Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Jul. 16, 2018
Document and Entity Information
Amendment Flag	false
Entity Registrant Name	INTERPUBLIC GROUP OF COMPANIES, INC.
Entity Central Index Key	0000051644
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Entity Common Stock, Shares Outstanding		383,785,420

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net Revenue	$ 1,948.2	$ 1,834.6	$ 3,722.2	$ 3,509.9
Billable expenses	443.6	351.2	838.7	739.7
Total revenue	2,391.8	2,185.8	4,560.9	4,249.6
OPERATING EXPENSES:
Salaries and related expenses	1,292.9	1,228.9	2,623.2	2,480.6
Office and other direct expenses	333.3	318.4	657.1	631.1
Billable expenses	443.6	351.2	838.7	739.7
Cost of services	2,069.8	1,898.5	4,119.0	3,851.4
Selling, general and administrative expenses	28.8	20.3	63.9	55.5
Depreciation and amortization	44.0	41.3	90.0	82.3
Total operating expenses	2,142.6	1,960.1	4,272.9	3,989.2
OPERATING INCOME	249.2	225.7	288.0	260.4
EXPENSES AND OTHER INCOME:
Interest expense	(26.1)	(25.7)	(46.0)	(46.6)
Interest income	4.7	4.7	8.7	9.9
Other expense, net	(16.3)	(15.4)	(40.7)	(14.6)
Total (expenses) and other income	(37.7)	(36.4)	(78.0)	(51.3)
Income before income taxes	211.5	189.3	210.0	209.1
Provision for income taxes	63.6	81.6	76.3	81.3
Income of consolidated companies	147.9	107.7	133.7	127.8
Equity in net (loss) income of unconsolidated affiliates	(0.1)	(0.1)	(2.0)	1.1
NET INCOME	147.8	107.6	131.7	128.9
Net (income) loss attributable to noncontrolling interests	(2.0)	0.1	0.0	3.5
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$ 145.8	$ 107.7	$ 131.7	$ 132.4
Earnings per share, Basic	$ 0.38	$ 0.27	$ 0.34	$ 0.34
Earnings per share, Diluted	$ 0.37	$ 0.27	$ 0.34	$ 0.33
Weighted-average number of common shares outstanding, Basic	383.6	392.3	383.5	392.0
Weighted-average number of common shares outstanding, Diluted	389.5	400.3	388.9	399.6
Dividends declared per common share	$ 0.21	$ 0.18	$ 0.42	$ 0.36

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 147.8	$ 107.6	$ 131.7	$ 128.9
Foreign currency translation:
Foreign currency translation adjustments	(116.4)	33.0	(94.0)	85.9
Reclassification adjustments recognized in net income	0.9	0.7	13.4	0.3
Foreign currency transaction and translation adjustment, net of tax	(115.5)	33.7	(80.6)	86.2
Available-for-sale securities:
Changes in fair value of available-for sale securities	0.0	0.0	0.0	0.1
Net unrealized gains/losses on available-for-sale securities, net of tax	0.0	0.0	0.0	0.1
Derivative instruments:
Recognition of previously unrealized losses in net income	0.6	0.6	1.1	1.1
Income tax effect	(0.1)	(0.2)	(0.3)	(0.4)
Net unrecognized gains/losses on derivative instruments, net of tax	0.5	0.4	0.8	0.7
Defined benefit pension and other postretirement plans:
Net actuarial (losses) gains for the period	(1.4)	0.8	(1.4)	0.8
Amortization of unrecognized losses, transition obligation and prior service cost included in net income	2.0	1.8	3.9	3.5
Settlement and curtailment losses included in net income	0.0	0.0	0.2	0.0
Other	(0.5)	(0.4)	(0.4)	(0.6)
Income tax effect	0.2	(0.5)	0.1	(0.6)
Defined benefit pension and other postretirement plans adjustment, net of tax	0.3	1.7	2.4	3.1
Other comprehensive (loss) income, net of tax	(114.7)	35.8	(77.4)	90.1
TOTAL COMPREHENSIVE INCOME	33.1	143.4	54.3	219.0
Less: comprehensive (loss) income attributable to noncontrolling interests	(0.1)	0.1	(1.8)	(2.8)
COMPREHENSIVE INCOME ATTRIBUTABLE TO IPG	$ 33.2	$ 143.3	$ 56.1	$ 221.8

Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
ASSETS:
Cash and cash equivalents	$ 493.2	$ 790.9
Accounts receivable, net of allowance of $44.5 and $42.7, respectively	4,247.7	4,585.0
Accounts receivable, billable to clients	1,945.8	1,747.4
Assets held for sale	19.6	5.7
Other current assets	439.3	346.5
Total current assets	7,145.6	7,475.5
Property and equipment, net of accumulated depreciation of $1,014.7 and $1,036.2, respectively	602.0	650.4
Deferred income taxes	261.0	234.0
Goodwill	3,788.1	3,820.4
Other non-current assets	560.9	524.4
TOTAL ASSETS	12,357.6	12,704.7
LIABILITIES:
Accounts payable	5,738.8	6,420.2
Accrued liabilities	551.5	674.7
Contract liabilities	510.8	484.7
Short-term borrowings	757.6	84.9
Current portion of long-term debt	0.1	2.0
Liabilities held for sale	26.5	8.8
Total current liabilities	7,585.3	7,675.3
Long-term debt	1,282.7	1,285.6
Deferred compensation	445.4	476.6
Other non-current liabilities	786.8	768.8
TOTAL LIABILITIES	10,100.2	10,206.3
Redeemable noncontrolling interests (see Note 5)	165.8	252.1
STOCKHOLDERS' EQUITY:
Common stock	39.0	38.6
Additional paid-in capital	1,022.9	955.2
Retained earnings	2,076.7	2,104.5
Accumulated other comprehensive loss, net of tax	(903.4)	(827.8)
Stockholders Equity Subtotal Before Treasury Stock	2,235.2	2,270.5
Less: Treasury stock	(173.5)	(59.0)
Total IPG stockholders' equity	2,061.7	2,211.5
Noncontrolling interests	29.9	34.8
TOTAL STOCKHOLDERS' EQUITY	2,091.6	2,246.3
TOTAL LIABILITIES AND EQUITY	12,357.6	12,704.7
Parentheticals:
Allowance for Doubtful Accounts Receivable	44.5	42.7
Accumulated Depreciation, Property and Equipment	$ 1,014.7	$ 1,036.2

Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 131.7	$ 128.9
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	90.0	82.3
Provision for uncollectible receivables	6.1	8.6
Amortization of restricted stock and other non-cash compensation	46.0	46.0
Net amortization of bond discounts and deferred financing costs	2.7	2.8
Deferred income tax (benefit) provision	(31.0)	9.5
Net losses on sales of businesses	44.2	12.2
Other	1.9	10.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	238.0	769.7
Accounts receivable, billable to clients	(233.7)	(165.5)
Other current assets	(124.6)	(84.5)
Accounts payable	(579.3)	(651.3)
Accrued liabilities	(175.9)	(313.9)
Contract liabilities	38.0	6.9
Other non-current assets and liabilities	(11.8)	(15.0)
Net cash used in operating activities	(557.7)	(153.1)
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(61.5)	(68.9)
Acquisitions, net of cash acquired	(8.5)	(12.6)
Other investing activities	12.4	(14.5)
Net cash used in investing activities	(57.6)	(96.0)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in short-term borrowings	669.3	153.5
Exercise of stock options	7.0	11.8
Common stock dividends	(161.2)	(141.4)
Repurchase of common stock	(114.5)	(115.0)
Tax payments for employee shares withheld	(28.0)	(37.8)
Acquisition-related payments	(16.0)	(36.3)
Distributions to noncontrolling interests	(10.6)	(10.9)
Repayment of long-term debt	(4.7)	(23.6)
Other financing activities	(0.3)	0.3
Net cash provided by (used in) financing activities	341.0	(199.4)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(27.5)	8.2
Net decrease in cash, cash equivalents and restricted cash	(301.8)	(440.3)
Cash, cash equivalents, and restricted cash at beginning of period	797.7	1,100.2
Cash, cash equivalents, and restricted cash at end of period	$ 495.9	$ 659.9

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock, Shares	Common Stock, Amount	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock	Total IPG Stockholders' Equity	Noncontrolling Interests
Balance, common stock shares at Dec. 31, 2016		394.3
Balance at Dec. 31, 2016	$ 2,090.4		$ 39.4	$ 1,199.2	$ 1,839.9	$ (964.4)	$ (63.3)	$ 2,050.8	$ 39.6
NET INCOME	128.9
Net income available to IPG common stockholders	132.4				132.4			132.4
Net income attributable to noncontrolling interest	(3.5)								(3.5)
Other comprehensive income (loss)	90.1					89.4		89.4
Other comprehensive income (loss), attributable to noncontrolling interest									0.7
Reclassifications related to redeemable noncontrolling interests	5.0								5.0
Distributions to noncontrolling interests	(11.4)								(11.4)
Change in redemption value of redeemable noncontrolling interests	(3.4)				(3.4)			(3.4)
Repurchase of Common Stock	(115.0)						(115.0)	(115.0)
Common stock dividend	(141.4)				(141.4)			(141.4)
Stock-based compensation, shares		5.5
Stock-based compensation, value	47.9		0.6	47.3				47.9
Exercise of stock options, shares		1.1
Exercise of stock options, value	11.9		0.1	11.8				11.9
Shares withheld for taxes, shares		(1.6)
Shares withheld for taxes, value	(38.4)		(0.2)	(38.2)				(38.4)
Other	(1.3)			0.1	(0.8)			(0.7)	0.6
Balance, common stock shares at Jun. 30, 2017		399.3
Balance at Jun. 30, 2017	2,063.3		39.9	1,220.2	1,826.7	(875.0)	(178.3)	2,033.5	29.8
Balance, common stock shares at Dec. 31, 2017		386.2
Balance at Dec. 31, 2017	2,246.3		38.6	955.2	2,104.5	(827.8)	(59.0)	2,211.5	34.8
NET INCOME	131.7
Net income available to IPG common stockholders	131.7				131.7			131.7
Net income attributable to noncontrolling interest	0.0
Other comprehensive income (loss)	(77.4)					(75.6)		(75.6)
Other comprehensive income (loss), attributable to noncontrolling interest									(1.8)
Reclassifications related to redeemable noncontrolling interests	6.3								6.3
Distributions to noncontrolling interests	(10.6)								(10.6)
Change in redemption value of redeemable noncontrolling interests	44.7			41.8	2.9			44.7
Repurchase of Common Stock	(114.5)						(114.5)	(114.5)
Common stock dividend	(161.2)				(161.2)			(161.2)
Stock-based compensation, shares		4.6
Stock-based compensation, value	48.5		0.5	48.0				48.5
Exercise of stock options, shares		0.9
Exercise of stock options, value	7.0			7.0				7.0
Shares withheld for taxes, shares		(1.2)
Shares withheld for taxes, value	(28.6)		(0.1)	(28.5)				(28.6)
Other	(0.6)			(0.6)	(1.2)			(1.8)	1.2
Balance, common stock shares at Jun. 30, 2018		390.5
Balance at Jun. 30, 2018	$ 2,091.6		$ 39.0	$ 1,022.9	$ 2,076.7	$ (903.4)	$ (173.5)	$ 2,061.7	$ 29.9

Basis of Presentation (Notes)	6 Months Ended
Basis of Presentation (Notes)	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The unaudited Consolidated Financial Statements have been prepared by The Interpublic Group of Companies, Inc. and its subsidiaries (the "Company," "IPG," "we," "us" or "our") in accordance with accounting principles generally accepted in the United States of America ("U.S. 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, they do not include certain information and disclosures required for complete financial statements. The preparation of financial statements in conformity with U.S. GAAP requires us to make judgments, assumptions and estimates that affect the amounts reported and disclosed. Actual results could differ from these estimates and assumptions. The consolidated results for interim periods are not necessarily indicative of results for the full year and should be read in conjunction with our 2017 Annual Report on Form 10-K. As of January 1, 2018, the Company has revised the presentation of its Consolidated Statements of Operations, which disaggregates net revenue and billable expenses within total revenue and separately presents cost of services; selling, general and administrative expenses; and depreciation and amortization within operating expenses. The revised presentation does not impact total revenue, operating expenses or operating income. Cost of services is comprised of the expenses of our revenue-producing operating segments, Integrated Agency Networks ("IAN") and Constituency Management Group ("CMG"), including salaries and related expenses, office and other direct expenses and billable expenses, and includes an allocation of the centrally managed expenses of our Corporate and other group. Office and other direct expenses include rent expense, professional fees, certain expenses incurred by our staff in servicing our clients and other costs directly attributable to client engagements. Selling, general and administrative expenses are primarily the unallocated expenses of our Corporate and other group, as disclosed further in Note 12, excluding depreciation and amortization. Depreciation and amortization of the fixed assets and intangible assets of the Company is disclosed as a separate operating expense. In the opinion of management, these unaudited Consolidated Financial Statements include all adjustments, consisting only of normal and recurring adjustments necessary for a fair statement of the information for each period contained therein. Certain reclassifications and immaterial revisions have been made to prior-period financial statements to conform to the current-period presentation.

