Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$ 328,415	$ 309,391	$ 967,243	$ 883,601
Cost of services sold	212,925	205,549	648,386	575,892
Office and general expenses	78,786	70,815	206,169	213,587
Depreciation and amortization	13,086	11,684	39,393	32,083
Operating profit	23,618	21,343	73,295	62,039
Other Income (Expense):
Other income, net	(15,623)	(9,641)	(29,315)	(8,648)
Interest expense, net	(14,524)	(13,917)	(42,684)	(40,376)
Loss from continuing operations before income taxes, equity in affiliates	(6,529)	(2,215)	1,296	13,015
Income tax benefit	(1,191)	(266)	(566)	2,764
Loss from continuing operations before equity in affiliates	(5,338)	(1,949)	1,862	10,251
Equity in earnings of non-consolidated affiliates	172	81	627	223
Income from continuing operations	(5,166)	(1,868)	2,489	10,474
Loss from discontinuing operations attributable to MDC Partners Inc., net of taxes	(1,316)	(1,369)	(6,281)	(2,976)
Net income (loss)	(6,482)	(3,237)	(3,792)	7,498
Net income attributable to the noncontrolling interests	(2,122)	(1,685)	(7,343)	(4,796)	$ (6,890)
Net loss attributable to MDC Partners Inc.	(8,604)	(4,922)	(11,135)	2,702
Stock based compensation	3,266	3,437	13,025	12,233
Supplemental Segment Information:
Capital expenditures	8,161	12,978	17,665	18,678
Goodwill and intangibles	944,702	993,783	944,702	993,783
Total Assets	1,617,201	1,707,326	1,617,201	1,707,326	$ 1,648,890
Strategic Marketing Services
Segment Reporting Information [Line Items]
Revenue	264,552	238,419	775,079	683,340
Cost of services sold	168,367	156,667	515,624	442,906
Office and general expenses	52,933	48,524	151,023	136,922
Depreciation and amortization	6,445	6,895	19,360	17,182
Operating profit	36,807	26,333	89,072	86,330
Other Income (Expense):
Net income attributable to the noncontrolling interests	(1,930)	(1,744)	(6,977)	(4,994)
Stock based compensation	2,594	1,816	9,205	6,067
Supplemental Segment Information:
Capital expenditures	7,524	12,133	16,083	16,228
Goodwill and intangibles	546,148	572,453	546,148	572,453
Total Assets	924,072	973,884	924,072	973,884
Performance Marketing Services
Segment Reporting Information [Line Items]
Revenue	63,863	70,972	192,164	200,261
Cost of services sold	44,558	48,882	132,762	132,986
Office and general expenses	10,777	11,354	22,586	43,640
Depreciation and amortization	5,577	4,368	16,797	13,545
Operating profit	2,951	6,368	20,019	10,090
Other Income (Expense):
Net income attributable to the noncontrolling interests	(192)	59	(366)	198
Stock based compensation	508	477	2,467	2,684
Supplemental Segment Information:
Capital expenditures	627	417	1,309	1,216
Goodwill and intangibles	398,554	421,330	398,554	421,330
Total Assets	555,728	553,637	555,728	553,637
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Cost of services sold	0	0	0	0
Office and general expenses	15,076	10,937	32,560	33,025
Depreciation and amortization	1,064	421	3,236	1,356
Operating profit	(16,140)	(11,358)	(35,796)	(34,381)
Other Income (Expense):
Net income attributable to the noncontrolling interests	0	0	0	0
Stock based compensation	164	1,144	1,353	3,482
Supplemental Segment Information:
Capital expenditures	10	428	273	1,234
Goodwill and intangibles	0	0	0	0
Total Assets	$ 137,401	$ 179,805	$ 137,401	$ 179,805