Stagwell (STGW) 10-Q 1 Nov 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 2017	Dec. 31, 2016
Document Information [Line Items]
Entity Registrant Name	MDC PARTNERS INC
Entity Central Index Key	876,883
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Trading Symbol	MDCA
Document Type	10-Q
Document Fiscal Year Focus	2,017
Document Period End Date	Sep. 30, 2017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		58,357,062
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,755
Convertible Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Document Information [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares	95,000	95,000	0

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share, Basic	$ 0.25	$ (0.62)	$ 0.24	$ (1.08)
Earnings Per Share, Diluted	$ 0.24	$ (0.62)	$ 0.24	$ (1.08)
Revenue:
Services	$ 375,800,000	$ 349,254,000	$ 1,111,032,000	$ 995,343,000
Operating expenses:
Cost of services sold	249,418,000	235,659,000	754,803,000	675,940,000
Office and general expenses	77,910,000	83,303,000	251,313,000	233,840,000
Depreciation and amortization	11,252,000	11,412,000	32,916,000	34,068,000
Goodwill, Impairment Loss	0	29,631,000	0	29,631,000
Costs and Expenses, Total	338,580,000	360,005,000	1,039,032,000	973,479,000
Operating profit	37,220,000	(10,751,000)	72,000,000	21,864,000
Other income (expense):
Other, net	8,649,000	(6,008,000)	17,812,000	9,530,000
Interest and Debt Expense	16,403,000	16,540,000	48,859,000	49,289,000
Loss on redemption of notes	0	0	0	(33,298,000)
Interest income	145,000	218,000	550,000	599,000
Nonoperating Income (Expense), Total	(7,609,000)	(22,330,000)	(30,497,000)	(72,458,000)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	29,611,000	(33,081,000)	41,503,000	(50,594,000)
Income tax expense	9,049,000	(1,930,000)	17,659,000	1,180,000
Income (loss) before equity in earnings of non-consolidated affiliates	20,562,000	(31,151,000)	23,844,000	(51,774,000)
Equity in earnings (loss) of non-consolidated affiliates	1,422,000	70,000	1,924,000	9,000
Net income (loss)	21,984,000	(31,081,000)	25,768,000	(51,765,000)
Net income attributable to noncontrolling interests	(3,491,000)	(1,059,000)	(6,588,000)	(3,172,000)
Net income (loss) attributable to MDC Partners Inc.	$ 18,493,000	$ (32,140,000)	$ 19,180,000	$ (54,937,000)
Weighted average number of common shares outstanding:
Weighted Average Number of Shares Outstanding, Basic and Diluted	57,566,707	52,244,819	53,915,536	50,861,890
Share-based Compensation	$ 6,380,000	$ 5,228,000	$ 16,870,000	$ 15,443,000
Net Income (Loss) Available to Common Stockholders, Basic	16,545,000	(32,140,000)	14,815,000	(54,937,000)
Cost of Sales [Member]
Weighted average number of common shares outstanding:
Share-based Compensation	5,310,000	3,026,000	12,558,000	10,393,000
General and Administrative Expense [Member]
Weighted average number of common shares outstanding:
Share-based Compensation	1,070,000	2,202,000	4,312,000	5,050,000
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock [Member]
Other income (expense):
Accretion on convertible preferred shares	$ (1,948,000)	$ 0	$ (4,365,000)	$ 0

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Comprehensive income (loss)
Net income (loss)	$ 21,984	$ (31,081)	$ 25,768	$ (51,765)
Other comprehensive income (loss), net of applicable tax:
Foreign currency translation adjustment	1,912	(2,331)	1,294	8,354
Other comprehensive income (loss)	(1,912)	2,331	(1,294)	(8,354)
Comprehensive income (loss) for the period	20,072	(28,750)	24,474	(60,119)
Comprehensive income attributable to the noncontrolling interests	(4,695)	(569)	(9,063)	(4,481)
Comprehensive income (loss) attributable to MDC Partners Inc.	$ 15,377	$ (29,319)	$ 15,411	$ (64,600)

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 18,861	$ 27,921
Cash held in trusts	5,182	5,341
Accounts receivable, less allowance for doubtful accounts of $1,933 and $1,523	438,765	388,340
Expenditures billable to clients	42,332	33,118
Other current assets	27,647	34,862
Total current assets	532,787	489,582
Fixed assets, at cost, less accumulated depreciation of $115,884 and $105,134	91,153	78,377
Investments in non-consolidated affiliates	5,655	4,745
Goodwill	839,361	844,759
Other intangible assets, net	74,685	85,071
Deferred tax assets	39,598	41,793
Other assets	34,592	33,051
Total assets	1,617,831	1,577,378
Current liabilities:
Accounts payable	232,704	251,456
Trust liability	5,182	5,341
Accruals and other liabilities	289,471	303,581
Advance billings	165,600	133,925
Current portion of long-term debt	300	228
Current portion of deferred acquisition consideration	59,849	108,290
Total current liabilities	753,106	802,821
Long-term debt, less current portion	930,889	936,208
Long-term portion of deferred acquisition consideration	88,419	121,274
Other liabilities	54,657	56,012
Deferred tax liabilities	119,602	110,359
Total liabilities	1,946,673	2,026,674
Redeemable noncontrolling interests (Note 2)	60,092	60,180
Shareholders’ deficit:
Charges in excess of capital	(307,454)	(311,581)
Accumulated deficit	(562,668)	(581,848)
Total shareholders’ deficit	(388,934)	(509,476)
Total liabilities, redeemable noncontrolling interests, and shareholders’ deficit	1,617,831	1,577,378
Common Class A
Shareholders’ deficit:
Common shares	351,075	317,784
Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Shareholders’ deficit:
Convertible preference shares (liquidation preference $97,417)	90,220
Total shareholders’ deficit	90,220	0
Share Capital To Be Issued [Member]
Shareholders’ deficit:
Shares to be issued, 100,000 shares in 2016	0	2,360
Share Capital To Be Issued [Member] | Common Class A
Shareholders’ deficit:
Shares to be issued, 100,000 shares in 2016	0	2,360
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Shareholders’ deficit:
Accumulated other comprehensive loss	(5,593)	(1,824)
Total shareholders’ deficit	(5,593)	(1,824)
Parent [Member]
Shareholders’ deficit:
MDC Partners Inc. shareholders’ deficit	(434,420)	(575,109)
Total shareholders’ deficit	(434,420)	(575,109)
Noncontrolling Interest [Member]
Shareholders’ deficit:
Noncontrolling interests	45,486	65,633
Total shareholders’ deficit	$ 45,486	$ 65,633

CONDENSED CONSOLIDATED BALANCE5

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 2,800	$ 1,523
Accumulated depreciation (in dollars)	$ 118,241	$ 105,134
Stock Issued During Period, Shares, Convertible Preferred Shares	90,220,000
Common stock, shares issued	56,314,344	52,802,058
Convertible Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Preferred Stock, Liquidation Preference, Value	$ 99,365	$ 0
Stock Issued During Period, Shares, Convertible Preferred Shares	95,000	0
Shares, Outstanding	95,000	0
Common Stock [Member]
Shares, Outstanding	56,314,344	52,802,058
Common stock, shares outstanding	56,314,344	52,802,058
Common Stock [Member] | Common Class A
Shares, Outstanding	56,310,589	52,798,303
Common Stock [Member] | Common Class B
Shares, Outstanding	3,755
Share Capital To Be Issued [Member]
Shares to be issued, shares	0	100,000

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 25,768,000	$ (51,765,000)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Stock-based compensation	16,870,000	15,443,000
Depreciation	18,000,000	16,853,000
Amortization of intangibles	14,916,000	17,215,000
Amortization of deferred finance charges	2,018,000	8,736,000
Goodwill, Impairment Loss	0	29,631,000
Adjustment to deferred acquisition consideration	13,354,000	17,363,000
Deferred income tax	8,125,000	(553,000)
(Gain) loss on sale of assets	1,245,000	377,000
(Earnings) losses of non-consolidated affiliates	(1,924,000)	(9,000)
Other non-current assets and liabilities	(4,388,000)	1,853,000
Foreign exchange	(15,113,000)	(12,806,000)
Changes in working capital:
Accounts receivable	(54,723,000)	(47,767,000)
Expenditures billable to clients	(9,294,000)	5,551,000
Prepaid expenses and other current assets	6,400,000	(16,851,000)
Accounts payable, accruals and other liabilities	(31,149,000)	(77,355,000)
Advance billings	32,015,000	25,824,000
Net cash provided by (used in) operating activities	22,120,000	(41,387,000)
Cash flows used in investing activities:
Capital expenditures	(28,305,000)	(19,723,000)
Deposits	(1,461,000)	0
Acquisitions, net of cash acquired	0	2,531,000
Distributions from non-consolidated affiliates	(1,530,000)	(2,571,000)
Net Cash Provided by (Used in) Investing Activities	(19,503,000)	(14,663,000)
Cash flows provided by financing activities:
Acquisition related payments	(89,126,000)	(129,616,000)
Repayment of long-term debt	(310,000)	(381,000)
Purchase of shares	(1,239,000)	(2,798,000)
Premium paid on redemption of notes	0	(26,873,000)
Deferred financing costs	0	(21,569,000)
Distributions to noncontrolling interests	(5,272,000)	(6,549,000)
Payment of dividends	(284,000)	(32,580,000)
Net Cash Provided by (Used in) Financing Activities	(11,683,000)	15,131,000
Effect of exchange rate changes on cash and cash equivalents	6,000	1,196,000
Decrease in cash and cash equivalents	(9,060,000)	(39,723,000)
Cash and cash equivalents at beginning of period	27,921,000	61,458,000
Cash and cash equivalents at end of period	18,861,000	21,735,000
Supplemental disclosures:
Cash income taxes paid	6,909,000	2,798,000
Cash interest paid	32,324,000	27,979,000
Change in cash held in trusts	(159,000)	147,000
Non-cash transactions:
Capital leases	621,000	0
Dividends payable	453,000	1,077,000
Deferred acquisition consideration settled through issuance of shares	27,852,000
Proceeds from Sale of Other Assets, Investing Activities	11,120,000	215,000
Payments of Distributions to Affiliates	673,000	4,885,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	0	34,219,000
Leasehold improvements financed by landlord	0	7,250,000
Six Point Seven Five Percentage Notes [Member]
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Loss on redemption of notes	0	26,873,000
Cash flows provided by financing activities:
Repayment of 6.75% Notes	0	(735,000,000)
Six Point Five Zero Percentage Notes [Domain]
Cash flows provided by financing activities:
Proceeds from issuance of 6.50% Notes	0	900,000,000
Wells Fargo Capital Finance, LLC | Revolving Credit Facility [Member]
Cash flows provided by financing activities:
Repayments of revolving credit agreement	(1,093,508,000)	(1,255,608,000)
Proceeds from revolving credit agreement	1,087,688,000	1,326,105,000
Common Stock [Member]
Non-cash transactions:
Deferred acquisition consideration settled through issuance of shares	28,727,000
Series 4 Convertible Preferred Stock [Domain]
Cash flows provided by financing activities:
Proceeds from issuance of convertible preference shares	95,000,000	0
Convertible Preferred Stock [Member]
Cash flows provided by financing activities:
Convertible preference shares issuance costs	$ (4,632,000)	0
Common Class A [Member] | Common Stock [Member]
Non-cash transactions:
Deferred acquisition consideration settled through issuance of shares		$ 10,458,000

CONDENSED STATEMENTS OF SHAREHO

CONDENSED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Common Class A	Convertible Preferred Stock [Member]Series 4 Convertible Preferred Stock [Domain]	Common Stock	Common StockCommon Class A	Common StockCommon 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]
Common Stock, Value, Issued		$ 317,784
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, To be Issued							100,000
Common Stock, Value, To be Issued							$ 2,360	$ 2,360
Balance at Dec. 31, 2016	$ (509,476)		$ 0	$ 317,784					$ 0	$ (311,581)	$ (581,848)	$ (1,824)	$ (575,109)	$ 65,633
Balance (in shares) at Dec. 31, 2016			0	52,802,058	52,798,303
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	19,180										19,180		19,180	0
Other Comprehensive income (loss)	(1,294)											(3,769)	(3,769)	2,475
Issuance of restricted stock	$ 0			$ 5,803					(5,803)				$ 0
Stock Issued During Period, Shares, New Issues	90,220,000		95,000										90,220,000
Stock Issued During Period, Value, Convertible Preferred Shares			$ 90,220
Deferred acquisition consideration settled through issuance of shares	$ 27,852			$ 28,727					1,485				$ 27,852
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)				273,169
Shares acquired and cancelled	(1,239)			$ (1,239)									(1,239)
Stock Issued During Period, Shares, New Issues				3,353,939
Shares acquired and cancelled (in shares)				(114,822)
Stock-based compensation	6,082								6,082				6,082
Temporary Equity, Accretion to Redemption Value	(300)								(300)				(300)
Noncontrolling Interest, Increase from Business Combination	2,315								2,315				2,315
Noncontrolling Interest, Decrease from Deconsolidation	(10,657)
Adjustments to Additional Paid in Capital, Other	348								348				348
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(9,650)												2,315	(11,965)
Transfer to charges in excess of capital									(4,127)	4,127
Balance at Sep. 30, 2017	$ (388,934)		$ 90,220	$ 351,075					$ 0	$ (307,454)	$ (562,668)	$ (5,593)	$ (434,420)	$ 45,486
Balance (in shares) at Sep. 30, 2017			95,000	56,314,344	56,310,589	3,755
Common Stock, Value, Issued		$ 351,075
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, To be Issued							0
Common Stock, Value, To be Issued							$ 0	$ 0