Summary of Significant Accounting Policies (Notes)	6 Months Ended
Summary of Significant Accounting Policies (Notes)	Jun. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2: Summary of Significant Accounting Policies Effective January 1, 2018, IPG adopted Accounting Standards Codification Topic 606, Revenue from Contracts with Customers, ("ASC 606") using the full retrospective transition method. Under this method, the Company will revise its consolidated financial statements for the years ended December 31, 2016 and 2017, and applicable interim periods within the year ended December 31, 2017, as if ASC 606 had been effective for those periods. ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. We only apply the five-step model to contracts when it is probable that IPG will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within each contract and determine those that are distinct performance obligations. We then assess whether IPG acts as an agent or a principal for each identified performance obligation and include revenue within the transaction price for third-party costs when we determine that we act as principal. Revenue Recognition We recognize revenue when the control to promised goods or services transfers to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services. Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications and marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting around the world. Our revenues are directly dependent upon the advertising, marketing and corporate communications requirements of our existing clients and our ability to win new clients. Depending on the terms of the client contract, revenue is derived from diverse arrangements involving fees for services performed, commissions, performance incentive provisions and combinations of the three. Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding pass-through expenses charged to a client. Revenues for the creation, planning and placement of advertising are determined primarily on a negotiated fee basis and, to a lesser extent, on a commission basis. Fees are usually calculated to reflect hourly rates plus proportional overhead and a mark-up. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative or quantitative metrics, or both. Commissions are earned based on services provided and are usually derived from a percentage or fee over the total cost to complete the assignment. Commissions can also be derived when clients pay us the gross rate billed by media and we pay for media at a lower net rate; the difference is the commission that we earn, which we either retain in full or share with the client depending on the nature of the applicable services agreement. We also generate revenue in negotiated fees from our public relations, sales promotion, event marketing, sports and entertainment marketing, and corporate and brand identity services. Billable expenses include pass-through expenses related to event and advertising production costs for performance obligations where we have determined that we are acting as principal that are rebilled to our clients, as well as out-of-pocket costs. Out-of-pocket costs often include expenses related to airfare, mileage, hotel stays, out-of-town meals and telecommunication charges for client service staff. We record these billable expenses within total revenue with a corresponding offset to operating expenses. Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. As is customary in the industry, our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have right to payment for all services provided through the end of the contract or termination date. Our client contracts may include provisions for incentive compensation and vendor rebates and credits. Our largest clients are multinational entities and, as such, we often provide services to these clients out of multiple offices and across many of our agencies. In arranging for such services, it is possible that we will enter into global, regional and local agreements. Agreements of this nature are reviewed by legal counsel to determine the governing terms to be followed by the offices and agencies involved. When we receive credits from our vendors and media outlets for transactions entered into on behalf of our clients, they are generally remitted back to our clients; however, they may be retained by us based on specific terms of our contracts and local laws. If amounts are to be passed through to clients, they are recorded as liabilities until settlement or, if retained by us, are recorded as revenue when earned. For media contracts that can be canceled by the customer at any time without compensation, the contract does not exist until media airs, at which point revenue is recognized. Timing of Recognition We have determined that we generally satisfy our performance obligations over time, except for certain commission-based contracts, which are recognized at a point in time, typically the date of broadcast or publication. Fees are generally recognized based on proportional performance utilizing periodically updated estimates to complete. Performance Obligations Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Principal vs. Agent For each identified performance obligation in the contract with the customer, we assess whether our agency or the third-party supplier is the principal or agent. We control the specified services before transferring those services to the customer and act as the principal if we are primarily responsible for the integration of products and services into the deliverable to our customer, have inventory risk, or discretion in establishing pricing. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. We have determined that we primarily act as principal for creative, media planning, in-house production, event, public relations and branding services, where we control the specified services before transferring those services to the customer because we are primarily responsible for the integration of products and services into the deliverable to our customer. We generally do not have inventory risk or discretion in establishing pricing in our contracts with customers. If the third-party supplier, rather than IPG, is primarily responsible for the integration of products and services into the deliverable to our customer, then we generally act as the agent and solely arrange for the third-party supplier to provide services to the customer. For performance obligations for which we act as the agent (primarily production and media buying), we record our revenue as the net amount of our gross billings less pass-through expenses charged to a customer. Variable Consideration Revenue for our services is measured based on the consideration specified in a contract with a customer. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to either qualitative or quantitative metrics, or both. Incentive compensation is estimated using the most likely amount 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 performance incentives are related. Practical Expedients As part of our adoption of ASC 606, we apply the practical expedient and do not disclose information about remaining performance obligations that have original expected durations of one year or less. Amounts related to those performance obligations with expected durations of greater than one year are immaterial. We apply the practical expedient and do not capitalize costs to obtain a contract as these amounts would generally be recognized over less than one year and are not material. Additionally, we report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions.

Revenue (Notes)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Revenue

Adoption of ASC 606

Effective with the adoption of ASC 606 on January 1, 2018 using the full retrospective transition method, the Company will revise its consolidated financial statements for the years ended December 31, 2016 and 2017, and applicable interim periods within the year ended December 31, 2017, as if ASC 606 had been effective for those periods. ASC 606, which accelerates the recognition of revenue primarily as a result of estimating variable consideration, mostly impacts the timing of revenue recognition between quarters, but also can affect, to a lesser extent, the amount of annual revenue recognized. Although ASC 606 results in an increase in the number of performance obligations within certain of our contractual arrangements, the amount or timing of revenue recognized is not materially impacted. ASC 606 also results in an increase in third-party costs being included in revenue and costs, primarily in connection with our events businesses, which has no impact on operating income, net income or cash flows. The increases to retained earnings as of December 31, 2017 and 2016 as a result of adopting ASC 606 were not material. The following tables summarize the effects of adopting ASC 606.

CONSOLIDATED STATEMENT OF OPERATIONS



	Three months ended June 30, 2017								Six months ended June 30, 2017
	As Revised ¹			ASC 606 Adjustments		As Adjusted			As Revised ¹			ASC 606 Adjustments		As Adjusted
REVENUE:
Net revenue	$	1,815.4		$	19.2	$	1,834.6		$	3,485.7		$	24.2	$	3,509.9
Billable expenses	69.5			281.7		351.2			153.1			586.6		739.7
Total revenue	1,884.9			300.9		2,185.8			3,638.8			610.8		4,249.6

OPERATING EXPENSES:
Salaries and related expenses	1,228.9			—		1,228.9			2,480.6			—		2,480.6
Office and other direct expenses	318.4			—		318.4			631.1			—		631.1
Billable expenses	69.5			281.7		351.2			153.1			586.6		739.7
Cost of services	1,616.8			281.7		1,898.5			3,264.8			586.6		3,851.4
Selling, general and administrative expenses	20.3			—		20.3			55.5			—		55.5
Depreciation and amortization	41.3			—		41.3			82.3			—		82.3
Total operating expenses	1,678.4			281.7		1,960.1			3,402.6			586.6		3,989.2

OPERATING INCOME	206.5			19.2		225.7			236.2			24.2		260.4

EXPENSES AND OTHER INCOME:
Interest expense	(25.7		)	—		(25.7		)	(46.6		)	—		(46.6		)
Interest income	4.7			—		4.7			9.9			—		9.9
Other income, net	(15.4		)	—		(15.4		)	(14.6		)	—		(14.6		)
Total (expenses) and other income	(36.4		)	—		(36.4		)	(51.3		)	—		(51.3		)

Income before income taxes	170.1			19.2		189.3			184.9			24.2		209.1
Benefit of income taxes	75.4			6.2		81.6			73.3			8.0		81.3
Income of consolidated companies	94.7			13.0		107.7			111.6			16.2		127.8
Equity in net (loss) income of unconsolidated affiliates	(0.1		)	—		(0.1		)	1.1			—		1.1
NET INCOME	94.6			13.0		107.6			112.7			16.2		128.9
Net loss attributable to noncontrolling interests	0.1			—		0.1			3.5			—		3.5
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$	94.7		$	13.0	$	107.7		$	116.2		$	16.2	$	132.4

Earnings per share available to IPG common stockholders:
Basic	$	0.24		$	0.03	$	0.27		$	0.30		$	0.04	$	0.34
Diluted	$	0.24		$	0.03	$	0.27		$	0.29		$	0.04	$	0.33

Weighted-average number of common shares outstanding:
Basic	392.3			—		392.3			392.0			—		392.0
Diluted	400.3			—		400.3			399.6			—		399.6

Dividends declared per common share	$	0.18				$	0.18		$	0.36				$	0.36


1	These amounts have been revised for the new presentation as described in Note 1.

CONSOLIDATED BALANCE SHEET



	December 31, 2017
	As Reported			ASC 606 Adjustments			As Adjusted
ASSETS:
Cash and cash equivalents	$	790.9		$	—		$	790.9
Accounts receivable, net of allowance of $42.7	4,585.0			—			4,585.0
Expenditures billable to clients	1,747.4			(1,747.4		)	—
Accounts receivable, billable to clients	—			1,747.4			1,747.4
Assets held for sale	5.7			—			5.7
Other current assets	335.1			11.4			346.5
Total current assets	7,464.1			11.4			7,475.5
Property and equipment, net of accumulated depreciation of $1,036.2	650.4			—			650.4
Deferred income taxes	236.0			(2.0		)	234.0
Goodwill	3,820.4			—			3,820.4
Other non-current assets	524.3			0.1			524.4
TOTAL ASSETS	$	12,695.2		$	9.5		$	12,704.7

LIABILITIES:
Accounts payable	$	6,907.8		$	(487.6	)	$	6,420.2
Accrued liabilities	674.7			—			674.7
Contract liabilities	—			484.7			484.7
Short-term borrowings	84.9			—			84.9
Current portion of long-term debt	2.0			—			2.0
Liabilities held for sale	8.8			—			8.8
Total current liabilities	7,678.2			(2.9		)	7,675.3
Long-term debt	1,285.6			—			1,285.6
Deferred compensation	476.6			—			476.6
Other non-current liabilities	766.9			1.9			768.8
TOTAL LIABILITIES	10,207.3			(1.0		)	10,206.3

Redeemable noncontrolling interests	252.1			—			252.1

STOCKHOLDERS’ EQUITY:
Common stock	38.6			—			38.6
Additional paid-in capital	955.2			—			955.2
Retained earnings	2,093.6			10.9			2,104.5
Accumulated other comprehensive loss, net of tax	(827.4		)	(0.4		)	(827.8		)
	2,260.0			10.5			2,270.5
Less: Treasury stock	(59.0		)	—			(59.0		)
Total IPG stockholders’ equity	2,201.0			10.5			2,211.5
Noncontrolling interests	34.8			—			34.8
TOTAL STOCKHOLDERS’ EQUITY	2,235.8			10.5			2,246.3
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$	12,695.2		$	9.5		$	12,704.7

CONSOLIDATED STATEMENT OF CASH FLOWS



	Six months ended June 30, 2017
	As Reported			ASC 606 Adjustments			As Adjusted
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$	112.7		$	16.2		$	128.9
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	82.3			—			82.3
Provision for uncollectible receivables	8.6			—			8.6
Amortization of restricted stock and other non-cash compensation	46.0			—			46.0
Net amortization of bond discounts and deferred financing costs	2.8			—			2.8
Deferred income tax provision	1.5			8.0			9.5
Net losses on sales of businesses	12.2			—			12.2
Other	10.2			—			10.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	769.7			—			769.7
Expenditures billable to clients	(165.3		)	165.3			—
Accounts receivable, billable to clients	—			(165.5		)	(165.5		)
Other current assets	(82.0		)	(2.5		)	(84.5		)
Accounts payable	(622.9		)	(28.4		)	(651.3		)
Accrued liabilities	(313.9		)	—			(313.9		)
Contract liabilities	—			6.9			6.9
Other non-current assets and liabilities	(15.0		)	—			(15.0		)
Net cash used in operating activities	(153.1		)	—			(153.1		)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities	(96.0		)	—			(96.0		)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net cash used in financing activities	(199.4		)	—			(199.4		)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	8.2			—			8.2
Net decrease in cash, cash equivalents and restricted cash	(440.3		)	—			(440.3		)
Cash, cash equivalents and restricted cash at beginning of period	1,100.2			—			1,100.2
Cash, cash equivalents and restricted cash at end of period	$	659.9		$	—		$	659.9

Retained earnings as of December 31, 2016 and June 30, 2017 increased by $35.6 and $51.8, respectively, as a result of the adoption of ASC 606. Accumulated other comprehensive loss, net of tax, as of December 31, 2016 and June 30, 2017 decreased by $1.9 and $0.8, respectively, as a result of the adoption of the ASC 606.

