254,146,000
Operating income	131,959,000	48,431,000	72,110,000
Other Income (Expenses):
Other income, net	1,346,000	414,000	7,238,000
Foreign exchange gain (loss)	18,137,000	(213,000)	(39,328,000)
Interest expense and finance charges	(65,123,000)		(57,903,000)
Loss on redemption of Notes	0	(33,298,000)	0
Interest income	759,000	808,000	467,000
Nonoperating Income (Expense), Total	(44,881,000)	(98,147,000)	(89,526,000)
Income (loss) from continuing operations before income taxes and equity in earnings of non-consolidated affiliates	87,078,000	(49,716,000)	(17,416,000)
Income tax (benefit) expense	(168,064,000)	(9,404,000)	3,761,000
Income (loss) from continuing operations before equity in earnings of non-consolidated affiliates	255,142,000	(40,312,000)	(21,177,000)
Equity in earnings (losses) of non-consolidated affiliates	2,081,000	(309,000)	1,058,000
Income (loss) from continuing operations	257,223,000	(40,621,000)	(20,119,000)
Loss from discontinued operations attributable to MDC Partners Inc., net of taxes	0	0	(6,281,000)
Net income (loss)	257,223,000	(40,621,000)	(26,400,000)
Net income attributable to the noncontrolling interests	(15,375,000)	(5,218,000)	(9,054,000)
Net income (loss) attributable to MDC Partners Inc.	241,848,000	(45,839,000)	(35,454,000)
Accretion on Convertible Preferred Shares	(6,352,000)	0	0
Net Income (Loss) Available to Common Stockholders, Basic	$ 235,496,000	$ (45,839,000)	$ (35,454,000)
Income (Loss) from Continuing Operations, Per Basic Share	$ 3.72	$ (0.89)	$ (0.58)
Basic
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0.00	0.00	(0.13)
Earnings Per Share, Basic	3.72	(0.89)	(0.71)
Income (Loss) from Continuing Operations, Per Diluted Share	3.71	(0.89)	(0.58)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.00	0.00	(0.13)
Earnings Per Share, Diluted	$ 3.71	$ (0.89)	$ (0.71)
Weighted Average Number of Shares Outstanding, Basic	55,255,797	51,345,807	49,875,282
Stock-based compensation expense is included in the following line items above:
Cost of services sold	$ 24,350,000	$ 21,003,000	$ 17,796,000
Share-based Compensation	$ 24,350,000	$ 21,003,000	$ 17,796,000
Weighted Average Number of Shares Outstanding, Diluted	55,481,786	51,345,807	49,875,282
Cost of Sales [Member]
Stock-based compensation expense is included in the following line items above:
Cost of services sold	$ 19,015,000	$ 14,237,000	$ 11,710,000
Share-based Compensation	19,015,000	14,237,000	11,710,000
General and Administrative Expense [Member]
Stock-based compensation expense is included in the following line items above:
Cost of services sold	5,335,000	6,766,000	6,086,000
Share-based Compensation	$ 5,335,000	$ 6,766,000	$ 6,086,000