Stagwell (STGW) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 18, 2019	Dec. 31, 2018	Dec. 31, 2017
Document Information [Line Items]
Entity Registrant Name	MDC PARTNERS INC
Entity Central Index Key	0000876883
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Document Type	10-Q
Entity Small Business	false
Document Fiscal Year Focus	2019
Document Period End Date	Sep. 30, 2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		145,000,000
Common Stock [Member] | Common Class A
Document Information [Line Items]
Shares outstanding (shares)		72,142,668	57,517,568
Common Stock [Member] | Common Class B
Document Information [Line Items]
Shares outstanding (shares)		3,749	3,755	3,755

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Services	$ 342,907	$ 375,830	$ 1,033,828	$ 1,082,541
Operating expenses:
Cost of services sold	222,448	238,690	700,351	735,110
Office and general expenses	79,726	102,380	234,120	270,137
Depreciation and amortization	9,368	11,134	28,869	35,212
Goodwill and other asset impairment	1,944	21,008	1,944	23,325
Costs and Expenses, Total	313,486	373,212	965,284	1,063,784
Operating income	29,421	2,618	68,544	18,757
Other income (expense):
Interest expense and finance charges, net	(16,110)	(17,063)	(49,284)	(50,005)
Other, net	(431)	189	(4,559)	1,222
Foreign exchange gain (loss)	(3,973)	3,275	4,401	(9,934)
Nonoperating Income (Expense), Total	(20,514)	(13,599)	(49,442)	(58,717)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	8,907	(10,981)	19,102	(39,960)
Income tax expense (benefit)	3,457	2,986	6,292	(3,367)
Income (loss) before equity in earnings of non-consolidated affiliates	5,450	(13,967)	12,810	(36,593)
Equity in earnings of non-consolidated affiliates	63	300	352	358
Net income (loss)	5,513	(13,667)	13,162	(36,235)
Net income attributable to the noncontrolling interest	(7,265)	(2,458)	(10,737)	(5,900)
Net income (loss) attributable to MDC Partners Inc.	$ (1,752)	(16,125)	$ 2,425	$ (42,135)
Accretion on and net income allocated to convertible preference shares		$ 2,109
Basic and diluted
Income (Loss) from Continuing Operations, Per Diluted Share	$ (0.07)	$ (0.32)	$ (0.10)	$ (0.85)
Weighted Average Number of Common Shares Outstanding:
Weighted Average Number of Shares Outstanding, Basic	72,044,480	57,498,661	68,154,306	57,117,797
Weighted Average Number of Shares Outstanding, Diluted	72,044,480	57,498,661	68,154,306	57,117,797
Stock-based compensation	$ 6,026	$ 6,242	$ 12,632	$ 16,882
Cost of services sold
Weighted Average Number of Common Shares Outstanding:
Stock-based compensation	5,193	4,390	12,180	11,784
Office and general expenses
Weighted Average Number of Common Shares Outstanding:
Stock-based compensation	833	$ 1,852	$ 452	5,098
Series 4 Convertible Preferred Stock [Domain] | Preferred Stock
Other income (expense):
Accretion on and net income allocated to convertible preference shares	$ 3,306			$ 6,204

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive income (loss)
Net loss	$ 5,513	$ (13,667)	$ 13,162	$ (36,235)
Other comprehensive income (loss), net of applicable tax:
Foreign currency translation adjustment	(1,461)	(1,327)	(7,505)	(898)
Other comprehensive loss	(1,461)	(1,327)	(7,505)	(898)
Comprehensive income (loss) for the period	4,052	(14,994)	5,657	(37,133)
Comprehensive income attributable to the noncontrolling interests	6,969	2,931	10,830	4,367
Comprehensive loss attributable to MDC Partners Inc.	$ (2,917)	$ (17,925)	$ (5,173)	$ (41,500)

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS $ in Thousands	Sep. 30, 2019USD ($)
Current Assets:
Cash and cash equivalents	$ 27,280
Accounts receivable, less allowance for doubtful accounts of $2,728 and $1,879	411,805
Expenditures billable to clients	38,652
Assets held for sale	0
Other current assets	35,939
Total Current Assets	513,676
Fixed assets, at cost, less accumulated depreciation of $147,342 and $128,546	82,946
Right-of-use assets - operating leases	234,137
Investments in non-consolidated affiliates	6,824
Goodwill	740,955
Other intangible assets, net of accumulated amortization of $171,941 and $161,868	56,734
Deferred tax assets	92,439
Other assets	24,018
Total Assets	1,751,729
Current Liabilities:
Accounts payable	178,946
Accruals and other liabilities	280,783
Liabilities held for sale	0
Advance billings	169,857
Current portion of lease liabilities - operating leases	47,722
Current portion of deferred acquisition consideration	31,579
Total Current Liabilities	708,887
Long-term debt	895,379
Long-term portion of deferred acquisition consideration	24,611
Long-term lease liabilities - operating leases	230,209
Other liabilities	17,933
Deferred tax liabilities	7,486
Total Liabilities	1,884,505
Redeemable Noncontrolling Interests	41,519
Shareholders’ Deficit:
Convertible preference shares, 145,000 authorized, issued and outstanding at September 30, 2019 and 95,000 at December 31, 2018	152,746
Common stock and other paid-in capital	98,364
Accumulated deficit	(462,483)
Accumulated other comprehensive (loss) income	(2,878)
MDC Partners Inc. Shareholders' Deficit	(214,251)
Noncontrolling interests	39,956
Total Shareholders' Deficit	(174,295)
Total Liabilities, Redeemable Noncontrolling Interests and Shareholders' Deficit	$ 1,751,729

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ 5,513	$ (13,667)	$ 13,162	$ (36,235)
Adjustments to reconcile net income (loss) to cash used in operating activities:
Stock-based compensation	6,026	6,242	12,632	16,882
Depreciation			18,796	20,944
Amortization of intangibles			10,073	14,268
Amortization of deferred finance charges and debt discount			2,504	2,402
Goodwill and other asset impairment	1,944	21,008	1,944	23,325
Adjustment to deferred acquisition consideration			(3,627)	8,522
Deferred income taxes			6,292	(6,690)
Loss on sale of assets			3,361	(1,408)
Earnings of non-consolidated affiliates	(63)	(300)	(352)	(358)
Other non-current assets and liabilities			(3,017)	(956)
Foreign exchange			(5,145)	9,125
Changes in working capital:
Accounts receivable			835	8,574
Expenditures billable to clients			3,716	(28,171)
Prepaid expenses and other current assets			3,280	(11,516)
Accounts payable, accruals and other current liabilities			(96,527)	(49,587)
Acquisition related payments			(4,816)	(28,263)
Advance billings			31,049	27,413
Net cash used in operating activities			(5,840)	(31,729)
Cash flows from investing activities:
Capital expenditures	(5,863)	(5,543)	(13,786)	(15,232)
Proceeds from sale of assets			23,050	0
Acquisitions, net of cash acquired			(5,778)	(34,303)
Other investments			(179)	1,180
Net cash provided by (used in) investing activities			3,307	(48,355)
Cash flows from financing activities:
Acquisition related payments			(30,155)	(32,240)
Distributions to noncontrolling interests			(9,982)	(10,410)	$ (13,419)
Payment of dividends			(56)	(182)
Purchase of shares			(577)	(776)
Other			0	(260)
Net cash provided by (used in) financing activities			(2,202)	59,122
Effect of exchange rate changes on cash, cash equivalents, and cash held in trusts			8	(161)
Net decrease in cash, cash equivalents, and cash held in trusts including cash classified within assets held for sale			(4,727)	(21,123)
Change in cash and cash equivalents classified within assets held for sale			4,441	0
Net decrease in cash and cash equivalents			(3,593)
Cash and cash equivalents at beginning of period			30,873	46,179	46,179
Cash and cash equivalents at end of period	$ 27,280	$ 25,056	27,280	25,056	$ 30,873
Supplemental disclosures:
Cash income taxes paid			3,631	4,822
Cash interest paid			32,525	33,011
Wells Fargo Capital Finance, LLC | Revolving Credit Facility
Cash flows from financing activities:
Repayment of revolving credit facility			(1,172,909)	(1,121,300)
Proceeds from revolving credit facility			1,112,857	1,224,290
Change in cash and cash equivalents held in trusts classified within held for sale			(3,307)	0
Series 4 Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance of common and convertible preference shares, net of issuance costs			$ 98,620	$ 0

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	AOCI Attributable to Parent [Member]	Accumulated Other Comprehensive Income (Loss)	MDC Partners Inc. Shareholders' Deficit	Noncontrolling Interest	Common Class A [Member]Common Stock	Series 4 Convertible Preferred Stock [Member]Convertible Preferred Stock	Contingent Consideration, Liability Settlements [Domain]Series 4 Convertible Preferred Stock [Member]Convertible Preferred Stock
Balance at Dec. 31, 2017	$ (155,513)			$ 38,191	$ (340,000)	$ (1,954)		$ (213,543)	$ 58,030
Balance (in shares) at Dec. 31, 2017											95,000
Common stock, balance (in shares) at Dec. 31, 2017			56,375,131
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	(16,125)							(16,125)
Shares acquired and cancelled	(283)			(283)				(283)
Balance at Mar. 31, 2018	(177,940)	$ 90,123		50,619	(383,305)	(1,319)		(243,882)	65,942
Balance (in shares) at Mar. 31, 2018		95,000,000
Common stock, balance (in shares) at Mar. 31, 2018			57,515,439
Adjustments to Additional Paid in Capital, Changes due to Business Combinations								3,809
Balance at Dec. 31, 2017	(155,513)			38,191	(340,000)	(1,954)		(213,543)	58,030
Balance (in shares) at Dec. 31, 2017											95,000
Common stock, balance (in shares) at Dec. 31, 2017			56,375,131
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	(42,135)
Other comprehensive loss	(898)
Balance at Sep. 30, 2018		$ 90,123
Adjustments to Additional Paid in Capital, Changes due to Business Combinations				(745)				(745)
Balance at Dec. 31, 2018	(246,967)	$ 90,123		58,579	(464,903)	4,720		(311,481)	64,514
Balance (in shares) at Dec. 31, 2018										57,517,568
Common stock, balance (in shares) at Dec. 31, 2018			57,521,323
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	2,425
Other comprehensive loss	(7,505)						$ (7,598)	(7,598)	93
Issuance of common and preference shares (in shares)		50,000,000
Issuance of common and convertible preference shares	98,620			35,997				98,620				$ 62,623
Issuance of restricted stock	0
Issuance of restricted stock (in shares)			566,932
Shares acquired and cancelled	(577)			(577)				(577)
Shares acquired and cancelled (in shares)			(227,552)
Stock-based compensation	1,918			1,918				1,918
Changes in redemption value of redeemable noncontrolling interests	3,496			3,496				3,496
Changes in ownership interest									(24,642)
Balance at Sep. 30, 2019	$ (174,295)	$ 152,746		$ 98,364	$ (462,483)	$ (2,878)		$ (214,251)	$ 39,956
Balance (in shares) at Sep. 30, 2019		145,000,000									145,000,000
Common stock, balance (in shares) at Sep. 30, 2019			72,146,417

