Stagwell (STGW) 10-Q 29 Oct 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 23, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-13718
Entity Registrant Name	MDC Partners Inc
Entity Incorporation, State or Country Code	Z4
Entity Tax Identification Number	98-0364441
Entity Address, Address Line One	One World Trade Center, Floor 65
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10007
City Area Code	646
Local Phone Number	429-1800
Title of 12(b) Security	Class A Subordinate Voting Shares, no par value
Trading Symbol	MDCA
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000876883
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		73,528,105
Common Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		3,743

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue:
Services	$ 283,423	$ 342,907	$ 870,843	$ 1,033,828
Operating expenses:
Cost of services sold	172,531	222,448	560,856	700,351
Office and general expenses	72,512	79,726	205,075	234,120
Depreciation and amortization	9,332	9,368		28,869
Impairment and other losses	159	1,944	19,159	1,944
Costs and Expenses, Total	254,534	313,486	812,527	965,284
Operating income	28,889	29,421	58,316	68,544
Other income (expense):
Interest expense and finance charges, net	(15,266)	(16,110)	(46,819)	(49,284)
Other, net	505	(431)	22,723	(4,559)
Foreign exchange gain (loss)	2,159	(3,973)	(7,256)	4,401
Nonoperating Income (Expense), Total	(12,602)	(20,514)	(31,352)	(49,442)
Income before income taxes and equity in earnings of non-consolidated affiliates	16,287	8,907	26,964	19,102
Income tax expense	1,452	3,457	7,029	6,292
Income before equity in earnings of non-consolidated affiliates	14,835	5,450	19,935	12,810
Equity in earnings (losses) of non-consolidated affiliates	(31)	63	(829)	352
Net income	14,804	5,513	19,106	13,162
Net income attributable to the noncontrolling interest	(10,728)	(7,265)	(14,620)	(10,737)
Net income (loss) attributable to MDC Partners Inc.	4,076	(1,752)	4,486	2,425
Net income (loss) attributable to MDC Partners Inc. common shareholders	$ 360	$ (5,058)	$ (6,042)	$ (6,506)
Basic and diluted
Earnings per share, basic	$ 0	$ (0.07)	$ (0.08)	$ (0.10)
Earnings per share, diluted	$ 0	$ (0.07)	$ (0.08)	$ (0.10)
Weighted Average Number of Common Shares Outstanding:
Weighted Average Number of Shares Outstanding, Basic	73,207,619	72,044,480	72,713,257	68,154,306
Weighted Average Number of Shares Outstanding, Diluted	73,476,779	72,044,480	72,713,257	68,154,306
Series 4 Convertible Preferred Stock [Domain] | Preferred Stock
Other income (expense):
Accretion on and net income allocated to convertible preference shares	$ (3,716)	$ (3,306)		$ 8,931

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Comprehensive income (loss)
Net loss	$ 14,804	$ 5,513	$ 19,106	$ 13,162
Other comprehensive income (loss), net of applicable tax:
Foreign currency translation adjustment	2,375	(1,461)	11,171	(7,505)
Other comprehensive income (loss)	2,375	(1,461)	11,171	(7,505)
Comprehensive income for the period	17,179	4,052	30,277	5,657
Comprehensive income attributable to the noncontrolling interests	(10,962)	(6,969)	(14,755)	(10,830)
Comprehensive income (loss) attributable to MDC Partners Inc.	$ 6,217	$ (2,917)	$ 15,522	$ (5,173)

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 37,075	$ 106,933
Accounts receivable, less allowance for doubtful accounts of $3,703 and $3,304	403,636	449,288
Expenditures billable to clients	21,884	30,133
Other current assets	67,585	35,613
Total Current Assets	530,180	621,967
Fixed assets, at cost, less accumulated depreciation of $138,859 and $129,579	87,908	81,054
Right of use assets - operating leases	227,362	223,622
Goodwill	710,013	731,691
Other intangible assets, net	46,600	54,893
Deferred tax assets	82,576	84,900
Other assets	21,493	30,179
Total Assets	1,706,132	1,828,306
Current Liabilities:
Accounts payable	128,643	200,148
Accruals and other liabilities	323,414	353,575
Advance billings	157,101	171,742
Current portion of lease liabilities - operating leases	40,038	48,659
Current portion of deferred acquisition consideration	39,321	45,521
Total Current Liabilities	688,517	819,645
Long-term debt	860,422	887,630
Long-term portion of deferred acquisition consideration	6,824	29,699
Long-term lease liabilities - operating leases	257,107	219,163
Other liabilities	38,439	25,771
Total Liabilities	1,851,309	1,981,908
Redeemable Noncontrolling Interests	25,172	36,973
Commitments, Contingencies, and Guarantees (Note 9)
Shareholders’ Deficit:
Convertible preference shares, 145,000 authorized, issued and outstanding at September 30, 2020 and December 31, 2019	152,746	152,746
Common stock and other paid-in capital	106,037	101,469
Accumulated deficit	(476,293)	(480,779)
Accumulated other comprehensive loss (income)	6,768	(4,269)
MDC Partners Inc. Shareholders' Deficit	(210,742)	(230,833)
Noncontrolling interests	40,393	40,258
Total Shareholders' Deficit	(170,349)	(190,575)
Total Liabilities, Redeemable Noncontrolling Interests and Shareholders' Deficit	$ 1,706,132	$ 1,828,306

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 3,703	$ 3,304
Fixed assets, accumulated depreciation	$ 138,859	$ 129,579
Preference shares, authorized (in shares)	145,000	95,000
Preference shares, issued (in shares)	145,000	95,000
Preference shares, outstanding (in shares)	145,000	95,000

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ 19,106	$ 13,162
Adjustments to reconcile net income to cash used in operating activities:
Stock-based compensation	10,568	12,632
Depreciation and amortization	27,437	28,869
Impairment and other losses	19,159	1,944
Adjustment to deferred acquisition consideration	515	(3,627)
Deferred income taxes	2,263	6,292
Gain on sale of assets and other	(4,199)	(2,649)
Changes in working capital:
Accounts receivable	43,708	835
Expenditures billable to clients	8,248	3,716
Prepaid expenses and other current assets	1,991	3,280
Accounts payable, accruals and other current liabilities	(109,256)	(96,527)
Acquisition related payments	(7,514)	(4,816)
Advance billings	(14,517)	31,049
Net cash used in operating activities	(2,491)	(5,840)
Cash flows from investing activities:
Capital expenditures	(11,474)	(13,786)
Proceeds from sale of assets	19,616	23,050
Acquisitions, net of cash acquired	(1,816)	(5,778)
Other	(1,777)	(179)
Net cash provided by investing activities	4,549	3,307
Cash flows from financing activities:
Acquisition related payments	(35,331)	(30,155)
Distributions to noncontrolling interests and other	(14,639)	(10,615)
Repurchase of Senior Notes	(21,999)	0
Net cash used in financing activities	(71,969)	(2,202)
Effect of exchange rate changes on cash, cash equivalents, and cash held in trusts	53	8
Net decrease in cash and cash equivalents, including cash classified within current assets held for sale	(69,858)	(4,727)
Change in cash and cash equivalents held in trusts classified within held for sale	0	(3,307)
Change in cash and cash equivalents classified within assets held for sale	0	4,441
Net decrease in cash and cash equivalents	(69,858)	(3,593)
Cash and cash equivalents at beginning of period	106,933	30,873
Cash and cash equivalents at end of period	37,075	27,280
Supplemental disclosures:
Cash income taxes paid	2,700	3,631
Cash interest paid	29,311	32,525
Wells Fargo Capital Finance, LLC | Revolving Credit Facility
Cash flows from financing activities:
Repayments of borrowings under revolving credit facility	(456,428)	(1,172,909)
Proceeds from borrowings under revolving credit facility	456,428	1,112,857
Series 4 Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance of common and convertible preference shares, net of issuance costs	$ 0	$ 98,620

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	MDC Partners Inc. Shareholders' Deficit	Noncontrolling Interest	Series 4 Convertible Preferred Stock [Member]Convertible Preferred Stock
Balance at Dec. 31, 2018	$ (257,590)	$ 90,123		$ 58,579	$ (475,526)	$ 4,720	$ (322,104)	$ 64,514
Balance (in shares) at Dec. 31, 2018									95,000,000
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				2,425		2,425
Other comprehensive income	(7,505)					(7,598)	(7,598)	93
Issuance of common and preference shares (in shares)		50,000,000	14,285,714
Issuance of common and convertible preference shares	98,620	$ 62,623		35,997			98,620
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
Business acquisitions and step-up transactions, net of tax	(745)			(745)			(745)
Changes in ownership interest	(24,935)			(293)			(293)	(24,642)
Business acquisitions and step-up transactions, net of tax							745
Other	25			11	5		16	9
Balance at Sep. 30, 2019	(184,918)	152,746		98,364	(473,106)	(2,878)	(224,874)	39,956
Balance (in shares) at Sep. 30, 2019									145,000,000
Common stock, balance (in shares) at Sep. 30, 2019			72,146,417
Balance at Jun. 30, 2019	(182,600)	152,746		97,455	(471,349)	(1,713)	(222,861)	40,261
Balance (in shares) at Jun. 30, 2019									145,000,000
Common stock, balance (in shares) at Jun. 30, 2019			71,947,743
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	(1,752)				(1,752)		(1,752)
Other comprehensive income	(1,461)					(1,165)	(1,165)	(296)
Issuance of restricted stock	0
Issuance of restricted stock (in shares)			372,953
Shares acquired and cancelled	(499)			(499)			(499)
Shares acquired and cancelled (in shares)			(174,279)
Stock-based compensation	1,409			1,409			1,409
Changes in redemption value of redeemable noncontrolling interests	767			767			767
Business acquisitions and step-up transactions, net of tax	(648)			(648)			(648)
Changes in ownership interest	(109)			(109)			(109)	0
Business acquisitions and step-up transactions, net of tax							(648)
Other	25			11	5		16	9
Balance at Sep. 30, 2019	(184,918)	152,746		98,364	(473,106)	(2,878)	(224,874)	39,956
Balance (in shares) at Sep. 30, 2019									145,000,000
Common stock, balance (in shares) at Sep. 30, 2019			72,146,417
Balance at Dec. 31, 2019	(190,575)	152,746		101,469	(480,779)	(4,269)	(230,833)	40,258
Balance (in shares) at Dec. 31, 2019									145,000,000
Common stock, balance (in shares) at Dec. 31, 2019			72,154,603
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	4,486				4,486		4,486
Other comprehensive income	11,171					11,036	11,036	135
Issuance of restricted stock	0
Issuance of restricted stock (in shares)			1,807,984
Shares acquired and cancelled	(861)			(861)			(861)
Shares acquired and cancelled (in shares)			(407,894)
Stock-based compensation	5,243			5,243			5,243
Changes in redemption value of redeemable noncontrolling interests	(1,056)			(1,056)			(1,056)
Business acquisitions and step-up transactions, net of tax	1,626			1,626			(1,626)
Other	(383)			(384)	0	1	(383)	0
Balance at Sep. 30, 2020	(170,349)	152,746		106,037	(476,293)	6,768	(210,742)	40,393
Balance (in shares) at Sep. 30, 2020									145,000,000
Common stock, balance (in shares) at Sep. 30, 2020			73,554,693
Balance at Jun. 30, 2020	(184,603)	152,746		98,234	(480,368)	4,627	(224,761)	40,158
Balance (in shares) at Jun. 30, 2020									145,000,000
Common stock, balance (in shares) at Jun. 30, 2020			72,587,390
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to MDC Partners Inc.	4,076						4,076
Other comprehensive income	2,375					2,141	2,141	234
Issuance of restricted stock	0
Issuance of restricted stock (in shares)			1,047,423
Shares acquired and cancelled	(129)			(129)			(129)
Shares acquired and cancelled (in shares)			(80,120)
Stock-based compensation	4,210			4,210			4,210
Changes in redemption value of redeemable noncontrolling interests	1,574			1,574			1,574
Business acquisitions and step-up transactions, net of tax	2,129			2,129			2,129
Other	19			19	(1)		18	1
Balance at Sep. 30, 2020	$ (170,349)	$ 152,746		$ 106,037	$ (476,293)	$ 6,768	$ (210,742)	$ 40,393
Balance (in shares) at Sep. 30, 2020									145,000,000
Common stock, balance (in shares) at Sep. 30, 2020			73,554,693