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Acquisitions	Valuations of acquired companies are based on a number of factors, including specialized know-how, reputation, competitive position and service offerings. The Company’s acquisition strategy has been focused on acquiring the expertise of an assembled workforce in order to continue to build upon the core capabilities of its various strategic business platforms to better serve the Company’s clients. The Company’s strategy includes acquiring ownership stakes in well-managed businesses with strong reputations in the industry. The Company’s model of “Perpetual Partnership” often involves acquiring a majority interest rather than a 100% interest and leaving management owners with a significant financial interest in the performance of the acquired entity for a minimum period of time, typically not less than five years. The Company’s acquisition model in this scenario typically provides for (i) an initial payment at the time of closing, (ii) additional contingent purchase price obligations based on the future performance of the acquired entity, and (iii) an option by the Company to purchase (and in some instances a requirement to so purchase) the remaining interest of the acquired entity under a predetermined formula. Contingent purchase price obligations. The Company’s contingent purchase price obligations are generally payable within a five year period following the acquisition date, and are based on (i) the achievement of specific thresholds of future earnings, and (ii) in certain cases, the growth rate of those earnings. Contingent purchase price obligations are recorded as deferred acquisition consideration on the balance sheet at the acquisition date fair value and adjusted at each reporting period through operating income or net interest expense, depending on the nature of the arrangement. On occasion, the Company may initiate a renegotiation of previously acquired ownership interests and any resulting change in the estimated amount of consideration to be paid is adjusted in the reporting period through operating income or net interest expense, depending on the nature of the arrangement. See Notes 2 , 9 , and 12 for additional information on the deferred acquisition consideration. Options to purchase . When acquiring less than 100% ownership, the Company may enter into agreements that give the Company an option to purchase, or require the Company to purchase, the incremental ownership interests under certain circumstances. Where the option to purchase the incremental ownership is within the Company’s control, the amounts are recorded as noncontrolling interests in the equity section of the Company’s balance sheet. Where the incremental purchase may be required of the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity at their estimated acquisition date redemption value and adjusted at each reporting period for changes to their estimated redemption value through additional paid-in capital (but not less than their initial redemption value), except for foreign currency translation adjustments. On occasion, the Company may initiate a renegotiation to acquire an incremental ownership interest and the amount of consideration paid may differ materially from the balance sheet amounts. See Note 12 for additional information on redeemable noncontrolling interests. Employment conditions. From time to time, specifically when the projected success of an acquisition is deemed to be dependent on retention of specific personnel, such acquisition may include deferred payments that are contingent upon employment terms as well as financial performance. The Company accounts for those payments through operating income as stock-based compensation over the required retention period. For the three and nine months ended September 30, 2017 and 2016 , stock-based compensation included $4,064 and $9,792 , respectively, and $2,259 and $7,184 , respectively, of expense relating to those payments. Distributions to noncontrolling shareholders. If noncontrolling shareholders have the right to receive distributions based on the profitability of an acquired entity, the amount is recorded as income attributable to noncontrolling interests. However, there are circumstances when the Company acquires a majority interest and the selling shareholders waive their right to receive distributions with respect to their retained interest for a period of time, typically not less than five years. Under this model, the right to receive such distributions typically begins concurrently with the purchase option period and, therefore, if such option is exercised at the first available date, the Company may not record any noncontrolling interest over the entire period from the initial acquisition date through the acquisition date of the remaining interests. 2017 Acquisitions In 2017, the Company entered into various non-material transactions in connection with certain of its majority-owned entities. As a result of the foregoing, the Company made total cash closing payments of $3,858 , increased fixed deferred consideration liability by $7,208 , reduced redeemable noncontrolling interests by $816 , reduced noncontrolling interests equity by $11,965 , reduced noncontrolling interest payable by $397 , and increased additional paid-in capital by $2,316 . In addition, a stock-based compensation charge of $996 has been recognized representing the consideration paid in excess of the fair value of the interest acquired. 2017 Dispositions During the three months ended September 30, 2017, the Company sold all of its ownership interests in three subsidiaries resulting in recognition of a net loss on sale of business of $1,424 . The net assets reflected in the calculation of the net loss on sale was inclusive of goodwill of $17,593 . Goodwill was allocated to the subsidiaries based on the relative fair value of the sold subsidiaries compared to the fair value of the respective reporting units. See Note 1 for details. Additionally, the Company recorded a reduction in noncontrolling interests of $10,657 . 2016 Acquisitions Effective July 1, 2016, the Company acquired 100% of the equity interests of Forsman & Bodenfors AB (“F&B”), an advertising agency based in Sweden, for an estimated aggregate purchase price at acquisition date of $49,837 , consisting of a closing payment of 1,900,000 MDC Class A subordinate voting shares with an acquisition date fair value of $34,219 , plus additional deferred acquisition payments with an estimated present value at acquisition date of $15,618 . The amount of additional payments are based on the financial results of the acquired business for 2015 and 2016 as well as for the value of the Company’s shares from July 1, 2016 up to and including the close of business on November 2, 2016. During the three months ended June 30, 2017, the Company paid cash of $3,055 and issued an additional 2,450,000 MDC Class A subordinate voting shares with a fair value of $20,800 as a settlement of deferred acquisition consideration. An allocation of excess purchase price consideration of this acquisition to the fair value of the net assets acquired resulted in identifiable intangibles of $36,698 , consisting primarily of customer lists, trade names and covenants not to compete, and goodwill of $24,778 , including the value of the assembled workforce. The identified assets have a weighted average useful life of approximately 10.8 years and will be amortized in a manner represented by the pattern in which the economic benefits of such assets are expected to be realized. In addition, the Company has recorded $2,275 as the present value of redeemable noncontrolling interests and $5,514 as the present value of noncontrolling interests both relating to the noncontrolling interest of F&B’s subsidiaries. None of the intangibles and goodwill are tax deductible and the Company recorded a deferred tax liability of $8,074 related to the intangibles. F&B’s results are included in the Global Integrated Agencies segment. During the six months ended June 30, 2017, F&B earned revenue of $43,535 and incurred a net loss of $4,460 , which is included in our consolidated results for the nine months ended September 30, 2017. The net loss was attributable to an increase in the deferred acquisition payment liability related to such acquisition, driven by the decrease in t he future market performance of the Company’s stock price and the amortization of the intangibles identified in the allocation of the purchase price consideration. Effective April 1, 2016, the Company acquired the remaining 40% ownership interests of Luntz Global Partners LLC. In 2016, the Company also entered into various non-material transactions in connection with other majority-owned entities. As a result of the foregoing, the Company made total cash closing payments of $1,581 , eliminated the contingent deferred acquisition payments of $4,052 and fixed deferred acquisition payments of $467 related to certain initial acquisition of the equity interests, reduced other assets by $428 , reduced redeemable noncontrolling interests by $1,005 , reduced noncontrolling interests by $19,354 , increased accruals and other liabilities by $94 , and increased additional paid-in capital by $22,775 . Additional deferred payments with an estimated present value at acquisition date of $2,393 that are contingent upon service conditions have been excluded from deferred acquisition consideration and will be expensed as stock-based compensation over the required service period. 2016 Dispositions Effective September 30, 2016, the Company sold all of its ownership interests in Bryan Mills to the noncontrolling shareholders and recognized a loss of $800. The net assets reflected in the calculation of the loss on sale was inclusive of goodwill of $764 . Noncontrolling Interests Changes in the Company’s ownership interests in its less than 100% owned subsidiaries during the three and nine months ended September 30, 2017 and 2016 were as follows: Net Income (Loss) Attributable to MDC Partners Inc. and Transfers (to) from the Noncontrolling Interests Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Net income (loss) attributable to MDC Partners Inc. $ 18,493 $ (32,140 ) $ 19,180 $ (54,937 ) Transfers from the noncontrolling interest: (Decrease) increase in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of Redeemable Noncontrolling Interests and Noncontrolling Interests (337 ) (520 ) 2,315 22,498 Net transfers from noncontrolling interests $ (337 ) $ (520 ) $ 2,315 $ 22,498 Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ 18,156 $ (32,660 ) $ 21,495 $ (32,439 )

Accruals and Other Liabilities

Accruals and Other Liabilities	9 Months Ended
	Sep. 30, 2017
Accrued and Other Liabilities [Abstract]
Accruals and Other Liabilities	At September 30, 2017 and December 31, 2016 , accruals and other liabilities included accrued media of $169,460 and $201,872 , respectively; and included amounts due to noncontrolling interest holders for their share of profits, which will be distributed within the next twelve months of $5,802 and $4,154 , respectively. Changes in amounts due to noncontrolling interest holders included in accrued and other liabilities for the year ended December 31, 2016 and nine months ended September 30, 2017 were as follows: Noncontrolling Balance, December 31, 2015 $ 5,473 Income attributable to noncontrolling interests 5,218 Distributions made (7,772 ) Other (1) 1,235 Balance, December 31, 2016 $ 4,154 Income attributable to noncontrolling interests 6,588 Distributions made (5,272 ) Other (1) 332 Balance, September 30, 2017 $ 5,802 (1) Other consists primarily of business acquisitions, sale of a business, step-up transactions, and cumulative translation adjustments. At September 30, 2017 and December 31, 2016 , accounts payable included $47,430 and $80,193 of outstanding checks, respectively.

Debt

Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Debt	6.50% Notes On March 23, 2016, MDC entered into an indenture (the “Indenture”) among MDC, its existing and future restricted subsidiaries that guarantee, are co-borrowers under, or grant liens to secure, the Credit Agreement, as guarantors (the “Guarantors”) and The Bank of New York Mellon, as trustee, relating to the issuance by MDC of $900,000 aggregate principal amount of the 6.50% Notes. The 6.50% Notes were sold in a private placement in reliance on exceptions from registration under the Securities Act of 1933. The 6.50% Notes bear interest at a rate of 6.50% per annum, accruing from March 23, 2016. Interest is payable semiannually in arrears on May 1 and November 1 of each year, beginning November 1, 2016. The 6.50% Notes mature on May 1, 2024 , unless earlier redeemed or repurchased. The Company received net proceeds from the offering of the 6.50% Notes equal to approximately $880,000 . The Company used the net proceeds to redeem all of its existing 6.75% Notes, together with accrued interest, related premiums, fees and expenses and recorded a charge for the loss on redemption of such notes of $33,298 , including write offs of unamortized original issue premium and debt issuance costs. Remaining proceeds were used for general corporate purposes, including funding of deferred acquisition consideration. The 6.50% Notes are guaranteed on a senior unsecured basis by all of MDC’s existing and future restricted subsidiaries that guarantee, or are co-borrowers under or grant liens to secure, the Credit Agreement. The 6.50% Notes are unsecured and unsubordinated obligations of MDC and rank (i) equally in right of payment with all of MDC’s or any Guarantor’s existing and future senior indebtedness, (ii) senior in right of payment to MDC’s or any Guarantor’s existing and future subordinated indebtedness, (iii) effectively subordinated to all of MDC’s or any Guarantor’s existing and future secured indebtedness to the extent of the collateral securing such indebtedness, including the Credit Agreement, and (iv) structurally subordinated to all existing and future liabilities of MDC’s subsidiaries that are not Guarantors. MDC may, at its option, redeem the 6.50% Notes in whole at any time or in part from time to time, on and after May 1, 2019 (i) at a redemption price of 104.875% of the principal amount thereof if redeemed during the twelve-month period beginning on May 1, 2019 , (ii) at a redemption price of 103.250% of the principal amount thereof if redeemed during the twelve-month period beginning on May 1, 2020 , (iii) at a redemption price of 101.625% of the principal amount thereof if redeemed during the twelve-month period beginning on May 1, 2021 , and (iv) at a redemption price of 100% of the principal amount thereof if redeemed on May 1, 2022 and thereafter. Prior to May 1, 2019 , MDC may, at its option, redeem some or all of the 6.50% Notes at a price equal to 100% of the principal amount of the 6.50% Notes plus a “make whole” premium and accrued and unpaid interest. MDC may also redeem, at its option, prior to May 1, 2019 , up to 35% of the 6.50% Notes with the proceeds from one or more equity offerings at a redemption price of 106.50% of the principal amount thereof. If MDC experiences certain kinds of changes of control (as defined in the Indenture), holders of the 6.50% Notes may require MDC to repurchase any 6.50% Notes held by them at a price equal to 101% of the principal amount of the 6.50% Notes plus accrued and unpaid interest. In addition, if MDC sells assets under certain circumstances, it must apply the proceeds from such sale and offer to repurchase the 6.50% Notes at a price equal to 100% of the principal amount plus accrued and unpaid interest. The Indenture includes covenants that, among other things, restrict MDC’s ability and the ability of its restricted subsidiaries (as defined in the Indenture) to incur or guarantee additional indebtedness; pay dividends on or redeem or repurchase the capital stock of MDC; make certain types of investments; create restrictions on the payment of dividends or other amounts from MDC’s restricted subsidiaries; sell assets; enter into transactions with affiliates; create liens; enter into sale and leaseback transactions; and consolidate or merge with or into, or sell substantially all of MDC’s assets to, another person. These covenants are subject to a number of important limitations and exceptions. The 6.50% Notes are also subject to customary events of default, including a cross-payment default and cross-acceleration provision. Redemption of 6.75% Notes On March 23, 2016, the Company redeemed the 6.75% Notes in whole at a redemption price of 103.375% of the principal amount thereof with the proceeds from the issuance of the 6.50% Notes. Credit Agreement On March 20, 2013, MDC, Maxxcom Inc. (a subsidiary of MDC) and each of their subsidiaries party thereto entered into an amended and restated, $225,000 senior secured revolving credit agreement due 2018 (the “Credit Agreement”) with Wells Fargo Capital Finance, LLC, as agent, and the lenders from time to time party thereto. Advances under the Credit Agreement are to be used for working capital and general corporate purposes, in each case pursuant to the terms of the Credit Agreement. Capitalized terms used in this section and not otherwise defined have the meanings set forth in the Credit Agreement. Effective October 23, 2014, MDC and its subsidiaries entered into an amendment to its Credit Agreement. The amendment: (i) expanded the commitments under the facility by $100,000 , from $225,000 to $325,000 ; (ii) extended the date by an additional eighteen months to September 30, 2019 ; (iii) reduced the base borrowing interest rate by 25 basis points (the applicable margin for borrowing is 1.00% in the case of Base Rate Loans and 1.75% in the case of LIBOR Rate Loans); and (iv) modified certain covenants to provide the Company with increased flexibility to fund its continued growth and other general corporate purposes. Effective May 3, 2016, MDC and its subsidiaries entered into an additional amendment to its Credit Agreement. The amendment: (i) extends the date by an additional nineteen months to May 3, 2021 ; (ii) reduces the base borrowing interest rate by 25 basis points; (iii) provides the Company the ability to borrow in foreign currencies; and (iv) certain other modifications to provide additional flexibility in operating the Company’s business. Advances under the Credit Agreement bear interest as follows: (a)(i) LIBOR Rate Loans bear interest at the LIBOR Rate and (ii) Base Rate Loans bear interest at the Base Rate, plus (b) an applicable margin. The initial applicable margin for borrowing is 1.50% in the case of Base Rate Loans and 1.75% in the case of LIBOR Rate Loans. In addition to paying interest on outstanding principal under the Credit Agreement, MDC is required to pay an unused revolver fee to lenders under the Credit Agreement in respect of unused commitments thereunder. The Credit Agreement is guaranteed by substantially all of MDC’s present and future subsidiaries, other than immaterial subsidiaries and subject to customary exceptions. The Credit Agreement includes covenants that, among other things, restrict MDC’s ability and the ability of its subsidiaries to incur or guarantee additional indebtedness; pay dividends on or redeem or repurchase the capital stock of MDC; make certain types of investments; impose limitations on dividends or other amounts from MDC’s subsidiaries; incur certain liens, sell or otherwise dispose of certain assets; enter into transactions with affiliates; enter into sale and leaseback transactions; and consolidate or merge with or into, or sell substantially all of MDC’s assets to, another person. These covenants are subject to a number of important limitations and exceptions. The Credit Agreement also contains financial covenants, including a total leverage ratio, a senior leverage ratio, a fixed charge coverage ratio and a minimum earnings level (each as more fully described in the Credit Agreement). The Credit Agreement is also subject to customary events of default. The Company is currently in compliance with all of the terms and conditions of its Credit Agreement, and management believes, based on its current financial projections, that the Company will be in compliance with the covenants over the next twelve months. At September 30, 2017 , there were $48,607 borrowings under the Credit Agreement. At September 30, 2017 , the Company had issued $5,009 of undrawn outstanding letters of credit.