Disaggregation of Revenue

The following is a description of the principal activities, by reportable segment, from which we generate revenue. For more detailed information about reportable segments, see Note 12.

Integrated Agency Networks

The IAN segment of IPG principally generates revenue from providing advertising and media services as well as a comprehensive array of global communications and marketing services. Within IAN’s advertising business, we typically identify two performance obligations for creative and production services. Depending on the arrangement, we typically act as the principal for our creative services and as the agent for our production services. Within our media business, we also identify two performance obligations for media planning and media buying services. We typically act as the principal for our media planning services and as the agent for media buying services. Generally, our branding arrangements consist of two performance obligations, and we act as the principal for both performance obligations.

Constituency Management Group

The CMG segment generates revenue from providing events and public relations services as well as sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting. In CMG’s events and public relations arrangements, we typically identify one performance obligation, for which we act as the principal in most arrangements. Generally, our branding arrangements consist of two performance obligations, and we act as the principal for both performance obligations.

Principal Geographic Markets

Our agencies are located in over 100 countries, including every significant world market. Our geographic revenue breakdown is listed below.



	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	1,445.7	$	1,350.8	$	2,796.4	$	2,666.0
International:
United Kingdom	201.6		166.0		406.0		341.0
Continental Europe	205.1		176.3		386.8		334.5
Asia Pacific	304.2		260.5		535.7		480.8
Latin America	92.5		94.5		172.5		170.3
Other	142.7		137.7		263.5		257.0
Total International	946.1		835.0		1,764.5		1,583.6
Total Consolidated	$	2,391.8	$	2,185.8	$	4,560.9	$	4,249.6



	Three months ended June 30,				Six months ended June 30,
Net revenue:	2018		2017		2018		2017
United States	$	1,171.5	$	1,127.6	$	2,263.8	$	2,184.7
International:
United Kingdom	175.7		141.7		339.2		276.9
Continental Europe	178.7		154.6		337.4		295.5
Asia Pacific	214.2		205.3		393.0		379.0
Latin America	82.0		85.7		155.9		154.7
Other	126.1		119.7		232.9		219.1
Total International	776.7		707.0		1,458.4		1,325.2
Total Consolidated	$	1,948.2	$	1,834.6	$	3,722.2	$	3,509.9



IAN	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	1,063.2	$	1,022.3	$	2,086.4	$	1,992.2
International	749.3		689.0		1,411.6		1,286.9
Total IAN	$	1,812.5	$	1,711.3	$	3,498.0	$	3,279.1

Net revenue:
United States	$	963.3	$	926.3	$	1,861.3	$	1,788.3
International	665.8		607.7		1,249.1		1,136.8
Total IAN	$	1,629.1	$	1,534.0	$	3,110.4	$	2,925.1



CMG	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	382.5	$	328.5	$	710.0	$	673.8
International	196.8		146.0		352.9		296.7
Total CMG	$	579.3	$	474.5	$	1,062.9	$	970.5

Net revenue:
United States	$	208.2	$	201.3	$	402.5	$	396.4
International	110.9		99.3		209.3		188.4
Total CMG	$	319.1	$	300.6	$	611.8	$	584.8

Contract Balances

The following table provides information about receivables, contract assets and contract liabilities from contracts with customers.



	June 30, 2018		December 31, 2017
Accounts receivable, net of allowance of $44.5 and $42.7, respectively	$	4,247.7	$	4,585.0
Accounts receivable, billable to clients	1,945.8		1,747.4
Contract assets	44.9		11.5
Contract liabilities (deferred revenue)	510.8		484.7

Contract assets are primarily comprised of contract incentives that are generally satisfied annually under the terms of our contracts and are transferred to accounts receivable when the rights to payment becomes unconditional. Contract liabilities relate to advance consideration received from customers under the terms of our contracts primarily related to reimbursements of third party expenses, whether we act as principal or agent, and to a lesser extent, periodic retainer fees, both of which are generally recognized shortly after billing.

Debt and Credit Arrangements (Notes)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Debt and Credit Arrangements

Long-Term Debt

A summary of the carrying amounts and fair values of our long-term debt is listed below.



	Effective Interest Rate	June 30, 2018				December 31, 2017
	Effective Interest Rate	Book Value		Fair Value ¹		Book Value		Fair Value ¹
4.00% Senior Notes due 2022 (less unamortized discount and issuance costs of $1.2 and $0.9, respectively)	4.13%	$	247.9	$	251.6	$	247.6	$	259.0
3.75% Senior Notes due 2023 (less unamortized discount and issuance costs of $0.7 and $1.9, respectively)	4.32%	497.4		495.6		497.1		513.2
4.20% Senior Notes due 2024 (less unamortized discount and issuance costs of $0.6 and $2.4, respectively)	4.24%	497.0		503.3		496.7		524.2
Other notes payable and capitalized leases		40.5		40.5		46.2		46.2
Total long-term debt		1,282.8				1,287.6
Less: current portion		0.1				2.0
Long-term debt, excluding current portion		$	1,282.7			$	1,285.6


1	See Note 13 for information on the fair value measurement of our long-term debt.

Credit Agreements

We maintain a committed corporate credit facility, which has been amended and restated from time to time (the "Credit Agreement"). We use our Credit Agreement to increase our financial flexibility, to provide letters of credit primarily to support obligations of our subsidiaries and to support our commercial paper program. The Credit Agreement is a revolving facility, expiring in October 2022, under which amounts borrowed by us or any of our subsidiaries designated under the Credit Agreement may be repaid and reborrowed, subject to an aggregate lending limit of $1,500.0, or the equivalent in other currencies. The Company has the ability to increase the commitments under the Credit Agreement from time to time by an additional amount of up to $250.0, provided the Company receives commitments for such increases and satisfies certain other conditions. The aggregate available amount of letters of credit outstanding may decrease or increase, subject to a sublimit on letters of credit of $50.0, or the equivalent in other currencies. Our obligations under the Credit Agreement are unsecured. As of June 30, 2018, there were no borrowings under the Credit Agreement; however, we had $8.5 of letters of credit under the Credit Agreement, which reduced our total availability to $1,491.5. We were in compliance with all of our covenants in the Credit Agreement as of June 30, 2018.

We also have uncommitted lines of credit with various banks, which permit borrowings at variable interest rates and which are primarily used to fund working capital needs. We have guaranteed the repayment of some of these borrowings made by certain subsidiaries. If we lose access to these credit lines, we would have to provide funding directly to some of our operations. As of June 30, 2018, the Company had uncommitted lines of credit in an aggregate amount of $1,127.0, under which we had outstanding borrowings of $81.6 classified as short-term borrowings on our Consolidated Balance Sheet. The average amount outstanding during the second quarter of 2018 was $94.0, with a weighted-average interest rate of approximately 4.8%.

Commercial Paper

We have a commercial paper program under which the Company is authorized to issue unsecured commercial paper up to a maximum aggregate amount outstanding at any time of $1,500.0. Borrowings under the program are supported by the Credit Agreement described above. Proceeds of the commercial paper are used for working capital and general corporate purposes, including the repayment of maturing indebtedness and other short-term liquidity needs. The maturities of the commercial paper vary but may not exceed 397 days from the date of issue. As of June 30, 2018, there was $676.0 commercial paper outstanding. The average amount outstanding under the program during the second quarter of 2018 was $988.0, with a weighted-average interest rate of 2.5% and a weighted-average maturity of thirty days.

Acquisitions (Notes)

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Acquisitions

We continue to evaluate strategic opportunities to expand our industry expertise, strengthen our position in high-growth and key strategic geographical markets and industry sectors, advance our technological capabilities and improve our operational efficiency through both acquisitions and increased ownership interests in current investments. Our acquisitions typically provide for an initial payment at the time of closing and additional contingent purchase price payments based on the future performance of the acquired entity. We have entered into agreements that may require us to purchase additional equity interests in certain consolidated and unconsolidated subsidiaries. The amounts at which we record these transactions in our financial statements are based on estimates of the future financial performance of the acquired entity, the timing of the exercise of these rights, foreign currency exchange rates and other factors.

During the first half of 2018, we completed two acquisitions, including a full-service digital agency based in Brazil and an entertainment marketing and brand licensing agency in the fashion and lifestyle sector based in the U.K. Both of our acquisitions were included in the CMG operating segment. During the first half of 2018, we recorded $14.2 of goodwill and intangible assets related to our acquisitions.

During the first half of 2017, we completed three acquisitions, including a content creation and marketing agency based in the Netherlands, an independent media agency and digital consultancy based in Finland, and an integrated marketing communications agency based in Canada. All three of our acquisitions were included in the IAN operating segment. During the first half of 2017, we recorded $22.9 of goodwill and intangible assets related to our acquisitions.

The results of operations of our acquired companies were included in our consolidated results from the closing date of each acquisition. Details of cash paid for current and prior years' acquisitions are listed below.



	Six months ended June 30,
	2018			2017
Cost of investment: current-year acquisitions	$	8.7		$	14.8
Cost of investment: prior-year acquisitions	16.2			37.1
Less: net cash acquired	(0.4		)	(3.0		)
Total cost of investment	24.5			48.9
Operating payments ¹	18.2			34.7
Total cash paid for acquisitions ²	$	42.7		$	83.6

Represents cash payments for amounts that have been recognized in operating expenses since the date of acquisition either relating to adjustments to estimates in excess of the initial value of contingent payments recorded or were contingent upon the future employment of the former owners of the acquired companies. Amounts are reflected in the operating section of the unaudited Consolidated Statements of Cash Flows.

Of the total cash paid for acquisitions, $8.5 and $12.6 for the six months ended June 30, 2018 and 2017, respectively, are classified under the investing section of the unaudited Consolidated Statements of Cash Flows, as acquisitions, net of cash acquired. These amounts relate to initial payments for new transactions. Of the total cash paid for acquisitions, $16.0 and $36.3 for the six months ended June 30, 2018 and 2017, respectively, are classified under the financing section of the unaudited Consolidated Statements of Cash Flows as acquisition-related payments. These amounts relate to deferred payments and increases in our ownership interest for prior acquisitions.

Many of our acquisitions include provisions under which the noncontrolling equity owners may require us to purchase additional interests in a subsidiary at their discretion. Redeemable noncontrolling interests are adjusted quarterly to their estimated redemption value, but not less than their initial fair value. Any adjustments to the redemption value impact retained earnings, except for foreign currency translation adjustments.

The following table presents changes in our redeemable noncontrolling interests.



	Six months ended June 30,
	2018			2017
Balance at beginning of period	$	252.1		$	252.8
Change in related noncontrolling interests balance	(14.6		)	(6.5		)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0			3.0
Redemptions	(32.2		)	(13.2		)
Redemption value adjustments	(39.5		)	7.3
Balance at end of period	$	165.8		$	243.4

Earnings Per Share (Notes)

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share

The following sets forth basic and diluted earnings per common share available to IPG common stockholders.



	Three months ended June 30,				Six months ended June 30,
	2018		2017		2018		2017
Net income available to IPG common stockholders	$	145.8	$	107.7	$	131.7	$	132.4

Weighted-average number of common shares outstanding - basic	383.6		392.3		383.5		392.0
Dilutive effect of stock options and restricted shares	5.9		8.0		5.4		7.6
Weighted-average number of common shares outstanding - diluted	389.5		400.3		388.9		399.6

Earnings per share available to IPG common stockholders:
Basic	$	0.38	$	0.27	$	0.34	$	0.34
Diluted	$	0.37	$	0.27	$	0.34	$	0.33

Supplementary Data (Notes)

6 Months Ended

Jun. 30, 2018

Supplementary Data [Abstract]

Accrued Liabilities

The following table presents the components of accrued liabilities.



	June 30, 2018		December 31, 2017
Salaries, benefits and related expenses	$	310.7	$	441.7
Acquisition obligations	65.7		42.0
Office and related expenses	48.8		53.2
Interest	16.9		16.4
Other	109.4		121.4
Total accrued liabilities	$	551.5	$	674.7

Other Income, Net

Other Expense, Net

Results of operations for the three and six months ended June 30, 2018 and 2017 include certain items that are not directly associated with our revenue-producing operations.



	Three months ended June 30,						Six months ended June 30,
	2018			2017			2018			2017
Net losses on sales of businesses	$	(19.8	)	$	(13.1	)	$	(44.2	)	$	(12.2	)
Other	3.5			(2.3		)	3.5			(2.4		)
Total other expense, net	$	(16.3	)	$	(15.4	)	$	(40.7	)	$	(14.6	)

Net losses on sales of businesses – During the three and six months ended June 30, 2018 and 2017, the amounts recognized were related to sales of businesses and the classification of certain assets and liabilities, consisting primarily of cash, accounts receivable and accounts payable, as held for sale within our IAN operating segment.

Share Repurchase Program

In February 2018, our Board of Directors (the "Board") authorized a new share repurchase program to repurchase from time to time up to $300.0, excluding fees, of our common stock, which was in addition to the remaining amount available to be repurchased from the $300.0 authorization made by the Board in February 2017.