Basis of Presentation and Recen

Basis of Presentation and Recent Developments	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Recent Developments	asis of Presentation and Recent Developments MDC Partners Inc. (the “Company” or “MDC”), incorporated under the laws of Canada, is a leading provider of global marketing, advertising, activation, communications and strategic consulting solutions. Through its Networks (and underlying agencies generally referred to as “Partner Firms”), MDC delivers a wide range of customized services in order to drive growth and business performance for its clients. The accompanying consolidated financial statements include the accounts of MDC, its subsidiaries and variable interest entities for which the Company is the primary beneficiary. MDC 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 about current and future results of operations and cash flows 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, 2019, as revised in the Company’s Current Report on Form 8-K filed August 31, 2020 (“2019 Form 10-K”). The COVID-19 pandemic has negatively impacted the Company’s results of operations, financial position, and cash flows. While it is difficult to predict the full scale of the impact, the Company has taken actions to address the impact of the pandemic, such as working closely with our clients, reducing our expenses and monitoring liquidity. The impact of the pandemic and the corresponding actions are reflected in our judgments, assumptions and estimates in the preparation of the financial statements. However, if the duration of the COVID-19 pandemic is longer and the operational impact is greater than estimated, the judgments, assumptions and estimates will be updated and could result in different results in the future. 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. The Company reorganized its management structure in 2020 which resulted in a change to our reportable segments. Prior periods presented have been recast to reflect the change in reportable segments. The Company began to present the Integrated Agencies Network reportable segment, which aggregated four operating segments (Constellation, Anomaly Alliance, Doner Partner Network and Colle McVoy), in the first quarter of 2020. In connection with our discussions with the SEC, the Company has changed the prior presentation for the Integrated Agencies Network. Beginning in the second quarter of 2020, the Company separated the Integrated Agencies Network into two reportable segments: Integrated Networks - Group A (Anomaly Alliance and Colle McVoy) and Integrated Networks - Group B (Constellation and Doner Partner Network). The change was made to aggregate the operating segments that have the most similar historical average long-term profitability. See Note 14 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for further information. Recent Developments

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions 2020 Acquisition On July 1, 2020, the Company acquired the remaining 10% ownership interest of Veritas it did not already own for an aggregate purchase price of $2,187, of which $1,087 was a deferred cash payment. As a result of the transaction, the Company reduced noncontrolling and redeemable noncontrolling interests by $2,651. The difference between the purchase price and the noncontrolling interest of $464 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. On March 19, 2020, the Company acquired the remaining 22.5% ownership interest of KWT Global it did not already own for an aggregate purchase price of $2,118, comprised of a closing cash payment of $729 and contingent deferred acquisition payments with an estimated present value at the acquisition date of $1,389. The contingent deferred payments are based on the financial results of the underlying business from 2019 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $1,615. The difference between the purchase price and the redeemable noncontrolling interest of $503 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. 2020 Disposition On February 14, 2020, the Company sold substantially all the assets and certain liabilities of Sloane and Company LLC (“Sloane”), an indirectly wholly owned subsidiary of the Company, to an affiliate of The Stagwell Group LLC (“Stagwell”), for an aggregate sale price of $26,696, consisting of cash received at closing plus contingent deferred payments expected to be paid over the next two years. The sale resulted in a gain of $16,827, which is included in Other, net within the Unaudited Condensed Consolidated Statements of Operations. Sloane was included within Allison & Partners which is included within the All Other category. 2019 Acquisitions On November 15, 2019, the Company acquired the remaining 35% ownership interest of Laird + Partners it did not already own for an aggregate purchase price of $2,389, comprised of a closing cash payment of $1,588 and contingent deferred acquisition payments with an estimated present value at the acquisition date of $801. The contingent deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $5,045. The difference between the purchase price and the redeemable noncontrolling interest of $2,656 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. Effective April 1, 2019, the Company acquired the remaining 35% ownership interest of HPR Partners LLC (Hunter) it did not already own for an aggregate purchase price of $10,234, comprised of a closing cash payment of $3,890 and additional contingent deferred acquisition payments with an estimated present value at the acquisition date of $6,344. The contingent deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $9,486. The difference between the purchase price and the redeemable noncontrolling interest of $745 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets 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 received cash plus the assumption of certain liabilities totaling approximately $50,000 in the aggregate. The sale resulted in a loss of $3,000, which was included in Other, net within the Unaudited Condensed Consolidated Statements of Operations. 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, 2020 and December 31, 2019. September 30, December 31, 2020 2019 Beginning Balance of contingent payments $ 74,671 $ 82,598 Payments (41,326) (30,719) Redemption value adjustments (1) 2,814 15,451 Additions - acquisitions and step-up transactions 7,703 7,145 Other 2,020 196 Ending Balance of contingent payments $ 45,882 $ 74,671 Fixed payments 263 549 $ 46,145 $ 75,220 (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 Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s Statements of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Loss (Income) attributable to fair value adjustments $ 2,803 $ 1,943 $ 515 $ (3,627) Stock-based compensation 770 1,540 2,299 1,010 Redemption value adjustments $ 3,573 $ 3,483 $ 2,814 $ (2,617)

Revenue

Revenue	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The Company’s revenue recognition policies are established in accordance with 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 globally. 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 following table presents revenue disaggregated by client industry vertical for the three and nine months ended September 30, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, Industry Reportable Segment 2020 2019 2020 2019 Food & Beverage All $ 48,153 $ 64,774 $ 152,586 $ 204,743 Retail All 39,390 39,420 108,882 111,899 Consumer Products All 37,175 38,510 111,371 119,866 Communications All 20,227 48,147 58,234 136,819 Automotive All 13,399 19,125 51,610 55,857 Technology All 41,220 28,148 129,569 84,294 Healthcare All 25,120 25,152 71,970 74,403 Financials All 22,529 28,054 66,282 81,049 Transportation and Travel/Lodging All 9,674 20,541 35,226 65,111 Other All 26,536 31,036 85,113 99,787 $ 283,423 $ 342,907 $ 870,843 $ 1,033,828 MDC has historically focused its operations primarily where the Company was founded in North America, the largest market for its services in the world. MDC’s Partner Firms are located in the United States, Canada, and an additional eleven 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, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, Geographic Location Reportable Segment 2020 2019 2020 2019 United States All $ 228,255 $ 271,671 $ 703,158 $ 819,347 Canada All 20,299 25,895 55,164 72,837 Other All 34,869 45,341 112,521 141,644 $ 283,423 $ 342,907 $ 870,843 $ 1,033,828 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 $70,999 and $65,004 at September 30, 2020 and December 31, 2019, 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 $21,884 and $30,133 at September 30, 2020 and December 31, 2019, 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 and within Accruals and other liabilities on the Company’s Unaudited Condensed Consolidated Balance Sheets. In arrangements in which we are acting as an agent, the revenue recognition related to the contract liability is presented on a net basis within the Condensed Consolidated Statements of Operations. Advance billings at September 30, 2020 and December 31, 2019 were $157,101 and $171,742, respectively. The decrease in the advance billings balance of $14,641 for the nine months ended September 30, 2020 was primarily driven by cash payments received or due in advance of satisfying our performance obligations, offset by $127,961 of revenues recognized that were included in the advance billings balances as of December 31, 2019 and reductions due to the incurrence of third-party costs. Contract liabilities classified within Accruals and other liabilities at September 30, 2020 and December 31, 2019 were $197,650 and $216,931, respectively. The decrease in the balance of $19,281 for the nine months ended September 30, 2020 was primarily driven by cash payments received or due in advance of satisfying our performance obligations, offset by $190,342 of revenues recognized that were included in the balance as of December 31, 2019 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, 2020 were not materially impacted by write offs, impairment losses or any other factors. The majority of our contracts are for periods of one year or less. For those contracts with a term of more than one year, we had approximately $14,556 of unsatisfied performance obligations as of September 30, 2020, of which we expect to recognize approximately 66% in 2020, 31% in 2021 and 3% in 2022.

Income (Loss) Per Common Share

Income (Loss) Per Common Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Loss Per Common Share	Income (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, 2020 2019 2020 2019 Numerator: Net income (loss) attributable to MDC Partners Inc. $ 4,076 $ (1,752) $ 4,486 $ 2,425 Accretion on convertible preference shares (3,579) (3,306) (10,528) (8,931) Net income allocated to convertible preference shares (137) — — — Net income (loss) attributable to MDC Partners Inc. common shareholders $ 360 $ (5,058) $ (6,042) $ (6,506) Denominator: Basic weighted average number of common shares outstanding 73,207,619 72,044,480 72,713,257 68,154,306 Dilutive effect of equity awards 269,160 — — — Diluted weighted average number of common shares outstanding 73,476,779 72,044,480 72,713,257 68,154,306 Basic $ — $ (0.07) $ (0.08) $ (0.10) Diluted $ — $ (0.07) $ (0.08) $ (0.10) Anti-dilutive stock awards 2,325,800 3,714,595 3,539,060 3,714,595 Restricted stock and restricted stock unit awards of 3,220,342 and 135,386 as of September 30, 2020 and 2019 respectively, are excluded from the computation of diluted income (loss) per common share because the performance contingency necessary for vesting has not been met as of the reporting date. In addition, there were 145,000 Preference Shares outstanding which were convertible into 28,287,863 and 26,133,613 Class A common shares at September 30, 2020 and 2019, 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.