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	asis of Presentation and Recent Developments The accompanying consolidated financial statements include the accounts of MDC Partners Inc. (the “Company” or “MDC”), its subsidiaries and variable interest entities for which the Company is the primary beneficiary. References herein to “Partner Firms” generally refer to the Company’s subsidiary agencies. MDC Partners Inc. has prepared the unaudited condensed consolidated interim financial statements included herein in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for reporting interim financial information on Form 10-Q. Accordingly, the financial statements have been condensed and do not include certain information and disclosures pursuant to these rules. The preparation of financial statements in conformity with GAAP requires us to make judgments, assumptions and estimates that affect the amounts reported and disclosed. Actual results could differ from these estimates and assumptions. The consolidated results for interim periods are not necessarily indicative of results for the full year and should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”). The accompanying financial statements reflect all adjustments, consisting of normally recurring accruals, which in the opinion of management are necessary for a fair presentation, in all material respects, of the information contained therein. Intercompany balances and transactions have been eliminated in consolidation. Certain reclassifications have been made to the prior year financial information to conform to the current year presentation. Due to changes in the composition of certain businesses and the Company’s internal management and reporting structure during 2019, reportable segment results for the 2018 periods presented have been recast to reflect the reclassification of certain businesses between segments. See Note 12 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The Company’s revenue recognition policies are established in accordance with the Revenue Recognition topics of ASC 606, and accordingly, revenue is recognized when control of the promised goods or services is transferred to our clients, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. The MDC network provides an extensive range of services to our clients offering a variety of marketing and communication capabilities including strategy, creative and production for advertising campaigns across a variety of platforms (print, digital, social media, television broadcast), public relations services including strategy, editorial, crisis support or issues management, media training, influencer engagement and events management. We also provide media buying and planning across a range of platforms (out-of-home, paid search, social media, lead generation, programmatic, television broadcast), experiential marketing and application/website design and development. The primary source of the Company’s revenue is from agency arrangements in the form of fees for services performed, commissions, and from performance incentives or bonuses, depending on the terms of the client contract. In all circumstances, revenue is only recognized when collection is reasonably assured. Certain of the Company’s contractual arrangements have more than one performance obligation. For such arrangements, revenue is allocated to each performance obligation based on its relative stand-alone selling price. Stand-alone selling prices are determined based on the prices charged to clients or using expected cost plus margin. The determination of our performance obligations is specific to the services included within each contract. Based on a client’s requirements within the contract, and how these services are provided, multiple services could represent separate performance obligations or be combined and considered one performance obligation. Contracts that contain services that are not significantly integrated or interdependent, and that do not significantly modify or customize each other, are considered separate performance obligations. Typically, we consider media planning, media buying, creative (or strategy), production and experiential marketing services to be separate performance obligations if included in the same contract as each of these services can be provided on a stand-alone basis, and do not significantly modify or customize each other. Public relations services and application/website design and development are typically each considered one performance obligation as there is a significant integration of these services into a combined output. We typically satisfy our performance obligations over time, as services are performed. Fees for services are typically recognized using input methods (direct labor hours, materials and third-party costs) that correspond with efforts incurred to date in relation to total estimated efforts to complete the contract. Point in time recognition primarily relates to certain commission-based contracts, which are recognized upon the placement of advertisements in various media when the Company has no further performance obligation. Revenue is recognized net of sales and other taxes due to be collected and remitted to governmental authorities. The Company’s contracts typically provide for termination by either party within 30 to 90 days. Although payment terms vary by client, they are typically within 30 to 60 days. In addition, the Company generally has the right to payment for all services provided through the end of the contract or termination date. Within each contract, we identify whether the Company is principal or agent at the performance obligation level. In arrangements where the Company has substantive control over the service before transferring it to the client, and is primarily responsible for integrating the services into the final deliverables, we act as principal. In these arrangements, revenue is recorded at the gross amount billed. Accordingly, for these contracts the Company has included reimbursed expenses in revenue. In other arrangements where a third-party supplier, rather than the Company, is primarily responsible for the integration of services into the final deliverables, and thus the Company is solely arranging for the third-party supplier to provide these services to our client, we generally act as agent and record revenue equal to the net amount retained, when the fee or commission is earned. The role of MDC’s agencies under a production services agreement is to facilitate a client’s purchasing of production capabilities from a third-party production company in accordance with the client’s strategy and guidelines. The obligation of MDC’s agencies under media buying services is to negotiate and purchase advertising media from a third-party media vendor on behalf of a client to execute its media plan. We do not obtain control prior to transferring these services to our clients; therefore, we primarily act as agent for production and media buying services. A small portion of the Company’s contractual arrangements with clients include performance incentive provisions, which allow the Company to earn additional revenues as a result of its performance relative to both quantitative and qualitative goals. Incentive compensation is primarily estimated using the most likely amount method and is included in revenue up to the amount that is not expected to result in a reversal of a significant amount of cumulative revenue recognized. We recognize revenue related to performance incentives as we satisfy the performance obligation to which the performance incentives are related. Disaggregated Revenue Data The Company provides a broad range of services to a large base of clients across the full spectrum of industry verticals on a global basis. The primary source of revenue is from agency arrangements in the form of fees for services performed, commissions, and from performance incentives or bonuses. Certain clients may engage with the Company in various geographic locations, across multiple disciplines, and through multiple Partner Firms. Representation of a client rarely means that MDC handles marketing communications for all brands or product lines of the client in every geographical location. The Company’s Partner firms often cooperate with one another through referrals and the sharing of both services and expertise, which enables MDC to service clients’ varied marketing needs by crafting custom integrated solutions. Additionally, the Company maintains separate, independent operating companies to enable it to effectively manage potential conflicts of interest by representing competing clients across the MDC network. The following table presents revenue disaggregated by client industry vertical for the three and nine months ended September 30, 2019 and 2018 : Three Months Ended September 30, Nine Months Ended September 30, Industry Reportable Segment 2019 2018 2019 2018 Food & Beverage All $ 64,774 $ 80,919 $ 204,743 $ 234,203 Retail All 39,420 40,421 111,899 116,832 Consumer Products All 38,510 40,124 119,866 118,097 Communications All 48,147 46,779 136,819 128,232 Automotive All 19,125 21,282 55,857 67,070 Technology All 28,148 26,005 84,294 71,085 Healthcare All 25,152 33,751 74,403 101,753 Financials All 28,054 30,378 81,049 83,079 Transportation and Travel/Lodging All 20,541 19,357 65,111 53,021 Other All 31,036 36,814 99,787 109,169 $ 342,907 $ 375,830 $ 1,033,828 $ 1,082,541 MDC has historically largely focused where the Company was founded in North America, the largest market for its services in the world. In recent years the Company has expanded its global footprint to support clients looking for help to grow their businesses in new markets. Today, MDC’s Partner Firms are located in the United States, Canada, and an additional twelve countries around the world. In the past, some clients have responded to weakening economic conditions with reductions to their marketing budgets, which included discretionary components that are easier to reduce in the short term than other operating expenses. The following table presents revenue disaggregated by geography for the three and nine months ended September 30, 2019 and 2018 : Three Months Ended September 30, Nine Months Ended September 30, Geographic Location Reportable Segment 2019 2018 2019 2018 United States All $ 271,671 $ 296,544 $ 819,347 $ 848,336 Canada All, excluding Media Services 25,895 32,132 72,837 91,597 Other All, excluding Media Services 45,341 47,154 141,644 142,608 $ 342,907 $ 375,830 $ 1,033,828 $ 1,082,541 Contract assets and liabilities Contract assets consist of fees and reimbursable outside vendor costs incurred on behalf of clients when providing advertising, marketing and corporate communications services that have not yet been invoiced to clients. Unbilled service fees were $81,703 and $64,362 at September 30, 2019 and December 31, 2018 , respectively, and are included as a component of accounts receivable on the Unaudited Condensed Consolidated Balance Sheets . Outside vendor costs incurred on behalf of clients which have yet to be invoiced were $38,652 and $42,369 at September 30, 2019 and December 31, 2018 , respectively, and are included on the Unaudited Condensed Consolidated Balance Sheets as expenditures billable to clients. Such amounts are invoiced to clients at various times over the course of providing services. Contract liabilities consist of fees billed to clients in excess of fees recognized as revenue and are classified as advance billings on the Company’s Unaudited Condensed Consolidated Balance Sheets . Advance billings at September 30, 2019 and December 31, 2018 were $169,857 and $138,505 , respectively. The increase in the advance billings balance of $31,352 for the nine months ended September 30, 2019 was primarily driven by cash payments received or due in advance of satisfying our performance obligations, offset by $114,927 of revenues recognized that were included in the advance billings balances as of December 31, 2018 and reductions due to the incurrence of third-party costs. Changes in the contract asset and liability balances during the nine months ended September 30, 2019 and December 31, 2018 were not materially impacted by write offs, impairment losses or any other factors.

Loss Per Common Share

Loss Per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Loss Per Common Share	Loss) Per Common Share The following table sets forth the computation of basic and diluted income (loss) per common share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Accretion on convertible preference shares (3,306 ) (2,109 ) (8,931 ) (6,204 ) Net income allocated to convertible preference shares — — — — Net loss attributable to MDC Partners Inc. common shareholders $ (5,058 ) $ (18,234 ) $ (6,506 ) $ (48,339 ) Adjustment to net income allocated to convertible preference shares — — — — Numerator for dilutive loss per common share: Net loss attributable to MDC Partners Inc. common shareholders $ (5,058 ) $ (18,234 ) $ (6,506 ) $ (48,339 ) Denominator: Basic weighted average number of common shares outstanding 72,044,480 57,498,661 68,154,306 57,117,797 Effect of dilutive securities: Impact of stock options and non-vested stock under employee stock incentive plans — — — — Diluted weighted average number of common shares outstanding 72,044,480 57,498,661 68,154,306 57,117,797 Basic $ (0.07 ) $ (0.32 ) $ (0.10 ) $ (0.85 ) Diluted $ (0.07 ) $ (0.32 ) $ (0.10 ) $ (0.85 ) Anti-dilutive stock awards 3,714,595 1,524,218 3,714,595 1,524,218 Restricted stock and restricted stock unit awards of 135,386 and 1,015,637 as of September 30, 2019 and 2018 respectively, which are contingent upon the Company meeting a cumulative three year earnings target and contingent upon continued employment, are excluded from the computation of diluted income per common share as the contingencies were not satisfied at September 30, 2019 and 2018 , respectively. In addition, there were 145,000 and 95,000 Preference Shares outstanding which were convertible into 26,133,613 and 10,755,602 Class A common shares at September 30, 2019 and 2018 , respectively. These Preference Shares were anti-dilutive for each period presented in the table above and are therefore excluded from the diluted income (loss) per common share calculation.