We may effect such repurchases through open market purchases, trading plans established in accordance with SEC rules, derivative transactions or other means. The timing and amount of repurchases in future periods will depend on market conditions and other funding requirements.

The following table presents our share repurchase activity under our share repurchase programs for the six months ended June 30, 2018 and 2017.



	Six months ended June 30,
	2018		2017
Number of shares repurchased	5.0		4.8
Aggregate cost, including fees	$	114.5	$	115.0
Average price per share, including fees	$	23.02	$	24.13

As of June 30, 2018, $341.0, excluding fees, remains available for repurchase under the share repurchase programs. The share repurchase programs have no expiration date.

Income Taxes (Notes)	6 Months Ended
Income Taxes (Notes)	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three and six months ended June 30, 2018, our effective income tax rates were negatively impacted by losses in certain foreign jurisdictions where we receive no tax benefit due to 100% valuation allowances and by losses on sales of businesses, and the classification of certain assets as held for sale, for which we received a minimal tax benefit, partially offset by additional research and development credits based on the conclusion of multi-year studies. The Tax Cuts and Jobs Act of 2017 imposed a new tax on certain foreign earnings generated in 2018 and forward. These global intangible low-taxed income ("GILTI") tax rules are complex. U.S. GAAP allows us to choose an accounting policy which treats the U.S. tax under GILTI provisions as either a current expense, as incurred, or as a component of the Company’s measurement of deferred taxes. The Company has elected to account for the GILTI tax as a current expense. We have various tax years under examination by tax authorities in various countries, and in various states, such as New York, in which we have significant business operations. It is not yet known whether these examinations will, in the aggregate, result in our paying additional taxes. We believe our tax reserves are adequate in relation to the potential for additional assessments in each of the jurisdictions in which we are subject to taxation. We regularly assess the likelihood of additional tax assessments in those jurisdictions and, if necessary, adjust our reserves as additional information or events require. With respect to all tax years open to examination by U.S. federal, various state and local, and non-U.S. tax authorities, we currently anticipate that total unrecognized tax benefits will decrease by an amount between $30.0 and $40.0 in the next twelve months, a portion of which will affect our effective income tax rate, primarily as a result of the settlement of tax examinations and the lapsing of statutes of limitations. We are effectively settled with respect to U.S. federal income tax audits through 2012, with the exception of 2009. With limited exceptions, we are no longer subject to state and local income tax audits for years prior to 2007 or non-U.S. income tax audits for years prior to 2006.

Incentive Compensation Plans (Notes)

6 Months Ended

Jun. 30, 2018

Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]

Incentive Compensation Plans

We issue stock-based compensation and cash awards to our employees under a plan established by the Compensation and Leadership Talent Committee of the Board of Directors (the “Compensation Committee”) and approved by our shareholders. We issued the following stock-based awards under the 2014 Performance Incentive Plan (the "2014 PIP") during the six months ended June 30, 2018.



	Awards	Weighted-average grant-date fair value (per award)
Restricted stock (shares or units)	1.8	$	23.62
Performance-based stock (shares)	2.9	$	21.13
Restricted stock units (settled in cash)	0.1	$	23.63
Total stock-based compensation awards	4.8

During the six months ended June 30, 2018, the Compensation Committee granted performance cash awards under the 2014 PIP and restricted cash awards under the 2009 Restricted Cash Plan with a total annual target value of $55.7 and $19.8, respectively. Cash awards are expensed over the vesting period, which is typically three years.

Accumulated Other Comprehensive Loss, Net of Tax (Notes)

6 Months Ended

Jun. 30, 2018

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Comprehensive Income (Loss) Note [Text Block]

Accumulated Other Comprehensive Loss, Net of Tax

The following tables present the changes in accumulated other comprehensive loss, net of tax, by component.



	Foreign Currency Translation Adjustments			Derivative Instruments			Defined Benefit Pension and Other Postretirement Plans			Total
Balance as of December 31, 2017	$	(585.3	)	$	(6.8	)	$	(235.7	)	$	(827.8	)
Other comprehensive loss before reclassifications	(92.2		)	0.0			(0.9		)	(93.1		)
Amount reclassified from accumulated other comprehensive loss, net of tax	13.4			0.8			3.3			17.5
Balance as of June 30, 2018	$	(664.1	)	$	(6.0	)	$	(233.3	)	$	(903.4	)



	Foreign Currency Translation Adjustments			Available-for-Sale Securities		Derivative Instruments			Defined Benefit Pension and Other Postretirement Plans			Total
Balance as of December 31, 2016	$	(718.6	)	$	0.6	$	(8.4	)	$	(238.0	)	$	(964.4	)
Other comprehensive income before reclassifications	85.2			0.1		0.0			0.4			85.7
Amount reclassified from accumulated other comprehensive loss, net of tax	0.3			0.0		0.7			2.7			3.7
Balance as of June 30, 2017	$	(633.1	)	$	0.7	$	(7.7	)	$	(234.9	)	$	(875.0	)

Amounts reclassified from accumulated other comprehensive loss, net of tax, for the three and six months ended June 30, 2018 and 2017 are as follows:



	Three months ended June 30,						Six months ended June 30,						Affected Line Item in the Consolidated Statements of Operations
	2018			2017			2018			2017
Foreign currency translation adjustments	$	0.9		$	0.7		$	13.4		$	0.3		Other expense, net
Losses on derivative instruments	0.6			0.6			1.1			1.1			Interest expense
Amortization of defined benefit pension and postretirement plan items	2.0			1.8			4.1			3.5			Other expense, net
Tax effect	(0.5		)	(0.6		)	(1.1		)	(1.2		)	Provision for income taxes
Total amount reclassified from accumulated other comprehensive loss, net of tax	$	3.0		$	2.5		$	17.5		$	3.7

Employee Benefits (Notes)

6 Months Ended

Jun. 30, 2018

Defined Benefit Plan [Abstract]

Employee Benefits

We have a defined benefit pension plan that covers certain U.S. employees (the “Domestic Pension Plan”). We also have numerous funded and unfunded plans outside the U.S. The Interpublic Limited Pension Plan in the U.K. is a defined benefit plan and is our most material foreign pension plan in terms of the benefit obligation and plan assets. Some of our domestic and foreign subsidiaries provide postretirement health benefits and life insurance to eligible employees and, in certain cases, their dependents. The domestic postretirement benefit plan is our most material postretirement benefit plan in terms of the benefit obligation. Certain immaterial foreign pension and postretirement benefit plans have been excluded from the table below.

The components of net periodic cost for the Domestic Pension Plan, the significant foreign pension plans and the domestic postretirement benefit plan are listed below.



	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Three months ended June 30,	2018			2017			2018			2017			2018			2017
Service cost	$	0.0		$	0.0		$	0.9		$	1.0		$	0.0		$	0.0
Interest cost	1.1			1.2			3.4			3.3			0.2			0.3
Expected return on plan assets	(1.5		)	(1.5		)	(4.8		)	(4.4		)	0.0			0.0
Amortization of:
Prior service cost (credit)	0.0			0.0			0.1			0.0			(0.1		)	0.0
Unrecognized actuarial losses	0.4			0.4			1.5			1.4			0.1			0.0
Net periodic cost	$	0.0		$	0.1		$	1.1		$	1.3		$	0.2		$	0.3



	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Six months ended June 30,	2018			2017			2018			2017			2018			2017
Service cost	$	0.0		$	0.0		$	2.0		$	1.9		$	0.0		$	0.0
Interest cost	2.2			2.5			6.8			6.6			0.5			0.6
Expected return on plan assets	(3.3		)	(3.1		)	(9.7		)	(8.7		)	0.0			0.0
Settlements and curtailments	0.0			0.0			0.2			0.0			0.0			0.0
Amortization of:
Prior service cost (credit)	0.0			0.0			0.1			0.0			(0.1		)	0.0
Unrecognized actuarial losses	0.8			0.8			3.0			2.7			0.1			0.0
Net periodic cost	$	(0.3	)	$	0.2		$	2.4		$	2.5		$	0.5		$	0.6

The components of net periodic cost other than the service cost component are included in the line item “Other expense, net” in the Consolidated Statements of Operations.

During the six months ended June 30, 2018, we contributed $1.9 and $9.9 of cash to our domestic and foreign pension plans, respectively. For the remainder of 2018, we expect to contribute approximately $8.0 and $9.0 of cash to our domestic and foreign pension plans, respectively.

Segment Information (Notes)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Segment Reporting Disclosure

Segment Information

As of June 30, 2018, we have two reportable segments: IAN and CMG. IAN is comprised of McCann Worldgroup, Foote, Cone & Belding ("FCB"), MullenLowe Group, IPG Mediabrands, our digital specialist agencies and our domestic integrated agencies. CMG is comprised of a number of our specialist marketing services offerings. We also report results for the “Corporate and other” group. The profitability measure employed by our chief operating decision maker for allocating resources to operating divisions and assessing operating division performance is segment operating income (loss). Segment information is presented consistently with the basis described in our 2017 Annual Report on Form 10-K. Summarized financial information concerning our reportable segments is shown in the following table.



	Three months ended June 30,						Six months ended June 30,
	2018			2017			2018			2017
Total revenue:
IAN	$	1,812.5		$	1,711.3		$	3,498.0		$	3,279.1
CMG	579.3			474.5			1,062.9			970.5
Total	$	2,391.8		$	2,185.8		$	4,560.9		$	4,249.6

Net revenue:
IAN	$	1,629.1		$	1,534.0		$	3,110.4		$	2,925.1
CMG	319.1			300.6			611.8			584.8
Total	$	1,948.2		$	1,834.6		$	3,722.2		$	3,509.9

Segment operating income (loss):
IAN	$	238.2		$	195.9		$	295.2		$	246.0
CMG	42.0			51.5			61.4			73.6
Corporate and other	(31.0		)	(21.7		)	(68.6		)	(59.2		)
Total	249.2			225.7			288.0			260.4

Interest expense, net	(21.4		)	(21.0		)	(37.3		)	(36.7		)
Other expense, net	(16.3		)	(15.4		)	(40.7		)	(14.6		)
Income before income taxes	$	211.5		$	189.3		$	210.0		$	209.1

Depreciation and amortization
IAN	$	35.8		$	33.9		$	73.2		$	66.6
CMG	6.0			6.0			12.1			12.0
Corporate and other	2.2			1.4			4.7			3.7
Total	$	44.0		$	41.3		$	90.0		$	82.3

Capital expenditures:
IAN	$	31.9		$	31.4		$	47.7		$	48.6
CMG	1.9			4.0			3.0			6.7
Corporate and other	4.9			8.7			10.8			13.6
Total	$	38.7		$	44.1		$	61.5		$	68.9

	June 30, 2018			December 31, 2017
Total assets:
IAN	$	10,840.0		$	10,978.0
CMG	1,476.8			1,427.4
Corporate and other	40.8			299.3
Total	$	12,357.6		$	12,704.7

Fair Value Measurements (Notes)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

Authoritative guidance for fair value measurements establishes a fair value hierarchy which requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value:



Level 1		Unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2		Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3		Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Financial Instruments that are Measured at Fair Value on a Recurring Basis

We primarily apply the market approach to determine the fair value of financial instruments that are measured at fair value on a recurring basis. There were no changes to our valuation techniques used to determine the fair value of financial instruments during the six months ended June 30, 2018. The following tables present information about our financial instruments measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017, and indicate the fair value hierarchy of the valuation techniques utilized to determine such fair value.



	June 30, 2018								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total		Balance Sheet Classification
Assets
Cash equivalents	$	111.8	$	0.0	$	0.0	$	111.8	Cash and cash equivalents
Liabilities
Contingent acquisition obligations¹	$	0.0	$	0.0	$	147.2	$	147.2

	December 31, 2017								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total		Balance Sheet Classification
Assets
Cash equivalents	$	201.6	$	0.0	$	0.0	$	201.6	Cash and cash equivalents
Liabilities
Contingent acquisition obligations ¹	$	0.0	$	0.0	$	147.0	$	147.0

Contingent acquisition obligations includes deferred acquisition payments and unconditional obligations to purchase additional noncontrolling equity shares of consolidated subsidiaries. Fair value measurement of the obligations is based upon actual and projected operating performance targets as specified in the related agreements. The increase in this balance of $0.2 from December 31, 2017 to June 30, 2018 is primarily due to new acquisitions and option exercises offset by payments. The amounts payable within the next twelve months are classified in accrued liabilities; any amounts payable thereafter are classified in other non-current liabilities.

Financial Instruments that are not Measured at Fair Value on a Recurring Basis

The following table presents information about our financial instruments that are not measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017, and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value.



