Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$ 302,222	$ 274,854
Cost of services sold	210,419	181,468
Office and general expenses	74,308	71,336
Depreciation and amortization	12,300	10,482
Operating Profit (Loss)	5,195	11,568
Other Income (Expense):
Other income, net	(18,040)	(6,571)
Interest expense, net	(14,977)	(12,619)
Loss from continuing operations before income taxes, equity in affiliates	(27,822)	(7,622)
Income tax benefit	(4,054)	(346)
Loss from continuing operations before equity in affiliates	(23,768)	(7,276)
Equity in earnings of non-consolidated affiliates	351	63
Loss from continuing operations	(23,417)	(7,213)
Loss from discontinuing operations attributable to MDC Partners Inc., net of taxes	(6,294)	(271)
Net loss	(29,711)	(7,484)
Net income attributable to the noncontrolling interests	(2,380)	(1,362)
Net loss attributable to MDC Partners Inc.	(32,091)	(8,846)	(32,091)	(8,846)
Stock based compensation	4,445	4,368
Supplemental Segment Information:
Capital expenditures	5,656	2,496
Goodwill and intangibles	916,222	946,655
Total Assets	1,640,125	1,570,272			1,648,890
Strategic Marketing Services
Segment Reporting Information [Line Items]
Revenue	240,436	214,804
Cost of services sold	166,026	140,560
Office and general expenses	49,156	45,046
Depreciation and amortization	6,423	5,148
Operating Profit (Loss)	18,831	24,050
Other Income (Expense):
Net income attributable to the noncontrolling interests	(2,293)	(1,390)
Stock based compensation	2,524	2,139
Supplemental Segment Information:
Capital expenditures	5,330	1,702
Goodwill and intangibles	553,066	522,170
Total Assets	918,200	860,571
Performance Marketing Services
Segment Reporting Information [Line Items]
Revenue	61,786	60,050
Cost of services sold	44,393	40,908
Office and general expenses	11,154	16,315
Depreciation and amortization	5,430	4,832
Operating Profit (Loss)	809	(2,005)
Other Income (Expense):
Net income attributable to the noncontrolling interests	(87)	28
Stock based compensation	1,121	1,277
Supplemental Segment Information:
Capital expenditures	258	253
Goodwill and intangibles	363,156	424,485
Total Assets	565,411	573,308
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0
Cost of services sold	0	0
Office and general expenses	13,998	9,975
Depreciation and amortization	447	502
Operating Profit (Loss)	(14,445)	(10,477)
Other Income (Expense):
Net income attributable to the noncontrolling interests	0	0
Stock based compensation	800	952
Supplemental Segment Information:
Capital expenditures	68	541
Goodwill and intangibles	0	0
Total Assets	$ 156,514	$ 136,393