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions 2019 Acquisition Effective April 1, 2019, the Company acquired the 35% ownership interest of HPR Partners LLC (Hunter) it did not own for an aggregate purchase price of $10,234 , comprised of a closing cash payment of $3,890 and additional deferred acquisition payments with an estimated present value at the acquisition date of $6,344 . The deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As of the acquisition date, the fair value of the additional interest acquired was $20,178 . The fair value was measured using a discounted cash flow model. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $9,486 . The difference between the purchase price and the noncontrolling interest of $745 was recorded in common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheet. 2019 Disposition On March 8, 2019, the Company consummated the sale of Kingsdale, an operating segment with operations in Toronto and New York City that provides shareholder advisory services. As consideration for the sale, the Company was paid cash plus the assumption of certain liabilities totaling approximately $50 million in the aggregate. The sale resulted in a loss of approximately $3 million , which is included in Other, net within the Unaudited Condensed Consolidated Statement of Operations. Assets and Liabilities Held for Sale - Change in Plan to Sell In the fourth quarter of 2018, the Company initiated a process to sell its ownership interest in a foreign office within the Global Integrated Agencies reportable segment. The assets and liabilities of the entity were classified as Assets and Liabilities held for sale, at their fair value less cost to sell, within the Consolidated Balance Sheet as of December 31, 2018. In the second quarter of 2019 , following the appointment of Mark Penn as Chief Executive Officer, management changed its strategy and plan to sell the foreign office. In the second quarter of 2019, in connection with management’s decision, the amounts classified within assets and liabilities held for sale were reclassified into the respective line items within the Unaudited Condensed Consolidated Balance Sheet. 2018 Acquisitions On September 7, 2018, a subsidiary of the Company purchased a 100% interest in OneChocolate Communications Limited and OneChocolate Communications LLC, PR (“OneChocolate”) a digital marketing consultancy headquartered in London, UK, for an aggregate purchase price of $3,231 , working capital of $966 and additional deferred acquisition payments with an estimated present value of $2,146 . OneChocolate’s results are reflected in the Allison & Partners operating segment which is included in the Specialist Communications reportable segment which had an immaterial impact on our results. On July 1, 2018, the Company acquired the remaining 14.87% and 3% of membership interests of Doner Partners, LLC and Source Marketing LLC, respectively, for an aggregate purchase price of $7,618 , comprised of a closing cash payment of $3,279 and additional deferred acquisition payments with an estimated present value of $4,305 as of December 31, 2018. As of the acquisition date, the fair value of the additional interests acquired was $16,361 for Doner Partners LLC. The fair values were measured using a discounted cash flow model. As a result of the transaction, the Company reduced noncontrolling interest by $11,946 and redeemable noncontrolling interest by $933 . On April 2, 2018, the Company purchased 51% of the membership interests of Instrument LLC (“Instrument”), a digital creative agency based in Portland, Oregon, for an aggregate purchase price of $35,591 . The acquisition is expected to facilitate the Company’s growth and help to build its portfolio of modern, innovative and digital-first agencies. The purchase price consisted of a cash payment of $28,561 and the issuance of 1,011,561 shares of the Company’s Class A subordinate voting stock with an acquisition date fair value of $7,030 . The Company issued these shares in a transaction exempt from the registration requirements of the Securities Act of 1933, as amended, pursuant to Section 4(a)(2) of the Securities Act. The purchase price allocation for Instrument resulted in tangible assets of $10,304 , identifiable intangibles of $23,130 , consisting primarily of customer lists and a trade name, and goodwill of $32,776 . In addition, the Company has recorded $27,357 as the fair value of noncontrolling interests, which was derived from the Company’s purchase price less a discount related to the noncontrolling parties’ lack of control. The identified assets have a weighted average useful life of approximately six 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. The goodwill is tax deductible. Instruments’ results are included in the All Other category from a segment reporting perspective. The Company has a controlling financial interest in Instrument through its majority voting interest, and as such, has aggregated the acquired Partner Firm’s financial data into the Company’s Unaudited Condensed Consolidated Financial Statements . The operating results of Instrument in the current year are not material. Effective January 1, 2018, the Company acquired the remaining 24.5% ownership interest of Allison & Partners LLC for an aggregate purchase price of $10,023 , comprised of a closing cash payment of $300 and additional deferred acquisition payments with an estimated present value at the acquisition date of $9,723 . The deferred payments are based on the future financial results of the underlying business from 2017 to 2020 with final payments due in 2021. As of the acquisition date, the fair value of the additional interest acquired was $20,096 . The fair value was measured using a discounted cash flow model. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $8,857 . The difference of $1,166 between the purchase price and the noncontrolling interest was recorded in additional paid-in capital. Deferred Acquisition Consideration Deferred acquisition consideration on the balance sheet consists of deferred obligations related to contingent and fixed purchase price payments, and to a lesser extent, contingent and fixed retention payments tied to continued employment of specific personnel. Contingent deferred acquisition consideration is recorded at the acquisition date fair value and adjusted at each reporting period through operating income, for contingent purchase price payments, or net interest expense, for fixed purchase price payments. The Company accounts for retention payments through operating income as stock-based compensation over the required retention period. The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2019 and December 31, 2018 . September 30, December 31, 2019 2018 Beginning Balance of contingent payments $ 82,598 $ 119,086 Payments (30,719 ) (54,947 ) Redemption value adjustments (1) (2,617 ) 3,512 Additions - acquisitions and step-up transactions 6,344 14,943 Other 35 4 Ending Balance of contingent payments $ 55,641 $ 82,598 Fixed payments 549 1,097 $ 56,190 $ 83,695 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments and stock-based compensation charges relating to acquisition payments that are tied to continued employment. Redemption value adjustments are recorded within cost of services sold and office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s statement of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Income) loss attributable to fair value adjustments $ 1,943 $ 11,003 $ (3,627 ) $ 8,522 Stock-based compensation 1,540 3,076 1,010 7,758 Redemption value adjustments $ 3,483 $ 14,079 $ (2,617 ) $ 16,280

Deferred Acquisition Considerat

Deferred Acquisition Consideration	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Deferred Acquisition Consideration	Acquisitions and Dispositions 2019 Acquisition Effective April 1, 2019, the Company acquired the 35% ownership interest of HPR Partners LLC (Hunter) it did not own for an aggregate purchase price of $10,234 , comprised of a closing cash payment of $3,890 and additional deferred acquisition payments with an estimated present value at the acquisition date of $6,344 . The deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As of the acquisition date, the fair value of the additional interest acquired was $20,178 . The fair value was measured using a discounted cash flow model. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $9,486 . The difference between the purchase price and the noncontrolling interest of $745 was recorded in common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheet. 2019 Disposition On March 8, 2019, the Company consummated the sale of Kingsdale, an operating segment with operations in Toronto and New York City that provides shareholder advisory services. As consideration for the sale, the Company was paid cash plus the assumption of certain liabilities totaling approximately $50 million in the aggregate. The sale resulted in a loss of approximately $3 million , which is included in Other, net within the Unaudited Condensed Consolidated Statement of Operations. Assets and Liabilities Held for Sale - Change in Plan to Sell In the fourth quarter of 2018, the Company initiated a process to sell its ownership interest in a foreign office within the Global Integrated Agencies reportable segment. The assets and liabilities of the entity were classified as Assets and Liabilities held for sale, at their fair value less cost to sell, within the Consolidated Balance Sheet as of December 31, 2018. In the second quarter of 2019 , following the appointment of Mark Penn as Chief Executive Officer, management changed its strategy and plan to sell the foreign office. In the second quarter of 2019, in connection with management’s decision, the amounts classified within assets and liabilities held for sale were reclassified into the respective line items within the Unaudited Condensed Consolidated Balance Sheet. 2018 Acquisitions On September 7, 2018, a subsidiary of the Company purchased a 100% interest in OneChocolate Communications Limited and OneChocolate Communications LLC, PR (“OneChocolate”) a digital marketing consultancy headquartered in London, UK, for an aggregate purchase price of $3,231 , working capital of $966 and additional deferred acquisition payments with an estimated present value of $2,146 . OneChocolate’s results are reflected in the Allison & Partners operating segment which is included in the Specialist Communications reportable segment which had an immaterial impact on our results. On July 1, 2018, the Company acquired the remaining 14.87% and 3% of membership interests of Doner Partners, LLC and Source Marketing LLC, respectively, for an aggregate purchase price of $7,618 , comprised of a closing cash payment of $3,279 and additional deferred acquisition payments with an estimated present value of $4,305 as of December 31, 2018. As of the acquisition date, the fair value of the additional interests acquired was $16,361 for Doner Partners LLC. The fair values were measured using a discounted cash flow model. As a result of the transaction, the Company reduced noncontrolling interest by $11,946 and redeemable noncontrolling interest by $933 . On April 2, 2018, the Company purchased 51% of the membership interests of Instrument LLC (“Instrument”), a digital creative agency based in Portland, Oregon, for an aggregate purchase price of $35,591 . The acquisition is expected to facilitate the Company’s growth and help to build its portfolio of modern, innovative and digital-first agencies. The purchase price consisted of a cash payment of $28,561 and the issuance of 1,011,561 shares of the Company’s Class A subordinate voting stock with an acquisition date fair value of $7,030 . The Company issued these shares in a transaction exempt from the registration requirements of the Securities Act of 1933, as amended, pursuant to Section 4(a)(2) of the Securities Act. The purchase price allocation for Instrument resulted in tangible assets of $10,304 , identifiable intangibles of $23,130 , consisting primarily of customer lists and a trade name, and goodwill of $32,776 . In addition, the Company has recorded $27,357 as the fair value of noncontrolling interests, which was derived from the Company’s purchase price less a discount related to the noncontrolling parties’ lack of control. The identified assets have a weighted average useful life of approximately six 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. The goodwill is tax deductible. Instruments’ results are included in the All Other category from a segment reporting perspective. The Company has a controlling financial interest in Instrument through its majority voting interest, and as such, has aggregated the acquired Partner Firm’s financial data into the Company’s Unaudited Condensed Consolidated Financial Statements . The operating results of Instrument in the current year are not material. Effective January 1, 2018, the Company acquired the remaining 24.5% ownership interest of Allison & Partners LLC for an aggregate purchase price of $10,023 , comprised of a closing cash payment of $300 and additional deferred acquisition payments with an estimated present value at the acquisition date of $9,723 . The deferred payments are based on the future financial results of the underlying business from 2017 to 2020 with final payments due in 2021. As of the acquisition date, the fair value of the additional interest acquired was $20,096 . The fair value was measured using a discounted cash flow model. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $8,857 . The difference of $1,166 between the purchase price and the noncontrolling interest was recorded in additional paid-in capital. Deferred Acquisition Consideration Deferred acquisition consideration on the balance sheet consists of deferred obligations related to contingent and fixed purchase price payments, and to a lesser extent, contingent and fixed retention payments tied to continued employment of specific personnel. Contingent deferred acquisition consideration is recorded at the acquisition date fair value and adjusted at each reporting period through operating income, for contingent purchase price payments, or net interest expense, for fixed purchase price payments. The Company accounts for retention payments through operating income as stock-based compensation over the required retention period. The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2019 and December 31, 2018 . September 30, December 31, 2019 2018 Beginning Balance of contingent payments $ 82,598 $ 119,086 Payments (30,719 ) (54,947 ) Redemption value adjustments (1) (2,617 ) 3,512 Additions - acquisitions and step-up transactions 6,344 14,943 Other 35 4 Ending Balance of contingent payments $ 55,641 $ 82,598 Fixed payments 549 1,097 $ 56,190 $ 83,695 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments and stock-based compensation charges relating to acquisition payments that are tied to continued employment. Redemption value adjustments are recorded within cost of services sold and office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s statement of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Income) loss attributable to fair value adjustments $ 1,943 $ 11,003 $ (3,627 ) $ 8,522 Stock-based compensation 1,540 3,076 1,010 7,758 Redemption value adjustments $ 3,483 $ 14,079 $ (2,617 ) $ 16,280