	June 30, 2018								December 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Total long-term debt	$	0.0	$	1,250.5	$	40.5	$	1,291.0	$	0.0	$	1,296.4	$	46.2	$	1,342.6

Our long-term debt is comprised of senior notes and other notes payable. The fair value of our senior notes, which are traded over-the-counter, is based on quoted prices in markets that are not active. Therefore, these senior notes are classified as Level 2 within the fair value hierarchy. Our other notes payable are not actively traded, and their fair value is not solely derived from readily observable inputs. The fair value of our other notes payable is determined based on a discounted cash flow model and other proprietary valuation methods, and therefore is classified as Level 3 within the fair value hierarchy. See Note 4 for further information on our long-term debt.

Non-financial Assets and Liabilities that are Measured at Fair Value on a Nonrecurring Basis

Certain non-financial assets and liabilities are measured at fair value on a nonrecurring basis, primarily goodwill, intangible assets, and property and equipment. Accordingly, these assets are not measured and adjusted to fair value on an ongoing basis but are subject to periodic evaluations for potential impairment.

Commitments and Contingencies (Notes)	6 Months Ended
Commitments and Contingencies (Notes)	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters We are involved in various legal proceedings, and subject to investigations, inspections, audits, inquiries and similar actions by governmental authorities, arising in the normal course of business. The types of allegations that arise in connection with such legal proceedings may vary in nature, but can include claims related to contract, employment, tax and intellectual property matters. We evaluate all cases each reporting period and record liabilities for losses from legal proceedings when we determine that it is probable that the outcome in a legal proceeding will be unfavorable and the amount, or potential range, of loss can be reasonably estimated. In certain cases, we cannot reasonably estimate the potential loss because, for example, the litigation is in its early stages. While any outcome related to litigation or such governmental proceedings in which we are involved cannot be predicted with certainty, management believes that the outcome of these matters, individually and in the aggregate, will not have a material adverse effect on our financial condition, results of operations or cash flows. As previously disclosed, on April 10, 2015, a federal judge in Brazil authorized the search of the records of an agency's offices in São Paulo and Brasilia, in connection with an ongoing investigation by Brazilian authorities involving payments potentially connected to local government contracts. The Company had previously investigated the matter and taken a number of remedial and disciplinary actions. The Company has been in the process of concluding a settlement related to these matters with government agencies, and that settlement was fully executed in April 2018. The Company has previously provided for such settlement in its Consolidated Financial Statements. In December 2016, one of the Company's standalone domestic agencies was contacted by the Department of Justice Antitrust Division for documents regarding video production practices and is cooperating with the government. Guarantees As discussed in our 2017 Annual Report on Form 10-K, we have guaranteed certain obligations of our subsidiaries relating principally to operating leases, uncommitted lines of credit and cash pooling arrangements. As of June 30, 2018 and December 31, 2017, the amount of parent company guarantees on lease obligations was $823.6 and $829.2, respectively, the amount of parent company guarantees relating to uncommitted lines of credit was $322.7 and $308.8, respectively, and the amount of parent company guarantees related to daylight overdrafts, primarily utilized to manage intra-day overdrafts due to timing of transactions under cash pooling arrangements without resulting in incremental borrowings, was $193.0 and $182.2, respectively.

Recent Accounting Standards (Notes)	6 Months Ended
Recent Accounting Standards (Notes)	Jun. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Standards	Recent Accounting Standards Accounting pronouncements not listed below were assessed and determined to be not applicable or are expected to have minimal impact on our Consolidated Financial Statements. Revenue Recognition See Notes 2 and 3 for further discussion on the adoption of ASC 606. Derivatives and Hedging In August 2017, the Financial Accounting Standards Board (the "FASB") issued amended guidance on hedge accounting which expands an entity’s ability to hedge non-financial and financial risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The new guidance also eliminates the requirement to separately measure and report hedge ineffectiveness. This amended guidance is effective beginning January 1, 2019, with early adoption permitted. We are currently assessing the impact the adoption of the amended guidance will have on our Consolidated Financial Statements. Financial Instrument Credit Losses In June 2016, the FASB issued amended guidance on the accounting for credit losses on certain types of financial instruments, including trade receivables. The new model uses a forward-looking expected loss method, as opposed to the incurred loss method in current U.S. GAAP, which will generally result in earlier recognition of allowances for losses. This amended guidance is effective beginning January 1, 2020, with early adoption permitted as early as January 1, 2019. We are currently assessing the impact the adoption of the amended guidance will have on our Consolidated Financial Statements. Leases In February 2016, the FASB issued amended guidance on lease accounting which requires an entity to recognize a right-of-use asset and a corresponding lease liability on its balance sheet for virtually all of its leases with a term of more than 12 months, including those classified as operating leases. Both the asset and liability will initially be measured at the present value of the future minimum lease payments, with the asset being subject to adjustments such as initial direct costs. Consistent with current U.S. GAAP, the presentation of expenses and cash flows will depend primarily on the classification of the lease as either a finance or an operating lease. The new standard also requires additional quantitative and qualitative disclosures regarding the amount, timing and uncertainty of cash flows arising from leases in order to provide additional information about the nature of an organization’s leasing activities. This amended guidance, which will be effective beginning January 1, 2019, requires modified retrospective application, with early adoption permitted. We expect the adoption of this amended guidance to have a significant impact on our Consolidated Balance Sheets but not on our Consolidated Statements of Operations. Fair Value Measurements In January 2016, the FASB issued amended guidance that updates the fair value presentation requirements for certain financial instruments. Equity investments with readily determinable fair values, other than those accounted for using the equity method of accounting, will be measured at fair value with changes recorded through current earnings rather than other comprehensive income. This amended guidance was effective January 1, 2018. The adoption of this amended guidance did not have a significant impact on our Consolidated Financial Statements.

Subsequent Events (Notes)	3 Months Ended
Subsequent Events (Notes)	Jun. 30, 2018
Subsequent Events [Abstract]
AMS Acquisition	Subsequent Events On July 2, 2018, we entered into a Membership Interest Purchase Agreement (the “Purchase Agreement”) with Acxiom Corporation (“Acxiom”), LiveRamp, Inc., a wholly owned subsidiary of Acxiom, and Acxiom Holdings, Inc. Upon satisfaction of the terms and subject to the conditions set forth in the Purchase Agreement, we will acquire the Acxiom Marketing Solutions business for $2,300.0 in cash, subject to customary adjustments (the “AMS Acquisition”). The consummation of the transaction is subject to customary closing conditions, including, among other things, approval of Acxiom’s stockholders, certain regulatory approvals and completion of a series of internal Acxiom reorganization transactions. The transaction is anticipated to close in the fourth quarter of 2018. As previously disclosed, we have entered into a commitment letter with Citigroup Global Markets, Inc. (on behalf of various Citi affiliates) and JPMorgan Chase Bank, N.A. (the “Commitment Parties”), dated as of July 2, 2018, pursuant to which, subject to certain terms and conditions, the Commitment Parties have agreed to provide a 364-day senior unsecured bridge loan facility in an aggregate principal amount of up to $2,300.0 to fund the consideration for the AMS Acquisition (the "Bridge Facility"). We expect that, prior to the consummation of the AMS Acquisition, we will enter into debt financing arrangements with third-party lenders and engage in debt securities offerings, which will be used to fund the AMS Acquisition and related expenses in lieu of funding under the Bridge Facility. The commitment with respect to the Bridge Facility is subject to certain customary closing conditions, including the consummation of the AMS Acquisition in accordance with the terms of the Purchase Agreement.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2018
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition We recognize revenue when the control to promised goods or services transfers to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services. Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications and marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting around the world. Our revenues are directly dependent upon the advertising, marketing and corporate communications requirements of our existing clients and our ability to win new clients. Depending on the terms of the client contract, revenue is derived from diverse arrangements involving fees for services performed, commissions, performance incentive provisions and combinations of the three. Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding pass-through expenses charged to a client. Revenues for the creation, planning and placement of advertising are determined primarily on a negotiated fee basis and, to a lesser extent, on a commission basis. Fees are usually calculated to reflect hourly rates plus proportional overhead and a mark-up. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative or quantitative metrics, or both. Commissions are earned based on services provided and are usually derived from a percentage or fee over the total cost to complete the assignment. Commissions can also be derived when clients pay us the gross rate billed by media and we pay for media at a lower net rate; the difference is the commission that we earn, which we either retain in full or share with the client depending on the nature of the applicable services agreement. We also generate revenue in negotiated fees from our public relations, sales promotion, event marketing, sports and entertainment marketing, and corporate and brand identity services. Billable expenses include pass-through expenses related to event and advertising production costs for performance obligations where we have determined that we are acting as principal that are rebilled to our clients, as well as out-of-pocket costs. Out-of-pocket costs often include expenses related to airfare, mileage, hotel stays, out-of-town meals and telecommunication charges for client service staff. We record these billable expenses within total revenue with a corresponding offset to operating expenses. Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. As is customary in the industry, our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have right to payment for all services provided through the end of the contract or termination date. Our client contracts may include provisions for incentive compensation and vendor rebates and credits. Our largest clients are multinational entities and, as such, we often provide services to these clients out of multiple offices and across many of our agencies. In arranging for such services, it is possible that we will enter into global, regional and local agreements. Agreements of this nature are reviewed by legal counsel to determine the governing terms to be followed by the offices and agencies involved. When we receive credits from our vendors and media outlets for transactions entered into on behalf of our clients, they are generally remitted back to our clients; however, they may be retained by us based on specific terms of our contracts and local laws. If amounts are to be passed through to clients, they are recorded as liabilities until settlement or, if retained by us, are recorded as revenue when earned. For media contracts that can be canceled by the customer at any time without compensation, the contract does not exist until media airs, at which point revenue is recognized. Timing of Recognition We have determined that we generally satisfy our performance obligations over time, except for certain commission-based contracts, which are recognized at a point in time, typically the date of broadcast or publication. Fees are generally recognized based on proportional performance utilizing periodically updated estimates to complete. Performance Obligations Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Principal vs. Agent For each identified performance obligation in the contract with the customer, we assess whether our agency or the third-party supplier is the principal or agent. We control the specified services before transferring those services to the customer and act as the principal if we are primarily responsible for the integration of products and services into the deliverable to our customer, have inventory risk, or discretion in establishing pricing. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. We have determined that we primarily act as principal for creative, media planning, in-house production, event, public relations and branding services, where we control the specified services before transferring those services to the customer because we are primarily responsible for the integration of products and services into the deliverable to our customer. We generally do not have inventory risk or discretion in establishing pricing in our contracts with customers. If the third-party supplier, rather than IPG, is primarily responsible for the integration of products and services into the deliverable to our customer, then we generally act as the agent and solely arrange for the third-party supplier to provide services to the customer. For performance obligations for which we act as the agent (primarily production and media buying), we record our revenue as the net amount of our gross billings less pass-through expenses charged to a customer. Variable Consideration Revenue for our services is measured based on the consideration specified in a contract with a customer. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to either qualitative or quantitative metrics, or both. Incentive compensation is estimated using the most likely amount 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 performance incentives are related. Practical Expedients As part of our adoption of ASC 606, we apply the practical expedient and do not disclose information about remaining performance obligations that have original expected durations of one year or less. Amounts related to those performance obligations with expected durations of greater than one year are immaterial. We apply the practical expedient and do not capitalize costs to obtain a contract as these amounts would generally be recognized over less than one year and are not material. Additionally, we report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions.