Convertible Preference Shares (

Convertible Preference Shares (Notes)	9 Months Ended
	Sep. 30, 2017
Convertible Preference Shares [Abstract]
Convertible Preference Shares	On March 7, 2017 (the “Issue Date”), the Company issued 95,000 newly created Preference Shares to affiliates of The Goldman Sachs Group, Inc. (collectively, the “Purchaser”) pursuant to a $95,000 private placement. The Company received proceeds of approximately $90,220 , net of fees and estimated expenses, which were primarily used to pay down existing debt under the Company’s credit facility and for general corporate purposes. In connection with the closing of the transaction, effective March 7, 2017, the Company increased the size of its Board of Directors (the “Board”) to seven members and appointed one nominee designated by the Purchaser. Except as required by law, the Preference Shares do not have voting rights, and are not redeemable at the option of the Purchaser. The holders of the Preference Shares have the right to convert their Preference Shares in whole at any time and from time to time, and in part at any time and from time to time after the ninetieth day following the original issuance date of the Preference Shares, into a number of Class A Shares equal to the then-applicable liquidation preference divided by the applicable conversion price at such time (the “Conversion Price”). The initial liquidation per share preference of each Preference Share is $1,000 . The initial Conversion Price will be $10.00 per Preference Share, subject to customary adjustments for share splits and combinations, dividends, recapitalizations and other matters, including weighted average anti-dilution protection for certain issuances of equity or equity-linked securities. The Preference Shares’ liquidation preference accretes at 8.0% per annum, compounded quarterly until the five-year anniversary of the Issue Date. During the nine months ended September 30, 2017 , the Preference Shares accreted at a monthly rate of approximately $6.84 per Preference Share, for total accretion of $4,365 , bringing the aggregate liquidation preference to $99,365 as of September 30, 2017 . The accretion is considered in the calculation of net income (loss) attributable to MDC Partners Inc. common shareholders. See Notes 2 and 3 . Holders of the Preference Shares are entitled to dividends in an amount equal to any dividends that would otherwise have been payable on the Class A Shares issued upon conversion of the Preference Shares. The Preference Shares are convertible at the Company’s option (i) on and after the two-year anniversary of the Issue Date, if the closing trading price of the Class A Shares over a specified period prior to conversion is at least 125% of the Conversion Price or (ii) after the fifth anniversary of the Issue Date, if the closing trading price of the Class A Shares over a specified period prior to conversion is at least equal to the Conversion Price. Following certain change in control transactions of the Company in which holders of Preference Shares are not entitled to receive cash or qualifying listed securities with a value at least equal to the liquidation preference plus accrued and unpaid dividends, (i) holders will be entitled to cash dividends on the liquidation preference at an increasing rate (beginning at 7% ), and (ii) the Company will have a right to redeem the Preference Shares for cash at the greater of their liquidation preference plus accrued and unpaid dividends or their as-converted value.

Other Income

Other Income	9 Months Ended
	Sep. 30, 2017
Other Income and Expenses [Abstract]
Other Nonoperating Income and Expense [Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Other income (expense) $ (7 ) $ 26 $ 271 $ (220 ) Loss on sale of business (1) (1,424 ) (800 ) (1,424 ) (800 ) Gain on sale of investments (2) 168 682 168 682 Foreign currency transaction gain (loss) 9,912 (5,916 ) 18,797 9,868 $ 8,649 $ (6,008 ) $ 17,812 $ 9,530 (1) During the three months ended September 30, 2017, the Company sold all of its ownership interests in three subsidiaries resulting in recognition of a net loss on sale of business of $1,424 . See Note 4 for further information. Effective September 30, 2016, the Company sold all of its ownership interests in Bryan Mills to the noncontrolling shareholders and recognized a loss of $800 .

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Deferred Acquisition Consideration. In addition to the consideration paid by the Company in respect of certain of its acquisitions at closing, additional consideration may be payable, or may be potentially payable based on the achievement of certain threshold levels of earnings. See Notes 2 , 4 , and 9 . Options to purchase. Noncontrolling shareholders in certain subsidiaries have the right in certain circumstances to require the Company to acquire the remaining ownership interests held by them. The noncontrolling shareholders’ ability to exercise any such option right is subject to the satisfaction of certain conditions, including conditions requiring notice in advance of exercise and specific employment termination conditions. In addition, these rights cannot be exercised prior to specified staggered exercise dates. The exercise of these rights at their earliest contractual date would result in obligations of the Company to fund the related amounts during the remainder of 2017 to 2023 . It is not determinable, at this time, if or when the owners of these rights will exercise all or a portion of these rights. The amount payable by the Company in the event such rights are exercised is dependent on various valuation formulas and on future events, such as the average earnings of the relevant subsidiary through the date of exercise, the growth rate of the earnings of the relevant subsidiary during that period and, in some cases, the currency exchange rate at the date of payment. Management estimates, assuming that the subsidiaries owned by the Company at September 30, 2017 , perform over the relevant future periods at their trailing twelve-months earnings levels, that these rights, if all exercised, could require the Company, in future periods, to pay an aggregate amount of approximately $15,493 to the owners of such rights to acquire such ownership interests in the relevant subsidiaries. Of this amount, the Company is entitled, at its option, to fund approximately $202 by the issuance of share capital. In addition, the Company is obligated under similar contractual rights to pay an aggregate amount of approximately $42,268 only upon termination of such owner’s employment with the applicable subsidiary or death. The amount the Company would be required to pay to the noncontrolling interest holders should the Company acquire the remaining ownership interests is $2,330 less than the initial redemption value recorded in redeemable noncontrolling interests. Included in redeemable noncontrolling interests at September 30, 2017 was $60,092 of these options to purchase because they are not within the control of the Company. The ultimate amount payable relating to these transactions will vary because it is dependent on the future results of operations of the subject businesses and the timing of when these rights are exercised. Natural Disasters. Certain of the Company’s operations are located in regions of the United States which typically are subject to hurricanes. During the nine months ended September 30, 2017 and 2016 , these operations did not incur any costs related to damages resulting from hurricanes. Guarantees . Generally, the Company has indemnified the purchasers of certain assets in the event that a third party asserts a claim against the purchaser that relates to a liability retained by the Company. These types of indemnification guarantees typically extend for a number of years. Historically, the Company has not made any significant indemnification payments under such agreements and no amount has been accrued in the accompanying consolidated financial statements with respect to these indemnification guarantees. The Company continues to monitor the conditions that are subject to guarantees and indemnifications to identify whether it is probable that a loss has occurred, and would recognize any such losses under any guarantees or indemnifications in the period when those losses are probable and estimable. Legal Proceedings. The Company’s operating entities are involved in legal proceedings of various types. While any litigation contains an element of uncertainty, the Company has no reason to believe that the outcome of such proceedings or claims will have a material adverse effect on the financial condition or results of operations of the Company. In addition, the Company is involved in class action suits as described below. Class Action Litigation in Canada. On August 7, 2015, Roberto Paniccia issued a Statement of Claim in the Ontario Superior Court of Justice in the City of Brantford, Ontario seeking to certify a class action suit naming the following as defendants: MDC, former CEO Miles S. Nadal, former CAO Michael C. Sabatino, CFO David Doft and BDO U.S.A. LLP. The Plaintiff alleges violations of section 138.1 of the Ontario Securities Act (and equivalent legislation in other Canadian provinces and territories) as well as common law misrepresentation based on allegedly materially false and misleading statements in the Company’s public statements, as well as omitting to disclose material facts with respect to the SEC investigation. The Company intends to continue to vigorously defend this Canadian suit on the same basis as which the U.S. class action was previously dismissed. A first case management meeting has been held. The plaintiff has served his material for leave to proceed under the Securities Act. MDC and the other defendants have served a motion to limit the scope of the proposed class definition to Canadian residents who purchased and sold shares of MDC stock on the Toronto Stock Exchange. Those motions are returnable in the fourth quarter of 2017. Antitrust Subpoena. One of the Company’s subsidiaries received a subpoena from the U.S. Department of Justice Antitrust Division concerning the Division’s ongoing investigation of production practices in the advertising industry. The Company and its subsidiary are fully cooperating with this confidential investigation. Commitments. At September 30, 2017 , the Company had issued $5,009 of undrawn outstanding letters of credit. In addition, the Company has commitments to fund investments in an aggregate amount of $198 .

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	In May 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting, which provides guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC 718. This guidance is effective for annual and interim periods beginning after December 15, 2017, and early adoption is permitted. Amendments in this ASU will be applied prospectively to any award modified on or after the adoption date. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits, which requires the presentation of the service cost component of the net periodic pension and postretirement benefits costs in the same line item in the statement of operations as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of the net periodic pension and postretirement benefits costs are required to be presented as non-operating expenses in the statement of operations. This guidance is effective for annual periods beginning after December 15, 2017 and early adoption is permitted. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment, which eliminates step two from the two-step goodwill impairment test. Under the new guidance, an entity will perform its goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value provided the loss recognized does not exceed the total amount of goodwill allocated to that reporting unit. This guidance is effective for annual or interim goodwill impairment tests performed in fiscal years beginning after December 15, 2019. The Company will early adopt this guidance for our impairment test performed during 2017, and does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows. This new guidance is intended to reduce diversity in practice regarding the classification of certain transactions in the statement of cash flows. This guidance is effective January 1, 2018 and requires a retrospective transition method. Early adoption is permitted. The Company currently classifies all cash outflows for contingent consideration as a financing activity. Upon adoption the Company is required to classify only the original estimated liability as a financing activity and any changes as an operating activity. In February 2016, the FASB issued ASU 2016-02, which amends the ASC and creates Topic 842, Leases. Topic 842 will require lessees to recognize right-to-use assets and lease liabilities for those leases classified as operating leases under previous U.S. GAAP on the balance sheet. This guidance is effective for annual periods beginning after December 15, 2018 and early adoption is permitted. While not yet in a position to assess the full impact of the application of the new standard, the Company expects that the impact of recording the lease liabilities and the corresponding right-to-use assets will have a significant impact on its total assets and liabilities with a minimal impact on equity. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Liabilities , which will require equity investments, except equity method investments, to be measured at fair value and any changes in fair value will be recognized in results of operations. This guidance is effective for annual and interim periods beginning after December 15, 2017 and early application is not permitted. Additionally, this guidance provides for the recognition of the cumulative effect of retrospective application of the new standard in the period of initial application. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which will replace all existing revenue guidance under U.S GAAP. The core principle of ASU 2014-09 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration expected to be received in exchange for those goods or services. On July 9, 2015, the FASB approved a one year deferral of the effective date of ASU 2014-09 to all annual and interim periods beginning after December 15, 2017. ASU 2014-09 provides for one of two methods of transition: (i) retrospective application to each prior period presented (Full Retrospective); or (ii) recognition of the cumulative effect of retrospective application of the new standard as of the beginning of the period of initial application (Modified Retrospective). The Company plans to apply ASU 2014-09 on the effective date of January 1, 2018, and intends to apply the Modified Retrospective method. Based on the Company’s assessment, the application of the new standard will result in a change in the timing of our revenue recognition within certain of the Company’s arrangements. Performance incentives are currently recognized in revenue when specific quantitative goals are achieved, or when the Company’s performance against qualitative goals is determined by the client. Under the new standard, the Company will be required to estimate the amount of the incentive that will be earned at the inception of the contract and recognize such incentive over the term of the contract. While performance incentives are not material to the Company’s revenue, this will result in an acceleration of revenue recognition for certain contract incentives compared to the current method. Further, based on the Company’s initial assessment, it is expected that an input measure such as cost to cost or labor hours would be an appropriate measure of progress in the majority of situations for which over time revenue recognition is applied. Furthermore, in certain businesses, the Company records revenue as a principal and includes certain third-party-pass-through and out-of-pocket costs, which are billed to clients in connection with the services provided. In March 2016, the FASB issued further guidance on principal versus agent considerations; however, our initial assessments indicate that such change is not expected to have a material effect on the Company’s results of operations. The Company is continuing to evaluate the standard’s impact on the consolidated results of operations and financial condition, and the related disclosure requirements.
New Accounting Pronouncements, Policy [Policy Text Block]	In May 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting, which provides guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC 718. This guidance is effective for annual and interim periods beginning after December 15, 2017, and early adoption is permitted. Amendments in this ASU will be applied prospectively to any award modified on or after the adoption date. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits, which requires the presentation of the service cost component of the net periodic pension and postretirement benefits costs in the same line item in the statement of operations as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of the net periodic pension and postretirement benefits costs are required to be presented as non-operating expenses in the statement of operations. This guidance is effective for annual periods beginning after December 15, 2017 and early adoption is permitted. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment, which eliminates step two from the two-step goodwill impairment test. Under the new guidance, an entity will perform its goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value provided the loss recognized does not exceed the total amount of goodwill allocated to that reporting unit. This guidance is effective for annual or interim goodwill impairment tests performed in fiscal years beginning after December 15, 2019. The Company will early adopt this guidance for our impairment test performed during 2017, and does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows. This new guidance is intended to reduce diversity in practice regarding the classification of certain transactions in the statement of cash flows. This guidance is effective January 1, 2018 and requires a retrospective transition method. Early adoption is permitted. The Company currently classifies all cash outflows for contingent consideration as a financing activity. Upon adoption the Company is required to classify only the original estimated liability as a financing activity and any changes as an operating activity. In February 2016, the FASB issued ASU 2016-02, which amends the ASC and creates Topic 842, Leases. Topic 842 will require lessees to recognize right-to-use assets and lease liabilities for those leases classified as operating leases under previous U.S. GAAP on the balance sheet. This guidance is effective for annual periods beginning after December 15, 2018 and early adoption is permitted. While not yet in a position to assess the full impact of the application of the new standard, the Company expects that the impact of recording the lease liabilities and the corresponding right-to-use assets will have a significant impact on its total assets and liabilities with a minimal impact on equity. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Liabilities , which will require equity investments, except equity method investments, to be measured at fair value and any changes in fair value will be recognized in results of operations. This guidance is effective for annual and interim periods beginning after December 15, 2017 and early application is not permitted. Additionally, this guidance provides for the recognition of the cumulative effect of retrospective application of the new standard in the period of initial application. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which will replace all existing revenue guidance under U.S GAAP. The core principle of ASU 2014-09 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration expected to be received in exchange for those goods or services. On July 9, 2015, the FASB approved a one year deferral of the effective date of ASU 2014-09 to all annual and interim periods beginning after December 15, 2017. ASU 2014-09 provides for one of two methods of transition: (i) retrospective application to each prior period presented (Full Retrospective); or (ii) recognition of the cumulative effect of retrospective application of the new standard as of the beginning of the period of initial application (Modified Retrospective). The Company plans to apply ASU 2014-09 on the effective date of January 1, 2018, and intends to apply the Modified Retrospective method. Based on the Company’s assessment, the application of the new standard will result in a change in the timing of our revenue recognition within certain of the Company’s arrangements. Performance incentives are currently recognized in revenue when specific quantitative goals are achieved, or when the Company’s performance against qualitative goals is determined by the client. Under the new standard, the Company will be required to estimate the amount of the incentive that will be earned at the inception of the contract and recognize such incentive over the term of the contract. While performance incentives are not material to the Company’s revenue, this will result in an acceleration of revenue recognition for certain contract incentives compared to the current method. Further, based on the Company’s initial assessment, it is expected that an input measure such as cost to cost or labor hours would be an appropriate measure of progress in the majority of situations for which over time revenue recognition is applied. Furthermore, in certain businesses, the Company records revenue as a principal and includes certain third-party-pass-through and out-of-pocket costs, which are billed to clients in connection with the services provided. In March 2016, the FASB issued further guidance on principal versus agent considerations; however, our initial assessments indicate that such change is not expected to have a material effect on the Company’s results of operations. The Company is continuing to evaluate the standard’s impact on the consolidated results of operations and financial condition, and the related disclosure requirements.