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases Effective January 1, 2019, the Company adopted FASB ASC Topic 842, Leases (“ASC 842”). As a result, comparative prior periods have not been adjusted and continue to be reported under FASB ASC Topic 840, Leases. See Note 14 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the Company’s adoption of ASC 842. The policies described herein refer to those in effect as of January 1, 2019. The Company leases office space in North America, Europe, Asia, South America, and Australia. This space is primarily used for office and administrative purposes by the Company’s employees in performing professional services. These leases are classified as operating leases and expire between years 2019 through 2032. The Company’s finance leases are immaterial. The Company’s leasing policies are established in accordance with ASC 842, and accordingly, the Company recognizes on the balance sheet at the time of lease commencement a right-of-use lease asset and a lease liability, initially measured at the present value of the lease payments. Right-of-use lease assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. All right-of-use lease assets are reviewed for impairment. As the Company’s implicit rate in its leases is not readily determinable, in determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the commencement date. Lease payments included in the measurement of the lease liability are comprised of noncancelable lease payments, payments based upon an index or rate, payments for optional renewal periods where it is reasonably certain the renewal period will be exercised, and payments for early termination options unless it is reasonably certain the lease will not be terminated early. Lease costs are recognized in the Consolidated Statement of Operations over the lease term on a straight-line basis. 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. Some of the Company’s leases contain variable lease payments, including payments based upon an index or rate. Variable lease payments based upon an index or rate are initially measured using the index or rate in effect at the lease commencement date and are included within the lease liabilities. Lease liabilities are not remeasured as a result of changes in the index or rate, rather changes in these types of payments are recognized in the period in which the obligation for those payments is incurred. In addition, some of our leases contain variable payments for utilities, insurance, real estate tax, repairs and maintenance, and other variable operating expenses. Such amounts are not included in the measurement of the lease liability and are recognized in the period when the facts and circumstances on which the variable lease payments are based upon occur. The Company’s leases include options to extend or renew the lease through 2040. The renewal and extension options are not included in the lease term as the Company is not reasonably certain that it will exercise its option. From time to time, the Company enters into sublease arrangements both with unrelated third-parties and with our partner agencies. These leases are classified as operating leases and expire between years 2019 through 2032. Sublease income is recognized over the lease term on a straight-line basis. Currently, the Company subleases office space in North America, Europe and Australia. As of September 30, 2019 , the Company has entered into two operating leases for which the commencement date has not yet occurred as this leased space is in the process of being prepared by the landlord for occupancy. Accordingly, these leases represent an obligation of the Company that is not on the Consolidated Balance Sheet as of September 30, 2019 . The aggregate future liability related to these leases is approximately $12 million . The discount rate used for leases accounted for under ASC 842 is the Company’s collateralized credit adjusted borrowing rate. The following table presents lease costs and other quantitative information for the three and nine months ended September 30, 2019 : Three Months Ended September 30, Nine Months Ended September 30, 2019 2019 Lease Cost: Operating lease cost $ 16,605 $ 50,519 Variable lease cost 4,960 14,285 Sublease rental income (2,376 ) (6,565 ) Total lease cost $ 19,189 $ 58,239 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 16,988 $ 52,163 Right-of-use assets obtained in exchange for operating lease liabilities $ 8,783 $ 267,796 Weighted average remaining lease term (in years) - Operating leases 7.0 7.0 Weighted average discount rate - Operating leases 8.7 8.7 In the three months ended September 30, 2019 , the Company recorded an impairment charge of $1.9 million to reduce the carrying value of a right-of-use lease asset and related leasehold improvements of one of its agencies within its Global Integrated Agencies segment. The Company evaluated the facts and circumstances related to the use of the asset which indicated that it may not be recoverable. Using adjusted quoted market prices to develop expected future cash flows, it was determined that the fair value of the asset was less than its carrying value. This impairment charge is included in Other Asset Impairment within the Unaudited Condensed Consolidated Statement of Operations. Operating lease expense is included in office and general expenses in the Unaudited Condensed Consolidated Statement of Operations. The Company’s lease expense for leases with a term of 12 months or less is immaterial. Rental expense for the three and nine months ended September 30, 2018 was $15,768 and $49,309 , respectively, offset by $1,233 and $2,873 , respectively in sublease rental income. The following table presents minimum future rental payments under the Company’s leases at September 30, 2019 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2019 $ 17,454 2020 68,981 2021 58,759 2022 48,272 2023 43,732 Thereafter 139,476 Total 376,674 Less: Present value discount (98,743 ) Lease liability $ 277,931

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt As of September 30, 2019 and December 31, 2018 , the Company’s indebtedness was comprised as follows: September 30, 2019 December 31, 2018 Revolving credit agreement $ 8,091 $ 68,143 6.50% Notes due 2024 900,000 900,000 Debt issuance costs (12,712 ) (14,036 ) $ 895,379 $ 954,107 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 senior unsecured notes due 2024 (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, payable semiannually in arrears on May 1 and November 1, at a rate of 6.50% per annum. The 6.50% Notes mature on May 1, 2024 , unless earlier redeemed or repurchased. 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 , at varying prices based on the timing of the redemption. The Indenture includes covenants that 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. The Company was in compliance with all covenants at September 30, 2019 . Credit Agreement The Company is party to a $250,000 secured revolving credit facility due May 3, 2021. The amounts outstanding under the revolving credit facility as of September 30, 2019 and December 31, 2018 are presented in the table above and additional details are provided below. On March 12, 2019 (the “Amendment Effective Date”), the Company, Maxxcom Inc. (a subsidiary of the Company) (“Maxxcom”) and each of their subsidiaries party thereto entered into an Amendment to the existing senior secured revolving credit facility, dated as of May 3, 2016 (as amended, the “Credit Agreement”), among the Company, Maxxcom, each of their subsidiaries party thereto, Wells Fargo Capital Finance, LLC, as agent (“Wells Fargo”), 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. The Amendment provides financial covenant relief by increasing the total leverage ratio applicable on each testing date after the Amendment Effective Date through the period ending December 31, 2020 from 5.5 :1.0 to 6.25 :1.0. The total leverage ratio applicable on each testing date after December 31, 2020 will revert to 5.5 :1.0. In connection with the Amendment, the Company reduced the aggregate maximum amount of revolving commitments provided by the lenders under the Credit Agreement to $250 million from $325 million . 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 0.75% in the case of Base Rate Loans and 1.50% 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, which includes financial and non-financial covenants, is guaranteed by substantially all of MDC’s present and future subsidiaries, other than immaterial subsidiaries and subject to customary exceptions and collateralized by a portion of MDC’s outstanding receivable balance. The Company is currently in compliance with all of the terms and conditions of its Credit Agreement. At September 30, 2019 and December 31, 2018 , the Company had issued undrawn outstanding letters of credit of $4,744 and $4,701 , respectively.

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2019
Share Capital [Abstract]
Share Capital	Share Capital The authorized and outstanding share capital of the Company is as follows: Series 6 Convertible Preference Shares On March 14, 2019 (the “Series 6 Issue Date”), the Company entered into a securities purchase agreement with Stagwell Agency Holdings LLC (“Stagwell Holdings”), an affiliate of Stagwell Group LLC (“Stagwell”), pursuant to which Stagwell Holdings agreed to purchase (i) 14,285,714 newly authorized Class A shares (the “Stagwell Class A Shares”) for an aggregate contractual purchase price of $50,000 and (ii) 50,000 newly authorized Series 6 convertible preference shares (“Series 6 Preference Shares”) for an aggregate contractual purchase price of $50,000 . The Company received proceeds of approximately $98,620 , 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. The proceeds allocated to the Stagwell Class A Shares were $35,997 and to Series 6 Preference Shares were $62,623 based on their relative fair value calculated by utilizing a Monte Carlo Simulation model. In connection with the closing of the transaction, the Company increased the size of its Board of Directors (the “Board”) and appointed two nominees designated by Stagwell Holdings. Except as required by law, the Series 6 Preference Shares do not have voting rights and are not redeemable at the option of Stagwell Holdings. The holders of the Series 6 Preference Shares have the right to convert their Series 6 Preference Shares in whole at any time and from time to time, and in part at any time and from time to time, 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 preference per share of each Series 6 Preference Share is $1,000 . The initial Conversion Price is $5.00 per Series 6 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 Series 6 Preference Shares’ liquidation preference accretes at 8.0% per annum, compounded quarterly until the five -year anniversary of the Series 6 Issue Date. During the nine months ended September 30, 2019 , the Series 6 Preference Shares accreted at a monthly rate of $6.83 , for total accretion of $2,216 , bringing the aggregate liquidation preference to $52,217 as of September 30, 2019 . The accretion is considered in the calculation of net loss attributable to MDC Partners Inc. common shareholders. See Note 3 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information regarding the Series 6 Preference Shares. Holders of the Series 6 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 Series 6 Preference Shares. The Series 6 Preference Shares are convertible at the Company’s option (i) on and after the two -year anniversary of the Series 6 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 Series 6 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 Series 6 Preference Shares for cash at the greater of their liquidation preference plus accrued and unpaid dividends or their as-converted value. Effective March 18, 2019, the Company’s Board appointed Mark Penn as the Chief Executive Officer and as a director of the Board. Mr. Penn is manager of Stagwell. Effective April 18, 2019, Mr. Penn was also appointed as Chairman of the Board. Series 4 Convertible Preference Shares On March 7, 2017 (the “Series 4 Issue Date”), the Company issued 95,000 newly created Preference Shares (“Series 4 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 $90,123 , 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, the Company increased the size of its Board and appointed one nominee designated by the Purchaser. Except as required by law, the Series 4 Preference Shares do not have voting rights and are not redeemable at the option of the Purchaser. Subsequent to the ninetieth day following the Series 4 Issue Date, the holders of the Series 4 Preference Shares have the right to convert their Series 4 Preference Shares in whole at any time and from time to time and in part at any time and from time to time 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 preference per share of each Series 4 Preference Share is $1,000 . The Conversion Price of a Series 4 Preference Share is 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. In connection with the anti-dilution protection provision triggered by the issuance of equity securities to Stagwell Holdings, the Conversion Price per Series 4 Preference Share was reduced to $7.42 from the initial Conversion Price of $10.00 . The Series 4 Preference Shares’ liquidation preference accretes at 8.0% per annum, compounded quarterly until the five-year anniversary of the Series 4 Issue Date. During the nine months ended September 30, 2019 , the Series 4 Preference Shares accreted at a monthly rate of approximately $8.01 per Series 4 Preference Share, for total accretion of $6,715 , bringing the aggregate liquidation preference to $116,422 as of September 30, 2019 . The accretion is considered in the calculation of net income (loss) attributable to MDC Partners Inc. common shareholders. See Note 3 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information regarding the Series 4 Preference Shares. Holders of the Series 4 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 Series 4 Preference Shares. The Series 4 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 Series 4 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 Series 4 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 Series 4 Preference Shares for cash at the greater of their liquidation preference plus accrued and unpaid dividends or their as-converted value. Class A Common Shares (“Class A Shares”) These are an unlimited number of subordinate voting shares, carrying one vote each, entitled to dividends equal to or greater than Class B Shares, convertible at the option of the holder into one Class B Share for each Class A Share after the occurrence of certain events related to an offer to purchase all Class B shares. There were 72,142,668 (including the Class A Shares issued to Stagwell) and 57,517,568 Class A Shares issued and outstanding as of September 30, 2019 and December 31, 2018 , respectively. Class B Common Shares (“Class B Shares”) These are an unlimited number of voting shares, carrying twenty votes each, convertible at any time at the option of the holder into one Class A share for each Class B share. There were 3,749 and 3,755 Class B Shares issued and outstanding as of September 30, 2019 and December 31, 2018 , respectively.

