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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Services	$ 393,662	$ 375,830	$ 379,743	$ 326,968	$ 402,747	$ 375,800	$ 390,532	$ 344,700	$ 1,476,203	$ 1,513,779	$ 1,385,785
Cost of services sold	256,088	238,690	253,390	243,030	268,673	249,418	267,822	237,563	991,198	1,023,476	936,133
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	(75,713)	(13,667)	5,951	(28,519)	231,455	21,984	13,467	(9,683)	(111,948)	257,223	(40,621)
Net income (loss) attributable to MDC Partners Inc.	$ (81,598)	$ (16,125)	$ 3,406	$ (29,416)	$ 222,668	$ 18,493	$ 11,253	$ (10,566)	$ (123,733)	$ 241,848	$ (45,839)
Continuing operations (in dollars per share)									$ (2.31)	$ 3.72	$ (0.89)
Net income (loss) (in dollars per share)	$ (1.46)	$ (0.32)	$ 0.02	$ (0.56)	$ 3.33	$ 0.25	$ 0.14	$ (0.21)	(2.31)	3.72	(0.89)
Continuing operations (in dollars per share)									(2.31)	3.71	(0.89)
Net income (loss) (in dollars per share)	$ (1.46)	$ (0.32)	$ 0.02	$ (0.56)	$ 3.30	$ 0.24	$ 0.14	$ (0.21)	$ (2.31)	$ 3.71	$ (0.89)