Revenue (Tables)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Consolidated Statement of Operations

CONSOLIDATED STATEMENT OF OPERATIONS



	Three months ended June 30, 2017								Six months ended June 30, 2017
	As Revised ¹			ASC 606 Adjustments		As Adjusted			As Revised ¹			ASC 606 Adjustments		As Adjusted
REVENUE:
Net revenue	$	1,815.4		$	19.2	$	1,834.6		$	3,485.7		$	24.2	$	3,509.9
Billable expenses	69.5			281.7		351.2			153.1			586.6		739.7
Total revenue	1,884.9			300.9		2,185.8			3,638.8			610.8		4,249.6

OPERATING EXPENSES:
Salaries and related expenses	1,228.9			—		1,228.9			2,480.6			—		2,480.6
Office and other direct expenses	318.4			—		318.4			631.1			—		631.1
Billable expenses	69.5			281.7		351.2			153.1			586.6		739.7
Cost of services	1,616.8			281.7		1,898.5			3,264.8			586.6		3,851.4
Selling, general and administrative expenses	20.3			—		20.3			55.5			—		55.5
Depreciation and amortization	41.3			—		41.3			82.3			—		82.3
Total operating expenses	1,678.4			281.7		1,960.1			3,402.6			586.6		3,989.2

OPERATING INCOME	206.5			19.2		225.7			236.2			24.2		260.4

EXPENSES AND OTHER INCOME:
Interest expense	(25.7		)	—		(25.7		)	(46.6		)	—		(46.6		)
Interest income	4.7			—		4.7			9.9			—		9.9
Other income, net	(15.4		)	—		(15.4		)	(14.6		)	—		(14.6		)
Total (expenses) and other income	(36.4		)	—		(36.4		)	(51.3		)	—		(51.3		)

Income before income taxes	170.1			19.2		189.3			184.9			24.2		209.1
Benefit of income taxes	75.4			6.2		81.6			73.3			8.0		81.3
Income of consolidated companies	94.7			13.0		107.7			111.6			16.2		127.8
Equity in net (loss) income of unconsolidated affiliates	(0.1		)	—		(0.1		)	1.1			—		1.1
NET INCOME	94.6			13.0		107.6			112.7			16.2		128.9
Net loss attributable to noncontrolling interests	0.1			—		0.1			3.5			—		3.5
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$	94.7		$	13.0	$	107.7		$	116.2		$	16.2	$	132.4

Earnings per share available to IPG common stockholders:
Basic	$	0.24		$	0.03	$	0.27		$	0.30		$	0.04	$	0.34
Diluted	$	0.24		$	0.03	$	0.27		$	0.29		$	0.04	$	0.33

Weighted-average number of common shares outstanding:
Basic	392.3			—		392.3			392.0			—		392.0
Diluted	400.3			—		400.3			399.6			—		399.6

Dividends declared per common share	$	0.18				$	0.18		$	0.36				$	0.36


1	These amounts have been revised for the new presentation as described in Note 1.

Condensed Balance Sheet

CONSOLIDATED BALANCE SHEET



	December 31, 2017
	As Reported			ASC 606 Adjustments			As Adjusted
ASSETS:
Cash and cash equivalents	$	790.9		$	—		$	790.9
Accounts receivable, net of allowance of $42.7	4,585.0			—			4,585.0
Expenditures billable to clients	1,747.4			(1,747.4		)	—
Accounts receivable, billable to clients	—			1,747.4			1,747.4
Assets held for sale	5.7			—			5.7
Other current assets	335.1			11.4			346.5
Total current assets	7,464.1			11.4			7,475.5
Property and equipment, net of accumulated depreciation of $1,036.2	650.4			—			650.4
Deferred income taxes	236.0			(2.0		)	234.0
Goodwill	3,820.4			—			3,820.4
Other non-current assets	524.3			0.1			524.4
TOTAL ASSETS	$	12,695.2		$	9.5		$	12,704.7

LIABILITIES:
Accounts payable	$	6,907.8		$	(487.6	)	$	6,420.2
Accrued liabilities	674.7			—			674.7
Contract liabilities	—			484.7			484.7
Short-term borrowings	84.9			—			84.9
Current portion of long-term debt	2.0			—			2.0
Liabilities held for sale	8.8			—			8.8
Total current liabilities	7,678.2			(2.9		)	7,675.3
Long-term debt	1,285.6			—			1,285.6
Deferred compensation	476.6			—			476.6
Other non-current liabilities	766.9			1.9			768.8
TOTAL LIABILITIES	10,207.3			(1.0		)	10,206.3

Redeemable noncontrolling interests	252.1			—			252.1

STOCKHOLDERS’ EQUITY:
Common stock	38.6			—			38.6
Additional paid-in capital	955.2			—			955.2
Retained earnings	2,093.6			10.9			2,104.5
Accumulated other comprehensive loss, net of tax	(827.4		)	(0.4		)	(827.8		)
	2,260.0			10.5			2,270.5
Less: Treasury stock	(59.0		)	—			(59.0		)
Total IPG stockholders’ equity	2,201.0			10.5			2,211.5
Noncontrolling interests	34.8			—			34.8
TOTAL STOCKHOLDERS’ EQUITY	2,235.8			10.5			2,246.3
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$	12,695.2		$	9.5		$	12,704.7

Condensed Statements of Cash Flows

CONSOLIDATED STATEMENT OF CASH FLOWS



	Six months ended June 30, 2017
	As Reported			ASC 606 Adjustments			As Adjusted
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$	112.7		$	16.2		$	128.9
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	82.3			—			82.3
Provision for uncollectible receivables	8.6			—			8.6
Amortization of restricted stock and other non-cash compensation	46.0			—			46.0
Net amortization of bond discounts and deferred financing costs	2.8			—			2.8
Deferred income tax provision	1.5			8.0			9.5
Net losses on sales of businesses	12.2			—			12.2
Other	10.2			—			10.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	769.7			—			769.7
Expenditures billable to clients	(165.3		)	165.3			—
Accounts receivable, billable to clients	—			(165.5		)	(165.5		)
Other current assets	(82.0		)	(2.5		)	(84.5		)
Accounts payable	(622.9		)	(28.4		)	(651.3		)
Accrued liabilities	(313.9		)	—			(313.9		)
Contract liabilities	—			6.9			6.9
Other non-current assets and liabilities	(15.0		)	—			(15.0		)
Net cash used in operating activities	(153.1		)	—			(153.1		)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities	(96.0		)	—			(96.0		)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net cash used in financing activities	(199.4		)	—			(199.4		)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	8.2			—			8.2
Net decrease in cash, cash equivalents and restricted cash	(440.3		)	—			(440.3		)
Cash, cash equivalents and restricted cash at beginning of period	1,100.2			—			1,100.2
Cash, cash equivalents and restricted cash at end of period	$	659.9		$	—		$	659.9

Disaggregation of Revenue Principal Geographic Markets



	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	1,445.7	$	1,350.8	$	2,796.4	$	2,666.0
International:
United Kingdom	201.6		166.0		406.0		341.0
Continental Europe	205.1		176.3		386.8		334.5
Asia Pacific	304.2		260.5		535.7		480.8
Latin America	92.5		94.5		172.5		170.3
Other	142.7		137.7		263.5		257.0
Total International	946.1		835.0		1,764.5		1,583.6
Total Consolidated	$	2,391.8	$	2,185.8	$	4,560.9	$	4,249.6



	Three months ended June 30,				Six months ended June 30,
Net revenue:	2018		2017		2018		2017
United States	$	1,171.5	$	1,127.6	$	2,263.8	$	2,184.7
International:
United Kingdom	175.7		141.7		339.2		276.9
Continental Europe	178.7		154.6		337.4		295.5
Asia Pacific	214.2		205.3		393.0		379.0
Latin America	82.0		85.7		155.9		154.7
Other	126.1		119.7		232.9		219.1
Total International	776.7		707.0		1,458.4		1,325.2
Total Consolidated	$	1,948.2	$	1,834.6	$	3,722.2	$	3,509.9



IAN	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	1,063.2	$	1,022.3	$	2,086.4	$	1,992.2
International	749.3		689.0		1,411.6		1,286.9
Total IAN	$	1,812.5	$	1,711.3	$	3,498.0	$	3,279.1

Net revenue:
United States	$	963.3	$	926.3	$	1,861.3	$	1,788.3
International	665.8		607.7		1,249.1		1,136.8
Total IAN	$	1,629.1	$	1,534.0	$	3,110.4	$	2,925.1



CMG	Three months ended June 30,				Six months ended June 30,
Total revenue:	2018		2017		2018		2017
United States	$	382.5	$	328.5	$	710.0	$	673.8
International	196.8		146.0		352.9		296.7
Total CMG	$	579.3	$	474.5	$	1,062.9	$	970.5

Net revenue:
United States	$	208.2	$	201.3	$	402.5	$	396.4
International	110.9		99.3		209.3		188.4
Total CMG	$	319.1	$	300.6	$	611.8	$	584.8

Contract Balances



	June 30, 2018		December 31, 2017
Accounts receivable, net of allowance of $44.5 and $42.7, respectively	$	4,247.7	$	4,585.0
Accounts receivable, billable to clients	1,945.8		1,747.4
Contract assets	44.9		11.5
Contract liabilities (deferred revenue)	510.8		484.7

Debt and Credit Arrangements (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Summary of Carrying Amounts and Fair Values of Long-term Debt

A summary of the carrying amounts and fair values of our long-term debt is listed below.



	Effective Interest Rate	June 30, 2018				December 31, 2017
	Effective Interest Rate	Book Value		Fair Value ¹		Book Value		Fair Value ¹
4.00% Senior Notes due 2022 (less unamortized discount and issuance costs of $1.2 and $0.9, respectively)	4.13%	$	247.9	$	251.6	$	247.6	$	259.0
3.75% Senior Notes due 2023 (less unamortized discount and issuance costs of $0.7 and $1.9, respectively)	4.32%	497.4		495.6		497.1		513.2
4.20% Senior Notes due 2024 (less unamortized discount and issuance costs of $0.6 and $2.4, respectively)	4.24%	497.0		503.3		496.7		524.2
Other notes payable and capitalized leases		40.5		40.5		46.2		46.2
Total long-term debt		1,282.8				1,287.6
Less: current portion		0.1				2.0
Long-term debt, excluding current portion		$	1,282.7			$	1,285.6


1	See Note 13 for information on the fair value measurement of our long-term debt.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Acquisitions Acquisitions (Tables)

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Cash Paid For Current And Prior Years' Acquisitions [Table Text Block]



	Six months ended June 30,
	2018			2017
Cost of investment: current-year acquisitions	$	8.7		$	14.8
Cost of investment: prior-year acquisitions	16.2			37.1
Less: net cash acquired	(0.4		)	(3.0		)
Total cost of investment	24.5			48.9
Operating payments ¹	18.2			34.7
Total cash paid for acquisitions ²	$	42.7		$	83.6

Redeemable Noncontrolling Interest [Table Text Block]

The following table presents changes in our redeemable noncontrolling interests.



	Six months ended June 30,
	2018			2017
Balance at beginning of period	$	252.1		$	252.8
Change in related noncontrolling interests balance	(14.6		)	(6.5		)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0			3.0
Redemptions	(32.2		)	(13.2		)
Redemption value adjustments	(39.5		)	7.3
Balance at end of period	$	165.8		$	243.4

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following sets forth basic and diluted earnings per common share available to IPG common stockholders.



	Three months ended June 30,				Six months ended June 30,
	2018		2017		2018		2017
Net income available to IPG common stockholders	$	145.8	$	107.7	$	131.7	$	132.4

Weighted-average number of common shares outstanding - basic	383.6		392.3		383.5		392.0
Dilutive effect of stock options and restricted shares	5.9		8.0		5.4		7.6
Weighted-average number of common shares outstanding - diluted	389.5		400.3		388.9		399.6

Earnings per share available to IPG common stockholders:
Basic	$	0.38	$	0.27	$	0.34	$	0.34
Diluted	$	0.37	$	0.27	$	0.34	$	0.33

Supplementary Data (Tables)

6 Months Ended

Jun. 30, 2018

Supplementary Data [Abstract]

Accrued Liabilities

The following table presents the components of accrued liabilities.



	June 30, 2018		December 31, 2017
Salaries, benefits and related expenses	$	310.7	$	441.7
Acquisition obligations	65.7		42.0
Office and related expenses	48.8		53.2
Interest	16.9		16.4
Other	109.4		121.4
Total accrued liabilities	$	551.5	$	674.7

Other Income (Expense), Net

Results of operations for the three and six months ended June 30, 2018 and 2017 include certain items that are not directly associated with our revenue-producing operations.



	Three months ended June 30,						Six months ended June 30,
	2018			2017			2018			2017
Net losses on sales of businesses	$	(19.8	)	$	(13.1	)	$	(44.2	)	$	(12.2	)
Other	3.5			(2.3		)	3.5			(2.4		)
Total other expense, net	$	(16.3	)	$	(15.4	)	$	(40.7	)	$	(14.6	)

Share Repurchase Program

The following table presents our share repurchase activity under our share repurchase programs for the six months ended June 30, 2018 and 2017.



	Six months ended June 30,
	2018		2017
Number of shares repurchased	5.0		4.8
Aggregate cost, including fees	$	114.5	$	115.0
Average price per share, including fees	$	23.02	$	24.13

Incentive Compensation Plans (Tables)

6 Months Ended

Jun. 30, 2018

Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]

Stock-based Compensation Awards

We issued the following stock-based awards under the 2014 Performance Incentive Plan (the "2014 PIP") during the six months ended June 30, 2018.



	Awards	Weighted-average grant-date fair value (per award)
Restricted stock (shares or units)	1.8	$	23.62
Performance-based stock (shares)	2.9	$	21.13
Restricted stock units (settled in cash)	0.1	$	23.63
Total stock-based compensation awards	4.8

Accumulated Other Comprehensive Loss, Net of Tax (Tables)

6 Months Ended

Jun. 30, 2018

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

Accumulated Other Comprehensive Loss, Net of Tax

The following tables present the changes in accumulated other comprehensive loss, net of tax, by component.