Significant Accounting Policies

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Subsidiary and Equity Investment Stock Transaction, Policy [Policy Text Block]	Subsidiary and Equity Investment Stock Transactions. Transactions involving the purchase, sale or issuance of stock of a subsidiary where control is maintained are recorded as a reduction in the redeemable noncontrolling interests or noncontrolling interests, as applicable. Any difference between the purchase price and noncontrolling interest are recorded to additional paid-in capital. In circumstances where the purchase of shares of an equity investment results in obtaining control, the existing carrying value of the investment is remeasured to the acquisition date fair value and any gain or loss is recognized in results of operations.
Earnings Per Share, Policy [Policy Text Block]	Income (Loss) per Common Share . Basic income (loss) per common share is based upon the weighted average number of common shares outstanding during each period. Share capital to be issued, as reflected in shareholders’ deficit on the balance sheet, are also included if there is no circumstance under which those shares would not be issued. Diluted income (loss) per common share is based on the above, in addition, if dilutive, it also includes common share equivalents, which include outstanding options, stock appreciation rights, and unvested restricted stock units. In periods of net loss, all potentially issuable common shares are excluded from diluted net loss per common share because they are anti-dilutive. During the first quarter of 2017, the Company issued and sold 95,000 newly authorized Series 4 Convertible Preference Shares (the “Preference Shares”) in a private placement. The two-class method is applied to calculate basic net income (loss) attributable to MDC Partners, Inc. per common share in periods in which shares of convertible preference shares were outstanding, as shares of convertible preference shares are participating securities due to their dividend rights. See Notes 7 and 8 . The two-class method is an earnings allocation method under which earnings per share is calculated for common stock considering a participating security’s rights to undistributed earnings as if all such earnings had been distributed during the period. Either the two-class method or the if-converted method is applied to calculate diluted net income per common share, depending on which method results in more dilution. The Company’s participating securities are not included in the computation of net loss per common share in periods of net loss because the convertible preference shareholders have no contractual obligation to participate in losses. As of September 30, 2017 , options and other rights to purchase 1,118,085 shares of common stock were outstanding, of which 741,712 and 805,413 shares of non-vested restricted stock and restricted stock units were anti-dilutive during the three and nine months ended September 30, 2017 , respectively, and therefore excluded from the computation of diluted income per common share. Additionally, 1,443,921 shares of non-vested restricted stock and restricted stock unit awards, which are contingent upon the Company meeting an undefined cumulative three year earnings target and continued employment, are excluded from the computation of diluted income per common share as the contingency has not been satisfied at September 30, 2017 . Lastly, there were 95,000 shares of Preference Shares outstanding which were convertible into 9,936,514 Class A common shares at September 30, 2017 . These Preference Shares were anti-dilutive for the three and nine months ended September 30, 2017 , and are therefore excluded from the diluted loss per common share calculation for the period. As of September 30, 2016 , options and other rights to purchase 918,260 shares of common stock were outstanding, of which 880,760 shares of non-vested restricted stock and restricted stock units were anti-dilutive during the three and nine months ended September 30, 2016 and therefore excluded from the computation of diluted income per common share. Additionally, 523,321 shares of non-vested restricted stock and restricted stock unit awards, which are contingent upon the Company meeting an undefined cumulative three year earnings target and continued employment, are excluded from the computation of diluted income per common share as the contingency had not been satisfied as of September 30, 2016 .
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency Translation . The Company’s financial statements were prepared in accordance with the requirements of FASB ASC Topic 830, Foreign Currency Matters. The functional currency of the Company is the Canadian dollar and it has decided to use U.S. dollars as its reporting currency for consolidated reporting purposes. Generally, the Company’s subsidiaries use their local currency as their functional currency. Accordingly, the currency impacts of the translation of the balance sheets of the Company’s non-U.S. dollar based subsidiaries to U.S. dollar statements are included as cumulative translation adjustments in accumulated other comprehensive income. Translation of intercompany debt, which is not intended to be repaid, is included in cumulative translation adjustments. Cumulative translation adjustments are not included in net earnings unless they are actually realized through a sale or upon complete or substantially complete liquidation of the Company’s net investment in the foreign operation. Translation of current intercompany balances are included in net earnings. The balance sheets of non-U.S. dollar based subsidiaries are translated at the period end rate. The income statements of non-U.S. dollar based subsidiaries are translated at average exchange rates for the period. Gains and losses arising from the Company’s foreign currency transactions are reflected in net earnings. Unrealized gains or losses arising on the translation of certain intercompany foreign currency transactions that are of a long-term nature (that is settlement is not planned or anticipated in the future) are included as cumulative translation adjustments in accumulated other comprehensive loss.
Guarantees, Indemnifications and Warranties Policies [Policy Text Block]	Guarantees . Guarantees issued or modified by the Company to third parties after January 1, 2003 are generally recognized at the inception or modification of the guarantee as a liability for the obligations it has undertaken in issuing the guarantee, including its ongoing obligation to stand ready to perform over the term of the guarantee in the event that the specified triggering events or conditions occur. The initial measurement of that liability is the fair value of the guarantee. The recognition of a liability is required even if it is not probable that payments will be required under a guarantee. The Company’s liability associated with guarantees is not significant. See Note 12 .
Premiums Receivable, Allowance for Doubtful Accounts, Estimation Methodology, Policy [Policy Text Block]	Allowance for Doubtful Accounts . Trade receivables are stated at invoiced amounts less allowances for doubtful accounts. The allowances represent estimated uncollectible receivables associated with potential customer defaults usually due to customers’ potential insolvency. The allowances include amounts for certain customers where a risk of default has been specifically identified. The assessment of the likelihood of customer defaults is based on various factors, including the length of time the receivables are past due, historical experience and existing economic conditions.
Expenditures Billable To Clients, Policy [Policy Text Block]	Expenditures Billable to Clients . Expenditures billable to clients consist principally of outside vendor costs incurred on behalf of clients when providing advertising, marketing and corporate communications services that have not yet been invoiced to clients. Such amounts are invoiced to clients at various times over the course of the production process.
Property, Plant and Equipment, Policy [Policy Text Block]	Fixed Assets . Fixed assets are stated at cost, net of accumulated depreciation. Computers, furniture and fixtures are depreciated on a straight-line basis over periods of three to seven years. Leasehold improvements are depreciated on a straight-line basis over the lesser of the term of the related lease or the estimated useful life of the asset. Repairs and maintenance costs are expensed as incurred.
Equity Method Investments [Policy Text Block]	Equity Method Investments. The equity method is used to account for investments in entities in which the Company has an ownership interest of less than 50% and has significant influence, or joint control by contractual arrangement, (i) over the operating and financial policies of the affiliate or (ii) has an ownership interest greater than 50% ; however, the substantive participating rights of the noncontrolling interest shareholders preclude the Company from exercising unilateral control over the operating and financial policies of the affiliate. The Company’s investments that were accounted for using the equity method include a 30% undivided interest in a real estate joint venture and various interests in investment funds. The Company’s management periodically evaluates these investments to determine if there has been a decline in value that is other than temporary. These investments are included in investments in non-consolidated affiliates on the balance sheet.
Principles of Consolidation	Principles of Consolidation . The accompanying condensed consolidated financial statements include the accounts of MDC Partners Inc. and its domestic and international controlled subsidiaries that are not considered variable interest entities, and variable interest entities for which the Company is the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation.
Reclassification, Policy [Policy Text Block]	Reclassifications . Certain reclassifications have been made to the prior period financial statements to conform to the current period presentation. During the nine months ended September 30, 2017 , the Company changed the presentation of book overdrafts on its statement of cash flows to classify the associated cash flows as operating activities. Book overdrafts were previously presented within financing activities. This resulted in cash inflows of $17,532 being reclassified from financing activities to operating activities for the nine months ended September 30, 2016 . There was no impact on the Company’s consolidated statements of operations, comprehensive income (loss), or balance sheets.
Use of Estimates, Policy	Use of Estimates. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities including goodwill, intangible assets, contingent deferred acquisition consideration, valuation allowances for receivables, deferred tax assets and the amounts of revenue and expenses reported during the period. These estimates are evaluated on an ongoing basis and are based on historical experience, current conditions and various other assumptions believed to be reasonable under the circumstances. Actual results could differ from these estimates.
Fair Value	Fair Value. The Company applies the fair value measurement guidance of the Financial Accounting Standards Board (the “FASB”) Accounting Standards Codification (the “ASC”) Topic 820, Fair Value Measurements, for financial assets and liabilities that are required to be measured at fair value and for non-financial assets and liabilities that are not required to be measured at fair value on a recurring basis, including goodwill and other identifiable intangible assets. The measurement of fair value requires the use of techniques based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions. The inputs create the following fair value hierarchy: • Level 1 - Quoted prices for identical instruments in active markets. • Level 2 - Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations where inputs are observable or where significant value drivers are observable. • Level 3 - Instruments where significant value drivers are unobservable to third parties. When available, the Company uses quoted market prices to determine the fair value of its financial instruments and classifies such items in Level 1. In some cases, quoted market prices are used for similar instruments in active markets and the Company classifies such items in Level 2.
Concentration of Credit Risk	Concentration of Credit Risk. The Company provides marketing communications services to clients who operate in most industry sectors. Credit is granted to qualified clients in the ordinary course of business. Due to the diversified nature of the Company’s client base, the Company does not believe that it is exposed to a concentration of credit risk. No client accounted for more than 10% of the Company’s consolidated accounts receivable at September 30, 2017 and December 31, 2016 . No client accounted for 10% of the Company’s revenue for the three and nine months ended September 30, 2017 or the three and nine months ended September 30, 2016 .
Cash and Cash Equivalents	Cash and Cash Equivalents. The Company’s cash equivalents are primarily comprised of investments in overnight interest-bearing deposits, commercial paper and money market instruments and other short-term investments with original maturity dates of three months or less at the time of purchase. The Company has a concentration of credit risk in that there are cash deposits in excess of federally insured amounts.
Cash in Trust, Policy [Policy Text Block]	Cash in Trust. A subsidiary of the Company holds restricted cash in trust accounts related to funds received on behalf of clients. Such amounts are held in escrow under depositary service agreements and distributed at the direction of the clients. The funds are presented as a corresponding liability on the balance sheet.
Cost Method Investments, Policy	Cost Method Investments. From time to time, the Company makes non-material cost based investments in start-up advertising technology companies and innovative consumer product companies where the Company does not exercise significant influence over the operating and financial policies of the investee. The total net cost basis of these investments, which is included in other assets on the balance sheet as of September 30, 2017 and December 31, 2016 , was $10,350 and $10,132 , respectively. These investments are periodically evaluated to determine whether a significant event or change in circumstances has occurred that may impact the fair value of each investment other than temporary declines below book value. A variety of factors are considered when determining if a decline is other than temporary, including, among others, the financial condition and prospects of the investee, as well as the Company’s investment intent. In addition, the Company’s partner agencies may receive minority equity interests from start-up companies in lieu of fees.
Business Combinations	Business Combinations. Business combinations are accounted for using the acquisition method and accordingly, the assets acquired (including identified intangible assets), the liabilities assumed and any noncontrolling interest in the acquired business are recorded at their acquisition date fair values. The Company’s acquisition model typically provides for an initial payment at closing and for future additional contingent purchase price obligations. Contingent purchase price obligations are recorded as deferred acquisition consideration on the balance sheet at the acquisition date fair value and are remeasured at each reporting period. Changes in such estimated values are recorded in the results of operations. For further information see Notes 4 and 9 . For the three and nine months ended September 30, 2017 and 2016 , $2,462 of income and $12,152 of expense, respectively, and $11,152 and $17,180 of expense, respectively, related to changes in such estimated values and was recorded in results of operations. The Company expenses acquisition related costs as incurred. For the three and nine months ended September 30, 2017 and 2016 , $216 and $693 respectively, and $806 and $2,266 , respectively, of acquisition related costs were charged to operations. For each acquisition, the Company undertakes a detailed review to identify intangible assets and a valuation is performed for all such identified assets. The Company uses several market participant measurements to determine the estimated value. This approach includes consideration of similar and recent transactions, as well as utilizing discounted expected cash flow methodologies. Like most service businesses, a substantial portion of the intangible asset value that the Company acquires is the specialized know-how of the workforce, which is treated as part of goodwill and is not required to be valued separately. The majority of the value of the identifiable intangible assets acquired is derived from customer relationships, including the related customer contracts, as well as trade names. In executing the Company’s overall acquisition strategy, one of the primary drivers in identifying and executing a specific transaction is the existence of, or the ability to expand the existing, client relationships. The expected benefits of the Company’s acquisitions are typically shared across multiple agencies and regions.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interests . Many of the Company’s acquisitions include contractual arrangements where the noncontrolling shareholders have an option to purchase, or may require the Company to purchase, such noncontrolling shareholders’ incremental ownership interests under certain circumstances and the Company has similar call options under the same contractual terms. The amount of consideration under these contractual arrangements is not a fixed amount, but rather is dependent upon various valuation formulas as described in Note 12 . In the event that an incremental purchase may be required of the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity on the balance sheet at their acquisition date fair value and adjusted for changes to their estimated redemption value through additional paid-in capital (but not less than their initial redemption value), except for foreign currency translation adjustments. These adjustments will not impact the calculation of earnings (loss) per share if the redemption values are less than the estimated fair values. For the three and nine months ended September 30, 2017 and 2016 , there was no related impact on the Company’s earnings (loss) per share calculation. Changes in the estimated redemption amounts of the redeemable noncontrolling interests are adjusted at each reporting period with a corresponding adjustment to equity. These adjustments will not impact the calculation of earnings (loss) per share. The following table presents changes in redeemable noncontrolling interests: Nine Months Ended September 30, 2017 Year Ended December 31, 2016 Beginning Balance $ 60,180 $ 69,471 Redemptions (816 ) (1,708 ) Additions (1) — 2,274 Changes in redemption value 299 (9,604 ) Currency translation adjustments 429 (253 ) Ending Balance $ 60,092 $ 60,180 (1) Additions consist of transfers from noncontrolling interests related to step-up transactions and new acquisitions.
