Segment Information - Schedule of Segment Reporting Information, by Segment (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment reportable_segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment									4
Services	$ 393,662,000	$ 375,830,000	$ 379,743,000	$ 326,968,000	$ 402,747,000	$ 375,800,000	$ 390,532,000	$ 344,700,000	$ 1,476,203,000	$ 1,513,779,000	$ 1,385,785,000
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
Goodwill, Impairment Loss									74,560,000	3,238,000
Operating income									9,696,000	131,959,000	48,431,000
Other Income (Expense):
Other income, net									230,000	1,346,000	414,000
Foreign Currency Transaction Gain (Loss), before Tax	(13,324,000)				(660,000)				(23,258,000)	18,137,000	(213,000)
Interest expense, finance charges, and loss on redemption of notes, net									(67,075,000)	(64,364,000)	(65,050,000)
Gain (Loss) on Repurchase of Debt Instrument									0	0	(33,298,000)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates									(80,407,000)	87,078,000	(49,716,000)
Income tax 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 losses of non-consolidated affiliates									62,000	2,081,000	(309,000)
Income (loss) from continuing operations	(75,713,000)	(13,667,000)	5,951,000	(28,519,000)	231,455,000	21,984,000	13,467,000	(9,683,000)	(111,948,000)	257,223,000	(40,621,000)
Stock-based compensation									5,892,000	5,335,000	5,808,000
Capital expenditures from continuing operations									20,264,000	32,958,000	29,432,000
Intangible Assets, Net (Including Goodwill)	808,720,000				906,540,000				808,720,000	906,540,000
Total assets	1,611,573,000				1,698,892,000				1,611,573,000	1,698,892,000
Net Income (Loss) Attributable to Noncontrolling Interest									(11,785,000)	(15,375,000)	(5,218,000)
Net income (loss) attributable to MDC Partners Inc.	(81,598,000)	$ (16,125,000)	$ 3,406,000	$ (29,416,000)	222,668,000	$ 18,493,000	$ 11,253,000	$ (10,566,000)	(123,733,000)	241,848,000	(45,839,000)
Share-based Compensation	$ 1,534,000				$ 7,480,000				18,416,000	24,350,000	21,003,000
Global Integrated Agencies [Member]
Segment Reporting Information [Line Items]
Services									698,872,000	797,347,400	712,793,000
Depreciation and amortization									23,571,000	23,831,000	21,555,000
Goodwill, Impairment Loss									17,828,000	2,741,000
Operating income									44,868,000	71,857,000	59,193,000
Other Income (Expense):
Capital expenditures from continuing operations									10,088,000	20,760,000	16,486,000
Share-based Compensation									$ 8,521,000	15,225,000	12,177,000
Number of Operating Segments | segment									5
All Other [Domain]
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss									$ 4,691,000	0
Domestic Creative Agencies [Member]
Segment Reporting Information [Line Items]
Services									102,063,000	104,417,400	97,199,000
Depreciation and amortization									1,583,000	1,582,000	1,811,000
Goodwill, Impairment Loss									0	0
Operating income									18,552,000	19,333,000	18,089,000
Other Income (Expense):
Capital expenditures from continuing operations									951,000	1,168,000	1,153,000
Share-based Compensation									$ 1,100,000	887,000	651,000
Number of Operating Segments | segment									5
Specialist Communications [Member]
Segment Reporting Information [Line Items]
Services									$ 179,065,000	172,565,000	170,285,000
Depreciation and amortization									4,252,000	4,714,000	6,637,000
Goodwill, Impairment Loss									0	0
Operating income									18,629,000	20,728,000	1,940,000
Other Income (Expense):
Capital expenditures from continuing operations									3,618,000	1,288,000	2,741,000
Share-based Compensation									$ 714,000	2,954,000	3,629,000
Number of Operating Segments | segment									5
Media Services [Member]
Segment Reporting Information [Line Items]
Services									$ 140,753,000	166,216,000	157,696,000
Depreciation and amortization									3,119,000	4,052,000	6,091,000
Goodwill, Impairment Loss									52,041,000	497,000
Operating income									(51,196,000)	13,126,000	5,554,000
Other Income (Expense):
Capital expenditures from continuing operations									966,000	3,842,000	5,266,000
Share-based Compensation									$ 318,000	656,000	318,000
Number of Operating Segments | segment									2
All Other [Member]
Segment Reporting Information [Line Items]
Services									$ 355,450,000	273,234,000	247,812,000
Depreciation and amortization									12,909,000	8,197,000	8,768,000
Operating income									34,000,000	47,771,000	7,773,000
Other Income (Expense):
Capital expenditures from continuing operations									4,574,000	5,877,000	3,753,000
Share-based Compensation									3,104,000	2,494,000	1,703,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization									762,000	1,098,000	1,584,000
Operating income									(55,157,000)	(40,856,000)	(44,118,000)
Other Income (Expense):
Capital expenditures from continuing operations									67,000	23,000	33,000
Share-based Compensation									$ 4,659,000	$ 2,134,000	$ 2,525,000