Noncontrolling and Redeemable N

Noncontrolling and Redeemable Noncontrolling Interests	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Noncontrolling and Redeemable Noncontrolling Interests	When acquiring less than 100% ownership of an entity, 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 Unaudited Condensed Consolidated Balance Sheets . 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 amounts recorded in the Company’s Unaudited Condensed Consolidated Balance Sheets . Noncontrolling Interests Changes in amounts due to noncontrolling interest holders included in accruals and other liabilities on the Unaudited Condensed Consolidated Balance Sheets for the year ended December 31, 2018 and nine months ended September 30, 2019 were as follows: Noncontrolling Balance, December 31, 2017 $ 11,030 Income attributable to noncontrolling interests 11,785 Distributions made (13,419 ) Other (1) (118 ) Balance, December 31, 2018 $ 9,278 Income attributable to noncontrolling interests 10,737 Distributions made (9,982 ) Other (1) (36 ) Balance, September 30, 2019 $ 9,997 (1) Other consists of cumulative translation adjustments. Changes in the Company’s ownership interests in our less than 100% owned subsidiaries during the three and nine months ended September 30, 2019 and 2018 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Transfers from the noncontrolling interest: Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of redeemable noncontrolling interests and noncontrolling interests (648 ) 4,975 (745 ) 3,809 Net transfers from noncontrolling interests $ (648 ) $ 4,975 $ (745 ) $ 3,809 Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ (2,400 ) $ (11,150 ) $ 1,680 $ (38,326 ) Redeemable Noncontrolling Interests The following table presents changes in redeemable noncontrolling interests: Nine Months Ended September 30, 2019 Year Ended December 31, 2018 Beginning Balance $ 51,546 $ 62,886 Redemptions (9,486 ) (11,943 ) Granted — — Changes in redemption value (3,306 ) 1,067 Currency translation adjustments (190 ) (464 ) Other (1) 2,955 — Ending Balance $ 41,519 $ 51,546 (1) Other primarily consists of the redeemable noncontrolling interest balance related to a foreign entity that was classified as held for sale as of December 31, 2018 and reclassified in 2019. See Note 4 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information. 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 2019 to 2024. 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 redeemable noncontrolling interest of $41,519 as of September 30, 2019 , consists of $19,193 assuming that the subsidiaries perform over the relevant future periods at their discounted cash flows earnings level and such rights are exercised, $19,106 upon termination of such owner’s employment with the applicable subsidiary or death and $3,220 representing the initial redemption value (required floor) recorded for certain acquisitions in excess of the amount the Company would have to pay should the Company acquire the remaining ownership interests for such subsidiaries. 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 nine months ended September 30, 2019 and 2018 , there was no related impact on the Company’s loss per share calculation.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements A fair value measurement assumes a transaction to sell an asset or transfer a liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. The hierarchy for observable and unobservable inputs used to measure fair value into three broad levels are described below: • Level 1 - Quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities. The fair value hierarchy gives the highest priority to Level 1 inputs. • Level 2 - Observable prices that are based on inputs not quoted on active markets, but corroborated by market data. • Level 3 - Unobservable inputs are used when little or no market data is available. The fair value hierarchy gives the lowest priority to Level 3 inputs. Financial Liabilities that are not Measured at Fair Value on a Recurring Basis The following table presents certain information for our financial liability that is not measured at fair value on a recurring basis at September 30, 2019 and December 31, 2018 : September 30, 2019 December 31, 2018 Carrying Fair Value Carrying Fair Value Liabilities: 6.50% Senior Notes due 2024 $ 900,000 $ 823,500 $ 900,000 $ 834,750 Our long-term debt includes fixed rate debt. The fair value of this instrument is based on quoted market prices in markets that are not active. Therefore, this debt is classified as Level 2 within the fair value hierarchy. Financial Liabilities Measured at Fair Value on a Recurring Basis Contingent deferred acquisition consideration is recorded at the acquisition date fair value and adjusted at each reporting period. The estimated liability is determined in accordance with various contractual valuation formulas that may be dependent upon future events, such as the growth rate of the earnings of the relevant subsidiary during the contractual period and, in some cases, the currency exchange rate as of the date of payment (Level 3). See Note 5 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding contingent deferred acquisition consideration. At September 30, 2019 and December 31, 2018 , the carrying amount of the Company’s financial instruments, including cash and cash equivalents, accounts receivable and accounts payable, approximated fair value because of their short-term maturity. Non-financial Assets and Liabilities that are Measured at Fair Value on a Nonrecurring Basis Certain non-financial assets are measured at fair value on a nonrecurring basis, primarily goodwill and intangible assets (a Level 3 fair value assessment) and right-of-use lease assets (Level 2 fair value assessment). Accordingly, these assets are not measured and adjusted to fair value on an ongoing basis but are subject to periodic evaluations for potential impairment. The Company did not recognize an impairment of goodwill or intangible assets in the three and nine months ended September 30, 2019 as compared to an impairment of goodwill, intangible assets, and other assets of $21.0 million and $ 23.3 million in the three and nine months ended September 30, 2018 respectively. See Note 11 of the Notes to the Unaudited Condensed Consolidated Financial Statements for information related to the measurement of the fair value of goodwill and the impairment. In addition, the Company recognized an impairment charge of $1.9 million to reduce the carrying value of a right-of-use lease asset and related leasehold improvements in the three months ended September 30, 2019 . See Note 6 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information.

Supplemental Information

Supplemental Information	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Accounts Payable, Accruals and Other Liabilities At September 30, 2019 and December 31, 2018 , accruals and other liabilities included accrued media of $163,777 and $180,586 , respectively; and also included amounts due to noncontrolling interest holders for their share of profits. See Note 9 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding noncontrolling interest holders share of profits. Goodwill and Indefinite Lived Intangibles Goodwill and indefinite life 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. Goodwill balances as of each of September 30, 2019 and December 31, 2018 , were $740,955 . Income Taxes Our tax provision for interim periods is determined using an estimated annual effective tax rate, adjusted for discrete items arising in interim periods. Income tax expense for the three months ended September 30, 2019 was $3,457 (on income of $8,907 resulting in an effective tax rate of 38.8% ) compared to an expense of $2,986 (on loss of $10,981 resulting in an effective tax rate of 27.2% ) for the three months ended September 30, 2018 . Income tax expense for the nine months ended September 30, 2019 was $6,292 (on income of $19,102 resulting in an effective tax rate of 32.9%) compared to a benefit of $3,367 (on a loss of $39,960 resulting in an effective tax rate of 8.4% ) for the nine months ended September 30, 2018 . The income tax expense and benefit for the three and nine months of 2018, respectively, were impacted by impairments and non-deductible stock compensation for which a tax benefit was not recognized.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company determines an operating segment if a component (i) engages in business activities from which it earns revenues and incurs expenses, (ii) has discrete financial information, and is (iii) regularly reviewed by the Chief Operating Decision Maker (“CODM”) to make decisions regarding resource allocation for the segment and assess its performance. Once operating segments are identified, the Company performs an analysis to determine if aggregation of operating segments is applicable. This determination is based upon a quantitative analysis of the expected and historic average long-term profitability for each operating segment, together with a qualitative assessment to determine if operating segments have similar operating characteristics. Due to changes in the composition of certain businesses and the Company’s internal management and reporting structure during 2019, reportable segment results for the 2018 periods presented have been recast to reflect the reclassification of certain businesses between segments. The changes were as follows: • Doner, previously within the Global Integrated Agencies reportable segment is now included within the Domestic Creative Agencies reportable segment. • HL Group Partners, previously within the Specialist Communications reportable segment, and Redscout, previously within the All Other category, are now included in the Yes & Company operating segment. The Yes & Company operating segment previously within the Media Services reportable segment is now included within the Domestic Creative Agencies reportable segment. • Attention, previously within the Forsman & Bodenfors operating segment, has operationally merged into MDC Media Partners, which is included within the Media Services reportable segment. • Varick Media, previously within the Yes & Company operating segment, is now included within MDC Media Partners, which is included within the Media Services reportable segment. The four reportable segments that result from applying the aggregation criteria are as follows: “Global Integrated Agencies”; “Domestic Creative Agencies”; “Specialist Communications”; and “Media Services.” In addition, the Company combines and discloses those operating segments that do not meet the aggregation criteria as “All Other.” The Company also reports corporate expenses, as further detailed below, as “Corporate.” All segments follow the same basis of presentation and accounting policies as those described throughout the Notes to the Unaudited Condensed Consolidated Financial Statements included herein and Note 2 of the Company’s Form 10-K for the year ended December 31, 2018. • The Global Integrated Agencies reportable segment is comprised of the Company’s four global, integrated operating segments (72andSunny, Anomaly, Crispin Porter + Bogusky, and Forsman & Bodenfors) serving multinational clients around the world. These operating segments share similar characteristics related to (i) the nature of their services; (ii) the type of global clients and the methods used to provide services; and (iii) the extent to which they may be impacted by global economic and geopolitical risks. In addition, these operating segments compete with each other for new business and from time to time have business move between them. The Company believes the historic and expected average long-term profitability is similar among the operating segments aggregated in the Global Integrated Agencies reportable segment. The operating segments within the Global Integrated Agencies reportable segment provides a range of different services for its clients, including strategy, creative and production for advertising campaigns across a variety of platforms (print, digital, social media, television broadcast). • The Domestic Creative Agencies reportable segment is comprised of seven operating segments that are primarily national advertising agencies (Colle McVoy, Doner, Laird + Partners, Mono Advertising, Union, Yamamoto, and Yes & Company) leveraging creative capabilities at their core. These operating segments share similar characteristics related to (i) the nature of their services; (ii) the type of domestic client accounts and the methods used to provide services; and (iii) the extent to which they may be impacted by domestic economic and policy factors within North America. In addition, these operating segments compete with each other for new business and from time to time have business move between them. The Company believes the historic and expected average long-term profitability is similar among the operating segments aggregated in the Domestic Creative Agencies reportable segment. The operating segments within the Domestic Creative Agencies reportable segment provide similar services as the Global Integrated Agencies. • The Specialist Communications reportable segment is comprised of four operating segments that are each communications agencies (Allison & Partners, Hunter, KWT Global, and Veritas) with core service offerings in public relations and related communications services. These operating segments share similar characteristics related to (i) the nature of their services; (ii) the type of client accounts and the methods used to provide services; (iii) the extent to which they may be impacted by domestic economic and policy factors within North America; and (iv) the regulatory environment regarding public relations and social media. In addition, these operating segments compete with each other for new business and from time to time have business move between them. The Company believes the historic and expected average long-term profitability is similar among the operating segments aggregated in the Specialist Communications reportable segment. The operating segments within the Specialist Communications reportable segment provide public relations and communications services including strategy, editorial, crisis support or issues management, media training, influencer engagement, and events management. • The Media Services reportable segment is comprised of a single operating segment known as MDC Media Partners. MDC Media Partners, which operates primarily in North America, performs media buying and planning as its core competency across a range of platforms (out-of-home, paid search, social media, lead generation, programmatic, television broadcast). • All Other consists of the Company’s remaining operating segments that provide a range of diverse marketing communication services, but generally do not have similar services offerings or financial characteristics as those aggregated in the reportable segments. The All Other category includes 6Degrees Communications, Concentric Partners, Gale Partners, Kenna, Kingsdale (through the date of sale on March 8, 2019), Instrument, Relevent, Team, Vitro, and Y Media Labs. The nature of the specialist services provided by these operating segments vary among each other and from those operating segments aggregated into the reportable segments. This results in these operating segments having current and long-term performance expectations inconsistent with those operating segments aggregated in the reportable segments. The operating segments within All Other provide a range of diverse marketing communication services, including application and website design and development, data and analytics, experiential marketing, customer research management, creative services, and branding. • Corporate consists of corporate office expenses incurred in connection with the strategic resources provided to the operating segments, as well as certain other centrally managed expenses that are not fully allocated to the operating segments. These office and general expenses include (i) salaries and related expenses for corporate office employees, including employees dedicated to supporting the operating segments, (ii) occupancy expenses relating to properties occupied by all corporate office employees, (iii) other office and general expenses including professional fees for the financial statement audits and other public company costs, and (iv) certain other professional fees managed by the corporate office. Additional expenses managed by the corporate office that are directly related to the operating segments are allocated to the appropriate reportable segment and the All Other category. Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Revenue: Global Integrated Agencies $ 145,890 $ 157,308 $ 429,977 $ 444,995 Domestic Creative Agencies 57,593 59,151 176,711 183,504 Specialist Communications 42,101 38,838 128,224 117,966 Media Services 21,222 29,593 75,815 90,948 All Other 76,101 90,940 223,101 245,128 Total $ 342,907 $ 375,830 $ 1,033,828 $ 1,082,541 Segment operating income (loss): Global Integrated Agencies $ 21,036 $ 23,486 $ 45,527 $ 28,247 Domestic Creative Agencies 7,216 (14,031 ) 22,533 (6,887 ) Specialist Communications 5,129 3,703 18,889 13,646 Media Services (1,677 ) 850 (3,630 ) (78 ) All Other 6,828 6,634 15,790 29,065 Corporate (9,111 ) (18,024 ) (30,565 ) (45,236 ) Total $ 29,421 $ 2,618 $ 68,544 $ 18,757 Other Income (Expenses): Interest expense and finance charges, net $ (16,110 ) $ (17,063 ) $ (49,284 ) $ (50,005 ) Foreign exchange gain (loss) (3,973 ) 3,275 4,401 (9,934 ) Other, net (431 ) 189 (4,559 ) 1,222 Income (loss) before income taxes and equity in earnings of non-consolidated affiliates 8,907 (10,981 ) 19,102 (39,960 ) Income tax expense (benefit) 3,457 2,986 6,292 (3,367 ) Income (loss) before equity in earnings of non-consolidated affiliates 5,450 (13,967 ) 12,810 (36,593 ) Equity in earnings of non-consolidated affiliates 63 300 352 358 Net income (loss) 5,513 (13,667 ) 13,162 (36,235 ) Net income attributable to the noncontrolling interest (7,265 ) (2,458 ) (10,737 ) (5,900 ) Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Depreciation and amortization: Global Integrated Agencies $ 4,009 $ 4,553 $ 12,511 $ 16,705 Domestic Creative Agencies 1,213 1,266 3,708 3,793 Specialist Communications 644 1,100 1,909 3,059 Media Services 755 675 2,531 1,995 All Other 2,555 3,341 7,580 9,077 Corporate 192 199 630 583 Total $ 9,368 $ 11,134 $ 28,869 $ 35,212 Stock-based compensation: Global Integrated Agencies $ 4,673 $ 3,241 $ 9,672 $ 8,176 Domestic Creative Agencies 352 550 1,338 2,056 Specialist Communications 45 52 123 291 Media Services 5 102 (11 ) 251 All Other 118 677 1,058 2,019 Corporate 833 1,620 452 4,089 Total $ 6,026 $ 6,242 $ 12,632 $ 16,882 Capital expenditures: Global Integrated Agencies $ 3,470 $ 1,927 $ 6,704 $ 6,581 Domestic Creative Agencies 694 967 1,757 2,440 Specialist Communications 198 732 680 3,176 Media Services (2 ) 385 165 699 All Other 1,492 1,500 4,450 2,271 Corporate 11 32 30 65 Total $ 5,863 $ 5,543 $ 13,786 $ 15,232 The Company’s CODM does not use segment assets to allocate resources or to assess performance of the segments and therefore, total segment assets have not been disclosed. See Note 2 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for a summary of the Company’s revenue by geographic region for three and nine months ended September 30, 2019 and 2018 .