Variable Interest Entity	Variable Interest Entity . Effective March 28, 2012, the Company invested in Doner Partners LLC (“Doner”). The Company acquired a 30% voting interest and convertible preferred interests that allow the Company to increase ordinary voting ownership to 70% at the Company’s option. Effective April 1, 2017, the Company acquired an additional 15% voting and convertible preferred interest that allowed the Company to increase ordinary voting ownership to 85% at the Company’s option. The Company now has a 45% voting interest. The Company has determined that (i) this entity is a variable interest entity, and (ii) the Company is the primary beneficiary because it receives a disproportionate share of profits and losses as compared to its ownership percentage. As such, Doner is consolidated for all periods subsequent to the date of investment. Doner is a full service integrated creative agency that is included as part of the Company’s portfolio in the Global Integrated Agencies segment. The Company’s Credit Agreement (see Note 6 ) is guaranteed and secured by all of Doner’s assets. Total assets and total liabilities of Doner included in the Company’s consolidated balance sheet at September 30, 2017 were $100,229 and $53,508 , respectively, and at December 31, 2016 were $102,456 and $57,622 , respectively.
Revenue Recognition	Revenue Recognition. The Company’s revenue recognition policies are established in accordance with the Revenue Recognition topics of the FASB ASC, and accordingly, revenue is recognized when all of the following criteria are satisfied: (i) persuasive evidence of an arrangement exists; (ii) the selling price is fixed or determinable; (iii) services have been performed or upon delivery of the products when ownership and risk of loss has transferred to the client; and (iv) collection of the resulting receivable is reasonably assured. The Company follows the Multiple-Element Arrangement topic of the FASB ASC, which addresses certain aspects of the accounting by a vendor for arrangements under which it will perform multiple revenue-generating activities and how to determine whether an arrangement involving multiple deliverables contains more than one unit of accounting. The Company follows the Principal Agent Consideration topic of the FASB ASC which addresses (i) whether revenue should be recorded at the gross amount billed because it has earned revenue from the sale of goods or services, or recorded at the net amount retained because it has earned a fee or commission, and (ii) that reimbursements received for out-of-pocket expenses incurred should be characterized in the income statement as revenue. Accordingly, the Company has included such reimbursed expenses in revenue. The Company earns revenue from agency arrangements in the form of retainer fees or commissions; from short-term project arrangements in the form of fixed fees or per diem fees for services; and from incentives or bonuses. Non-refundable retainer fees are generally recognized on a straight-line basis over the term of the specific customer arrangement. Commission revenue is earned and recognized upon the placement of advertisements in various media when the Company has no further performance obligations. Fixed fees for services are recognized upon completion of the earnings process and acceptance by the client. Per diem fees are recognized upon the performance of the Company’s services. In addition, for a limited number of certain service transactions, which require delivery of a number of service acts, the Company uses the proportional performance model, which generally results in revenue being recognized based on the straight-line method. For arrangements with customers for which the Company earns a fixed fee for development of customized mobile applications (“Apps”), revenue is recognized in accordance with the accounting guidance contained in ASC 605-35 and is primarily recognized using the proportional performance method of accounting. Performance is generally measured based upon the efforts incurred to date in relation to total estimated efforts to the completion of the contract. Fees billed to clients in excess of fees recognized as revenue are classified as advanced billings on the Company’s balance sheet. A small portion of the Company’s contractual arrangements with customers includes performance incentive provisions, which allow the Company to earn additional revenue as a result of its performance relative to both quantitative and qualitative goals. The Company recognizes the incentive portion of revenue under these arrangements when specific quantitative goals are assured, or when the Company’s clients determine performance against qualitative goals has been achieved. In all circumstances, revenue is only recognized when collection is reasonably assured. The Company records revenue net of sales and other taxes due to be collected and remitted to governmental authorities.
Cost of Services Sold [Policy Text Block]	Cost of Services Sold . Cost of services sold do not include depreciation charges for fixed assets.
Interest Expense	Interest Expense . Interest expense primarily consists of the cost of borrowing on the Company’s previously outstanding 6.75% Senior Notes due 2020 (the “6.75% Notes”); the Company’s currently outstanding 6.50% senior unsecured notes due 2024 (the “6.50% Notes”); and the Company’s $325 million senior secured revolving credit agreement due 2021 (the “Credit Agreement”). The Company uses the effective interest method to amortize the deferred financing costs on the 6.75% Notes and the 6.50% Notes as well as the original issue premium on the previously outstanding 6.75% Notes. The Company also uses the straight-line method to amortize the deferred financing costs on the Credit Agreement. For the three and nine months ended September 30, 2017 and 2016 , interest expense included $24 and $77 , respectively, and $30 and $181 , respectively, relating to present value adjustments for fixed deferred acquisition consideration payments. The Company redeemed the 6.75% Notes with the net proceeds from the issuance of the 6.50% Notes. For further information see Note 6 .
Income Tax	Income Taxes. The Company’s U.S. operating units are generally structured as limited liability companies, which are treated as partnerships for tax purposes. The Company is only taxed on its share of the profits, while noncontrolling holders are responsible for taxes on their share of the profits. Deferred income taxes reflect the tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, as well as the tax effect of carryforwards. The Company currently has a fully reserved valuation allowance on its deferred tax assets related to U.S. net operating losses. Realization of our deferred tax assets is evaluated on a quarterly basis and is based upon all available evidence. It is possible that sufficient positive evidence to support the realization of the Company’s net deferred tax assets will exist in the near future, and the previously provided valuation allowance could be reversed in whole or in part. During the nine months ended September 30, 2017 and 2016 , the Company’s effective tax rate was impacted by losses in certain tax jurisdictions where a valuation allowance was deemed necessary. During the second quarter of 2017, the Company identified and recorded out-of-period adjustments related to the misapplication of ASC 740 and ASC 850-740 accounting policies as they applied to the calculation of deferred tax liabilities. The corrections have resulted in a $6,916 increase to the Company’s deferred tax liability on the condensed consolidated balance sheet as of December 31, 2016. The Company has performed a qualitative and quantitative analysis of this misapplication and determined it not to be material to prior periods. The Company has revised prior period information presented on this Form 10-Q as follows: (i) for the three and nine months ended September 30, 2016, income tax expense has been decreased by $1,390 and decreased by $713 , respectively, (ii) basic and diluted net loss attributable to MDC Partners Inc. common shareholders for the nine months ended September 30, 2016 increased by $0.01 per share, and (iii) deferred tax liabilities and accumulated deficit increased by $6,916 as of December 31, 2016. The correction had no impact on the Company’s cash flows.
Share-based Compensation	Stock-Based Compensation. Under the fair value method, compensation cost is measured at fair value at the date of grant and is expensed over the service period, in this case the award’s vesting period. The Company recognizes forfeitures as they occur. When awards are exercised, share capital is credited by the sum of the consideration paid, together with the related portion previously credited to additional paid-in capital when compensation costs were charged against income or acquisition consideration. The Company uses its historical volatility derived over the expected term of the award to determine the volatility factor used in determining the fair value of the award. Stock-based awards that are settled in cash, or may be settled in cash at the option of employees, are recorded as liabilities. The measurement of the liability and compensation cost for these awards is based on the fair value of the award, and is recorded in operating income over the service period, in this case the award’s vesting period. Changes in the Company’s payment obligation prior to the settlement date of a stock-based award are recorded as compensation cost in operating income in the period of the change. The final payment amount for such awards is established on the date of the exercise of the award by the employee. Stock-based awards that are settled in cash or equity at the option of the Company are recorded at fair value on the date of grant and recorded as additional paid-in capital. The fair value measurement of the compensation cost for these awards is based on using the Black-Scholes option pricing-model and is recorded in operating income over the service period, in this case the award’s vesting period. It is the Company’s policy for issuing shares upon the exercise and/or vesting of an equity incentive award to verify the amount of shares to be issued, as well as the amount of proceeds to be collected (if any) and to deliver new shares to the exercising party. The Company has adopted the straight-line attribution method for determining the compensation cost to be recorded during each accounting period. The Company commences recording compensation expense related to awards that are based on performance conditions under the straight-line attribution method when it is probable that such performance conditions will be met. The Company treats benefits paid by shareholders or equity members to employees as a stock-based compensation charge with a corresponding credit to additional paid-in-capital. From time to time, certain acquisitions and step-up transactions include an element of compensation related payments. The Company accounts for those payments as stock-based compensation. In January 2017, the Company issued 327,500 Stock Appreciation Rights (“SARS”) to its employees. The SARS have an exercise price of $6.60 and will vest on the three year anniversary of the grant date. The Company will be recording a stock-based compensation charge of $770 from the date of the grant through 2020 for these SARS awards. During the nine months ended September 30, 2017 , the Company issued 243,000 shares of restricted stock and restricted stock units (collectively, “RSUs”) to its employees and directors. The RSUs have an aggregate grant date fair value of $1,966 and generally vest on the third anniversary of the date of grant. In addition, during the first quarter of 2017, the Company issued RSUs of which 930,600 awarded shares were outstanding as of September 30, 2017 . However, the vesting of these awards is contingent upon the Company meeting a cumulative three year financial performance target and continued employment through the March 1, 2020 vesting date. These RSU awards do not yet have an established grant date fair value because the financial performance target is not yet established. Once the Company defines the financial performance target, and assuming the achievement of such performance targets is expected, the grant date is established and the Company will record the compensation expense over the vesting period. Additionally, the Company still has outstanding RSUs of 513,321 which are also based on a cumulative financial performance target and will vest on March 1, 2019.
New Accounting Pronouncements	In May 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting, which provides guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC 718. This guidance is effective for annual and interim periods beginning after December 15, 2017, and early adoption is permitted. Amendments in this ASU will be applied prospectively to any award modified on or after the adoption date. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits, which requires the presentation of the service cost component of the net periodic pension and postretirement benefits costs in the same line item in the statement of operations as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of the net periodic pension and postretirement benefits costs are required to be presented as non-operating expenses in the statement of operations. This guidance is effective for annual periods beginning after December 15, 2017 and early adoption is permitted. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment, which eliminates step two from the two-step goodwill impairment test. Under the new guidance, an entity will perform its goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value provided the loss recognized does not exceed the total amount of goodwill allocated to that reporting unit. This guidance is effective for annual or interim goodwill impairment tests performed in fiscal years beginning after December 15, 2019. The Company will early adopt this guidance for our impairment test performed during 2017, and does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows. This new guidance is intended to reduce diversity in practice regarding the classification of certain transactions in the statement of cash flows. This guidance is effective January 1, 2018 and requires a retrospective transition method. Early adoption is permitted. The Company currently classifies all cash outflows for contingent consideration as a financing activity. Upon adoption the Company is required to classify only the original estimated liability as a financing activity and any changes as an operating activity. In February 2016, the FASB issued ASU 2016-02, which amends the ASC and creates Topic 842, Leases. Topic 842 will require lessees to recognize right-to-use assets and lease liabilities for those leases classified as operating leases under previous U.S. GAAP on the balance sheet. This guidance is effective for annual periods beginning after December 15, 2018 and early adoption is permitted. While not yet in a position to assess the full impact of the application of the new standard, the Company expects that the impact of recording the lease liabilities and the corresponding right-to-use assets will have a significant impact on its total assets and liabilities with a minimal impact on equity. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Liabilities , which will require equity investments, except equity method investments, to be measured at fair value and any changes in fair value will be recognized in results of operations. This guidance is effective for annual and interim periods beginning after December 15, 2017 and early application is not permitted. Additionally, this guidance provides for the recognition of the cumulative effect of retrospective application of the new standard in the period of initial application. The Company does not expect the application of this guidance to have a significant impact on its consolidated financial position or results of operations. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which will replace all existing revenue guidance under U.S GAAP. The core principle of ASU 2014-09 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration expected to be received in exchange for those goods or services. On July 9, 2015, the FASB approved a one year deferral of the effective date of ASU 2014-09 to all annual and interim periods beginning after December 15, 2017. ASU 2014-09 provides for one of two methods of transition: (i) retrospective application to each prior period presented (Full Retrospective); or (ii) recognition of the cumulative effect of retrospective application of the new standard as of the beginning of the period of initial application (Modified Retrospective). The Company plans to apply ASU 2014-09 on the effective date of January 1, 2018, and intends to apply the Modified Retrospective method. Based on the Company’s assessment, the application of the new standard will result in a change in the timing of our revenue recognition within certain of the Company’s arrangements. Performance incentives are currently recognized in revenue when specific quantitative goals are achieved, or when the Company’s performance against qualitative goals is determined by the client. Under the new standard, the Company will be required to estimate the amount of the incentive that will be earned at the inception of the contract and recognize such incentive over the term of the contract. While performance incentives are not material to the Company’s revenue, this will result in an acceleration of revenue recognition for certain contract incentives compared to the current method. Further, based on the Company’s initial assessment, it is expected that an input measure such as cost to cost or labor hours would be an appropriate measure of progress in the majority of situations for which over time revenue recognition is applied. Furthermore, in certain businesses, the Company records revenue as a principal and includes certain third-party-pass-through and out-of-pocket costs, which are billed to clients in connection with the services provided. In March 2016, the FASB issued further guidance on principal versus agent considerations; however, our initial assessments indicate that such change is not expected to have a material effect on the Company’s results of operations. The Company is continuing to evaluate the standard’s impact on the consolidated results of operations and financial condition, and the related disclosure requirements.
Goodwill and Intangible Assets, Intangible Assets, Indefinite-Lived, Policy [Policy Text Block]	Goodwill and Indefinite Lived Intangibles . In accordance with the FASB ASC Topic 350, Intangibles - Goodwill and Other, goodwill and indefinite lived intangible assets (trademarks) acquired as a result of a business combination, which are not subject to amortization, are tested for impairment annually as of October 1st of each year, or more frequently if indicators of potential impairment exist. For goodwill, impairment is assessed at the reporting unit level. For the nine months ended September 30, 2017 and the year ended December 31, 2016 , goodwill was $839,361 and $844,759 , respectively. For the three and nine months ended September 30, 2017 , there was a reduction in goodwill of $17,593 relating to the sale of certain subsidiaries, which was offset by $12,195 net foreign exchange translation adjustments. As a result of the these transactions, the Company performed interim goodwill testing on two reporting units and determined that there was no impairment charge in respect to the impacted reporting units. For the three and nine months ended September 30, 2016 , due to triggering events during the third quarter of 2016, the Company performed an interim goodwill impairment test and recognized goodwill impairment of $29,631 . In addition, in the third quarter of 2016, the Company sold all of its ownership interests in Bryan Mills Iradesso Corporation (“Bryan Mills”) to the noncontrolling shareholders, resulting in a write off of goodwill of $764 . See Note 4 for further information on the dispositions.

