CONDENSED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Common Stock Common Class A	Common Stock Common Class B	Share Capital To Be Issued [Member]	Share Capital To Be Issued [Member] Common Class A	Additional Paid-in Capital	Charges in Excess of Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Parent [Member]	Noncontrolling Interest [Member]	Contingent Consideration, Liability Settlements [Domain]	Contingent Consideration, Liability Settlements [Domain] Parent [Member]	Contingent Consideration Classified as Equity [Member]	Contingent Consideration Classified as Equity [Member] Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, To be Issued					0
Common Stock, Value, To be Issued					$ 0
Balance at Dec. 31, 2015	$ (487,073)	$ 269,841	$ 1	$ 0		$ 0	$ (315,261)	$ (526,990)	$ 6,257	$ (566,152)	$ 79,079
Balance (in shares) at Dec. 31, 2015		49,986,704.5	3,754.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	(55,650)							(55,650)		(55,650)	0
Other Comprehensive income (loss)	(8,354)	$ 0	0	0		0	0	0	(9,663)	(9,663)	1,309
Stock Issued During Period, Restricted Stock and Stock Options, Net of Forfeitures		283,290
Stock Issued During Period, Value, Restricted Stock and Stock Options, Net of Forfeitures		$ 3,648
Issuance of restricted stock	0		$ 0	$ 0		(3,648)	0	0	0	0	0
Stock Issued During Period, Shares, New Issues		691,559
Stock Issued During Period, Value, New Issues		$ 10,458										$ 12,818	$ 12,818
Stock Issued During Period, Value, Acquisitions														$ 34,219	$ 34,219
Stock Authorized During Period, Shares, To be Issued					100,000
Stock Authorized During Period, Value, To be Issued					$ 2,360
Issuance of restricted stock (in shares)			0	0
Shares acquired and cancelled	(2,798)	$ (2,798)	$ 0	$ 0		0	0	0	0	(2,798)	0
Shares acquired and cancelled (in shares)		(137,050)	0	0
Stock-based compensation	8,259	$ 0	$ 0	$ 0		8,259	0	0	0	8,259	0
Changes in redemption value of redeemable noncontrolling interests		0	0	0			0	0	0		0
Temporary Equity, Accretion to Redemption Value	10,626					10,626				10,626
Noncontrolling Interest, Increase from Business Combination	8,819					22,498				22,498	(13,679)
Changes in noncontrolling interests and redeemable noncontrolling interest from step-up transactions										22,498
Dividends paid and to be paid	(32,747)	0	0	0		(32,747)	0	0	0	(32,747)	0
Transfer to charges in excess of capital	0	0	0	$ 0		(4,988)	4,988	0	0	0	0
Balance at Sep. 30, 2016	$ (511,881)	$ 315,368	$ 1			$ 0	$ (310,273)	$ (582,640)	$ (3,406)	$ (578,590)	$ 66,709
Balance (in shares) at Sep. 30, 2016		52,724,504	3,755
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, To be Issued				100,000	100,000
Common Stock, Value, To be Issued				$ 2,360	$ 2,360