	Foreign Currency Translation Adjustments			Derivative Instruments			Defined Benefit Pension and Other Postretirement Plans			Total
Balance as of December 31, 2017	$	(585.3	)	$	(6.8	)	$	(235.7	)	$	(827.8	)
Other comprehensive loss before reclassifications	(92.2		)	0.0			(0.9		)	(93.1		)
Amount reclassified from accumulated other comprehensive loss, net of tax	13.4			0.8			3.3			17.5
Balance as of June 30, 2018	$	(664.1	)	$	(6.0	)	$	(233.3	)	$	(903.4	)



	Foreign Currency Translation Adjustments			Available-for-Sale Securities		Derivative Instruments			Defined Benefit Pension and Other Postretirement Plans			Total
Balance as of December 31, 2016	$	(718.6	)	$	0.6	$	(8.4	)	$	(238.0	)	$	(964.4	)
Other comprehensive income before reclassifications	85.2			0.1		0.0			0.4			85.7
Amount reclassified from accumulated other comprehensive loss, net of tax	0.3			0.0		0.7			2.7			3.7
Balance as of June 30, 2017	$	(633.1	)	$	0.7	$	(7.7	)	$	(234.9	)	$	(875.0	)

Reclassification out of Accumulated Other Comprehensive Income

Amounts reclassified from accumulated other comprehensive loss, net of tax, for the three and six months ended June 30, 2018 and 2017 are as follows:



	Three months ended June 30,						Six months ended June 30,						Affected Line Item in the Consolidated Statements of Operations
	2018			2017			2018			2017
Foreign currency translation adjustments	$	0.9		$	0.7		$	13.4		$	0.3		Other expense, net
Losses on derivative instruments	0.6			0.6			1.1			1.1			Interest expense
Amortization of defined benefit pension and postretirement plan items	2.0			1.8			4.1			3.5			Other expense, net
Tax effect	(0.5		)	(0.6		)	(1.1		)	(1.2		)	Provision for income taxes
Total amount reclassified from accumulated other comprehensive loss, net of tax	$	3.0		$	2.5		$	17.5		$	3.7

Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2018

Defined Benefit Plan [Abstract]

Schedule of Net Periodic Costs

The components of net periodic cost for the Domestic Pension Plan, the significant foreign pension plans and the domestic postretirement benefit plan are listed below.



	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Three months ended June 30,	2018			2017			2018			2017			2018			2017
Service cost	$	0.0		$	0.0		$	0.9		$	1.0		$	0.0		$	0.0
Interest cost	1.1			1.2			3.4			3.3			0.2			0.3
Expected return on plan assets	(1.5		)	(1.5		)	(4.8		)	(4.4		)	0.0			0.0
Amortization of:
Prior service cost (credit)	0.0			0.0			0.1			0.0			(0.1		)	0.0
Unrecognized actuarial losses	0.4			0.4			1.5			1.4			0.1			0.0
Net periodic cost	$	0.0		$	0.1		$	1.1		$	1.3		$	0.2		$	0.3



	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Six months ended June 30,	2018			2017			2018			2017			2018			2017
Service cost	$	0.0		$	0.0		$	2.0		$	1.9		$	0.0		$	0.0
Interest cost	2.2			2.5			6.8			6.6			0.5			0.6
Expected return on plan assets	(3.3		)	(3.1		)	(9.7		)	(8.7		)	0.0			0.0
Settlements and curtailments	0.0			0.0			0.2			0.0			0.0			0.0
Amortization of:
Prior service cost (credit)	0.0			0.0			0.1			0.0			(0.1		)	0.0
Unrecognized actuarial losses	0.8			0.8			3.0			2.7			0.1			0.0
Net periodic cost	$	(0.3	)	$	0.2		$	2.4		$	2.5		$	0.5		$	0.6

Segment Information (Tables)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

Summarized financial information concerning our reportable segments is shown in the following table.



	Three months ended June 30,						Six months ended June 30,
	2018			2017			2018			2017
Total revenue:
IAN	$	1,812.5		$	1,711.3		$	3,498.0		$	3,279.1
CMG	579.3			474.5			1,062.9			970.5
Total	$	2,391.8		$	2,185.8		$	4,560.9		$	4,249.6

Net revenue:
IAN	$	1,629.1		$	1,534.0		$	3,110.4		$	2,925.1
CMG	319.1			300.6			611.8			584.8
Total	$	1,948.2		$	1,834.6		$	3,722.2		$	3,509.9

Segment operating income (loss):
IAN	$	238.2		$	195.9		$	295.2		$	246.0
CMG	42.0			51.5			61.4			73.6
Corporate and other	(31.0		)	(21.7		)	(68.6		)	(59.2		)
Total	249.2			225.7			288.0			260.4

Interest expense, net	(21.4		)	(21.0		)	(37.3		)	(36.7		)
Other expense, net	(16.3		)	(15.4		)	(40.7		)	(14.6		)
Income before income taxes	$	211.5		$	189.3		$	210.0		$	209.1

Depreciation and amortization
IAN	$	35.8		$	33.9		$	73.2		$	66.6
CMG	6.0			6.0			12.1			12.0
Corporate and other	2.2			1.4			4.7			3.7
Total	$	44.0		$	41.3		$	90.0		$	82.3

Capital expenditures:
IAN	$	31.9		$	31.4		$	47.7		$	48.6
CMG	1.9			4.0			3.0			6.7
Corporate and other	4.9			8.7			10.8			13.6
Total	$	38.7		$	44.1		$	61.5		$	68.9

	June 30, 2018			December 31, 2017
Total assets:
IAN	$	10,840.0		$	10,978.0
CMG	1,476.8			1,427.4
Corporate and other	40.8			299.3
Total	$	12,357.6		$	12,704.7

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables present information about our financial instruments measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017, and indicate the fair value hierarchy of the valuation techniques utilized to determine such fair value.



	June 30, 2018								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total		Balance Sheet Classification
Assets
Cash equivalents	$	111.8	$	0.0	$	0.0	$	111.8	Cash and cash equivalents
Liabilities
Contingent acquisition obligations¹	$	0.0	$	0.0	$	147.2	$	147.2

	December 31, 2017								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total		Balance Sheet Classification
Assets
Cash equivalents	$	201.6	$	0.0	$	0.0	$	201.6	Cash and cash equivalents
Liabilities
Contingent acquisition obligations ¹	$	0.0	$	0.0	$	147.0	$	147.0

Fair Value, Assets and Liabilities Measured on Nonrecurring Basis



	June 30, 2018								December 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Total long-term debt	$	0.0	$	1,250.5	$	40.5	$	1,291.0	$	0.0	$	1,296.4	$	46.2	$	1,342.6

Revenue Income Statement (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Revenue	$ 1,948.2	$ 1,834.6	$ 3,722.2	$ 3,509.9
Billable expenses	443.6	351.2	838.7	739.7
Total revenue	2,391.8	2,185.8	4,560.9	4,249.6
OPERATING EXPENSES:
Salaries and related expenses	1,292.9	1,228.9	2,623.2	2,480.6
Office and other direct expenses	333.3	318.4	657.1	631.1
Billable expenses	443.6	351.2	838.7	739.7
Cost of services	2,069.8	1,898.5	4,119.0	3,851.4
Selling, general and administrative expenses	28.8	20.3	63.9	55.5
Depreciation and amortization	44.0	41.3	90.0	82.3
Total operating expenses	2,142.6	1,960.1	4,272.9	3,989.2
OPERATING INCOME	249.2	225.7	288.0	260.4
EXPENSES AND OTHER INCOME:
Interest expense	(26.1)	(25.7)	(46.0)	(46.6)
Interest income	4.7	4.7	8.7	9.9
Other income, net	(16.3)	(15.4)	(40.7)	(14.6)
Total (expenses) and other income	(37.7)	(36.4)	(78.0)	(51.3)
Income before income taxes	211.5	189.3	210.0	209.1
Benefit of income taxes	63.6	81.6	76.3	81.3
Income of consolidated companies	147.9	107.7	133.7	127.8
Equity in net income of unconsolidated affiliates	(0.1)	(0.1)	(2.0)	1.1
NET INCOME	147.8	107.6	131.7	128.9
Net (income) loss attributable to noncontrolling interests	(2.0)	0.1	0.0	3.5
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$ 145.8	$ 107.7	$ 131.7	$ 132.4
Earnings per share, Basic	$ 0.38	$ 0.27	$ 0.34	$ 0.34
Earnings per share, Diluted	$ 0.37	$ 0.27	$ 0.34	$ 0.33
Weighted-average number of common shares outstanding, Basic	383.6	392.3	383.5	392.0
Weighted-average number of common shares outstanding, Diluted	389.5	400.3	388.9	399.6
Dividends declared per common share	$ 0.21	$ 0.18	$ 0.42	$ 0.36
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Revenue		$ 1,815.4		$ 3,485.7
Billable expenses		69.5		153.1
Total revenue		1,884.9		3,638.8
OPERATING EXPENSES:
Salaries and related expenses		1,228.9		2,480.6
Office and other direct expenses		318.4		631.1
Billable expenses		69.5		153.1
Cost of services		1,616.8		3,264.8
Selling, general and administrative expenses		20.3		55.5
Depreciation and amortization		41.3		82.3
Total operating expenses		1,678.4		3,402.6
OPERATING INCOME		206.5		236.2
EXPENSES AND OTHER INCOME:
Interest expense		(25.7)		(46.6)
Interest income		4.7		9.9
Other income, net		(15.4)		(14.6)
Total (expenses) and other income		(36.4)		(51.3)
Income before income taxes		170.1		184.9
Benefit of income taxes		75.4		73.3
Income of consolidated companies		94.7		111.6
Equity in net income of unconsolidated affiliates		(0.1)		1.1
NET INCOME		94.6		112.7
Net (income) loss attributable to noncontrolling interests		0.1		3.5
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS		$ 94.7		$ 116.2
Earnings per share, Basic		$ 0.24		$ 0.30
Earnings per share, Diluted		$ 0.24		$ 0.29
Weighted-average number of common shares outstanding, Basic		392.3		392.0
Weighted-average number of common shares outstanding, Diluted		400.3		399.6
Dividends declared per common share		$ 0.18		$ 0.36
ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Revenue		$ 19.2		$ 24.2
Billable expenses		281.7		586.6
Total revenue		300.9		610.8
OPERATING EXPENSES:
Salaries and related expenses		0.0		0.0
Office and other direct expenses		0.0		0.0
Billable expenses		281.7		586.6
Cost of services		281.7		586.6
Selling, general and administrative expenses		0.0		0.0
Depreciation and amortization		0.0		0.0
Total operating expenses		281.7		586.6
OPERATING INCOME		19.2		24.2
EXPENSES AND OTHER INCOME:
Interest expense		0.0		0.0
Interest income		0.0		0.0
Other income, net		0.0		0.0
Total (expenses) and other income		0.0		0.0
Income before income taxes		19.2		24.2
Benefit of income taxes		6.2		8.0
Income of consolidated companies		13.0		16.2
Equity in net income of unconsolidated affiliates		0.0		0.0
NET INCOME		13.0		16.2
Net (income) loss attributable to noncontrolling interests		0.0		0.0
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS		$ 13.0		$ 16.2
Earnings per share, Basic		$ 0.03		$ 0.04
Earnings per share, Diluted		$ 0.03		$ 0.04
Weighted-average number of common shares outstanding, Basic		0.0		0.0
Weighted-average number of common shares outstanding, Diluted		0.0		0.0

