CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Services	$ 1,476,203,000	$ 1,513,779,000	$ 1,385,785,000
Operating Expenses:
Cost of services sold	991,198,000	1,023,476,000	936,133,000
Office and general expenses	349,056,000	310,455,000	306,251,000
Depreciation and amortization	46,196,000	43,474,000	46,446,000
Asset Impairment Charges	80,057,000	4,415,000	48,524,000
Costs and Expenses, Total	1,466,507,000	1,381,820,000	1,337,354,000
Operating income	9,696,000	131,959,000	48,431,000
Interest Expense, Other	(67,075,000)	(64,364,000)	(65,050,000)
Other Income (Expenses):
Interest expense and finance charges, net	230,000	1,346,000	414,000
Foreign exchange gain (loss)	23,258,000	(18,137,000)	213,000
Loss on redemption of Notes	0	0	(33,298,000)
Nonoperating Income (Expense), Total	(90,103,000)	(44,881,000)	(98,147,000)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	(80,407,000)	87,078,000	(49,716,000)
Income tax expense (benefit)	31,603,000	(168,064,000)	(9,404,000)
Income (loss) before equity in earnings of non-consolidated affiliates	(112,010,000)	255,142,000	(40,312,000)
Equity in earnings (losses) of non-consolidated affiliates	62,000	2,081,000	(309,000)
Income (loss) from continuing operations	(111,948,000)	257,223,000	(40,621,000)
Net income (loss)	(111,948,000)	257,223,000	(40,621,000)
Net income attributable to the noncontrolling interests	(11,785,000)	(15,375,000)	(5,218,000)
Net income (loss) attributable to MDC Partners Inc.	(123,733,000)	241,848,000	(45,839,000)
Accretion on Convertible Preferred Shares	(8,355,000)	6,352,000	0
Net Income (Loss) Available to Common Stockholders, Basic	$ (132,088,000)	$ 205,594,000	$ (45,839,000)
Income (Loss) from Continuing Operations, Per Basic Share	$ (2.31)	$ 3.72	$ (0.89)
Basic
Earnings Per Share, Basic	(2.31)	3.72	(0.89)
Income (Loss) from Continuing Operations, Per Diluted Share	(2.31)	3.71	(0.89)
Earnings Per Share, Diluted	$ (2.31)	$ 3.71	$ (0.89)
Weighted Average Number of Shares Outstanding, Basic	57,218,994	55,255,797	51,345,807
Stock-based compensation expense is included in the following line items above:
Cost of services sold	$ 18,416,000	$ 24,350,000	$ 21,003,000
Share-based Compensation	$ 18,416,000	$ 24,350,000	$ 21,003,000
Weighted Average Number of Shares Outstanding, Diluted	57,218,994	55,481,786	51,345,807
Cost of Sales [Member]
Stock-based compensation expense is included in the following line items above:
Cost of services sold	$ 12,513,000	$ 19,015,000	$ 14,237,000
Share-based Compensation	12,513,000	19,015,000	14,237,000
General and Administrative Expense [Member]
Stock-based compensation expense is included in the following line items above:
Cost of services sold	5,903,000	5,335,000	6,766,000
Share-based Compensation	5,903,000	5,335,000	$ 6,766,000
Convertible preference shares | Convertible Preference Shares
Other Income (Expenses):
Accretion on Convertible Preferred Shares	$ (8,355,000)	$ (36,254,000)