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies, and Guarantees 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. Deferred Acquisition Consideration and Options to Purchase. See Notes 5 and 9 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for information regarding potential payments associated with deferred acquisition consideration and the acquisition of noncontrolling shareholders’ ownership interest in subsidiaries. Natural Disasters. Certain of the Company’s operations are located in regions of the United States which typically are subject to hurricanes. During the three and nine months ended September 30, 2019 and 2018 , these operations did not incur any material 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. Commitments. At September 30, 2019 , the Company had $4,744 of undrawn letters of credit.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements Adopted In The Current Reporting Period Effective January 1, 2019, the Company adopted ASC 842. As a result, comparative prior periods have not been adjusted and continue to be reported under FASB ASC Topic 840, Leases. With the adoption of ASC 842, the Company has elected to apply the package of practical expedients: (1) whether a contract is or contains a lease, (2) the classification of existing leases, and (3) whether previously capitalized costs continue to qualify as initial indirect costs. Additionally, the Company elected the practical expedient to not separate non-lease components from lease components for all operating leases. The adoption of ASC 842 had a material impact on the Company’s Unaudited Condensed Consolidated Balance Sheets , resulting in the recognition, on January 1, 2019, of a lease liability of $299,243 which represents the present value of the remaining lease payments, and a right-of-use lease asset of $254,245 which represents the lease liability, offset by adjustments as appropriate under ASC 842. The adoption of ASC 842 did not have a material impact on the Company’s other Unaudited Condensed Consolidated Financial Statements .

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
By Location
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue		The following table presents revenue disaggregated by geography for the three and nine months ended September 30, 2019 and 2018 :
Industry Vertical
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The following table presents revenue disaggregated by client industry vertical for the three and nine months ended September 30, 2019 and 2018 : Three Months Ended September 30, Nine Months Ended September 30, Industry Reportable Segment 2019 2018 2019 2018 Food & Beverage All $ 64,774 $ 80,919 $ 204,743 $ 234,203 Retail All 39,420 40,421 111,899 116,832 Consumer Products All 38,510 40,124 119,866 118,097 Communications All 48,147 46,779 136,819 128,232 Automotive All 19,125 21,282 55,857 67,070 Technology All 28,148 26,005 84,294 71,085 Healthcare All 25,152 33,751 74,403 101,753 Financials All 28,054 30,378 81,049 83,079 Transportation and Travel/Lodging All 20,541 19,357 65,111 53,021 Other All 31,036 36,814 99,787 109,169 $ 342,907 $ 375,830 $ 1,033,828 $ 1,082,541

Loss Per Common Share (Tables)

Loss Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Accretion on convertible preference shares (3,306 ) (2,109 ) (8,931 ) (6,204 ) Net income allocated to convertible preference shares — — — — Net loss attributable to MDC Partners Inc. common shareholders $ (5,058 ) $ (18,234 ) $ (6,506 ) $ (48,339 ) Adjustment to net income allocated to convertible preference shares — — — — Numerator for dilutive loss per common share: Net loss attributable to MDC Partners Inc. common shareholders $ (5,058 ) $ (18,234 ) $ (6,506 ) $ (48,339 ) Denominator: Basic weighted average number of common shares outstanding 72,044,480 57,498,661 68,154,306 57,117,797 Effect of dilutive securities: Impact of stock options and non-vested stock under employee stock incentive plans — — — — Diluted weighted average number of common shares outstanding 72,044,480 57,498,661 68,154,306 57,117,797 Basic $ (0.07 ) $ (0.32 ) $ (0.10 ) $ (0.85 ) Diluted $ (0.07 ) $ (0.32 ) $ (0.10 ) $ (0.85 )

Deferred Acquisition Consider_2

Deferred Acquisition Consideration (Tables)	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Schedule of Changes in Contingent Deferred Acquisition Consideration	The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2019 and December 31, 2018 . September 30, December 31, 2019 2018 Beginning Balance of contingent payments $ 82,598 $ 119,086 Payments (30,719 ) (54,947 ) Redemption value adjustments (1) (2,617 ) 3,512 Additions - acquisitions and step-up transactions 6,344 14,943 Other 35 4 Ending Balance of contingent payments $ 55,641 $ 82,598 Fixed payments 549 1,097 $ 56,190 $ 83,695 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments and stock-based compensation charges relating to acquisition payments that are tied to continued employment. Redemption value adjustments are recorded within cost of services sold and office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s statement of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Income) loss attributable to fair value adjustments $ 1,943 $ 11,003 $ (3,627 ) $ 8,522 Stock-based compensation 1,540 3,076 1,010 7,758 Redemption value adjustments $ 3,483 $ 14,079 $ (2,617 ) $ 16,280

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease Costs and Other Quantitative Information	The following table presents lease costs and other quantitative information for the three and nine months ended September 30, 2019 : Three Months Ended September 30, Nine Months Ended September 30, 2019 2019 Lease Cost: Operating lease cost $ 16,605 $ 50,519 Variable lease cost 4,960 14,285 Sublease rental income (2,376 ) (6,565 ) Total lease cost $ 19,189 $ 58,239 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 16,988 $ 52,163 Right-of-use assets obtained in exchange for operating lease liabilities $ 8,783 $ 267,796 Weighted average remaining lease term (in years) - Operating leases 7.0 7.0 Weighted average discount rate - Operating leases 8.7 8.7
Minimum Future Rental Payments	The following table presents minimum future rental payments under the Company’s leases at September 30, 2019 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2019 $ 17,454 2020 68,981 2021 58,759 2022 48,272 2023 43,732 Thereafter 139,476 Total 376,674 Less: Present value discount (98,743 ) Lease liability $ 277,931

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Debt	September 30, 2019 December 31, 2018 Revolving credit agreement $ 8,091 $ 68,143 6.50% Notes due 2024 900,000 900,000 Debt issuance costs (12,712 ) (14,036 ) $ 895,379 $ 954,107

Noncontrolling and Redeemable_2

Noncontrolling and Redeemable Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Change In Noncontrolling Interest [Table Text Block]	Changes in amounts due to noncontrolling interest holders included in accruals and other liabilities on the Unaudited Condensed Consolidated Balance Sheets for the year ended December 31, 2018 and nine months ended September 30, 2019 were as follows: Noncontrolling Balance, December 31, 2017 $ 11,030 Income attributable to noncontrolling interests 11,785 Distributions made (13,419 ) Other (1) (118 ) Balance, December 31, 2018 $ 9,278 Income attributable to noncontrolling interests 10,737 Distributions made (9,982 ) Other (1) (36 ) Balance, September 30, 2019 $ 9,997
Noncontrolling Interest [Table Text Block]	Changes in the Company’s ownership interests in our less than 100% owned subsidiaries during the three and nine months ended September 30, 2019 and 2018 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Transfers from the noncontrolling interest: Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of redeemable noncontrolling interests and noncontrolling interests (648 ) 4,975 (745 ) 3,809 Net transfers from noncontrolling interests $ (648 ) $ 4,975 $ (745 ) $ 3,809 Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ (2,400 ) $ (11,150 ) $ 1,680 $ (38,326 )
Redeemable Noncontrolling Interest [Table Text Block]	The following table presents changes in redeemable noncontrolling interests: Nine Months Ended September 30, 2019 Year Ended December 31, 2018 Beginning Balance $ 51,546 $ 62,886 Redemptions (9,486 ) (11,943 ) Granted — — Changes in redemption value (3,306 ) 1,067 Currency translation adjustments (190 ) (464 ) Other (1) 2,955 — Ending Balance $ 41,519 $ 51,546

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Liability Measured on a Non-recurring Basis	The following table presents certain information for our financial liability that is not measured at fair value on a recurring basis at September 30, 2019 and December 31, 2018 : September 30, 2019 December 31, 2018 Carrying Fair Value Carrying Fair Value Liabilities: 6.50% Senior Notes due 2024 $ 900,000 $ 823,500 $ 900,000 $ 834,750

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Revenue: Global Integrated Agencies $ 145,890 $ 157,308 $ 429,977 $ 444,995 Domestic Creative Agencies 57,593 59,151 176,711 183,504 Specialist Communications 42,101 38,838 128,224 117,966 Media Services 21,222 29,593 75,815 90,948 All Other 76,101 90,940 223,101 245,128 Total $ 342,907 $ 375,830 $ 1,033,828 $ 1,082,541 Segment operating income (loss): Global Integrated Agencies $ 21,036 $ 23,486 $ 45,527 $ 28,247 Domestic Creative Agencies 7,216 (14,031 ) 22,533 (6,887 ) Specialist Communications 5,129 3,703 18,889 13,646 Media Services (1,677 ) 850 (3,630 ) (78 ) All Other 6,828 6,634 15,790 29,065 Corporate (9,111 ) (18,024 ) (30,565 ) (45,236 ) Total $ 29,421 $ 2,618 $ 68,544 $ 18,757 Other Income (Expenses): Interest expense and finance charges, net $ (16,110 ) $ (17,063 ) $ (49,284 ) $ (50,005 ) Foreign exchange gain (loss) (3,973 ) 3,275 4,401 (9,934 ) Other, net (431 ) 189 (4,559 ) 1,222 Income (loss) before income taxes and equity in earnings of non-consolidated affiliates 8,907 (10,981 ) 19,102 (39,960 ) Income tax expense (benefit) 3,457 2,986 6,292 (3,367 ) Income (loss) before equity in earnings of non-consolidated affiliates 5,450 (13,967 ) 12,810 (36,593 ) Equity in earnings of non-consolidated affiliates 63 300 352 358 Net income (loss) 5,513 (13,667 ) 13,162 (36,235 ) Net income attributable to the noncontrolling interest (7,265 ) (2,458 ) (10,737 ) (5,900 ) Net income (loss) attributable to MDC Partners Inc. $ (1,752 ) $ (16,125 ) $ 2,425 $ (42,135 ) Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Depreciation and amortization: Global Integrated Agencies $ 4,009 $ 4,553 $ 12,511 $ 16,705 Domestic Creative Agencies 1,213 1,266 3,708 3,793 Specialist Communications 644 1,100 1,909 3,059 Media Services 755 675 2,531 1,995 All Other 2,555 3,341 7,580 9,077 Corporate 192 199 630 583 Total $ 9,368 $ 11,134 $ 28,869 $ 35,212 Stock-based compensation: Global Integrated Agencies $ 4,673 $ 3,241 $ 9,672 $ 8,176 Domestic Creative Agencies 352 550 1,338 2,056 Specialist Communications 45 52 123 291 Media Services 5 102 (11 ) 251 All Other 118 677 1,058 2,019 Corporate 833 1,620 452 4,089 Total $ 6,026 $ 6,242 $ 12,632 $ 16,882 Capital expenditures: Global Integrated Agencies $ 3,470 $ 1,927 $ 6,704 $ 6,581 Domestic Creative Agencies 694 967 1,757 2,440 Specialist Communications 198 732 680 3,176 Media Services (2 ) 385 165 699 All Other 1,492 1,500 4,450 2,271 Corporate 11 32 30 65 Total $ 5,863 $ 5,543 $ 13,786 $ 15,232

