Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 402,747,000	$ 375,800,000	$ 390,532,000	$ 344,700,000	$ 390,442,000	$ 349,254,000	$ 337,047,000	$ 309,042,000	$ 1,513,779,000	$ 1,385,785,000	$ 1,326,256,000
Cost of services sold	268,673,000	249,418,000	267,822,000	237,563,000	260,193,000	235,659,000	228,835,000	211,446,000	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
Goodwill, Impairment Loss									3,238,000	48,524,000
Operating income									131,959,000	48,431,000	72,110,000
Other Income (Expense):
Other income, net									1,346,000	414,000	7,238,000
Foreign Currency Transaction Gain (Loss), before Tax	659				10,081				18,137,000	(213,000)	(39,328,000)
Interest expense, finance charges, and loss on redemption of notes, net									(64,364,000)	(65,858,000)	(57,436,000)
Gain (Loss) on Repurchase of Debt Instrument									0	(33,298,000)	0
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									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 losses of non-consolidated affiliates									2,081,000	(309,000)	1,058,000
Income (loss) from continuing operations	231,455,000	21,984,000	13,467,000	(9,683,000)	11,144,000	(31,081,000)	2,089,000	(22,773,000)	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 loss attributable to MDC Partners Inc.									257,223,000	(40,621,000)	(26,400,000)
Capital expenditures from continuing operations									32,958,000	29,432,000	23,575,000
Intangible Assets, Net (Including Goodwill)	906,540,000				929,830,000				906,540,000	929,830,000
Total assets	1,698,892,000				1,577,378,000				1,698,892,000	1,577,378,000
Net Income (Loss) Attributable to Noncontrolling Interest									(15,375,000)	(5,218,000)	(9,054,000)
Net income (loss) attributable to MDC Partners Inc.	222,668,000	$ 18,493,000	$ 11,253,000	$ (10,566,000)	9,098,000	$ (32,140,000)	$ 835,000	$ (23,632,000)	241,848,000	(45,839,000)	(35,454,000)
Share-based Compensation	$ 7,480,000				$ 5,560,000				24,350,000	21,003,000	17,796,000
Global Integrated Agencies [Member]
Segment Reporting Information [Line Items]
Revenue									786,644,000	696,410,000	652,987,000
Depreciation and amortization									23,800,000	21,447,000	20,599,000
Goodwill, Impairment Loss									0	0
Operating income									74,902,000	58,505,000	66,161,000
Other Income (Expense):
Capital expenditures from continuing operations									20,748,000	16,439,000	17,043,000
Share-based Compensation									15,203,000	12,141,000	6,981,000
All Other [Domain]
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss									3,238,000	29,631,000
Domestic Creative Agencies [Member]
Segment Reporting Information [Line Items]
Revenue									90,663,000	85,953,000	91,658,000
Depreciation and amortization									1,434,000	1,653,000	1,855,000
Goodwill, Impairment Loss									0	0
Operating income									16,977,000	16,583,000	17,535,000
Other Income (Expense):
Capital expenditures from continuing operations									1,032,000	1,055,000	1,321,000
Share-based Compensation									845,000	634,000	644,000
Specialist Communications [Member]
Segment Reporting Information [Line Items]
Revenue									172,565,000	170,285,000	153,920,000
Depreciation and amortization									4,714,000	6,637,000	11,201,000
Goodwill, Impairment Loss									0	18,893,000
Operating income									20,714,000	1,939,000	18,047,000
Other Income (Expense):
Capital expenditures from continuing operations									1,288,000	2,741,000	1,311,000
Share-based Compensation									2,954,000	3,629,000	1,510,000
Media Services [Member]
Segment Reporting Information [Line Items]
Revenue									142,387,000	131,498,000	132,419,000
Depreciation and amortization									3,629,000	5,718,000	4,660,000
Goodwill, Impairment Loss									0	0
Operating income									12,963,000	6,154,000	20,116,000
Other Income (Expense):
Capital expenditures from continuing operations									3,035,000	5,110,000	825,000
Share-based Compensation									614,000	301,000	471,000
All Other [Member]
Segment Reporting Information [Line Items]
Revenue									321,520,000	301,639,000	295,272,000
Depreciation and amortization									8,799,000	9,406,000	12,134,000
Operating income									47,259,000	9,368,000	15,423,000
Other Income (Expense):
Capital expenditures from continuing operations									6,832,000	4,054,000	2,704,000
Share-based Compensation									2,600,000	1,773,000	5,450,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization									1,098,000	1,585,000	1,774,000
Operating income									(40,856,000)	(44,118,000)	(65,172,000)
Other Income (Expense):
Capital expenditures from continuing operations									23,000	33,000	371,000
Share-based Compensation									$ 2,134,000	$ 2,525,000	$ 2,740,000