Noncontrolling and Redeemable Noncontrolling Interests - Noncontrolling Interest (Details) - USD ($) $ 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
Noncontrolling Interest [Line Items]
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)
Transfers (to) from the noncontrolling interests
Change from net income (loss) attributable to MDC Partners Inc. and transfers (to) from noncontrolling interests									(113,593)	244,163	(23,063)
Parent [Member]
Noncontrolling Interest [Line Items]
Net income (loss) attributable to MDC Partners Inc.									(123,733)	241,848	(45,839)
Transfers (to) from the noncontrolling interests
Adjustments to Additional Paid in Capital, Changes due to Business Combinations									10,140	2,315	22,776
Net Income Loss Including Transfer from Non Controlling Interests									$ (10,140)	$ (2,315)	$ (22,776)