Deferred Acquisition Considerat

Deferred Acquisition Consideration	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Deferred Acquisition Consideration	Acquisitions and Dispositions 2020 Acquisition On July 1, 2020, the Company acquired the remaining 10% ownership interest of Veritas it did not already own for an aggregate purchase price of $2,187, of which $1,087 was a deferred cash payment. As a result of the transaction, the Company reduced noncontrolling and redeemable noncontrolling interests by $2,651. The difference between the purchase price and the noncontrolling interest of $464 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. On March 19, 2020, the Company acquired the remaining 22.5% ownership interest of KWT Global it did not already own for an aggregate purchase price of $2,118, comprised of a closing cash payment of $729 and contingent deferred acquisition payments with an estimated present value at the acquisition date of $1,389. The contingent deferred payments are based on the financial results of the underlying business from 2019 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $1,615. The difference between the purchase price and the redeemable noncontrolling interest of $503 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. 2020 Disposition On February 14, 2020, the Company sold substantially all the assets and certain liabilities of Sloane and Company LLC (“Sloane”), an indirectly wholly owned subsidiary of the Company, to an affiliate of The Stagwell Group LLC (“Stagwell”), for an aggregate sale price of $26,696, consisting of cash received at closing plus contingent deferred payments expected to be paid over the next two years. The sale resulted in a gain of $16,827, which is included in Other, net within the Unaudited Condensed Consolidated Statements of Operations. Sloane was included within Allison & Partners which is included within the All Other category. 2019 Acquisitions On November 15, 2019, the Company acquired the remaining 35% ownership interest of Laird + Partners it did not already own for an aggregate purchase price of $2,389, comprised of a closing cash payment of $1,588 and contingent deferred acquisition payments with an estimated present value at the acquisition date of $801. The contingent deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $5,045. The difference between the purchase price and the redeemable noncontrolling interest of $2,656 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. Effective April 1, 2019, the Company acquired the remaining 35% ownership interest of HPR Partners LLC (Hunter) it did not already own for an aggregate purchase price of $10,234, comprised of a closing cash payment of $3,890 and additional contingent deferred acquisition payments with an estimated present value at the acquisition date of $6,344. The contingent deferred payments are based on the financial results of the underlying business from 2018 to 2020 with final payment due in 2021. As a result of the transaction, the Company reduced redeemable noncontrolling interests by $9,486. The difference between the purchase price and the redeemable noncontrolling interest of $745 was recorded in Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets 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 received cash plus the assumption of certain liabilities totaling approximately $50,000 in the aggregate. The sale resulted in a loss of $3,000, which was included in Other, net within the Unaudited Condensed Consolidated Statements of Operations. 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, 2020 and December 31, 2019. September 30, December 31, 2020 2019 Beginning Balance of contingent payments $ 74,671 $ 82,598 Payments (41,326) (30,719) Redemption value adjustments (1) 2,814 15,451 Additions - acquisitions and step-up transactions 7,703 7,145 Other 2,020 196 Ending Balance of contingent payments $ 45,882 $ 74,671 Fixed payments 263 549 $ 46,145 $ 75,220 (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 Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s Statements of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Loss (Income) attributable to fair value adjustments $ 2,803 $ 1,943 $ 515 $ (3,627) Stock-based compensation 770 1,540 2,299 1,010 Redemption value adjustments $ 3,573 $ 3,483 $ 2,814 $ (2,617)

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	Leases 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 2020 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 Unaudited Condensed Consolidated Statements 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 which the variable lease payments are based upon occur. Some of the Company’s leases include options to extend or renew the leases 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 2020 through 2025. Sublease income is recognized over the lease term on a straight-line basis. Currently, the Company subleases office space in North America, Asia, Europe and Australia. As of September 30, 2020, the Company has entered into three operating leases for which the commencement date has not yet occurred as the premises are in the process of being prepared for occupancy by the landlord. Accordingly, these three leases represent an obligation of the Company that is not reflected within the Unaudited Condensed Consolidated Balance Sheets as of September 30, 2020. The aggregate future liability related to these leases is approximately $12,677. 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, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Lease Cost: Operating lease cost $ 18,495 $ 16,605 $ 53,397 $ 50,519 Variable lease cost 3,580 4,960 11,808 14,285 Sublease rental income (2,940) (2,376) (8,637) (6,565) Total lease cost $ 19,135 $ 19,189 $ 56,568 $ 58,239 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 17,703 $ 16,988 $ 52,930 $ 52,163 Right-of-use assets obtained in exchange for operating lease liabilities and other non-cash adjustments $ (814) $ 8,783 $ 37,120 $ 267,796 Weighted average remaining lease term (in years) - Operating leases 7.35 7.0 7.35 7.0 Weighted average discount rate - Operating leases 10.6 8.7 10.6 8.7 In the nine months ended September 30, 2020, the Company recorded a charge of $5,777 primarily to reduce the carrying value of its right-of-use lease assets and related leasehold improvements of three of its agencies within its Integrated Networks - Group B reportable segment and leased space of Corporate. The Company evaluated the facts and circumstances related to the use of the assets which indicated that they may not be recoverable. Using adjusted quoted market prices to develop expected future cash flows, it was determined that the fair value of the assets were less than their carrying value. This impairment charge is included in Impairment and other losses within the Unaudited Condensed Consolidated Statements of Operations. In the three and nine months ended September 30, 2019, the Company recorded an impairment charge of $1,933 to reduce the carrying value of its right-of-use lease assets and related leasehold improvements. Operating lease expense is included in office and general expenses in the Unaudited Condensed Consolidated Statements of Operations. The Company’s lease expense for leases with a term of 12 months or less is immaterial. The following table presents minimum future rental payments under the Company’s leases at September 30, 2020 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2020 $ 17,241 2021 67,718 2022 61,473 2023 57,429 2024 50,894 Thereafter 190,461 Total 445,216 Less: Present value discount (148,071) Lease liability $ 297,145

Debt

Debt	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt	Debt As of September 30, 2020 and December 31, 2019, the Company’s indebtedness was comprised as follows: September 30, 2020 December 31, 2019 Revolving credit agreement $ — $ — 6.50% Notes due 2024 870,256 900,000 Debt issuance costs (9,834) (12,370) $ 860,422 $ 887,630 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 defined below), 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 notes due 2024 (the “6.50% Notes”). The 6.50% Notes were sold in a private placement in reliance on exemptions 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. In April 2020, the Company repurchased $29,744 of the 6.50% Notes, at a weighted average price equal to 73.90% of the principal amount totaling $21,999, and accrued interest of $946. As a result of the repurchase, we recognized an extinguishment gain of $7,388. MDC may, at its option, redeem the 6.50% Notes in whole at any time or in part from time to time, at varying prices based on the timing of the redemption. If MDC experiences certain kinds of changes of control (as defined in the Indenture), holders of the 6.50% Notes may require MDC to repurchase any 6.50% Notes held by them at a price equal to 101% of the principal amount of the 6.50% Notes plus accrued and unpaid interest. In addition, if MDC sells assets under certain circumstances, it must apply the proceeds from such sale and offer to repurchase the 6.50% Notes at a price equal to 100% of the principal amount plus accrued and unpaid interest. The Indenture includes covenants that, among other things, restrict MDC’s ability and the ability of its restricted subsidiaries (as defined in the Indenture) to incur or guarantee additional indebtedness; pay dividends on or redeem or repurchase the capital stock of MDC; make certain types of investments; create restrictions on the payment of dividends or other amounts from MDC’s restricted subsidiaries; sell assets; enter into transactions with affiliates; create liens; enter into sale and leaseback transactions; and consolidate or merge with or into, or sell substantially all of MDC’s assets to, another person. These covenants are subject to a number of important limitations and exceptions. The 6.50% Notes are also subject to customary events of default, including a cross-payment default and cross-acceleration provision. The Company was in compliance with all covenants at September 30, 2020. Revolving Credit Agreement The Company is party to a $211,500 secured revolving credit facility due February 3, 2022. On May 29, 2020, the Company, Maxxcom Inc., a subsidiary of the Company (“Maxxcom”), and each of their subsidiaries party thereto entered into an amendment (the “Second 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 Second Amendment reduced the aggregate maximum amount of revolving commitments provided by the lenders to $211,500 from $250,000, extended the maturity date of the Credit Agreement from May 3, 2021 to February 3, 2022, and expanded the eligibility criteria for certain of the Company’s receivables to be included in the borrowing base. Advances under the Credit Agreement, as amended by the Second Amendment, will bear interest as follows: (i) Non-Prime Rate Loans bear interest at the Non-Prime Rate plus the Non-Prime Rate Margin and (ii) all other Obligations bear interest at the Prime Rate, plus the Prime Rate Margin. The Non-Prime Rate Margin and Prime Rate Margin will range from 2.50% to 3.00% for Non-Prime Rate Loans and from 1.75% to 2.25% for Prime 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 Second Amendment increased the required minimum earnings before interest, taxes and depreciation and amortization from $105 million to $120 million measured on a trailing 12-month basis. The total leverage ratio applicable on each testing date through the period ending December 31, 2020 remained at 6.25:1.0. The total leverage ratio applicable on each testing date after December 31, 2020 will be 5.5:1.0. 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 was in compliance with all of the terms and conditions of its Credit Agreement as of September 30, 2020. At September 30, 2020 and December 31, 2019, the Company had issued undrawn outstanding letters of credit of $18,576 and $4,836, respectively.