Loss Per Common Share (Tables)

Loss Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following table sets forth the computation of basic and diluted income (loss) per common share: Three Months Ended Nine Months Ended 2017 2016 2017 2016 Numerator Net income (loss) attributable to MDC Partners Inc. $ 18,493 $ (32,140 ) $ 19,180 $ (54,937 ) Accretion on convertible preference shares (1,948 ) — (4,365 ) — Net income allocated to convertible preference shares (2,408 ) — (1,782 ) — Numerator for basic loss per common share - Net income (loss) attributable to MDC Partners Inc. common shareholders 14,137 (32,140 ) 13,033 (54,937 ) Effect of dilutive securities: Adjustment to net income allocated to convertible preference shares 13 — 9 — Numerator for diluted income (loss) per common share- Net income (loss) attributable to MDC Partners Inc. common shareholders $ 14,150 $ (32,140 ) $ 13,042 $ (54,937 ) Denominator Denominator for basic income (loss) per common share - weighted average common shares 57,566,707 52,244,819 53,915,536 50,861,890 Effect of dilutive securities: Impact of stock options and non-vested stock under employee stock incentive plans 376,373 — 312,672 — Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions 57,943,080 52,244,819 54,228,208 50,861,890 Basic income (loss) per common share $ 0.25 $ (0.62 ) $ 0.24 $ (1.08 ) Diluted income (loss) per common share $ 0.24 $ (0.62 ) $ 0.24 $ (1.08 )

Accruals and Other Liabilities

Accruals and Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Accrued and Other Liabilities [Abstract]
Accrued and Other Liabilities Disclosure	At September 30, 2017 and December 31, 2016 , accruals and other liabilities included accrued media of $169,460 and $201,872 , respectively; and included amounts due to noncontrolling interest holders for their share of profits, which will be distributed within the next twelve months of $5,802 and $4,154 , respectively. Changes in amounts due to noncontrolling interest holders included in accrued and other liabilities for the year ended December 31, 2016 and nine months ended September 30, 2017 were as follows: Noncontrolling Balance, December 31, 2015 $ 5,473 Income attributable to noncontrolling interests 5,218 Distributions made (7,772 ) Other (1) 1,235 Balance, December 31, 2016 $ 4,154 Income attributable to noncontrolling interests 6,588 Distributions made (5,272 ) Other (1) 332 Balance, September 30, 2017 $ 5,802 (1) Other consists primarily of business acquisitions, sale of a business, step-up transactions, and cumulative translation adjustments. At September 30, 2017 and December 31, 2016 , accounts payable included $47,430 and $80,193 of outstanding checks, respectively.

Other Income (Tables)

Other Income (Tables)	9 Months Ended
	Sep. 30, 2017
Other Income and Expenses [Abstract]
Schedule of Other Nonoperating Income, by Component [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Other income (expense) $ (7 ) $ 26 $ 271 $ (220 ) Loss on sale of business (1) (1,424 ) (800 ) (1,424 ) (800 ) Gain on sale of investments (2) 168 682 168 682 Foreign currency transaction gain (loss) 9,912 (5,916 ) 18,797 9,868 $ 8,649 $ (6,008 ) $ 17,812 $ 9,530

Significant Accounting Polici19

Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)Clients	Sep. 30, 2016USD ($)Clients	Sep. 30, 2017USD ($)Clients	Sep. 30, 2016USD ($)Clients	Dec. 31, 2016USD ($)Clients
Significant Accounting Policies [Line Items]
Clients exceeding consolidated accounts receivable percentage | Clients	0		0		0
Consolidated Accounts Receivable Percentage	10.00%		10.00%		10.00%
Clients exceeding consolidated largest client revenue | Clients	0	0	0	0
Consolidated Largest Client Revenue	10.00%	10.00%	10.00%
Option to purchase noncontrolling interest impairment charge	$ 0	$ 0	$ 0	$ 0
Beginning Balance			60,180,000
Redemptions	(337,000)	$ (520,000)	(9,650,000)
Granted			2,315,000	22,498,000
Ending Balance	60,092,000		60,092,000		$ 60,180,000
Redeemable Noncontrolling Interest [Member]
Significant Accounting Policies [Line Items]
Beginning Balance			60,180,000	$ 69,471,000	69,471,000
Redemptions			(816,000)		(1,708,000)
Granted			0		2,274,000
Changes in redemption value			299,000		(9,604,000)
Currency Translation Adjustments			429,000		(253,000)
Ending Balance	$ 60,092,000		$ 60,092,000		$ 60,180,000

Significant Accounting Polici20

Significant Accounting Policies (Details Textual)	May 01, 2024	Apr. 01, 2017	May 03, 2016	Mar. 23, 2016	Oct. 23, 2014USD ($)	Mar. 28, 2012	Sep. 30, 2017USD ($)Clientsshares	Mar. 31, 2017shares	Sep. 30, 2016USD ($)Clients	Sep. 30, 2017USD ($)Clientsshares	Sep. 30, 2016USD ($)Clients	Dec. 31, 2016USD ($)Clientsshares	Jan. 31, 2017$ / sharesshares	Dec. 31, 2015USD ($)	Mar. 20, 2013
Significant Accounting Policies [Line Items]
Deferred Tax Liability, Prior Period Correction												$ 6,916
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability									$ 1,390		$ 713
Increase (Decrease) in Book Overdrafts										$ 17,532,000
Stock Issued During Period, Shares, Convertible Preferred Shares | shares										90,220,000
Redeemable noncontrolling interests							$ 60,092,000			$ 60,092,000		60,180,000
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests							337,000		520,000	9,650,000
Noncontrolling Interest, Increase from Business Combination										2,315,000	22,498,000
Debt Issuance Costs, Net							$ (18,161,000)			$ (18,161,000)		$ (18,420,000)
Clients exceeding consolidated accounts receivable percentage | Clients							0			0		0
Interest Rate Percentage On Senior Notes							6.75%			6.75%
Put option noncontrolling interest impairment charge							$ 0		$ 0	$ 0	$ 0
Cost Method Investments							$ 10,350,000			$ 10,350,000		$ 10,132,000
Consolidated Accounts Receivable Percentage							10.00%			10.00%		10.00%
Clients exceeding consolidated largest client revenue | Clients							0		0	0	0
Consolidated Largest Client Revenue							10.00%		10.00%	10.00%
Business Combination, Acquisition Related Costs							$ 216,000		$ 806,000	$ 693,000	$ 2,266,000
Assets							1,617,831,000			1,617,831,000		$ 1,577,378,000
Liabilities							1,946,673,000			1,946,673,000		2,026,674,000
Restricted stock grant date fair value										27,852,000
Adjustment to deferred acquisition consideration included in interest expense							24,000		30,000	77,000	181,000
Goodwill							839,361,000			839,361,000		844,759,000
Goodwill, Impairment Loss							0		29,631,000	0	29,631,000
Goodwill, Written off Related to Sale of Business Unit										17,593,000	764,000
Doner [Member]
Significant Accounting Policies [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage		45.00%				30.00%
Assets							100,229,000			100,229,000		102,456,000
Liabilities							$ 53,508,000			53,508,000		57,622,000
Doner [Member]
Significant Accounting Policies [Line Items]
Ownership Interest Percentage Increase On Exercise Of Option		15.00%
Aggregate 2012 Acquisitions [Member] | Doner [Member]
Significant Accounting Policies [Line Items]
Ownership Interest Percentage Increase On Exercise Of Option						70.00%
Aggregate 2017 Step Up Transactions [Domain]
Significant Accounting Policies [Line Items]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										11,965
Noncontrolling Interest, Increase from Business Combination										$ 2,316
Aggregate 2017 Step Up Transactions [Domain] | Doner [Member]
Significant Accounting Policies [Line Items]
Ownership Interest Percentage Increase On Exercise Of Option		85.00%
Minimum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life										3 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life										7 years
Equity Method Investment, Ownership Percentage							50.00%			50.00%
Real Estate Joint Venture [Member]
Significant Accounting Policies [Line Items]
Equity Method Investment, Ownership Percentage							30.00%			30.00%
Wells Fargo Capital Finance, LLC
Significant Accounting Policies [Line Items]
Debt Instrument, Maturity Date			May 3, 2021		Sep. 30, 2019
Line of Credit Facility, Maximum Borrowing Capacity					$ 325,000,000
Contingent payment [Domain]
Significant Accounting Policies [Line Items]
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability							$ (2,462,000)		$ 11,152,000	$ 12,152,000	$ 17,180,000
Notes due 2020 [Member]
Significant Accounting Policies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							6.75%			6.75%
Six Point Seven Five Percentage Notes [Member]
Significant Accounting Policies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage															6.75%
Six Point Seven Five Percentage Notes [Member] | Wells Fargo Capital Finance, LLC
Significant Accounting Policies [Line Items]
Debt Instrument, Maturity Date				Apr. 1, 2020
Notes due 2024 [Domain]
Significant Accounting Policies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							6.50%			6.50%
Six Point Five Zero Percentage Notes [Domain]
Significant Accounting Policies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				6.50%			6.50%			6.50%
Restricted Stock Units (RSUs) [Member] | Common Class A
Significant Accounting Policies [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares										243,000
Restricted stock grant date fair value										$ 1,966,000
Scenario, Forecast [Member] | Six Point Five Zero Percentage Notes [Domain]
Significant Accounting Policies [Line Items]
Debt Instrument, Maturity Date	May 1, 2024
Scenario, Forecast [Member] | Six Point Five Zero Percentage Notes [Domain] | Wells Fargo Capital Finance, LLC
Significant Accounting Policies [Line Items]
Debt Instrument, Maturity Date	May 1, 2024
Noncontrolling Interest Equity [Domain] | Aggregate 2016 Step Up Transactions [Member]
Significant Accounting Policies [Line Items]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests												19,354
Redeemable Noncontrolling Interest [Member]
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interests							$ 60,092,000			60,092,000		60,180,000		$ 69,471,000
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										816,000		1,708,000
Noncontrolling Interest, Increase from Business Combination										0		2,274,000
Changes in redemption value										299,000		(9,604,000)
Redeemable Noncontrolling Interest Currency Adjustments										429,000		$ (253,000)
Stock Incentive Plan 2011 [Member] | Stock Appreciation Rights (SARs) [Member]
Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | shares													327,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares													$ 6.60
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options							$ 770,000			$ 770,000
Stock Incentive Plan 2011 [Member] | Contingent Restricted Stock Units (RSUs) [Member]
Significant Accounting Policies [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares										930,600
Stock Incentive Plan 2016 [Member] | Contingent Restricted Stock Units (RSUs) [Member]
Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | shares							513,321			513,321
Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Significant Accounting Policies [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares | shares								95,000		95,000		0

Loss Per Common Share (Details)

Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Class of Stock [Line Items]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]			The following table sets forth the computation of basic and diluted income (loss) per common share: Three Months Ended Nine Months Ended 2017 2016 2017 2016 Numerator Net income (loss) attributable to MDC Partners Inc. $ 18,493 $ (32,140 ) $ 19,180 $ (54,937 ) Accretion on convertible preference shares (1,948 ) — (4,365 ) — Net income allocated to convertible preference shares (2,408 ) — (1,782 ) — Numerator for basic loss per common share - Net income (loss) attributable to MDC Partners Inc. common shareholders 14,137 (32,140 ) 13,033 (54,937 ) Effect of dilutive securities: Adjustment to net income allocated to convertible preference shares 13 — 9 — Numerator for diluted income (loss) per common share- Net income (loss) attributable to MDC Partners Inc. common shareholders $ 14,150 $ (32,140 ) $ 13,042 $ (54,937 ) Denominator Denominator for basic income (loss) per common share - weighted average common shares 57,566,707 52,244,819 53,915,536 50,861,890 Effect of dilutive securities: Impact of stock options and non-vested stock under employee stock incentive plans 376,373 — 312,672 — Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions 57,943,080 52,244,819 54,228,208 50,861,890 Basic income (loss) per common share $ 0.25 $ (0.62 ) $ 0.24 $ (1.08 ) Diluted income (loss) per common share $ 0.24 $ (0.62 ) $ 0.24 $ (1.08 )
Net loss attributable to MDC Partners Inc.	$ 18,493	$ (32,140)	$ 19,180	$ (54,937)
Numerator
Income (Loss) from Continuing Operations Attributable to Parent	14,137	(32,140)	13,033	(54,937)
Adjustment to Net Income, Allocated to Convertible Shares	13	0	9	0
Income (Loss) from Continuing Operations Attributable to Parent, Diluted	$ 14,150	$ (32,140)	$ 13,042	$ (54,937)
Denominator
Denominator for basic income (loss) per common share - weighted average common shares	57,566,707	52,244,819	53,915,536	50,861,890
Effect of dilutive securities:	376,373	0	312,672	0
Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions	57,943,080	52,244,819	54,228,208	50,861,890
Income (loss) from continuing operations attributable to MDC Partners Inc. common shareholders (usd per share)	$ 245.58	$ (615.18)	$ 241.73	$ (1,080.12)
Income (loss) from continuing operations attributable to MDC Partners Inc. common shareholders (usd per share)	$ 244.21	$ (615.18)	$ 240.50	$ (1,080.12)
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock [Member]
Numerator
Accretion on convertible preferred shares	$ (1,948)	$ 0	$ (4,365)	$ 0
Net Income Allocated to Convertible Shares	$ (2,408)	$ 0	$ (1,782)	$ 0

Loss Per Common Share (Details

Loss Per Common Share (Details Textual) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Oct. 27, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Adjustment to Net Income, Allocated to Convertible Shares	$ 13		$ 0	$ 9	$ 0
Weighted Average Number Diluted Shares Outstanding Adjustment	376,373		0	312,672	0
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount				1,118,085	523,321
Stock Issued During Period, Shares, Convertible Preferred Shares				90,220,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements					918,260
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	741,712			805,413
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements					880,760
Contingent Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount				1,443,921
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Accretion on convertible preferred shares	$ (1,948)		$ 0	$ (4,365)	$ 0
Stock Issued During Period, Shares, Convertible Preferred Shares		95,000		95,000		0
Shares, Outstanding	95,000			95,000		0	95,000
Convertible Preferred Stock, Shares Issued upon Conversion	9,936,514			9,936,514
Net Income Allocated to Convertible Shares	$ (2,408)		$ 0	$ (1,782)	$ 0