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Services	$ 342,907	$ 375,830	$ 1,033,828	$ 1,082,541
United States
Disaggregation of Revenue [Line Items]
Services	271,671	296,544	819,347	848,336
Canada
Disaggregation of Revenue [Line Items]
Services	25,895	32,132	72,837	91,597
Other
Disaggregation of Revenue [Line Items]
Services	45,341	47,154	141,644	142,608
Food & Beverage
Disaggregation of Revenue [Line Items]
Services	64,774	80,919	204,743	234,203
Retail
Disaggregation of Revenue [Line Items]
Services	39,420	40,421	111,899	116,832
Consumer Products
Disaggregation of Revenue [Line Items]
Services	38,510	40,124	119,866	118,097
Communications
Disaggregation of Revenue [Line Items]
Services	48,147	46,779	136,819	128,232
Automotive
Disaggregation of Revenue [Line Items]
Services	19,125	21,282	55,857	67,070
Technology
Disaggregation of Revenue [Line Items]
Services	28,148	26,005	84,294	71,085
Healthcare
Disaggregation of Revenue [Line Items]
Services	25,152	33,751	74,403	101,753
Financials
Disaggregation of Revenue [Line Items]
Services	28,054	30,378	81,049	83,079
Transportation and Travel/Lodging
Disaggregation of Revenue [Line Items]
Services	20,541	19,357	65,111	53,021
Other
Disaggregation of Revenue [Line Items]
Services	$ 31,036	$ 36,814	$ 99,787	$ 109,169

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Unbilled service fees		$ 81,703	$ 64,362
Unbilled outside vendor costs, billable to clients		38,652	42,369
Advance billings		$ 169,857	$ 138,505
Revenue recognized	$ 114,927

Loss Per Common Share (Details)

Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.	$ (1,752)	$ (16,125)	$ (16,125)	$ (42,135)	$ 2,425	$ (42,135)
Numerator
Accretion on and net income allocated to convertible preference shares		2,109
Net loss attributable to MDC Partners Inc. common shareholders	$ (5,058)	$ (18,234)			$ (6,506)	$ (48,339)
Denominator
Denominator for basic income (loss) per common share - weighted average common shares	72,044,480	57,498,661			68,154,306	57,117,797
Weighted Average Number Diluted Shares Outstanding Adjustment	0	0			0	0
Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions	72,044,480	57,498,661			68,154,306	57,117,797
Income (loss) from continuing operations attributable to MDC Partners Inc. common shareholders (usd per share)	$ (0.07)	$ (0.32)			$ (0.10)	$ (0.85)
Income (loss) from continuing operations attributable to MDC Partners Inc. common shareholders (usd per share)	$ (0.07)	$ (0.32)			$ (0.10)	$ (0.85)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,714,595,000
Adjustment to Net Income, Allocated to Convertible Shares	$ 0	$ 0			$ 0	$ 0
Income (Loss) from Continuing Operations Attributable to Parent, Diluted	(5,058)	(18,234)			(6,506)	(48,339)
MDC Partners Inc. Shareholders' Deficit
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.			$ (16,125)	$ (42,135)
Series 4 Convertible Preferred Stock | Convertible Preferred Stock
Numerator
Accretion on and net income allocated to convertible preference shares	3,306	2,109			8,931	$ 6,204
Net Income Allocated to Convertible Shares	0	$ 0			$ 0
Denominator
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,524,218,000			3,714,595,000	1,524,218,000
Series 4 Convertible Preferred Stock [Domain] | Convertible Preferred Stock
Numerator
Accretion on and net income allocated to convertible preference shares	$ 3,306					$ 6,204
Net Income Allocated to Convertible Shares						$ 0

Loss Per Common Share (Details

Loss Per Common Share (Details Textual) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	3,714,595,000
Contingent Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)			135,386	1,015,637
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares outstanding (shares)	145,000,000		145,000,000			95,000,000
Series 4 Convertible Preferred Stock | Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)		1,524,218,000	3,714,595,000	1,524,218,000
Shares outstanding (shares)	145,000,000		145,000,000				95,000
Convertible preferred stock, common shares issuable upon conversion (shares)	26,133,613		26,133,613		10,755,602

Acquisitions and Dispositions (

Acquisitions and Dispositions (Details Textual) - USD ($)

Apr. 01, 2019

Mar. 08, 2019

Sep. 07, 2018

Jul. 01, 2018

Apr. 02, 2018

Jan. 01, 2018

Sep. 30, 2019

Mar. 31, 2019

Jun. 30, 2018

Jun. 30, 2018

Sep. 30, 2019

Dec. 31, 2018

Business Acquisition [Line Items]

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases

$ 6,344,000

Goodwill

$ 740,955,000

740,955,000

Deferred acquisition consideration

56,190,000

56,190,000

Business acquisitions and step-up transactions, net of tax

$ (648,000)

$ (6,972,000)

$ 19,219,000

Granted

$ 0

$ 0

Aggregate 2019 Step-up Transaction [Member]

Business Acquisition [Line Items]

Closing cash payment

$ 4,000

Business Acquisition Deferred Acquisition Consideration

$ 6,344

Aggregate 2018 Step-up Transaction [Member] [Member]

Business Acquisition [Line Items]

Closing cash payment

$ 3,279,000

Business Acquisition Deferred Acquisition Consideration

4,305

Instrument LLC [Member]

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

51.00%

Business Combination, Consideration Transferred, Other

$ 10,304,000

Finite-lived Intangible Assets Acquired

23,130,000

Goodwill

32,776

Aggregate purchase price

35,591,000

Closing cash payment

28,561,000

Granted

$ 27,357,000

Acquired Finite-lived Intangible Assets, Weighted Average Useful Life

6 years

Allison & Partners LLC

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

24.50%

Aggregate purchase price

$ 10,023,000

Closing cash payment

300,000

Deferred acquisition consideration

9,723,000

Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination

20,096

Business acquisitions and step-up transactions, net of tax

(8,857,000)

Granted

$ 1,166,000

Common Stock [Member]

Business Acquisition [Line Items]

Stock Issued During Period, Shares, Acquisitions

1,011,561

Hunter PR LLC [Member] [Domain]

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

35.00%

Aggregate purchase price

$ 10,000

Reduction in noncontrolling interests

$ 9,000

OneChocolate [Domain]

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

100.00%

Aggregate purchase price

$ 3,231,000

Business Acquisition Working Capital Payments

966

Doner [Domain]

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

14.87%

Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination

$ 16,361

Source [Domain]

Business Acquisition [Line Items]

Remaining ownership interest acquired (percent)

3.00%

Doner and Source [Domain]

Business Acquisition [Line Items]

Aggregate purchase price

$ 7,618,000

Business acquisitions and step-up transactions, net of tax

(11,946,000)

Reduction in noncontrolling interests

$ 933,000

Common Class A [Member] | Common Stock [Member]

Business Acquisition [Line Items]

Stock Issued During Period, Value, Acquisitions

$ 7,030,000

Common Class A [Member] | Common Stock [Member] | Instrument LLC [Member]

Business Acquisition [Line Items]

Stock Issued During Period, Shares, Acquisitions

1,011,561

Stock Issued During Period, Value, Acquisitions

$ 7,030,000

Kingsdale Partners LP [Member]

Business Acquisition [Line Items]

Proceeds from Divestiture of Businesses

$ 50,000,000

Loss on disposition of business

$ (3,000,000)

Deferred Acquisition Consider_3

Deferred Acquisition Consideration (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments			$ 30,719
Redemption value adjustments	$ 3,483	$ 14,079	(2,617)
Additions			6,344
Foreign translation adjustment			35
Ending balance of contingent payments	55,641		55,641
Deferred acquisition consideration	56,190		56,190
Stock-based compensation	1,540	3,076	1,010	$ 7,758
Fixed payments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deferred acquisition consideration					$ 549
Contingent Payment
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
(Income) loss attributable to fair value adjustments	$ 1,943	$ 11,003	$ (3,627)	$ 8,522

Leases - Lease Costs and Other

Leases - Lease Costs and Other Quantitative Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Leases [Abstract]
Operating lease cost	$ 16,605	$ 49	$ 50,519	$ 15,768
Variable lease cost	4,960		14,285
Sublease rental income	(2,376)	$ (1,233)	(6,565)	$ (3)
Total lease cost	19,189		58,239
Operating cash flows	16,988		52,163
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 8,783		$ 267,796
Weighted average remaining lease term (in years) - Operating leases	7 years 18 days		7 years 18 days
Weighted average discount rate - Operating leases	866.00%		866.00%

Leases - Minimum Future Rental

Leases - Minimum Future Rental Payments (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Remaining 2019	$ 17,454
2020	68,981
2021	58,759
2022	48,272
2023	43,732
Thereafter	139,476
Total	376,674
Less: Present value discount	(98,743)
Lease liability	$ 277,931

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Leases [Abstract]
Leases not yet commenced, liability					$ 12,000
Operating lease cost	$ 16,605	$ 49	$ 50,519	$ 15,768
Sublease rental income	$ 2,376	$ 1,233	$ 6,565	$ 3

Debt (Details)

Debt (Details) $ in Thousands	Sep. 30, 2019USD ($)
Debt [Line Items]
Revolving credit agreement	$ 8,091
Debt issuance costs	(12,712)
Debt, Long-term and Short-term, Combined Amount, Total	895,379
6.50% Notes due 2024
Debt [Line Items]
Senior Notes	$ 900,000

Debt (Details Textual)

Debt (Details Textual)	May 01, 2024	Mar. 23, 2016USD ($)	Jun. 30, 2018	Dec. 31, 2020	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 12, 2019USD ($)	Sep. 30, 2018	May 03, 2016USD ($)
Debt [Line Items]
Amount outstanding under the line of credit					$ 8,091,000
Amount of letters of credit outstanding					$ 4,744,000	$ 4,744,000
Wells Fargo Capital Finance, LLC | Base Rate
Debt [Line Items]
Interest rate, stated percentage									1.50%
Wells Fargo Capital Finance, LLC | Non-Prime Rate and Prime Rate on European Advances
Debt [Line Items]
Interest rate, stated percentage									0.75%
Wells Fargo Capital Finance, LLC | Revolving Credit Facility [Member]
Debt [Line Items]
Maximum borrowing capacity									$ 325,000,000
Ratio of Indebtedness to Net Capital									5.5
Senior Notes | 6.50% Notes due 2024
Debt [Line Items]
Aggregate principal amount		$ 900,000
Interest rate, stated percentage		6.50%						6.50%
Debt instrument, maturity date		May 1, 2024
Debt instrument, redemption date, one			May 1, 2019
Line of Credit [Member] | Amendment, Credit Agreement [Member]
Debt [Line Items]
Maximum borrowing capacity							$ 250,000,000
Ratio of Indebtedness to Net Capital							6.25
Forecast | Wells Fargo Capital Finance, LLC | 6.50% Notes due 2024
Debt [Line Items]
Debt instrument, maturity date	May 1, 2024
Forecast | Line of Credit [Member] | Amendment, Credit Agreement [Member]
Debt [Line Items]
Ratio of Indebtedness to Net Capital				5.5

Share Capital (Details Textual)