Noncontrolling and Redeemable N

Noncontrolling and Redeemable Noncontrolling Interests	9 Months Ended
	Sep. 30, 2020
Noncontrolling Interest [Abstract]
Noncontrolling and Redeemable Noncontrolling Interests	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, 2019 and nine months ended September 30, 2020 were as follows: Noncontrolling Balance, December 31, 2018 $ 9,278 Income attributable to noncontrolling interests 16,156 Distributions made (11,392) Other (14) Balance, December 31, 2019 $ 14,028 Income attributable to noncontrolling interests 14,620 Distributions made (14,499) Other (218) Balance, September 30, 2020 $ 13,931 Changes in the Company’s ownership interests in our less than 100% owned subsidiaries during the three and nine months ended September 30, 2020 and 2019 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Net income (loss) attributable to MDC Partners Inc. $ 4,076 $ (1,752) $ 4,486 $ 2,425 Transfers from the noncontrolling interest: Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests 2,129 (648) 1,626 (745) Net transfers from noncontrolling interests $ 2,129 $ (648) $ 1,626 $ (745) Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ 6,205 $ (2,400) $ 6,112 $ 1,680 Redeemable Noncontrolling Interests The following table presents changes in redeemable noncontrolling interests: Nine Months Ended September 30, 2020 Year Ended December 31, 2019 Beginning Balance $ 36,973 $ 51,546 Redemptions (12,289) (14,530) Granted — — Changes in redemption value 1,056 (3,163) Currency translation adjustments (568) 3 Other — 3,117 Ending Balance $ 25,172 $ 36,973 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 2020 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 $25,172 as of September 30, 2020, consists of $17,640 based on the performance of subsidiaries assuming the reporting date is the redemption date and such rights are exercised, $7,532 upon termination of such owner’s employment with the applicable subsidiary or death and $0 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.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2020
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 8 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, 2020 and 2019, 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, 2020, the Company had $18,576 of undrawn letters of credit. The Company entered into operating leases for which the commencement date has not yet occurred as of September 30, 2020. See Note 6 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information.

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2020
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, 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 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, 2020, the Series 6 Preference Shares accreted at a monthly rate of $7.39, for total accretion of $3,260, bringing the aggregate liquidation preference to $56,521 as of September 30, 2020. The accretion is considered in the calculation of net loss attributable to MDC Partners Inc. common shareholders. See Note 4 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. 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, 2020, the Series 4 Preference Shares accreted at a monthly rate of approximately $8.67 per Series 4 Preference Share, for total accretion of $7,268, bringing the aggregate liquidation preference to $126,019 as of September 30, 2020. The accretion is considered in the calculation of net income (loss) attributable to MDC Partners Inc. common shareholders. See Note 4 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, with a par value of $0, 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 73,550,950 and 72,150,854 Class A Shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively. Class B Common Shares (“Class B Shares”) These are an unlimited number of voting shares, carrying twenty votes each, with a par value of $0, convertible at any time at the option of the holder into one Class A share for each Class B share. There were 3,743 and 3,749 Class B Shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019: September 30, 2020 December 31, 2019 Carrying Fair Value Carrying Fair Value Liabilities: 6.50% Senior Notes due 2024 $ 870,256 $ 800,000 $ 900,000 $ 812,250 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 (Level 3 fair value measurement) 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 and is dependent upon significant assumptions, such as the growth rate of the earnings of the relevant subsidiary during the contractual period and the discount rate. These growth rates are consistent with the Company’s long-term forecasts. As of September 30, 2020, the discount rate used to measure these liabilities was 11.41%. As these estimates require the use of assumptions about future performance, which are uncertain at the time of estimation, the fair value measurements presented on the Unaudited Condensed Consolidated Balance Sheets are subject to material uncertainty. 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, 2020 and December 31, 2019, 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, intangible assets (Level 3 fair value measurement) and right-of-use lease assets (Level 2 fair value measurement). 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 months ended September 30, 2020. The company did not recognize an impairment of goodwill or intangible assets in the three and nine months ended September 30, 2019.

Supplemental Information

Supplemental Information	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental InformationImpairment and Other Losses The Company recognized a charge of $19,159 for the nine months ended September 30, 2020 consisting of a goodwill impairment of $13,382 and an impairment of right-of-use lease assets and losses of $5,777. Given the impact of the COVID-19 pandemic, the Company performed an interim goodwill impairment test in the second quarter of 2020 that resulted in a goodwill impairment, as discussed above, and the fair value of one reporting unit, with goodwill of approximately $130,780, exceeding its carrying value by a minimal percentage. If the duration of the COVID-19 pandemic is longer and the operational impact is greater than estimated, the Company could recognize an impairment of goodwill in the future. The Company used an income approach to measure its goodwill for impairment. This methodology incorporates the use of the discounted cash flow method. The income approach requires the exercise of significant judgment and inputs, including judgment about the amount and timing of expected future cash flows, assumed terminal value and appropriate discount rates. See Note 6 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for additional information regarding the impairment of right-of-use lease assets and losses. During the first quarter of 2020, the Company reassessed its estimate of the useful life of a trademark in the amount of $14,600, acquired as a result of a business combination. The Company revised the useful life to 5 years from indefinite lived. 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. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was enacted into law and the new legislation contains several key tax provisions, including the five-year net operating loss carryback, an adjusted business interest limitation, and payroll tax deferral. The Company is required to recognize the effect of tax law changes in the period of enactment, which required the Company to reassess the net realizability of its deferred tax assets and liabilities. The Company has assessed the applicability of the CARES Act and determined there is no impact. The Company had an income tax expense for the three months ended September 30, 2020 of $1,452 (on a pre-tax income of $16,287 resulting in an effective tax rate of 8.9%) compared to income tax expense of $3,457 (on pre-tax income of $8,907 resulting in an effective tax rate of 38.8%) for the three months ended September 30, 2019. The difference in effective tax rate of 8.9% in the three months ended September 30, 2020 as compared to 38.8% in the same period in 2019 results from a decrease in the estimated annual effective tax rate which is applied to the pre-tax income in the current period. Such decrease was primarily attributable to an increase in forecasted foreign earnings for which there is no tax expense provided due to valuation allowance, partially offset by an increase in base erosion and anti-abuse tax (“BEAT”). The Company had income tax expense for the nine months ended September 30, 2020 of $7,029 (on pre-tax income of $26,964 resulting in an effective tax rate of 26.1%) compared to an expense of $6,292 (on pre-tax income of $19,102 resulting in an effective tax rate of 32.9%) for the nine months ended September 30, 2019. The difference in effective tax rate of 26.1% in the nine months ended September 30, 2020 as compared to 32.9% in same period in 2019 results from a decrease in the estimated annual effective tax rate which is applied to the pre-tax income in the current period, such decrease primarily attributable to an increase in forecasted foreign earnings for which there is no tax expense provided due to valuation allowance, partially offset by an increase in base erosion and anti-abuse tax (“BEAT”). Payroll Taxes In accordance with the payroll tax deferral provision under the CARES Act, the Company is deferring the employer portion of the social security payroll tax of 6.2%. The Company anticipates the deferral through December 31, 2020 to be approximately $16,000 which is payable in equal installments on December 31, 2021 and 2022.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions In the ordinary course of business, the Company enters into transactions with related parties, including Stagwell and its affiliates. The transactions may range in the nature and value of services underlying the arrangements. Below are the related party transactions that are significant in nature: In October 2019, a Partner Firm of the Company entered into an arrangement with a Stagwell affiliate, in which the Stagwell affiliate and the Partner Firm will collaborate to provide various services to a client of the Partner Firm. The Partner Firm and the Stagwell affiliate pitched and won this business together, with the client ultimately determining the general scope of work for each agency. Under the arrangement, which was structured as a sub-contract due to client preference, the Partner Firm is expected to pay the Stagwell affiliate, for services provided by the Stagwell affiliate in connection with serving the client, approximately $816 which is expected to be recognized through the end of 2020. As of September 30, 2020, $225 was owed to the affiliate. During 2020, a Partner Firm of the Company entered into an arrangement with certain Stagwell affiliates to perform media planning, buying and reporting services. Under the arrangement, the Partner Firm is expected to receive from the Stagwell affiliate approximately $5,276, which is expected to be recognized through the end of 2020. As of September 30, 2020, $957 was due from the affiliate. In January 2020, a Partner Firm of the Company entered into an arrangement with a Stagwell affiliate to develop advertising technology for the Partner Firm. Under the arrangement the Partner Firm recorded approximately $475, of which $17 was owed to the affiliate as of September 30, 2020. This transaction has been completed. In August 2020, the Company entered into an arrangement with a Stagwell affiliate to provide audience and brand research, concept testing and landscape related to the ongoing new business pitches for clients of the Company. Under the arrangement the Company is expected to pay the Stagwell affiliate approximately $145, which is expected to be recognized through October 2020. As of September 30, 2020, $82 was owed to the affiliate. On February 14, 2020, Sloane sold substantially all its assets and certain liabilities to an affiliate of Stagwell. See Note 2 of the Notes to the Unaudited Condensed Consolidated Financial Statements for information related to this transaction.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2020
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”), who is Mark Penn, Chief Executive Officer and Chairman, 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. The CODM uses Adjusted EBITDA (defined below) as a key metric, to evaluate the operating and financial performance of a segment, identify trends affecting the segments, develop projections and make strategic business decisions. Adjusted EBITDA is defined as Net income (loss) attributable to MDC Partners Inc. common shareholders' plus or minus adjustments to operating income (loss), plus depreciation and amortization, stock-based compensation, deferred acquisition consideration adjustments, distributions from non-consolidated affiliates and other items, net. Distributions from non-consolidated affiliates includes (i) cash received for profit distributions from non-consolidated affiliates, and (ii) consideration from the sale of ownership interests in non-consolidated affiliates, less contributions to date, plus undistributed earnings (losses). Other items, net includes items such as severance expense and other restructuring expenses , including costs for leases that will either be terminated or sublet in connection with the centralization of our New York real estate portfolio. Effective in the first quarter of 2020, the Company reorganized its management structure resulting in the aggregation of certain Partner Firms into integrated groups (“Networks”). Mr. Penn appointed key agency executives that report directly into him to lead each Network. In connection with the reorganization, we reassessed our reportable segments to align our external reporting with how we operate the Networks under our new organizational structure. Prior periods presented have been recast to reflect the change in reportable segments. See Note 1 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for information regarding a change in reportable segments between the first and second quarter of 2020. The three reportable segments that result from our reassessment are as follows: “Integrated Networks - Group A,” “Integrated Networks - Group B” and the “Media & Data Network.” In addition, the Company combines and discloses 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 2019 Form 10-K. • The Integrated Networks - Group A reportable segment is comprised of the Anomaly Alliance (Anomaly, Concentric Partners, Hunter, Mono, Y Media Labs) and Colle McVoy operating segments. • The Integrated Networks - Group B reportable segment is comprised of the Constellation (72andSunny, CPB, Instrument and Redscout) and Doner Partner Network (6degrees, Doner, KWT, Union, Veritas and Yamamoto) operating segments. The operating segments aggregated within the Integrated Networks - Group A and B reportable segments provide a range of services for their clients, primarily including strategy, creative and production for advertising campaigns across a variety of platforms (print, digital, social media, television broadcast) as well as public relations and communications services, experiential, social media and influencer marketing. These operating segments share similar characteristics related to (i) the nature of their services; (ii) the type of 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. While the operating segments are similar in nature, the distinction between the Integrated Networks - Group A and B is the aggregation of operating segments that have the most similar historical and expected average long-term profitability. • The Media & Data Network reportable segment is comprised of a single operating segment that combines media buying and planning across a range of platforms (out-of-home, paid search, social media, lead generation, programmatic, television broadcast) with technology and data capabilities. The Media & Data Network includes Gale Partners, Kenna, MDC Media and Northstar. • All Other consists of the Company’s remaining operating segments that provide a range of services including advertising, public relations and 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 Allison & Partners, Bruce Mau, Forsman & Bodenfors, Hello, Team and Vitro. • 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, 2020 2019 2020 2019 Revenue: (Dollars in Thousands) Integrated Networks - Group A $ 87,064 $ 99,299 $ 260,420 $ 276,286 Integrated Networks - Group B 112,159 129,057 323,264 395,622 Media & Data Network 33,572 36,235 103,181 118,923 All Other 50,628 78,316 183,978 242,997 Total $ 283,423 $ 342,907 $ 870,843 $ 1,033,828 Adjusted EBITDA: Integrated Networks - Group A $ 21,009 $ 23,974 $ 54,516 $ 43,128 Integrated Networks - Group B 29,598 21,989 63,121 65,117 Media & Data Network 3,031 1,354 5,710 2,388 All Other 7,146 9,221 23,936 26,962 Corporate (6,726) (7,333) (17,496) (20,478) Total Adjusted EBITDA $ 54,058 $ 49,205 $ 129,787 $ 117,117 Depreciation and amortization $ (9,332) $ (9,368) $ (27,437) $ (28,869) Impairment and other losses (159) (1,944) (19,159) (1,944) Stock-based compensation (6,459) (6,026) (10,568) (12,632) Deferred acquisition consideration adjustments (2,803) (1,943) (515) 3,627 Distributions from non-consolidated affiliates (208) 202 (1,273) 171 Other items, net (6,208) (705) (12,519) (8,926) Total Operating Income $ 28,889 $ 29,421 $ 58,316 $ 68,544 Other Income (Expenses): Interest expense and finance charges, net $ (15,266) $ (16,110) $ (46,819) $ (49,284) Foreign exchange gain (loss) 2,159 (3,973) (7,256) 4,401 Other, net 505 (431) 22,723 (4,559) Income before income taxes and equity in earnings of non-consolidated affiliates 16,287 8,907 26,964 19,102 Income tax expense 1,452 3,457 7,029 6,292 Income before equity in earnings of non-consolidated affiliates 14,835 5,450 19,935 12,810 Equity in earnings (losses) of non-consolidated affiliates (31) 63 (829) 352 Net income 14,804 5,513 19,106 13,162 Net income attributable to the noncontrolling interest (10,728) (7,265) (14,620) (10,737) Net income (loss) attributable to MDC Partners Inc. 4,076 (1,752) 4,486 2,425 Accretion on and net income allocated to convertible preference shares (3,716) (3,306) (10,528) (8,931) Net income (loss) attributable to MDC Partners Inc. common shareholders $ 360 $ (5,058) $ (6,042) $ (6,506) Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Depreciation and amortization: (Dollars in Thousands) Integrated Networks - Group A $ 1,601 $ 2,132 $ 4,908 $ 6,420 Integrated Networks - Group B 4,813 3,872 13,726 11,964 Media & Data Network 786 1,004 2,401 3,332 All Other 1,933 2,168 5,735 6,523 Corporate 199 192 667 630 Total $ 9,332 $ 9,368 $ 27,437 $ 28,869 Stock-based compensation: Integrated Networks - Group A $ 4,024 $ 4,330 $ 5,880 $ 8,564 Integrated Networks - Group B 742 740 2,388 3,231 Media & Data Network 131 16 122 22 All Other 141 107 339 363 Corporate 1,421 833 1,839 452 Total $ 6,459 $ 6,026 $ 10,568 $ 12,632 Capital expenditures: Integrated Networks - Group A $ 269 $ 1,083 $ 835 $ 5,120 Integrated Networks - Group B 694 4,108 899 6,287 Media & Data Network 72 116 269 460 All Other 79 545 536 1,889 Corporate 23,073 11 25,338 30 Total $ 24,187 $ 5,863 $ 27,877 $ 13,786 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. Corporate’s capital expenditures in 2020 are primarily for leasehold improvements at its new headquarters at One World Trade Center in connection with the centralization of the Company’s New York real estate portfolio. As of September 30, 2020, the Company had $16,403 of capital expenditures that were incurred in the current year, but not yet paid. See Note 3 of the Notes to the Unaudited Condensed Consolidated Financial Statements included herein for a summary of the Company’s revenue by geographic region for the three and nine months ended September 30, 2020 and 2019.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, Geographic Location Reportable Segment 2020 2019 2020 2019 United States All $ 228,255 $ 271,671 $ 703,158 $ 819,347 Canada All 20,299 25,895 55,164 72,837 Other All 34,869 45,341 112,521 141,644 $ 283,423 $ 342,907 $ 870,843 $ 1,033,828
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, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, Industry Reportable Segment 2020 2019 2020 2019 Food & Beverage All $ 48,153 $ 64,774 $ 152,586 $ 204,743 Retail All 39,390 39,420 108,882 111,899 Consumer Products All 37,175 38,510 111,371 119,866 Communications All 20,227 48,147 58,234 136,819 Automotive All 13,399 19,125 51,610 55,857 Technology All 41,220 28,148 129,569 84,294 Healthcare All 25,120 25,152 71,970 74,403 Financials All 22,529 28,054 66,282 81,049 Transportation and Travel/Lodging All 9,674 20,541 35,226 65,111 Other All 26,536 31,036 85,113 99,787 $ 283,423 $ 342,907 $ 870,843 $ 1,033,828

