Segment Information (Details 1) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) reportable_segment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent			26.50%
Depreciation, Depletion, Amortization and Impairment, Nonproduction	$ 11,134	$ 11,252	$ 35,212	$ 32,916
Share-based Compensation	6,242	6,380	16,882	16,870
Payments to Acquire Property, Plant, and Equipment	5,543	7,149	$ 15,232	28,305
Number of reportable segments | reportable_segment			4
Revenue	375,830	375,800	$ 1,082,541	1,111,032
Segment operating income (loss)	2,618	37,220	18,757	72,000
Interest and Debt Expense	(17,063)	(16,258)	(50,005)	(48,309)
Foreign Currency Transaction Gain (Loss), before Tax	3,275	9,913	(9,934)	18,798
Other income (expense):
Other, net	189	(1,264)	1,222	(986)
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 the noncontrolling interest	(2,458)	(3,491)	(5,900)	(6,588)	$ (15,375)
Net income (loss) attributable to MDC Partners Inc.	(16,125)	18,493	(42,135)	19,180
Global Integrated Agencies
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	5,154	6,365	18,499	17,913
Share-based Compensation	3,360	3,840	8,492	9,912
Payments to Acquire Property, Plant, and Equipment	2,418	1,950	7,875	17,645
Revenue	177,398	196,974	510,360	585,290
Segment operating income (loss)	2,633	20,069	6,099	33,240
Domestic Creative Agencies
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	396	375	1,185	1,172
Share-based Compensation	175	187	945	534
Payments to Acquire Property, Plant, and Equipment	371	367	860	980
Revenue	24,798	28,096	75,503	77,325
Segment operating income (loss)	5,532	6,627	14,451	15,411
Specialized Communications
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	1,134	1,220	3,163	3,657
Share-based Compensation	43	659	542	2,264
Payments to Acquire Property, Plant, and Equipment	743	206	3,207	673
Revenue	42,636	40,670	129,724	125,470
Segment operating income (loss)	4,677	4,775	14,471	13,423
Media Services
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	781	1,011	2,315	3,232
Share-based Compensation	112	161	282	495
Payments to Acquire Property, Plant, and Equipment	428	2,308	845	4,107
Revenue	35,022	38,315	104,460	122,207
Segment operating income (loss)	1,387	2,555	407	9,169
All Other
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	3,470	2,026	9,467	6,078
Share-based Compensation	932	1,056	2,532	2,066
Payments to Acquire Property, Plant, and Equipment	1,551	2,317	2,380	4,896
Revenue	95,976	71,745	262,494	200,740
Segment operating income (loss)	6,413	13,920	28,565	29,740
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	199	255	583	864
Share-based Compensation	1,620	477	4,089	1,599
Payments to Acquire Property, Plant, and Equipment	32	1	65	4
Segment operating income (loss)	$ (18,024)	$ (10,726)	$ (45,236)	$ (28,983)