Share Capital (Details Textual) $ / shares in Units, $ in Thousands	Mar. 14, 2019USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2019USD ($)voteshares	Sep. 30, 2018USD ($)	Oct. 18, 2019shares	Dec. 31, 2018shares	Mar. 31, 2018shares	Dec. 31, 2017shares	Mar. 07, 2017$ / shares
Share Capital [Line Items]
Issuance of common and convertible preference shares				$ 98,620
Expenses for convertible preference shares			$ (97)
Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Proceeds from issuance of common and convertible preference shares, net of issuance costs				$ 98,620	$ 0
Preferred Stock
Share Capital [Line Items]
Proceeds from issuance of common and convertible preference shares, net of issuance costs	$ 98,620
Shares outstanding (shares) | shares				145,000,000				95,000,000
Preferred Stock | Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Preferred Stock, Liquidation Preference Per Share | $ / shares										$ 1,000
Preferred Stock, Conversion Price Per Preference Share | $ / shares	$ 7.42									$ 10
Preferred Stock, Accretion of Redemption Discount				$ 7
Preferred Stock, Liquidation Preference, Value				$ 116
Shares outstanding (shares) | shares				145,000,000					95,000
Expenses for convertible preference shares			$ (97)
Preferred Stock, Conversion Basis, Common Stock Class A Closing Trade Price					125.00%
Preferred Stock, Liquidation Preference Percentage Rate, Change of Control of the Company					7.00%
Preferred Stock | Series 6 Convertible Preferred Stock
Share Capital [Line Items]
Stock Issued During Period, Shares, Issued For Services, Convertible Preferred Shares | shares	50,000
Proceeds from issuance of common and convertible preference shares, net of issuance costs	$ 50,000
Preferred Stock, Liquidation Preference Per Share | $ / shares	$ 1,000
Preferred Stock, Conversion Price Per Preference Share | $ / shares	$ 5
Preferred Stock, Accretion Percentage, Preference	8.00%
Preferred Stock, Convertible Preference Shares, Accretion Period	5 years
Preferred Stock, Accretion of Redemption Discount		$ 2
Preferred Stock, Liquidation Preference, Value				$ 52
Preferred Stock, Convertible Preference Shares, Convertible at Company's Option, Term	2 years
Preferred Stock, Conversion Basis, Common Stock Class A Closing Trade Price	125.00%
Preferred Stock, Dividend Rate, Percentage	7.00%
Additional Paid-in Capital
Share Capital [Line Items]
Issuance of common and convertible preference shares				$ 35,997
Common Stock | Common Class A
Share Capital [Line Items]
Stock Issued During Period, Shares, Issued for Services | shares	14,285,714
Proceeds from Issuance of Common Stock	$ 50,000
Shares outstanding (shares) | shares						72,142,668	57,517,568
Common stock, voting rights, number of votes per share | vote				1
Common Stock | Common Class B
Share Capital [Line Items]
Shares outstanding (shares) | shares						3,749	3,755		3,755
Common stock, voting rights, number of votes per share | vote				20
Contingent Consideration, Liability Settlements [Domain] | Preferred Stock | Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Issuance of common and convertible preference shares				$ 62,623

Noncontrolling and Redeemable_3

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Amounts Due to Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Noncontrolling Interest [Abstract]
Beginning balance			$ 9,278	$ 11,030	$ 11,030
Income attributable to noncontrolling interests	$ 7,265	$ 2,458	10,737	5,900	11,785
Distributions made			(9,982)	$ (10,410)	(13,419)
Other			(36)		(118)
Ending balance	$ 9,997		$ 9,997		$ 9,278

Noncontrolling and Redeemable_4

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ (1,752)		$ (16,125)	$ (16,125)	$ (42,135)	$ 2,425	$ (42,135)
Decrease in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of redeemable noncontrolling interests and noncontrolling interests	648
Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests	2,400		11,150			(1,680)	38,326
MDC Partners Inc. Shareholders' Deficit
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.				$ (16,125)	$ (42,135)
Decrease in MDC Partners Inc. paid-in capital for purchase of equity interests in excess of redeemable noncontrolling interests and noncontrolling interests	$ (648)	$ 648	$ (4,975)			$ 745	$ (3,809)

Noncontrolling and Redeemable_5

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Noncontrolling Interest [Abstract]
Beginning Balance	$ 51,546	$ 62,886
Redemptions	(9,486)	(11,943)
Granted	0	0
Changes in redemption value	(3,306)	1,067
Currency translation adjustments	(190)	(464)
Ending Balance	$ 41,519	$ 51,546

Noncontrolling and Redeemable_6

Noncontrolling and Redeemable Noncontrolling Interests (Details Textual) - USD ($)	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by Parent (percent)			100.00%
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 41,519,000			$ 51,546,000	$ 62,886,000
Vesting over period [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	19,193,000
Termination, disability, or death [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value		$ 19,106,000
Acquisition Value in excess of Redemption Value [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 3,220,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - 6.50% Notes due 2024 - Fair Value, Inputs, Level 1 - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Liabilities:
Long term debt, Carrying Amount	$ 900,000	$ 900,000
Long term debt, Fair Value	$ 823,500	$ 834,750

Supplemental Information (Detai

Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued media	$ 163,777		$ 163,777		$ 180,586
Goodwill	740,955		740,955
Income tax expense (benefit)	3,457	$ 2,986	6,292	$ (3,367)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	$ 8,907	$ (10,981)	$ 19,102	$ (39,960)
Effective tax rate (percent)			38.80%	27.20%

Segment Information (Details 1)

Segment Information (Details 1) $ in Thousands	3 Months Ended			6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Jun. 30, 2019operating_segmentreportable_segment	Jun. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment				4
Revenue	$ 342,907	$ 375,830				$ 1,033,828	$ 1,082,541
Segment operating income (loss)	29,421	2,618				68,544	18,757
Interest expense and finance charges	(16,110)	(17,063)				(49,284)	(50,005)
Foreign exchange gain (loss)	(3,973)	3,275				4,401	(9,934)
Other, net	(431)	189				(4,559)	1,222
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	8,907	(10,981)				19,102	(39,960)
Income tax expense (benefit)	3,457	2,986				6,292	(3,367)
Income (loss) before equity in earnings of non-consolidated affiliates	5,450	(13,967)				12,810	(36,593)
Equity in earnings of non-consolidated affiliates	63	300				352	358
Net income (loss)	5,513	(13,667)				13,162	(36,235)
Net income attributable to the noncontrolling interest	(7,265)	(2,458)				(10,737)	(5,900)	$ (11,785)
Net income (loss) attributable to MDC Partners Inc.	(1,752)	(16,125)	$ (16,125)		$ (42,135)	2,425	(42,135)
Depreciation and amortization	9,368	11,134				28,869	35,212
Stock-based compensation	6,026	6,242				12,632	16,882
Capital expenditures	5,863	5,543				13,786	15,232
Global Integrated Agencies
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				4
Revenue	145,890	157,308				429,977	444,995
Segment operating income (loss)	21,036	23,486				45,527	28,247
Depreciation and amortization	4,009	4,553				12,511	16,705
Stock-based compensation	4,673	3,241				9,672	8,176
Capital expenditures	3,470	1,927				6,704	6,581
Domestic Creative Agencies
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				7
Revenue	57,593	59,151				176,711	183,504
Segment operating income (loss)	7,216	(14,031)				22,533	(6,887)
Depreciation and amortization	1,213	1,266				3,708	3,793
Stock-based compensation	352	550				1,338	2,056
Capital expenditures	694	967				1,757	2,440
Specialized Communications
Segment Reporting Information [Line Items]
Number of operating segments | operating_segment				4
Revenue	42,101	38,838				128,224	117,966
Segment operating income (loss)	5,129	3,703				18,889	13,646
Depreciation and amortization	644	1,100				1,909	3,059
Stock-based compensation	45	52				123	291
Capital expenditures	198	732				680	3,176
Media Services
Segment Reporting Information [Line Items]
Revenue	21,222	29,593				75,815	90,948
Segment operating income (loss)	(1,677)	850				(3,630)	(78)
Depreciation and amortization	755	675				2,531	1,995
Stock-based compensation	5	102				(11)	251
Capital expenditures	(2)	385				165	699
All Other
Segment Reporting Information [Line Items]
Revenue	76,101	90,940				223,101	245,128
Segment operating income (loss)	6,828	6,634				15,790	29,065
Depreciation and amortization	2,555	3,341				7,580	9,077
Stock-based compensation	118	677				1,058	2,019
Capital expenditures	1,492	1,500				4,450	2,271
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Segment operating income (loss)	(9,111)	(18,024)				(30,565)	(45,236)
Depreciation and amortization	192	199				630	583
Stock-based compensation	833	1,620				452	4,089
Capital expenditures	$ 11	$ 32				$ 30	$ 65

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Amount of letters of credit outstanding	$ 4,744	$ 4,744

New Accounting Pronouncements (

New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease liability	$ 277,931
Operating lease right-of-use asset	$ 234,137
Accounting Standards Update 2016-02 - ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease liability		$ 299,243
Operating lease right-of-use asset		$ 254,245

Uncategorized Items - mdca-2019

Label	Element	Value
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	$ 776,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	499,000
Noncontrolling Interest, Change in Redemption Value	us-gaap_MinorityInterestChangeInRedemptionValue	(109,000)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	2,450,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,774,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	1,409,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(2,347,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(4,409,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	767,000
Adjustments to Additional Paid in Capital, Other	us-gaap_AdjustmentsToAdditionalPaidInCapitalOther	(25,000)
Parent [Member]
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	776,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	499,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification	0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	us-gaap_MinorityInterestDecreaseFromRedemptions	(4,975,000)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	us-gaap_MinorityInterestDecreaseFromRedemptions	(3,809,000)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	2,450,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,774,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	1,409,000
Stock Issued During Period, Value, Convertible Preferred Shares	mdca_StockIssuedDuringPeriodValueConvertiblePreferredShares	(97,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(2,347,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(4,409,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	767,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(1,800,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	635,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(1,165,000)
Adjustments to Additional Paid in Capital, Other	us-gaap_AdjustmentsToAdditionalPaidInCapitalOther	(16,000)
Noncontrolling Interest [Member]
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	mdca_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	(11,947,000)
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	mdca_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	15,410,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	mdca_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	0
Noncontrolling Interest, Change in Redemption Value	us-gaap_MinorityInterestChangeInRedemptionValue	(5,965,000)
Noncontrolling Interest, Change in Redemption Value	us-gaap_MinorityInterestChangeInRedemptionValue	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	473,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(1,533,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(296,000)
Retained Earnings [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification	(1,170,000)
Additional Paid-in Capital [Member]
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	mdca_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	648,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	776,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	499,000
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	us-gaap_MinorityInterestDecreaseFromRedemptions	(4,975,000)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	us-gaap_MinorityInterestDecreaseFromRedemptions	(3,809,000)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	2,450,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,774,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	1,409,000
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(2,347,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	(4,409,000)
Increase (Decrease) in Redemption Value of Redeemable Noncontrolling Interests	mdca_IncreaseDecreaseinRedemptionValueofRedeemableNoncontrollingInterests	767,000
Adjustments to Additional Paid in Capital, Other	us-gaap_AdjustmentsToAdditionalPaidInCapitalOther	(11,000)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(1,800,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	635,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	$ (1,165,000)
Common Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	115,500
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	237,529
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	372,953
Stock Repurchased and Retired During Period, Shares	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares	54,089
Stock Repurchased and Retired During Period, Shares	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares	108,782
Stock Repurchased and Retired During Period, Shares	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares	174,279
Contingent Consideration, Liability Settlements [Domain]
Stock Issued During Period, Value, Acquisitions	us-gaap_StockIssuedDuringPeriodValueAcquisitions	$ 7,030,000
Contingent Consideration, Liability Settlements [Domain] | Parent [Member]
Stock Issued During Period, Value, Acquisitions	us-gaap_StockIssuedDuringPeriodValueAcquisitions	$ 7,030,000