Acquisitions (Details)

Acquisitions (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gain (Loss) on Disposition of Business	$ (1,424,000)	$ (800,000)	$ (1,424,000)	$ (800,000)
Business Combination Disclosure [Text Block]			Valuations of acquired companies are based on a number of factors, including specialized know-how, reputation, competitive position and service offerings. The Company’s acquisition strategy has been focused on acquiring the expertise of an assembled workforce in order to continue to build upon the core capabilities of its various strategic business platforms to better serve the Company’s clients. The Company’s strategy includes acquiring ownership stakes in well-managed businesses with strong reputations in the industry. The Company’s model of “Perpetual Partnership” often involves acquiring a majority interest rather than a 100% interest and leaving management owners with a significant financial interest in the performance of the acquired entity for a minimum period of time, typically not less than five years. The Company’s acquisition model in this scenario typically provides for (i) an initial payment at the time of closing, (ii) additional contingent purchase price obligations based on the future performance of the acquired entity, and (iii) an option by the Company to purchase (and in some instances a requirement to so purchase) the remaining interest of the acquired entity under a predetermined formula. Contingent purchase price obligations. The Company’s contingent purchase price obligations are generally payable within a five year period following the acquisition date, and are based on (i) the achievement of specific thresholds of future earnings, and (ii) in certain cases, the growth rate of those earnings. Contingent purchase price obligations are recorded as deferred acquisition consideration on the balance sheet at the acquisition date fair value and adjusted at each reporting period through operating income or net interest expense, depending on the nature of the arrangement. On occasion, the Company may initiate a renegotiation of previously acquired ownership interests and any resulting change in the estimated amount of consideration to be paid is adjusted in the reporting period through operating income or net interest expense, depending on the nature of the arrangement. See Notes 2 , 9 , and 12 for additional information on the deferred acquisition consideration. Options to purchase . When acquiring less than 100% ownership, the Company may enter into agreements that give the Company an option to purchase, or require the Company to purchase, the incremental ownership interests under certain circumstances. Where the option to purchase the incremental ownership is within the Company’s control, the amounts are recorded as noncontrolling interests in the equity section of the Company’s balance sheet. Where the incremental purchase may be required of the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity at their estimated acquisition date redemption value and adjusted at each reporting period for changes to their estimated redemption value through additional paid-in capital (but not less than their initial redemption value), except for foreign currency translation adjustments. On occasion, the Company may initiate a renegotiation to acquire an incremental ownership interest and the amount of consideration paid may differ materially from the balance sheet amounts. See Note 12 for additional information on redeemable noncontrolling interests. Employment conditions. From time to time, specifically when the projected success of an acquisition is deemed to be dependent on retention of specific personnel, such acquisition may include deferred payments that are contingent upon employment terms as well as financial performance. The Company accounts for those payments through operating income as stock-based compensation over the required retention period. For the three and nine months ended September 30, 2017 and 2016 , stock-based compensation included $4,064 and $9,792 , respectively, and $2,259 and $7,184 , respectively, of expense relating to those payments. Distributions to noncontrolling shareholders. If noncontrolling shareholders have the right to receive distributions based on the profitability of an acquired entity, the amount is recorded as income attributable to noncontrolling interests. However, there are circumstances when the Company acquires a majority interest and the selling shareholders waive their right to receive distributions with respect to their retained interest for a period of time, typically not less than five years. Under this model, the right to receive such distributions typically begins concurrently with the purchase option period and, therefore, if such option is exercised at the first available date, the Company may not record any noncontrolling interest over the entire period from the initial acquisition date through the acquisition date of the remaining interests. 2017 Acquisitions In 2017, the Company entered into various non-material transactions in connection with certain of its majority-owned entities. As a result of the foregoing, the Company made total cash closing payments of $3,858 , increased fixed deferred consideration liability by $7,208 , reduced redeemable noncontrolling interests by $816 , reduced noncontrolling interests equity by $11,965 , reduced noncontrolling interest payable by $397 , and increased additional paid-in capital by $2,316 . In addition, a stock-based compensation charge of $996 has been recognized representing the consideration paid in excess of the fair value of the interest acquired. 2017 Dispositions During the three months ended September 30, 2017, the Company sold all of its ownership interests in three subsidiaries resulting in recognition of a net loss on sale of business of $1,424 . The net assets reflected in the calculation of the net loss on sale was inclusive of goodwill of $17,593 . Goodwill was allocated to the subsidiaries based on the relative fair value of the sold subsidiaries compared to the fair value of the respective reporting units. See Note 1 for details. Additionally, the Company recorded a reduction in noncontrolling interests of $10,657 . 2016 Acquisitions Effective July 1, 2016, the Company acquired 100% of the equity interests of Forsman & Bodenfors AB (“F&B”), an advertising agency based in Sweden, for an estimated aggregate purchase price at acquisition date of $49,837 , consisting of a closing payment of 1,900,000 MDC Class A subordinate voting shares with an acquisition date fair value of $34,219 , plus additional deferred acquisition payments with an estimated present value at acquisition date of $15,618 . The amount of additional payments are based on the financial results of the acquired business for 2015 and 2016 as well as for the value of the Company’s shares from July 1, 2016 up to and including the close of business on November 2, 2016. During the three months ended June 30, 2017, the Company paid cash of $3,055 and issued an additional 2,450,000 MDC Class A subordinate voting shares with a fair value of $20,800 as a settlement of deferred acquisition consideration. An allocation of excess purchase price consideration of this acquisition to the fair value of the net assets acquired resulted in identifiable intangibles of $36,698 , consisting primarily of customer lists, trade names and covenants not to compete, and goodwill of $24,778 , including the value of the assembled workforce. The identified assets have a weighted average useful life of approximately 10.8 years and will be amortized in a manner represented by the pattern in which the economic benefits of such assets are expected to be realized. In addition, the Company has recorded $2,275 as the present value of redeemable noncontrolling interests and $5,514 as the present value of noncontrolling interests both relating to the noncontrolling interest of F&B’s subsidiaries. None of the intangibles and goodwill are tax deductible and the Company recorded a deferred tax liability of $8,074 related to the intangibles. F&B’s results are included in the Global Integrated Agencies segment. During the six months ended June 30, 2017, F&B earned revenue of $43,535 and incurred a net loss of $4,460 , which is included in our consolidated results for the nine months ended September 30, 2017. The net loss was attributable to an increase in the deferred acquisition payment liability related to such acquisition, driven by the decrease in t he future market performance of the Company’s stock price and the amortization of the intangibles identified in the allocation of the purchase price consideration. Effective April 1, 2016, the Company acquired the remaining 40% ownership interests of Luntz Global Partners LLC. In 2016, the Company also entered into various non-material transactions in connection with other majority-owned entities. As a result of the foregoing, the Company made total cash closing payments of $1,581 , eliminated the contingent deferred acquisition payments of $4,052 and fixed deferred acquisition payments of $467 related to certain initial acquisition of the equity interests, reduced other assets by $428 , reduced redeemable noncontrolling interests by $1,005 , reduced noncontrolling interests by $19,354 , increased accruals and other liabilities by $94 , and increased additional paid-in capital by $22,775 . Additional deferred payments with an estimated present value at acquisition date of $2,393 that are contingent upon service conditions have been excluded from deferred acquisition consideration and will be expensed as stock-based compensation over the required service period. 2016 Dispositions Effective September 30, 2016, the Company sold all of its ownership interests in Bryan Mills to the noncontrolling shareholders and recognized a loss of $800. The net assets reflected in the calculation of the loss on sale was inclusive of goodwill of $764 . Noncontrolling Interests Changes in the Company’s ownership interests in its less than 100% owned subsidiaries during the three and nine months ended September 30, 2017 and 2016 were as follows: Net Income (Loss) Attributable to MDC Partners Inc. and Transfers (to) from the Noncontrolling Interests Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Net income (loss) attributable to MDC Partners Inc. $ 18,493 $ (32,140 ) $ 19,180 $ (54,937 ) Transfers from the noncontrolling interest: (Decrease) increase in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of Redeemable Noncontrolling Interests and Noncontrolling Interests (337 ) (520 ) 2,315 22,498 Net transfers from noncontrolling interests $ (337 ) $ (520 ) $ 2,315 $ 22,498 Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ 18,156 $ (32,660 ) $ 21,495 $ (32,439 )
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(337,000)	(520,000)	$ (9,650,000)
Noncontrolling Interest, Increase from Business Combination			2,315,000	22,498,000
Net Income Loss Including Transfer from Non Controlling Interests	18,156,000	(32,660,000)	21,495,000	(32,439,000)
Noncontrolling Interest, Decrease from Deconsolidation			(10,657,000)
Net loss attributable to MDC Partners Inc.	18,493,000	(32,140,000)	19,180,000	(54,937,000)
Additional Paid-in Capital [Member]
Noncontrolling Interest, Increase from Business Combination			2,315,000
Parent [Member]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	$ (337,000)	$ (520,000)	2,315,000	$ 22,498,000
Noncontrolling Interest, Increase from Business Combination			2,315,000
Net loss attributable to MDC Partners Inc.			$ 19,180,000

Acquisitions (Details Textual)

Acquisitions (Details Textual) - USD ($)	Apr. 05, 2017	Jul. 01, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Apr. 01, 2016
Business Acquisition [Line Items]
Adjustments to deferred acquisition consideration included in share-based compensation			$ 4,064	$ 2,259		$ 9,792	$ 7,184
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests			(337,000)	(520,000)		(9,650,000)
Noncontrolling Interest, Increase from Business Combination						2,315,000	22,498,000
Stock-based compensation			6,380,000	5,228,000		16,870,000	15,443,000
Goodwill, Written off Related to Sale of Business Unit						17,593,000	764,000
Business Acquisition, Pro Forma Net Income (Loss)			18,493,000	(32,140,000)		19,180,000	(54,937,000)
Redeemable noncontrolling interests			$ 60,092,000			$ 60,092,000		$ 60,180,000
Noncontrolling Interest, Ownership Percentage by Parent			100.00%			100.00%
Net Income Loss Including Transfer from Non Controlling Interests			$ 18,156,000	(32,660,000)		$ 21,495,000	(32,439,000)
Forsman & Bodenfors AB [Domain]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue					$ 43,535
Business Acquisition, Pro Forma Net Income (Loss)					4,460
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ 36,698
Goodwill, Acquired During Period		$ 24,778
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years 9 months
Business Combination, Acquisition of Less than 100 Percent, Redeemable Noncontrolling Interest, Fair Value		$ 2,275
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		5,514
Business Acquisition, Goodwill, Expected Tax Deductible Amount		0
Deferred Taxes, Business Combination, Valuation Allowance, Available to Reduce Intangible Assets		$ 8,074
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Business Combination, Consideration Transferred		$ 49,837
Business Combination, Contingent Consideration, Liability		$ 15,618			$ 3,055
Luntz Global Partners L L C
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired									40.00%
Aggregate 2017 Step Up Transactions [Domain]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid						3,858
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests						(11,965)
Noncontrolling Interest, Period Increase (Decrease)						397
Noncontrolling Interest, Increase from Business Combination						2,316
Stock-based compensation						996
Business Combination, Acquisition of Less than 100 Percent, Redeemable Noncontrolling Interest, Fair Value						816
Business Combination, Contingent Consideration, Liability			7,208			7,208
Aggregate 2016 Step Up Transactions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid								1,581
Business Combination, Acquisition of Less than 100 Percent, Redeemable Noncontrolling Interest, Fair Value								1,005
Business Combinations, Assets Relinquished by Acquirer								428
Business Combinations, Liabilities Relinquished Previously due to Acquiree								94
Noncontrolling Interest [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests						(11,965,000)
Business Acquisition, Pro Forma Net Income (Loss)						0
Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Increase from Business Combination						2,315,000
Additional Paid-in Capital [Member] | Aggregate 2016 Step Up Transactions [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests								(22,775)
Contingent payment [Domain]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability			$ (2,462,000)	$ 11,152,000		$ 12,152,000	$ 17,180,000
Contingent payment [Domain] | Aggregate 2016 Step Up Transactions [Member]
Business Acquisition [Line Items]
Deferred Stock-based Compensation, Discounted								2,393
Business Combination, Consideration Transferred								4,052,000
Fixed payments [Member] | Aggregate 2016 Step Up Transactions [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred								467
Noncontrolling Interest Equity [Domain] | Aggregate 2016 Step Up Transactions [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests								$ (19,354)
Common Class A [Member] | Common Stock [Member] | Forsman & Bodenfors AB [Domain]
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions	2,450,000	1,900,000
Stock Issued During Period, Value, Acquisitions	$ 20,800	$ 34,219,000

Accruals and Other Liabilitie25

Accruals and Other Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accrued and Other Liabilities [Abstract]
Net Income (Loss) Attributable to Noncontrolling Interest	$ 3,491	$ 1,059	$ 6,588	$ 3,172	$ 5,218
Payments to Noncontrolling Interests			(5,272)	(6,549)	(7,772)
Beginning balance			4,154	$ 5,473	5,473
Other			332		1,235
Ending balance	$ 5,802		$ 5,802		$ 4,154

Accruals and Other Liabilitie26

Accruals and Other Liabilities (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Accrued and Other Liabilities [Abstract]
Accrued Media Cost, Current	$ 169,460	$ 201,872
Accrued and Other Liabilities Attributable To Noncontrolling Interest	5,802	4,154	$ 5,473
Outstanding Checks	$ 47,430	$ 80,193

Debt (Details)

Debt (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Debt [Line Items]
Debt Issuance Costs, Net	$ (18,161,000)	$ (18,420,000)
Revolving credit agreement	48,607,000	54,425,000
Debt, Long-term and Short-term, Combined Amount, Total	930,446,000	936,005,000
Obligations under capital leases	743,000	431,000
Debt and Capital Lease Obligations	931,189,000	936,436,000
Less current portion:	300,000	228,000
Long-term Debt, Excluding Current Maturities, Total	930,889,000	936,208,000
Notes due 2024 [Domain]
Debt [Line Items]
Senior Notes	$ 900,000,000	$ 900,000,000

Debt (Details Textual)

