Quarterly Results of Operations - Schedule of Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	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
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 402,747	$ 375,800	$ 390,532	$ 344,700	$ 390,442	$ 349,254	$ 337,047	$ 309,042	$ 1,513,779	$ 1,385,785	$ 1,326,256
Cost of services sold	268,673	249,418	267,822	237,563	260,193	235,659	228,835	211,446	1,023,476	936,133	879,716
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	231,455	21,984	13,467	(9,683)	11,144	(31,081)	2,089	(22,773)	257,223	(40,621)	(20,119)
Net income (loss) attributable to MDC Partners Inc.	$ 222,668	$ 18,493	$ 11,253	$ (10,566)	$ 9,098	$ (32,140)	$ 835	$ (23,632)	$ 241,848	$ (45,839)	$ (35,454)
Continuing operations (in dollars per share)	$ 3.33	$ 0.25	$ 0.14	$ (0.21)	$ 0.17	$ (0.62)	$ 0.02	$ (0.47)	$ 3.72	$ (0.89)	$ (0.58)
Net income (loss) (in dollars per share)	3.33	0.25	0.14	(0.21)	0.17	(0.62)	0.02	(0.47)	3.72	(0.89)	(0.71)
Continuing operations (in dollars per share)	3.30	0.24	0.14	(0.21)	0.17	(0.62)	0.02	(0.47)	3.71	(0.89)	(0.58)
Net income (loss) (in dollars per share)	$ 3.30	$ 0.24	$ 0.14	$ (0.21)	$ 0.17	$ (0.62)	$ 0.02	$ (0.47)	$ 3.71	$ (0.89)	$ (0.71)