Income (Loss) Per Common Share

Income (Loss) Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 2020 2019 Numerator: Net income (loss) attributable to MDC Partners Inc. $ 4,076 $ (1,752) $ 4,486 $ 2,425 Accretion on convertible preference shares (3,579) (3,306) (10,528) (8,931) Net income allocated to convertible preference shares (137) — — — Net income (loss) attributable to MDC Partners Inc. common shareholders $ 360 $ (5,058) $ (6,042) $ (6,506) Denominator: Basic weighted average number of common shares outstanding 73,207,619 72,044,480 72,713,257 68,154,306 Dilutive effect of equity awards 269,160 — — — Diluted weighted average number of common shares outstanding 73,476,779 72,044,480 72,713,257 68,154,306 Basic $ — $ (0.07) $ (0.08) $ (0.10) Diluted $ — $ (0.07) $ (0.08) $ (0.10)

Deferred Acquisition Consider_2

Deferred Acquisition Consideration (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019. September 30, December 31, 2020 2019 Beginning Balance of contingent payments $ 74,671 $ 82,598 Payments (41,326) (30,719) Redemption value adjustments (1) 2,814 15,451 Additions - acquisitions and step-up transactions 7,703 7,145 Other 2,020 196 Ending Balance of contingent payments $ 45,882 $ 74,671 Fixed payments 263 549 $ 46,145 $ 75,220 (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 Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. The following table presents the impact to the Company’s Statements of operations due to the redemption value adjustments for the contingent deferred acquisition consideration: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Loss (Income) attributable to fair value adjustments $ 2,803 $ 1,943 $ 515 $ (3,627) Stock-based compensation 770 1,540 2,299 1,010 Redemption value adjustments $ 3,573 $ 3,483 $ 2,814 $ (2,617)

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Lease Cost: Operating lease cost $ 18,495 $ 16,605 $ 53,397 $ 50,519 Variable lease cost 3,580 4,960 11,808 14,285 Sublease rental income (2,940) (2,376) (8,637) (6,565) Total lease cost $ 19,135 $ 19,189 $ 56,568 $ 58,239 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 17,703 $ 16,988 $ 52,930 $ 52,163 Right-of-use assets obtained in exchange for operating lease liabilities and other non-cash adjustments $ (814) $ 8,783 $ 37,120 $ 267,796 Weighted average remaining lease term (in years) - Operating leases 7.35 7.0 7.35 7.0 Weighted average discount rate - Operating leases 10.6 8.7 10.6 8.7
Minimum Future Rental Payments	The following table presents minimum future rental payments under the Company’s leases at September 30, 2020 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2020 $ 17,241 2021 67,718 2022 61,473 2023 57,429 2024 50,894 Thereafter 190,461 Total 445,216 Less: Present value discount (148,071) Lease liability $ 297,145

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Debt	September 30, 2020 December 31, 2019 Revolving credit agreement $ — $ — 6.50% Notes due 2024 870,256 900,000 Debt issuance costs (9,834) (12,370) $ 860,422 $ 887,630

Noncontrolling and Redeemable_2

Noncontrolling and Redeemable Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2019 and nine months ended September 30, 2020 were as follows: Noncontrolling Balance, December 31, 2018 $ 9,278 Income attributable to noncontrolling interests 16,156 Distributions made (11,392) Other (14) Balance, December 31, 2019 $ 14,028 Income attributable to noncontrolling interests 14,620 Distributions made (14,499) Other (218) Balance, September 30, 2020 $ 13,931
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, 2020 and 2019 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Net income (loss) attributable to MDC Partners Inc. $ 4,076 $ (1,752) $ 4,486 $ 2,425 Transfers from the noncontrolling interest: Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests 2,129 (648) 1,626 (745) Net transfers from noncontrolling interests $ 2,129 $ (648) $ 1,626 $ (745) Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests $ 6,205 $ (2,400) $ 6,112 $ 1,680
Redeemable Noncontrolling Interest [Table Text Block]	The following table presents changes in redeemable noncontrolling interests: Nine Months Ended September 30, 2020 Year Ended December 31, 2019 Beginning Balance $ 36,973 $ 51,546 Redemptions (12,289) (14,530) Granted — — Changes in redemption value 1,056 (3,163) Currency translation adjustments (568) 3 Other — 3,117 Ending Balance $ 25,172 $ 36,973

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019: September 30, 2020 December 31, 2019 Carrying Fair Value Carrying Fair Value Liabilities: 6.50% Senior Notes due 2024 $ 870,256 $ 800,000 $ 900,000 $ 812,250