Debt (Details Textual) - USD ($)	May 01, 2024	May 03, 2016	Mar. 23, 2016	Oct. 23, 2014	Mar. 20, 2013	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	May 01, 2019
Debt [Line Items]
Debt Issuance Costs, Net						$ 18,161,000		$ 18,161,000		$ 18,420,000
Long-term Line of Credit, Noncurrent						48,607,000		48,607,000		54,425,000
Loss on redemption of notes						0	$ 0	0	$ (33,298,000)
Interest Paid								32,324,000	$ 27,979,000
Letters of Credit Outstanding, Amount						5,009,000		5,009,000
Outstanding Checks						$ 47,430,000		$ 47,430,000		80,193,000
Six Point Five Zero Percentage Notes [Domain]
Debt [Line Items]
Debt Instrument, Face Amount			$ 900,000
Debt Instrument, Interest Rate, Stated Percentage			6.50%			6.50%		6.50%
Proceeds from Offering			$ 880,000
Debt Instrument, Redemption Date, One								May 1, 2019
Debt Instrument, Redemption Date, Two								May 1, 2020
Debt Instrument, Percentage Of Redemption Price, Redemption Date Three								101.625%
Debt Instrument, Redemption Date, Three								May 1, 2021
Debt Instrument, Redemption Date, Latest For Redemption At Face Amount								May 1, 2022
Debt Instrument, Percentage Of Redemption Price, Redemption Date One								104.875%
Debt Instrument, Percentage Of Redemption Price, Redemption Date Two								103.25%
Debt Instrument, Percentage Of Redemption Price, Redemption Date, Latest For Redemption At Face Amount								100.00%
Debt Instrument, Percentage Redeemable Redemption Date, Additional								106.50%
Debt Instrument, Percentage Of Redemption Price, Change In Ownership Control								101.00%
Notes due 2024 [Domain]
Debt [Line Items]
Senior Notes						$ 900,000,000		$ 900,000,000		900,000,000
Debt Instrument, Interest Rate, Stated Percentage						6.50%		6.50%
Notes due 2020 [Member]
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						6.75%		6.75%
6.75% Notes
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.75%
Loss on redemption of notes										$ 33,298
Debt Instrument, Percentage Of Redemption Price, Redemption Date One			103.375%
Wells Fargo Capital Finance, LLC
Debt [Line Items]
Line of Credit Facility, Increase (Decrease), Net				$ 100,000,000
Long-term Line of Credit					$ 225,000,000
Debt Instrument, Maturity Date		May 3, 2021		Sep. 30, 2019
Debt Instrument, Face Amount				$ 325,000,000
Line of Credit Facility, Description					Dec. 31, 2018
Wells Fargo Capital Finance, LLC | Base Rate
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.75%		1.00%
Wells Fargo Capital Finance, LLC | London Interbank Offered Rate (LIBOR)
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				1.75%
Wells Fargo Capital Finance, LLC | Non-Prime Rate and Prime Rate on European Advances [Member]
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.50%
Wells Fargo Capital Finance, LLC | 6.75% Notes
Debt [Line Items]
Debt Instrument, Maturity Date			Apr. 1, 2020
Scenario, Forecast [Member] | Six Point Five Zero Percentage Notes [Domain]
Debt [Line Items]
Debt Instrument, Maturity Date	May 1, 2024
Scenario, Forecast [Member] | Wells Fargo Capital Finance, LLC | Six Point Five Zero Percentage Notes [Domain]
Debt [Line Items]
Debt Instrument, Maturity Date	May 1, 2024
Scenario, Forecast [Member] | Optional redemption [Domain] | Six Point Five Zero Percentage Notes [Domain]
Debt [Line Items]
Debt Instrument, Percentage Of Redemption Price Redemption Date, Additional											35.00%

Share Capital (Details Textual)

Share Capital (Details Textual)	Oct. 27, 2017shares	Sep. 30, 2017voteshares	Dec. 31, 2016shares
Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Share Capital [Line Items]
Shares, Outstanding	95,000	95,000	0
Common Stock [Member]
Share Capital [Line Items]
Shares, Outstanding		56,314,344	52,802,058
Common Stock [Member] | Common Class A [Member]
Share Capital [Line Items]
Common Stock, Voting Rights, Number of Votes per Share | vote		1
Shares, Outstanding		56,310,589	52,798,303
Common Stock [Member] | Common Class B
Share Capital [Line Items]
Common Stock, Voting Rights, Number of Votes per Share | vote		20
Shares, Outstanding		3,755

Convertible Preference Shares30

Convertible Preference Shares (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Preferred Units [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares				90,220,000
Series 4 Convertible Preferred Stock [Domain]
Preferred Units [Line Items]
Proceeds from issuance of convertible preference shares				$ 95,000	$ 0
Convertible Preferred Stock [Member] | Series 4 Convertible Preferred Stock [Domain]
Preferred Units [Line Items]
Stock Issued During Period, Shares, Convertible Preferred Shares		95,000		95,000		0
Preferred Stock, Value, Issued				$ 90,220
Accretion on convertible preferred shares	$ 1,948		$ 0	4,365	$ 0
Preferred Stock, Liquidation Preference, Value	$ 99,365			$ 99,365		$ 0
Preferred Stock, Conversion Basis, Common Stock Class A Closing Trade Price		125.00%

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 144,847
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	73,358
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	19,233
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Other Adjustments	(27,118)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Foreign Currency Translation Adjustment	1,336
Fair Value, Inputs, Level 1 | Six Point Five Zero Percentage Notes [Domain]
Liabilities:
Long term debt, Carrying Amount	900,000	$ 900,000
Long term debt, Fair Value	$ 909,000	$ 812,250

Fair Value Measurements (Deta32

Fair Value Measurements (Details 1) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Ending balance of contingent payments	$ 144,847
Fair Value, Inputs, Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments	73,358
Additions	0
Redemption value adjustments	19,233
Other	(27,118)
Foreign translation adjustment	$ 1,336

Fair Value Measurements (Deta33

Fair Value Measurements (Details Textual) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred acquisition consideration settled through issuance of shares	$ 27,852,000
Common Stock [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred acquisition consideration settled through issuance of shares	$ 28,727,000
Stock Issued During Period, Shares, New Issues	3,353,939
Common Stock [Member] | Common Class A [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred acquisition consideration settled through issuance of shares		$ 10,458,000
Share Capital To Be Issued [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stock Authorized During Period, Value, To be Issued	$ (2,360,000)
Stock Authorized During Period, Shares, To be Issued	100,000
Aggregate 2016 Step Up Transactions [Member] | Contingent payment [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Consideration Transferred			$ 4,052,000
Aggregate 2016 Step Up Transactions [Member] | Fixed payments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Consideration Transferred			$ 467

Other Income (Details)

Other Income (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Noncontrolling Interest, Decrease from Deconsolidation			$ 10,657,000
Realized gain (loss) from disposal of cost and equity method investments		$ 682,000		$ 682,000
Other income (expense)	$ (7,000)	26,000	271,000	(220,000)
Gain (Loss) on Disposition of Business	1,424,000	800,000	1,424,000	800,000
Cost-method Investments, Realized Gains	168,000		168,000
Foreign currency transaction gain	9,912,000	(5,916,000)	18,797,000	9,868,000
Other, net	$ 8,649,000	$ (6,008,000)	$ 17,812,000	$ 9,530,000

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)reportable_segment	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment			4
Revenue	$ 375,800	$ 349,254	$ 1,111,032	$ 995,343
Cost of services sold	249,418	235,659	754,803	675,940
Office and general expenses	77,910	83,303	251,313	233,840
Depreciation, Depletion, Amortization and Impairment, Nonproduction	11,252	41,043	32,916	63,699
Operating profit	37,220	(10,751)	72,000	21,864
Other Income (Expense):
Other income, net	8,649	(6,008)	17,812	9,530
Interest and Debt Expense, net	16,258	16,322	48,309	48,690
Gain (Loss) on Repurchase of Debt Instrument	0	0	0	(33,298)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	29,611	(33,081)	41,503	(50,594)
Income Tax Expense (Benefit)	9,049	(1,930)	17,659	1,180
Income Loss From Continuing Operations Before Equity In Earnings Of Non-consolidated Affiliates	20,562	(31,151)	23,844	(51,774)
Income (Loss) from Equity Method Investments	1,422	70	1,924	9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	21,984	(31,081)	25,768	(51,765)
Net Income (Loss) Attributable to Noncontrolling Interest	(3,491)	(1,059)	(6,588)	(3,172)	$ (5,218)
Net Income (Loss) Attributable to Parent	18,493	(32,140)	19,180	(54,937)
Stock-based compensation	6,380	5,228	16,870	15,443
Supplemental Segment Information:
Capital expenditures	7,149	6,274	28,305	19,723
Total Assets	1,617,831		1,617,831		$ 1,577,378
Corporate [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion, Amortization and Impairment, Nonproduction	255	359	864	1,266
Operating profit	(10,724)	(7,051)	(28,982)	(32,982)
Other Income (Expense):
Stock-based compensation	477	605	1,599	2,059
Supplemental Segment Information:
Capital expenditures	1	0	4	32
Global Integrated Agencies [Member]
Segment Reporting Information [Line Items]
Revenue	193,979	177,262	576,935	489,880
Depreciation, Depletion, Amortization and Impairment, Nonproduction	6,359	6,111	17,889	14,986
Operating profit	19,819	2,873	33,765	24,316
Other Income (Expense):
Net Income (Loss) Attributable to Parent	18,493	(32,140)	19,180	(54,937)
Stock-based compensation	3,840	2,890	9,892	9,030
Supplemental Segment Information:
Capital expenditures	1,950	3,003	17,639	10,703
Domestic Creative Agencies [Member]
Segment Reporting Information [Line Items]
Revenue	24,173	22,181	67,473	66,274
Depreciation, Depletion, Amortization and Impairment, Nonproduction	336	353	1,062	1,263
Operating profit	5,716	4,688	13,563	14,779
Other Income (Expense):
Stock-based compensation	177	150	502	487
Supplemental Segment Information:
Capital expenditures	324	222	874	920
Specialized Communications [Member]
Segment Reporting Information [Line Items]
Revenue	40,670	40,309	125,470	123,006
Depreciation, Depletion, Amortization and Impairment, Nonproduction	1,220	189	3,657	5,123
Operating profit	4,775	11,101	13,410	17,860
Other Income (Expense):
Stock-based compensation	659	564	2,264	1,556
Supplemental Segment Information:
Capital expenditures	206	56	673	2,183
Media Services [Member]
Segment Reporting Information [Line Items]
Revenue	33,027	34,481	103,966	96,681
Depreciation, Depletion, Amortization and Impairment, Nonproduction	917	2,338	2,933	4,437
Operating profit	2,421	466	8,618	3,510
Other Income (Expense):
Stock-based compensation	150	70	464	187
Supplemental Segment Information:
Capital expenditures	2,171	2,008	3,455	2,634
All Other [Member]
Segment Reporting Information [Line Items]
Revenue	83,951	75,021	237,188	219,502
Depreciation, Depletion, Amortization and Impairment, Nonproduction	2,165	31,693	6,511	36,624
Operating profit	15,213	(22,828)	31,626	(5,619)
Other Income (Expense):
Stock-based compensation	1,077	949	2,149	2,124
Supplemental Segment Information:
Capital expenditures	2,497	985	5,660	3,251
CANADA
Segment Reporting Information [Line Items]
Revenue	31,418	30,233	88,471	92,253
Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue	54,680	44,515	153,714	103,394
UNITED STATES
Segment Reporting Information [Line Items]
Revenue	$ 289,702	$ 274,506	$ 868,847	$ 799,696

Segment Information (Details 1)

Segment Information (Details 1) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)reportable_segment	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | reportable_segment			4
Net Income (Loss) Attributable to Parent	$ 18,493	$ (32,140)	$ 19,180	$ (54,937)
Depreciation, Depletion and Amortization, Nonproduction	11,252	11,412	32,916	34,068
Share-based Compensation	6,380	5,228	16,870	15,443
Revenue	375,800	349,254	1,111,032	995,343
Income (Loss) from Equity Method Investments	1,422	70	1,924	9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	21,984	(31,081)	25,768	(51,765)
Net Income (Loss) Attributable to Noncontrolling Interest	3,491	1,059	6,588	3,172	$ 5,218
Cost of Services	249,418	235,659	754,803	675,940
General and Administrative Expense	77,910	83,303	251,313	233,840
Operating Income (Loss)	37,220	(10,751)	72,000	21,864
Other Nonoperating Income (Expense)	8,649	(6,008)	17,812	9,530
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	29,611	(33,081)	41,503	(50,594)
Income Tax Expense (Benefit)	9,049	(1,930)	17,659	1,180
Income Loss From Continuing Operations Before Equity In Earnings Of Non-consolidated Affiliates	20,562	(31,151)	23,844	(51,774)
Payments to Acquire Property, Plant, and Equipment	7,149	6,274	28,305	19,723
United States [Member]
Segment Reporting Information [Line Items]
Revenue	289,702	274,506	868,847	799,696
Canada [Member]
Segment Reporting Information [Line Items]
Revenue	31,418	30,233	88,471	92,253
Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue	54,680	44,515	153,714	103,394
Domestic Creative Agencies [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	177	150	502	487
Revenue	24,173	22,181	67,473	66,274
Operating Income (Loss)	5,716	4,688	13,563	14,779
Payments to Acquire Property, Plant, and Equipment	324	222	874	920
Specialized Communications [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	659	564	2,264	1,556
Revenue	40,670	40,309	125,470	123,006
Operating Income (Loss)	4,775	11,101	13,410	17,860
Payments to Acquire Property, Plant, and Equipment	206	56	673	2,183
Media Services [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	150	70	464	187
Revenue	33,027	34,481	103,966	96,681
Operating Income (Loss)	2,421	466	8,618	3,510
Payments to Acquire Property, Plant, and Equipment	2,171	2,008	3,455	2,634
All Other [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	1,077	949	2,149	2,124
Revenue	83,951	75,021	237,188	219,502
Operating Income (Loss)	15,213	(22,828)	31,626	(5,619)
Payments to Acquire Property, Plant, and Equipment	$ 2,497	$ 985	$ 5,660	$ 3,251

Commitments, Contingencies an37

Commitments, Contingencies and Guarantees (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Redeemable noncontrolling interests	$ 60,092	$ 60,180
Investment commitments	198
Amount of letters of credit outstanding	$ 5,009
Minimum [Member]
Other Commitments [Line Items]
Redeemable noncontrolling interest obligation, year of payment	2,017
Maximum [Member]
Other Commitments [Line Items]
Redeemable noncontrolling interest obligation, year of payment	2,023
Contractual redemption right [Member]
Other Commitments [Line Items]
Redemption value	$ 15,493
Contractual redemption right [Member] | Common Class A [Member]
Other Commitments [Line Items]
Redemption value	202
Termination or death redemption right [Member]
Other Commitments [Line Items]
Redemption value	42,268
Excess initial redemption value [Member]
Other Commitments [Line Items]
Redemption value	$ 2,330