UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Payments to Acquire Businesses, Net of Cash Acquired			$ 34,303	$ 0
Revenue:
Services	$ 375,830	$ 375,800	1,082,541	1,111,032
Cost of Goods and Services Sold	238,690	249,418	735,110	754,803
Operating expenses:
Office and general expenses	102,380	77,910	270,137	251,313
Depreciation and amortization	11,134	11,252	35,212	32,916
Goodwill and other asset impairment	21,008	0	23,325	0
Costs and Expenses, Total	373,212	338,580	1,063,784	1,039,032
Operating profit	2,618	37,220	18,757	72,000
Other income (expense):
Interest expense and finance charges	(17,063)	(16,258)	(50,005)	(48,309)
Other, net	189	(1,264)	1,222	(986)
Foreign Currency Transaction Gain (Loss), before Tax	3,275	9,913	(9,934)	18,798
Nonoperating Income (Expense), Total	(13,599)	(7,609)	(58,717)	(30,497)
Income (loss) before income taxes and equity in earnings (losses) of non-consolidated affiliates	(10,981)	29,611	(39,960)	41,503
Income tax expense (benefit)	2,986	9,049	(3,367)	17,659
Income (loss) before equity in earnings (losses) of non-consolidated affiliates	(13,967)	20,562	(36,593)	23,844
Equity in earnings of non-consolidated affiliates	300	1,422	358	1,924
Net income (loss)	(13,667)	21,984	(36,235)	25,768
Net income attributable to noncontrolling interests	(2,458)	(3,491)	(5,900)	(6,588)
Net income (loss) attributable to MDC Partners Inc.	(16,125)	18,493	(42,135)	19,180
Net income (loss) attributable to MDC Partners Inc. common shareholders	$ (18,234)	$ 14,137	$ (48,339)	$ 13,033
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.32)	$ 0.25	$ (0.85)	$ 0.24
Weighted Average Number of Common Shares Outstanding:
Stock-based compensation	$ 6,242	$ 6,380	$ 16,882	$ 16,870
Earnings Per Share, Basic		$ 0.25	$ (0.85)	$ 0.24
Income (Loss) from Continuing Operations, Per Diluted Share	$ (0.32)	0.24	(0.85)	0.24
Earnings Per Share, Diluted	$ (0.32)	$ 0.24	$ (0.85)	$ 0.24
Weighted Average Number of Shares Outstanding, Basic	57,498,661	57,566,707	57,117,797	53,915,536
Weighted Average Number of Shares Outstanding, Diluted	57,498,661	57,943,080	57,117,797	54,228,208
Cost of services sold
Weighted Average Number of Common Shares Outstanding:
Stock-based compensation	$ 4,390	$ 5,310	$ 11,784	$ 12,558
Office and general expenses
Weighted Average Number of Common Shares Outstanding:
Stock-based compensation	1,852	1,070	5,098	4,312
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock
Other income (expense):
Accretion on and net income allocated to convertible preference shares	(2,109)	(4,356)		(6,147)
Series 4 Convertible Preferred Stock [Member] | Convertible Preferred Stock
Other income (expense):
Accretion on and net income allocated to convertible preference shares	$ (2,109)	$ (1,948)	$ (6,204)	$ (4,365)