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Revenue: (Dollars in Thousands) Integrated Networks - Group A $ 87,064 $ 99,299 $ 260,420 $ 276,286 Integrated Networks - Group B 112,159 129,057 323,264 395,622 Media & Data Network 33,572 36,235 103,181 118,923 All Other 50,628 78,316 183,978 242,997 Total $ 283,423 $ 342,907 $ 870,843 $ 1,033,828 Adjusted EBITDA: Integrated Networks - Group A $ 21,009 $ 23,974 $ 54,516 $ 43,128 Integrated Networks - Group B 29,598 21,989 63,121 65,117 Media & Data Network 3,031 1,354 5,710 2,388 All Other 7,146 9,221 23,936 26,962 Corporate (6,726) (7,333) (17,496) (20,478) Total Adjusted EBITDA $ 54,058 $ 49,205 $ 129,787 $ 117,117 Depreciation and amortization $ (9,332) $ (9,368) $ (27,437) $ (28,869) Impairment and other losses (159) (1,944) (19,159) (1,944) Stock-based compensation (6,459) (6,026) (10,568) (12,632) Deferred acquisition consideration adjustments (2,803) (1,943) (515) 3,627 Distributions from non-consolidated affiliates (208) 202 (1,273) 171 Other items, net (6,208) (705) (12,519) (8,926) Total Operating Income $ 28,889 $ 29,421 $ 58,316 $ 68,544 Other Income (Expenses): Interest expense and finance charges, net $ (15,266) $ (16,110) $ (46,819) $ (49,284) Foreign exchange gain (loss) 2,159 (3,973) (7,256) 4,401 Other, net 505 (431) 22,723 (4,559) Income before income taxes and equity in earnings of non-consolidated affiliates 16,287 8,907 26,964 19,102 Income tax expense 1,452 3,457 7,029 6,292 Income before equity in earnings of non-consolidated affiliates 14,835 5,450 19,935 12,810 Equity in earnings (losses) of non-consolidated affiliates (31) 63 (829) 352 Net income 14,804 5,513 19,106 13,162 Net income attributable to the noncontrolling interest (10,728) (7,265) (14,620) (10,737) Net income (loss) attributable to MDC Partners Inc. 4,076 (1,752) 4,486 2,425 Accretion on and net income allocated to convertible preference shares (3,716) (3,306) (10,528) (8,931) Net income (loss) attributable to MDC Partners Inc. common shareholders $ 360 $ (5,058) $ (6,042) $ (6,506) Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Depreciation and amortization: (Dollars in Thousands) Integrated Networks - Group A $ 1,601 $ 2,132 $ 4,908 $ 6,420 Integrated Networks - Group B 4,813 3,872 13,726 11,964 Media & Data Network 786 1,004 2,401 3,332 All Other 1,933 2,168 5,735 6,523 Corporate 199 192 667 630 Total $ 9,332 $ 9,368 $ 27,437 $ 28,869 Stock-based compensation: Integrated Networks - Group A $ 4,024 $ 4,330 $ 5,880 $ 8,564 Integrated Networks - Group B 742 740 2,388 3,231 Media & Data Network 131 16 122 22 All Other 141 107 339 363 Corporate 1,421 833 1,839 452 Total $ 6,459 $ 6,026 $ 10,568 $ 12,632 Capital expenditures: Integrated Networks - Group A $ 269 $ 1,083 $ 835 $ 5,120 Integrated Networks - Group B 694 4,108 899 6,287 Media & Data Network 72 116 269 460 All Other 79 545 536 1,889 Corporate 23,073 11 25,338 30 Total $ 24,187 $ 5,863 $ 27,877 $ 13,786

Basis of Presentation and Rec_2

Basis of Presentation and Recent Developments (Details)	1 Months Ended	9 Months Ended		12 Months Ended
	Apr. 30, 2020USD ($)	Sep. 30, 2020reporting_segment	Sep. 30, 2020reportable_segment	Dec. 31, 2019operating_segment	Sep. 30, 2019	Mar. 23, 2016USD ($)
Debt [Line Items]
Number of operating segments | operating_segment				4
Number of reportable segments		2	3
6.50% Notes due 2024 | Senior Notes
Debt [Line Items]
Debt Acquired	$ 29,744,000
Aggregate principal amount						$ 900,000,000
Interest rate, stated percentage					6.50%	6.50%
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	73.90%
Long-term Debt	$ 21,999,000
Long-term Debt, Accrued Interest	946,000
Gain (Loss) on Extinguishment of Debt	$ 7,388,000

Acquisitions and Dispositions (

Acquisitions and Dispositions (Details Textual) - USD ($) $ in Thousands	Jul. 01, 2020	Mar. 19, 2020	Feb. 14, 2020	Nov. 15, 2019	Apr. 01, 2019	Mar. 08, 2019	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Aggregate purchase price for noncontrolling interest							$ 11,392		$ 14,499
Reduction of noncontrolling and redeemable noncontrolling interest								$ 648		$ 745
Deferred acquisition consideration									46,145		$ 75,220
Redeemable noncontrolling interest, redemptions, value							$ (14,530)		(12,289)
Veritas [Member]
Business Acquisition [Line Items]
Remaining ownership interest acquired	10.00%
Aggregate purchase price for noncontrolling interest	$ 2,187
Deferred cash payment for noncontrolling interest	1,087
Reduction of noncontrolling and redeemable noncontrolling interest	2,651
Difference between purchase price and noncontrolling interest recorded in common stock and other paid-in capital	$ 464
KWT Global [Member]
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)		22.50%
Aggregate purchase price		$ 2,118
Closing cash payment		729
Deferred acquisition consideration		1,389
Redeemable noncontrolling interest, redemptions, value									$ (1,615)
Reduction in noncontrolling interests		$ 503
Laird - Partners [Member]
Business Acquisition [Line Items]
Reduction of noncontrolling and redeemable noncontrolling interest				$ 5,045
Remaining ownership interest acquired (percent)				35.00%
Aggregate purchase price				$ 2,389
Closing cash payment				1,588
Deferred acquisition consideration				801
Reduction in noncontrolling interests				$ 2,656
Hunter PR LLC [Member]
Business Acquisition [Line Items]
Reduction of noncontrolling and redeemable noncontrolling interest					$ 9,486
Remaining ownership interest acquired (percent)					35.00%
Aggregate purchase price					$ 10,234
Closing cash payment					3,890
Deferred acquisition consideration					6,344
Reduction in noncontrolling interests					$ 745
Sloane and Company LLC [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses			$ 26,696
Gain (loss) on disposition of business			$ 16,827
Sloane and Company LLC [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Business Acquisition [Line Items]
Period of contingent payments expected after disposal			2 years
Kingsdale Partners LP [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses						$ 50
Gain (loss) on disposition of business						$ 3

Revenue - Additional Informatio

Revenue - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020country
Non-US And Canada [Member]
Disaggregation of Revenue [Line Items]
Number of countries in which entity operates	11
Minimum
Disaggregation of Revenue [Line Items]
Payment period	30 days
Termination period	30 days
Maximum
Disaggregation of Revenue [Line Items]
Payment period	60 days
Termination period	90 days

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Services	$ 283,423	$ 1,415,803	$ 342,907	$ 1,475,088	$ 1,513,779	$ 870,843	$ 1,033,828
United States
Disaggregation of Revenue [Line Items]
Services	228,255		271,671			703,158	819,347
Canada
Disaggregation of Revenue [Line Items]
Services	20,299		25,895			55,164	72,837
Other
Disaggregation of Revenue [Line Items]
Services	34,869		45,341			112,521	141,644
Food & Beverage
Disaggregation of Revenue [Line Items]
Services	48,153		64,774			152,586	204,743
Retail
Disaggregation of Revenue [Line Items]
Services	39,390		39,420			108,882	111,899
Consumer Products
Disaggregation of Revenue [Line Items]
Services	37,175		38,510			111,371	119,866
Communications
Disaggregation of Revenue [Line Items]
Services	20,227		48,147			58,234	136,819
Automotive
Disaggregation of Revenue [Line Items]
Services	13,399		19,125			51,610	55,857
Technology
Disaggregation of Revenue [Line Items]
Services	41,220		28,148			129,569	84,294
Healthcare
Disaggregation of Revenue [Line Items]
Services	25,120		25,152			71,970	74,403
Financials
Disaggregation of Revenue [Line Items]
Services	22,529		28,054			66,282	81,049
Transportation and Travel/Lodging
Disaggregation of Revenue [Line Items]
Services	9,674		20,541			35,226	65,111
Other
Disaggregation of Revenue [Line Items]
Services	$ 26,536		$ 31,036			$ 85,113	$ 99,787

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Unbilled service fees	$ 70,999		$ 65,004
Unbilled outside vendor costs, billable to clients	21,884		30,133
Advance billings	157,101		171,742
Decrease in advance billings	(14,641)
Revenue recognized		$ 127,961	190,342
Remaining performance obligation, amount	$ 14,556
Remaining performance obligation, current year, percentage	66.00%
Remaining performance obligation, year two, percentage	31.00%
Remaining performance obligation, year three, percentage	3.00%
Accrued Expenses and Other Current Liabilities
Disaggregation of Revenue [Line Items]
Advance billings	$ 197,650		$ 216,931
Decrease in advance billings	$ 19,281

Income (Loss) Per Common Shar_2

Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.	$ 4,076		$ (1,752)			$ 4,486	$ 2,425
Numerator
Net income (loss) attributable to MDC Partners Inc. common shareholders	$ 360	$ (17,557)	$ (5,058)	$ (138,362)	$ 204,832	$ (6,042)	$ (6,506)
Denominator
Denominator for basic income (loss) per common share - weighted average common shares	73,207,619	69,132,100	72,044,480	57,218,994	55,255,797	72,713,257	68,154,306
Impact of stock options and non-vested stock under employee stock incentive plans (in shares)	269,160		0			0	0
Denominator for diluted income (loss) per common share - adjusted weighted shares and assumed conversions	73,476,779	69,132,100	72,044,480	57,218,994	55,481,786	72,713,257	68,154,306
Earnings per share, basic	$ 0	$ (250)	$ (0.07)	$ (2,420)	$ 3,710	$ (0.08)	$ (0.10)
Earnings per share, diluted	$ 0	$ (250)	$ (0.07)	$ (2,420)	$ 3,700	$ (0.08)	$ (0.10)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,325,800,000					3,539,060,000
MDC Partners Inc. Shareholders' Deficit
Class of Stock [Line Items]
Net loss attributable to MDC Partners Inc.	$ 4,076		$ (1,752)			$ 4,486	$ 2,425
Series 4 Convertible Preferred Stock | Convertible Preferred Stock
Numerator
Accretion on and net income allocated to convertible preference shares	3,579		3,306			10,528	8,931
Net income allocated to convertible preference shares	$ (137)		$ 0			$ 0	$ 0
Denominator
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			3,714,595,000				3,714,595,000

Income (Loss) Per Common Shar_3

Income (Loss) Per Common Share (Details Textual) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	2,325,800,000		3,539,060,000
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)			3,220,342	135,386
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)		3,714,595,000		3,714,595,000
Shares outstanding (shares)	145,000,000	145,000,000	145,000,000	145,000,000	145,000,000	145,000,000	145,000,000	95,000,000
Convertible preferred stock, common shares issuable upon conversion (shares)	28,287,863		28,287,863			26,133,613

