Segment Information (Details 1) $ in Thousands	3 Months Ended			6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 operating_segment reportable_segment	Jun. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment				4
Revenue	$ 342,907	$ 375,830				$ 1,033,828	$ 1,082,541
Segment operating income (loss)	29,421	2,618				68,544	18,757
Interest expense and finance charges	(16,110)	(17,063)				(49,284)	(50,005)
Foreign exchange gain (loss)	(3,973)	3,275				4,401	(9,934)
Other, net	(431)	189				(4,559)	1,222
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	8,907	(10,981)				19,102	(39,960)
Income tax expense (benefit)	3,457	2,986				6,292	(3,367)
Income (loss) before equity in earnings of non-consolidated affiliates	5,450	(13,967)				12,810	(36,593)
Equity in earnings of non-consolidated affiliates	63	300				352	358
Net income (loss)	5,513	(13,667)				13,162	(36,235)
Net income attributable to the noncontrolling interest	(7,265)	(2,458)				(10,737)	(5,900)	$ (11,785)
Net income (loss) attributable to MDC Partners Inc.	(1,752)	(16,125)	$ (16,125)		$ (42,135)	2,425	(42,135)
Depreciation and amortization	9,368	11,134				28,869	35,212
Stock-based compensation	6,026	6,242				12,632	16,882
Capital expenditures	5,863	5,543				13,786	15,232
Global Integrated Agencies
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				4
Revenue	145,890	157,308				429,977	444,995
Segment operating income (loss)	21,036	23,486				45,527	28,247
Depreciation and amortization	4,009	4,553				12,511	16,705
Stock-based compensation	4,673	3,241				9,672	8,176
Capital expenditures	3,470	1,927				6,704	6,581
Domestic Creative Agencies
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				7
Revenue	57,593	59,151				176,711	183,504
Segment operating income (loss)	7,216	(14,031)				22,533	(6,887)
Depreciation and amortization	1,213	1,266				3,708	3,793
Stock-based compensation	352	550				1,338	2,056
Capital expenditures	694	967				1,757	2,440
Specialized Communications
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				4
Revenue	42,101	38,838				128,224	117,966
Segment operating income (loss)	5,129	3,703				18,889	13,646
Depreciation and amortization	644	1,100				1,909	3,059
Stock-based compensation	45	52				123	291
Capital expenditures	198	732				680	3,176
Media Services
Segment Reporting Information [Line Items]
Revenue	21,222	29,593				75,815	90,948
Segment operating income (loss)	(1,677)	850				(3,630)	(78)
Depreciation and amortization	755	675				2,531	1,995
Stock-based compensation	5	102				(11)	251
Capital expenditures	(2)	385				165	699
All Other
Segment Reporting Information [Line Items]
Revenue	76,101	90,940				223,101	245,128
Segment operating income (loss)	6,828	6,634				15,790	29,065
Depreciation and amortization	2,555	3,341				7,580	9,077
Stock-based compensation	118	677				1,058	2,019
Capital expenditures	1,492	1,500				4,450	2,271
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Segment operating income (loss)	(9,111)	(18,024)				(30,565)	(45,236)
Depreciation and amortization	192	199				630	583
Stock-based compensation	833	1,620				452	4,089
Capital expenditures	$ 11	$ 32				$ 30	$ 65