Deferred Acquisition Consider_3

Deferred Acquisition Consideration (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance of contingent payments		$ 74,671		$ 74,671	$ 82,598
Payments		30,719		41,326
Redemption value adjustments	$ 3,573	15,451	$ 3,483	2,814	(2,617)
Additions		7,145		7,703
Foreign translation adjustment		$ 196		2,020
Ending balance of contingent payments	45,882			45,882
Deferred acquisition consideration	46,145			46,145		$ 75,220
Loss (Income) attributable to fair value adjustments	(2,803)		(1,943)	(515)	3,627
Stock-based compensation	770		1,540	2,299	1,010
Fixed payments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deferred acquisition consideration	263			263		$ 549
Contingent Payment
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Loss (Income) attributable to fair value adjustments	$ 2,803		$ 1,943	$ 515	$ (3,627)

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Leases not yet commenced, liability	$ 12,677,000		$ 12,677,000
Impairment of right-of-use asset	$ 1,933	$ 5,777	$ 1,933

Leases - Lease Costs and Other

Leases - Lease Costs and Other Quantitative Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 18,495	$ 16,605	$ 53,397	$ 50,519
Variable lease cost	3,580	4,960	11,808	14,285
Sublease rental income	(2,940)	(2,376)	(8,637)	(6,565)
Total lease cost	19,135	19,189	56,568	58,239
Operating cash flows	17,703	16,988	52,930	52,163
Right-of-use assets obtained in exchange for new operating lease liabilities	$ (814)	$ 8,783	$ 37,120	$ 267,796
Weighted average remaining lease term (in years) - Operating leases	7 years 4 months 6 days	7 years	7 years 4 months 6 days	7 years
Weighted average discount rate - Operating leases	1060.00%	870.00%	1060.00%	870.00%

Leases - Minimum Future Rental

Leases - Minimum Future Rental Payments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Leases [Abstract]
Remaining 2019	$ 17,241
2020	67,718
2021	61,473
2022	57,429
2023	50,894
Thereafter	190,461
Total	445,216
Less: Present value discount	(148,071)
Lease liability	$ 297,145

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 30, 2020	Dec. 31, 2019
Debt [Line Items]
Revolving credit agreement	$ 0		$ 0
Debt issuance costs	(9,834)		(12,370)
Long-term Debt, Excluding Current Maturities	860,422		887,630
6.50% Notes due 2024 | Senior Notes
Debt [Line Items]
Long-term Debt		$ 21,999
6.50% Notes due 2024 | Fair Value, Inputs, Level 1 | Senior Notes
Debt [Line Items]
Long-term Debt	$ 870,256		$ 900,000

Debt (Details Textual)

Debt (Details Textual)	May 28, 2020USD ($)	Mar. 23, 2016USD ($)	Apr. 30, 2020USD ($)	Dec. 31, 2020	Sep. 30, 2020USD ($)	May 27, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019	Mar. 12, 2019USD ($)
Debt [Line Items]
Required minimum earnings before interest, taxes and depreciation and amortization	$ 120,000,000					$ 105,000,000
Amount outstanding under the line of credit					$ 0		$ 0
Amount of letters of credit outstanding					$ 18,576,000		$ 4,836,000
Prime Rate | Minimum
Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Prime Rate | Maximum
Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.25%
Non-Prime Rate | Minimum
Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.50%
Non-Prime Rate | Maximum
Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.00%
Senior Notes | 6.50% Notes due 2024
Debt [Line Items]
Aggregate principal amount		$ 900,000,000
Interest rate, stated percentage		6.50%						6.50%
Debt Acquired			$ 29,744,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed			73.90%
Long-term Debt			$ 21,999,000
Long-term Debt, Accrued Interest			946,000
Gain (Loss) on Extinguishment of Debt			$ 7,388,000
Percentage of redemption price, change in ownership controllatest for redemption at face amount		101.00%
Percentage of redemption price, redemption date, latest for redemption at face amounttion Price, Redemption Date, Latest For Redemption At Face Amount		100.00%
Line of Credit [Member] | Amendment, Credit Agreement [Member]
Debt [Line Items]
Maximum borrowing capacity	$ 250,000,000					$ 211,500,000			$ 211,500,000
Ratio of Indebtedness to Net Capital									6.25
Forecast | Line of Credit [Member] | Amendment, Credit Agreement [Member]
Debt [Line Items]
Ratio of Indebtedness to Net Capital				5.5

Noncontrolling and Redeemable_3

Noncontrolling and Redeemable Noncontrolling Interests (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 25,172	$ 36,973	$ 51,546
Vesting over period [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	17,640
Termination, disability, or death [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	7,532
Acquisition Value in excess of Redemption Value [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 0

Noncontrolling and Redeemable_4

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Amounts Due to Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Beginning balance		$ 14,028		$ 14,028	$ 9,278
Income attributable to noncontrolling interests	$ 10,728	16,156	$ 7,265	14,620	$ 10,737
Distributions made		(11,392)		(14,499)
Other		$ (14)		(218)
Ending balance	$ 13,931			$ 13,931

Noncontrolling and Redeemable_5

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ 4,076	$ (1,752)	$ 4,486	$ 2,425
Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests	2,129		1,626
Change from net income (loss) attributable to MDC Partners Inc. and transfers to noncontrolling interests	(6,205)	2,400	(6,112)	(1,680)
MDC Partners Inc. Shareholders' Deficit
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	4,076	(1,752)	4,486	2,425
Increase (decrease) in MDC Partners Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests	$ 2,129	$ (648)	$ (1,626)	$ 745

Noncontrolling and Redeemable_6

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020
Noncontrolling Interest [Abstract]
Beginning Balance	$ 36,973	$ 36,973
Redemptions	(14,530)	(12,289)
Changes in redemption value	(3,163)	1,056
Currency translation adjustments	3	(568)
Other	$ 3,117	0
Ending Balance		$ 25,172

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Amount of letters of credit outstanding	$ 18,576	$ 4,836

Share Capital (Details Textual)

Share Capital (Details Textual)	Mar. 14, 2019USD ($)$ / sharesshares	Mar. 07, 2017USD ($)$ / shares	Sep. 30, 2020USD ($)vote$ / sharesshares	Sep. 30, 2019USD ($)shares	Jun. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)shares	Jun. 30, 2019USD ($)shares	Dec. 31, 2018USD ($)shares
Share Capital [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ (170,349,000)	$ (184,918,000)	$ (184,603,000)	$ (190,575,000)	$ (182,600,000)	$ (257,590,000)
Issuance of common and convertible preference shares				98,620,000
Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Proceeds from issuance of common and convertible preference shares, net of issuance costs			0	98,620,000
Preferred Stock
Share Capital [Line Items]
Proceeds from issuance of common and convertible preference shares, net of issuance costs	$ 98,620,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 90,123,000	152,746,000	152,746,000	$ 152,746,000	$ 152,746,000	$ 152,746,000	$ 90,123,000
Issuance of common and convertible preference shares				$ 62,623,000
Stock issued during period (shares) | shares				50,000,000
Preferred Stock | Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Proceeds from issuance of common and convertible preference shares, net of issuance costs		$ 95,000
Preferred Stock, Conversion Price Per Preference Share | $ / shares	$ 7.42	$ 10
Preferred Stock, Accretion Percentage, Preference		8.00%
Preferred Stock, Accretion of Redemption Discount			7,268
Preferred Stock, Liquidation Preference, Value			$ 126,019
Preferred Stock, Convertible Preference Shares, Convertible at Company's Option, Term	2 years	5 years
Shares outstanding (shares) | shares			145,000,000	145,000,000	145,000,000	145,000,000	145,000,000	95,000,000
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	$ 50,000,000
Preferred Stock, Liquidation Preference Per Share | $ / shares	$ 1,000	$ 1,000
Preferred Stock, Conversion Price Per Preference Share | $ / shares	$ 5
Preferred Stock, Accretion Percentage, Preference	8.00%
Preferred Stock, Accretion Rate, Preference Per Share | $ / shares			$ 8.67
Preferred Stock, Convertible Preference Shares, Accretion Period	5 years
Preferred Stock, Monthly Accretion of Redemption Discount			$ 7.39
Preferred Stock, Accretion of Redemption Discount			3,260,000
Preferred Stock, Liquidation Preference, Value			56,521,000
Preferred Stock, Convertible Preference Shares, Convertible at Company's Option, Term	2 years	5 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]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 106,037,000	$ 98,364,000	$ 98,234,000	$ 101,469,000	$ 97,455,000	$ 58,579,000
Issuance of common and convertible preference shares	$ 35,997			$ 35,997,000
Common Stock
Share Capital [Line Items]
Stock issued during period (shares) | shares				14,285,714
Common Stock | Common Class A
Share Capital [Line Items]
Proceeds from Issuance of Common Stock	50,000,000
Shares outstanding (shares) | shares			73,550,950			72,150,854
Common stock, voting rights, number of votes per share | vote			1
Preferred Stock, Par or Stated Value Per Share | $ / shares			$ 0
Common Stock | Common Class B
Share Capital [Line Items]
Shares outstanding (shares) | shares			3,743			3,749
Common stock, voting rights, number of votes per share | vote			20
Preferred Stock, Par or Stated Value Per Share | $ / shares			$ 0
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

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Apr. 30, 2020	Dec. 31, 2019
Liabilities:
Discount rate		11.41%
Impairment of right-of-use asset	$ 1,933	$ 5,777	$ 1,933
6.50% Notes due 2024 | Senior Notes
Liabilities:
Long term debt, Carrying Amount				$ 21,999
6.50% Notes due 2024 | Fair Value, Inputs, Level 1 | Senior Notes
Liabilities:
Long term debt, Carrying Amount		870,256			$ 900,000
Long term debt, Fair Value		$ 800,000			$ 812,250

Supplemental Information (Detai

Supplemental Information (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Asset Impairment Charges	$ 159,000	$ 8,599,000	$ 1,944,000	$ 87,204,000	$ 5,471,000		$ 19,159,000	$ 1,944,000
Impairment of Right-Of-Use Asset			1,933,000				5,777,000	1,933,000
Goodwill	710,013,000						710,013,000			$ 731,691,000	$ 732,752,000
Indefinite-lived intangible assets acquired							$ 14,600,000
Finite-lived intangible assets, remaining amortization period							5 years
Income tax expense	1,452,000	10,316,000	3,457,000	29,615,000	(168,358,000)		$ 7,029,000	6,292,000
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	$ 16,287,000	20,867,000	$ 8,907,000	(88,669,000)	86,022,000		$ 26,964,000	$ 19,102,000
Effective tax rate (percent)	8.90%		38.80%				26.10%	32.90%
Revenues	$ 283,423,000	1,415,803,000	$ 342,907,000	1,475,088,000	1,513,779,000		$ 870,843,000	$ 1,033,828,000
Increase (Decrease) in Accounts Receivable							(43,708,000)	$ (835,000)
Goodwill, Impairment Loss							13,382,000
Payroll Tax Deferral Provision, CARES Act [Member]
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Accrued Payroll Taxes	$ 16,000,000						$ 16,000,000
Reporting Unit One [Member]
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Goodwill									$ 130,780,000
Restatement Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Asset Impairment Charges		780,000		7,147,000	1,056,000
Goodwill										$ (8,983,000)	$ (8,203,000)
Income tax expense		(217,000)		(1,988,000)	(294,000)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates		(780,000)		(8,262,000)	(1,056,000)
Increase (Decrease) in Deferred Income Tax Assets		217,000		1,988,000	294,000	$ 3,587,000
Revenues		0		(1,115,000)	0
Goodwill, Period Increase (Decrease)		(780,000)		(7,147,000)	(1,056,000)
Increase (Decrease) in Accounts Receivable				(1,115,000)
Increase (Decrease) in Deferred Income Taxes		$ 217,000		$ 1,988,000	$ 294,000	$ 3,587,000

Supplemental Information - Stat

Supplemental Information - Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Revenues	$ 283,423	$ 1,415,803	$ 342,907	$ 1,475,088	$ 1,513,779	$ 870,843	$ 1,033,828
Asset Impairment Charges	159	8,599	1,944	87,204	5,471	19,159	1,944
Costs and Expenses	254,534	1,336,343	313,486	1,473,654	1,382,876	812,527	965,284
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	16,287	20,867	8,907	(88,669)	86,022	26,964	19,102
Income Tax Expense (Benefit)	1,452	10,316	3,457	29,615	(168,358)	7,029	6,292
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 360	$ (17,557)	$ (5,058)	$ (138,362)	$ 204,832	$ (6,042)	$ (6,506)
Weighted Average Number of Shares Outstanding, Basic	73,207,619	69,132,100	72,044,480	57,218,994	55,255,797	72,713,257	68,154,306
Weighted Average Number of Shares Outstanding, Diluted	73,476,779	69,132,100	72,044,480	57,218,994	55,481,786	72,713,257	68,154,306
Income (Loss) from Continuing Operations, Per Basic Share	$ 0	$ (250)	$ (0.07)	$ (2,420)	$ 3,710	$ (0.08)	$ (0.10)
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0	$ (250)	$ (0.07)	$ (2,420)	$ 3,700	$ (0.08)	$ (0.10)
Previously Reported
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Revenues		$ 1,415,803		$ 1,476,203	$ 1,513,779
Asset Impairment Charges		7,819		80,057	4,415
Costs and Expenses		1,335,563		1,466,507	1,381,820
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		21,647		(80,407)	87,078
Income Tax Expense (Benefit)		10,533		31,603	(168,064)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent		$ (16,994)		$ (132,088)	$ 205,594
Weighted Average Number of Shares Outstanding, Basic		69,132,100		57,218,994	55,255,797
Weighted Average Number of Shares Outstanding, Diluted		69,132,100		57,218,994	55,481,786
Income (Loss) from Continuing Operations, Per Basic Share		$ (250)		$ (2,310)	$ 3,720
Income (Loss) from Continuing Operations, Per Diluted Share		$ (250)		$ (2,310)	$ 3,710
Restatement Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Revenues		$ 0		$ (1,115)	$ 0
Asset Impairment Charges		780		7,147	1,056
Costs and Expenses		780		7,147	1,056
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(780)		(8,262)	(1,056)
Income Tax Expense (Benefit)		(217)		(1,988)	(294)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent		$ (563)		$ (6,274)	$ (762)
Weighted Average Number of Shares Outstanding, Basic		0		0	0
Weighted Average Number of Shares Outstanding, Diluted		0		0	0
Income (Loss) from Continuing Operations, Per Basic Share		$ 0		$ (110)	$ (10)
Income (Loss) from Continuing Operations, Per Diluted Share		$ 0		$ (110)	$ (10)

Supplemental Information - Bala

Supplemental Information - Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Accounts Receivable, after Allowance for Credit Loss, Current	$ 403,636		$ 449,288			$ 394,085
Goodwill	710,013		731,691			732,752
Deferred tax assets	82,576		84,900			91,436
Assets	1,706,132		1,828,306			1,600,950
Accruals and other liabilities	323,414		353,575
Liabilities	1,851,309		1,981,908
Accumulated deficit	(476,293)		(480,779)			(475,526)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(170,349)	$ (184,603)	(190,575)	$ (184,918)	$ (182,600)	(257,590)
Liabilities and Equity	$ 1,706,132		1,828,306			1,600,950
Previously Reported
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Accounts Receivable, after Allowance for Credit Loss, Current			450,403			395,200
Goodwill			740,674			740,955
Deferred tax assets			85,988			92,741
Assets			1,839,492			1,611,573
Accumulated deficit			(469,593)			(464,903)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(179,389)			(246,967)
Liabilities and Equity			1,839,492			1,611,573
Restatement Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Accounts Receivable, after Allowance for Credit Loss, Current			(1,115)			(1,115)
Goodwill			(8,983)			(8,203)
Deferred tax assets			(1,088)			(1,305)
Assets			(11,186)			(10,623)
Accumulated deficit			(11,186)			(10,623)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(11,186)			(10,623)
Liabilities and Equity			$ (11,186)			$ (10,623)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
Sublease rental income		$ 2,940	$ 2,376	$ 8,637	$ 6,565
Stagwell Subsidiary [Member] | Services Provided By Subisidiary [Member]
Related Party Transaction [Line Items]
Due to Related Parties		816		816
Accounts Payable, Related Parties		225		225
Stagwell Subsidiary [Member] | Development of Advertising Technology [Member]
Related Party Transaction [Line Items]
Due to Related Parties		475		475
Accounts Payable, Related Parties		17		17
Stagwell Affiliate [Member] | Affiliated Entity [Member] | Arrangement To Perform Media, Planning, Buying And Reporting Services [Member]
Related Party Transaction [Line Items]
Accounts receivable, related parties, current		5,276		5,276
Due from (to) from related parties		957		957
Stagwell Affiliate [Member] | Affiliated Entity [Member] | Arrangement To Provide Audience And Brand Research, Concept Testing And Landscape For New Business [Member]
Related Party Transaction [Line Items]
Due from (to) from related parties		(82)		(82)
Accounts payable, related parties, current		$ 145		$ 145
Other Company [Member] | Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Sublease rental income	$ 140

Segment Information (Details 1)

Segment Information (Details 1) $ in Thousands	3 Months Ended					9 Months Ended				12 Months Ended
	Sep. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2020reporting_segment	Sep. 30, 2020reportable_segment	Sep. 30, 2019USD ($)	Dec. 31, 2019operating_segment
Segment Reporting Information [Line Items]
Number of reportable segments							2	3
Number of operating segments | operating_segment										4
Revenues	$ 283,423	$ 1,415,803	$ 342,907	$ 1,475,088	$ 1,513,779	$ 870,843			$ 1,033,828
Segment operating income (loss)	28,889		29,421			58,316			68,544
EBITDA	54,058		49,205			129,787			117,117
Interest expense and finance charges	(15,266)		(16,110)			(46,819)			(49,284)
Foreign exchange gain (loss)	2,159		(3,973)			(7,256)			4,401
Other, net	505		(431)			22,723			(4,559)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	16,287	20,867	8,907	(88,669)	86,022	26,964			19,102
Income tax expense	1,452	10,316	3,457	29,615	(168,358)	7,029			6,292
Income before equity in earnings of non-consolidated affiliates	14,835		5,450			19,935			12,810
Equity in earnings (losses) of non-consolidated affiliates	(31)		63			(829)			352
Net income	14,804		5,513			19,106			13,162
Net income attributable to the noncontrolling interest	(10,728)	(16,156)	(7,265)			(14,620)			(10,737)
Net income (loss) attributable to MDC Partners Inc.	4,076		(1,752)			4,486			2,425
Depreciation and amortization	(9,332)		(9,368)			(27,437)			(28,869)
Asset Impairment Charges	(159)	(8,599)	(1,944)	(87,204)	(5,471)	(19,159)			(1,944)
Depreciation, Depletion and Amortization, Nonproduction	9,332		9,368						28,869
Depreciation						27,437			28,869
Stock-based compensation	(6,459)		(6,026)			(10,568)			(12,632)
Capital expenditures	24,187		5,863			27,877			13,786
Change in contingent purchase price obligation	(2,803)		(1,943)			(515)			3,627
Proceeds from (Payments to) Noncontrolling Interests	(208)		202			(1,273)			171
Other Operating Income	(6,208)		(705)			(12,519)			(8,926)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	360	$ (17,557)	(5,058)	$ (138,362)	$ 204,832	(6,042)			(6,506)
Capital expenditures incurred but not yet paid						(16,403)
Global Integrated Agencies, Group A
Segment Reporting Information [Line Items]
Revenues	87,064		99,299			260,420			276,286
EBITDA	21,009		23,974			54,516			43,128
Depreciation and amortization	(1,601)		(2,132)			(4,908)			(6,420)
Stock-based compensation	(4,024)		(4,330)			(5,880)			(8,564)
Capital expenditures	269		1,083			835			5,120
Global Integrated Agencies, Group B
Segment Reporting Information [Line Items]
Revenues	112,159		129,057			323,264			395,622
EBITDA	29,598		21,989			63,121			65,117
Depreciation and amortization	(4,813)		(3,872)			(13,726)			(11,964)
Stock-based compensation	(742)		(740)			(2,388)			(3,231)
Capital expenditures	694		4,108			899			6,287
Media Services
Segment Reporting Information [Line Items]
Revenues	33,572		36,235			103,181			118,923
EBITDA	3,031		1,354			5,710			2,388
Depreciation and amortization	(786)		(1,004)			(2,401)			(3,332)
Stock-based compensation	(131)		(16)			(122)			(22)
Capital expenditures	72		116			269			460
All Other
Segment Reporting Information [Line Items]
Revenues	50,628		78,316			183,978			242,997
EBITDA	7,146		9,221			23,936			26,962
Depreciation and amortization	(1,933)		(2,168)			(5,735)			(6,523)
Stock-based compensation	(141)		(107)			(339)			(363)
Capital expenditures	79		545			536			1,889
Corporate, Non-Segment
Segment Reporting Information [Line Items]
EBITDA	(6,726)		(7,333)			(17,496)			(20,478)
Depreciation and amortization	(199)		(192)			(667)			(630)
Stock-based compensation	(1,421)		(833)			(1,839)			(452)
Capital expenditures	$ 23,073		$ 11			$ 25,338			$ 30