Revenue Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cash and cash equivalents	$ 493.2	$ 790.9
Accounts Receivable, net of allowance of $42.7	4,247.7	4,585.0
Expenditures billable to clients		0.0
Accounts receivable, billable to clients	1,945.8	1,747.4
Assets held for sale	19.6	5.7
Other current assets	439.3	346.5
Total current assets	7,145.6	7,475.5
Property and equipment, net of accumulated depreciation of $1,036.2	602.0	650.4
Deferred income taxes	261.0	234.0
Goodwill	3,788.1	3,820.4
Other non-current assets	560.9	524.4
TOTAL ASSETS	12,357.6	12,704.7
Accounts payable	5,738.8	6,420.2
Accrued liabilities	551.5	674.7
Contract liabilities	510.8	484.7
Short-term borrowings	757.6	84.9
Current portion of long-term debt	0.1	2.0
Liabilities held for sale	26.5	8.8
Total current liabilities	7,585.3	7,675.3
Long-term debt	1,282.7	1,285.6
Deferred compensation	445.4	476.6
Other non-current liabilities	786.8	768.8
TOTAL LIABILITIES	10,100.2	10,206.3
Redeemable noncontrolling interests	165.8	252.1	$ 243.4	$ 252.8
STOCKHOLDERS' EQUITY:
Common stock	39.0	38.6
Additional paid-in capital	1,022.9	955.2
Retained earnings	2,076.7	2,104.5
Accumulated other comprehensive loss, net of tax	(903.4)	(827.8)	(875.0)	(964.4)
Stockholders Equity Subtotal Before Treasury Stock	2,235.2	2,270.5
Less: Treasury stock	(173.5)	(59.0)
Total IPG stockholders' equity	2,061.7	2,211.5
Noncontrolling interests	29.9	34.8
TOTAL STOCKHOLDERS' EQUITY	2,091.6	2,246.3	2,063.3	2,090.4
TOTAL LIABILITIES AND EQUITY	$ 12,357.6	12,704.7
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cash and cash equivalents		790.9
Accounts Receivable, net of allowance of $42.7		4,585.0
Expenditures billable to clients		1,747.4
Accounts receivable, billable to clients		0.0
Assets held for sale		5.7
Other current assets		335.1
Total current assets		7,464.1
Property and equipment, net of accumulated depreciation of $1,036.2		650.4
Deferred income taxes		236.0
Goodwill		3,820.4
Other non-current assets		524.3
TOTAL ASSETS		12,695.2
Accounts payable		6,907.8
Accrued liabilities		674.7
Contract liabilities		0.0
Short-term borrowings		84.9
Current portion of long-term debt		2.0
Liabilities held for sale		8.8
Total current liabilities		7,678.2
Long-term debt		1,285.6
Deferred compensation		476.6
Other non-current liabilities		766.9
TOTAL LIABILITIES		10,207.3
Redeemable noncontrolling interests		252.1
STOCKHOLDERS' EQUITY:
Common stock		38.6
Additional paid-in capital		955.2
Retained earnings		2,093.6
Accumulated other comprehensive loss, net of tax		(827.4)
Stockholders Equity Subtotal Before Treasury Stock		2,260.0
Less: Treasury stock		(59.0)
Total IPG stockholders' equity		2,201.0
Noncontrolling interests		34.8
TOTAL STOCKHOLDERS' EQUITY		2,235.8
TOTAL LIABILITIES AND EQUITY		12,695.2
ASC 606 Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cash and cash equivalents		0.0
Accounts Receivable, net of allowance of $42.7		0.0
Expenditures billable to clients		(1,747.4)
Accounts receivable, billable to clients		1,747.4
Assets held for sale		0.0
Other current assets		11.4
Total current assets		11.4
Property and equipment, net of accumulated depreciation of $1,036.2		0.0
Deferred income taxes		(2.0)
Goodwill		0.0
Other non-current assets		0.1
TOTAL ASSETS		9.5
Accounts payable		(487.6)
Accrued liabilities		0.0
Contract liabilities		484.7
Short-term borrowings		0.0
Current portion of long-term debt		0.0
Liabilities held for sale		0.0
Total current liabilities		(2.9)
Long-term debt		0.0
Deferred compensation		0.0
Other non-current liabilities		1.9
TOTAL LIABILITIES		(1.0)
Redeemable noncontrolling interests		0.0
STOCKHOLDERS' EQUITY:
Common stock		0.0
Additional paid-in capital		0.0
Retained earnings		10.9	51.8	35.6
Accumulated other comprehensive loss, net of tax		(0.4)	$ (0.8)	$ (1.9)
Stockholders Equity Subtotal Before Treasury Stock		10.5
Less: Treasury stock		0.0
Total IPG stockholders' equity		10.5
Noncontrolling interests		0.0
TOTAL STOCKHOLDERS' EQUITY		10.5
TOTAL LIABILITIES AND EQUITY		$ 9.5

Revenue Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 147.8	$ 107.6	$ 131.7	$ 128.9
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	44.0	41.3	90.0	82.3
Provision for uncollectible receivables			6.1	8.6
Amortization of restricted stock and other non-cash compensation			46.0	46.0
Net amortization of bond discounts and deferred financing costs			2.7	2.8
Deferred income tax benefit			(31.0)	9.5
Net gains on sales of businesses	19.8	13.1	44.2	12.2
Other			1.9	10.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable			238.0	769.7
Expenditures billable to clients				0.0
Accounts receivable, billable to clients			(233.7)	(165.5)
Other current assets			(124.6)	(84.5)
Accounts payable			(579.3)	(651.3)
Accrued liabilities			(175.9)	(313.9)
Contract liabilities			38.0	6.9
Other non-current assets and liabilities			(11.8)	(15.0)
Net cash used in operating activities			(557.7)	(153.1)
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(38.7)	(44.1)	(61.5)	(68.9)
Acquisitions, net of cash acquired			(8.5)	(12.6)
Other investing activities			12.4	(14.5)
Net cash used in investing activities			(57.6)	(96.0)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in short-term borrowings			669.3	153.5
Exercise of stock options			7.0	11.8
Common stock dividends			(161.2)	(141.4)
Repurchase of common stock			(114.5)	(115.0)
Tax payments for employee shares withheld			(28.0)	(37.8)
Distributions to noncontrolling interests			(10.6)	(10.9)
Other financing activities			(0.3)	0.3
Net cash provided by (used in) financing activities			341.0	(199.4)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash			(27.5)	8.2
Net decrease in cash, cash equivalents and restricted cash			(301.8)	(440.3)
Cash, cash equivalents, and restricted cash at beginning of period			797.7	1,100.2
Cash, cash equivalents, and restricted cash at end of period	$ 495.9	659.9	$ 495.9	659.9
As Previously Reported
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income		94.6		112.7
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization				82.3
Provision for uncollectible receivables				8.6
Amortization of restricted stock and other non-cash compensation				46.0
Net amortization of bond discounts and deferred financing costs				2.8
Deferred income tax benefit				1.5
Net gains on sales of businesses				12.2
Other				10.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable				769.7
Expenditures billable to clients				(165.3)
Accounts receivable, billable to clients				0.0
Other current assets				(82.0)
Accounts payable				(622.9)
Accrued liabilities				(313.9)
Contract liabilities				0.0
Other non-current assets and liabilities				(15.0)
Net cash used in operating activities				(153.1)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities				(96.0)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net cash provided by (used in) financing activities				(199.4)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash				8.2
Net decrease in cash, cash equivalents and restricted cash				(440.3)
Cash, cash equivalents, and restricted cash at beginning of period				1,100.2
Cash, cash equivalents, and restricted cash at end of period		659.9		659.9
ASC 606 Adjustments
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income		13.0		16.2
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization				0.0
Provision for uncollectible receivables				0.0
Amortization of restricted stock and other non-cash compensation				0.0
Net amortization of bond discounts and deferred financing costs				0.0
Deferred income tax benefit				8.0
Net gains on sales of businesses				0.0
Other				0.0
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable				0.0
Expenditures billable to clients				165.3
Accounts receivable, billable to clients				(165.5)
Other current assets				(2.5)
Accounts payable				(28.4)
Accrued liabilities				0.0
Contract liabilities				6.9
Other non-current assets and liabilities				0.0
Net cash used in operating activities				0.0
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities				0.0
CASH FLOWS FROM FINANCING ACTIVITIES:
Net cash provided by (used in) financing activities				0.0
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash				0.0
Net decrease in cash, cash equivalents and restricted cash				0.0
Cash, cash equivalents, and restricted cash at beginning of period				0.0
Cash, cash equivalents, and restricted cash at end of period		$ 0.0		$ 0.0

Revenue Major Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total revenues:
Net Revenue	$ 1,948.2	$ 1,834.6	$ 3,722.2	$ 3,509.9
Total revenue	2,391.8	2,185.8	4,560.9	4,249.6
United States
Total revenues:
Net Revenue	1,171.5	1,127.6	2,263.8	2,184.7
Total revenue	1,445.7	1,350.8	2,796.4	2,666.0
Total International
Total revenues:
Net Revenue	776.7	707.0	1,458.4	1,325.2
Total revenue	946.1	835.0	1,764.5	1,583.6
United Kingdom
Total revenues:
Net Revenue	175.7	141.7	339.2	276.9
Total revenue	201.6	166.0	406.0	341.0
Continental Europe
Total revenues:
Net Revenue	178.7	154.6	337.4	295.5
Total revenue	205.1	176.3	386.8	334.5
Asia Pacific
Total revenues:
Net Revenue	214.2	205.3	393.0	379.0
Total revenue	304.2	260.5	535.7	480.8
Latin America
Total revenues:
Net Revenue	82.0	85.7	155.9	154.7
Total revenue	92.5	94.5	172.5	170.3
Other
Total revenues:
Net Revenue	126.1	119.7	232.9	219.1
Total revenue	142.7	137.7	263.5	257.0
IAN
Total revenues:
Net Revenue	1,629.1	1,534.0	3,110.4	2,925.1
Total revenue	1,812.5	1,711.3	3,498.0	3,279.1
IAN \| United States
Total revenues:
Net Revenue	963.3	926.3	1,861.3	1,788.3
Total revenue	1,063.2	1,022.3	2,086.4	1,992.2
IAN \| Total International
Total revenues:
Net Revenue	665.8	607.7	1,249.1	1,136.8
Total revenue	749.3	689.0	1,411.6	1,286.9
CMG
Total revenues:
Net Revenue	319.1	300.6	611.8	584.8
Total revenue	579.3	474.5	1,062.9	970.5
CMG \| United States
Total revenues:
Net Revenue	208.2	201.3	402.5	396.4
Total revenue	382.5	328.5	710.0	673.8
CMG \| Total International
Total revenues:
Net Revenue	110.9	99.3	209.3	188.4
Total revenue	$ 196.8	$ 146.0	$ 352.9	$ 296.7

Revenue Contract Balances (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, net of allowance of $44.5 and $42.7, respectively	$ 4,247.7	$ 4,585.0
Accounts receivable, billable to clients	1,945.8	1,747.4
Contract assets	44.9	11.5
Contract liabilities (deferred revenue)	$ 510.8	$ 484.7

Long-term Debt (Details) - USD ($)
$ in Millions

3 Months Ended

Jun. 30, 2018

Dec. 31, 2017

Debt Instrument [Line Items]

Long-term Debt, Gross

$ 1,282.8

$ 1,287.6

Long-term Debt, Current Maturities

0.1

2.0

Long-term Debt, Excluding Current Maturities

$ 1,282.7

1,285.6

4.00% Notes

Debt Instrument [Line Items]

Debt Instrument, Maturity Date

Mar. 15, 2022

Debt Instrument, Interest Rate, Stated Percentage

4.00%

Debt Instrument, Interest Rate, Effective Percentage

4.13%

Debt Instrument, Unamortized Discount

$ 1.2

Debt Instrument, Unamortized Debt Issuance Costs

0.9

Long-term Debt, Gross

247.9

247.6

Long-term Debt, Fair Value

^[1]

$ 251.6

259.0

3.75% Notes

Debt Instrument [Line Items]

Debt Instrument, Maturity Date

Feb. 15, 2023

Debt Instrument, Interest Rate, Stated Percentage

3.75%

Debt Instrument, Interest Rate, Effective Percentage

4.32%

Debt Instrument, Unamortized Discount

$ 0.7

Debt Instrument, Unamortized Debt Issuance Costs

1.9

Long-term Debt, Gross

497.4

497.1

Long-term Debt, Fair Value

^[1]

$ 495.6

513.2

4.20% Notes

Debt Instrument [Line Items]

Debt Instrument, Maturity Date

Apr. 15, 2024

Debt Instrument, Interest Rate, Stated Percentage

4.20%

Debt Instrument, Interest Rate, Effective Percentage

4.24%

Debt Instrument, Unamortized Discount

$ 0.6

Debt Instrument, Unamortized Debt Issuance Costs

2.4

Long-term Debt, Gross

497.0

496.7

Long-term Debt, Fair Value

^[1]

503.3

524.2

Other notes payable and capitalized leases

Debt Instrument [Line Items]

Long-term Debt, Gross

40.5

46.2

Long-term Debt, Fair Value

^[1]

$ 40.5

$ 46.2

[1]	See Note 13 for information on the fair value measurement of our long-term debt.

Credit Facilities (Details) $ in Millions	6 Months Ended
Credit Facilities (Details) $ in Millions	Jun. 30, 2018 USD ($)
Committed credit facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Expiration Date	Oct. 25, 2022
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500.0
Line of Credit Facility, Available Capacity Increase Amount	250.0
Line of Credit Facility, Limit on Letters of Credit	50.0
Line of Credit Outstanding, Amount	0.0
Letters of Credit Outstanding, Amount	8.5
Line of Credit Facility, Remaining Borrowing Capacity	1,491.5
Uncommitted credit facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,127.0
Line of Credit Outstanding, Amount	81.6
Line of Credit Facility, Average Outstanding Amount	$ 94.0
Short-term Debt, Weighted Average Interest Rate, over Time	4.80%

Commercial Paper (Details) $ in Millions	6 Months Ended
Commercial Paper (Details) $ in Millions	Jun. 30, 2018 USD ($)
Debt Disclosure [Abstract]
Commercial paper borrowing capacity	$ 1,500.0
Debt Instrument, Term	397 days
Commercial Paper	$ 676.0
Average amount borrowed under commercial paper during the period	$ 988.0
Commercial paper weighted average interest rate over time	2.50%
Commercial paper weighted-average maturity days outstanding	30

Acquisitions Acquisitions Narrative (Details) $ in Millions	6 Months Ended
Acquisitions Acquisitions Narrative (Details) $ in Millions	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Business Combinations [Abstract]
Goodwill and intangible assets related to acquisitions	$ 14.2	$ 22.9
Number of Businesses Acquired	2	3

Acquisitions Cash Paid for Acquisitions (Details) - USD ($)
$ in Millions

6 Months Ended

Jun. 30, 2018

Jun. 30, 2017

Cash Paid for Acquisitions [Abstract]

Cost of investment: current-year acquisitions

$ 8.7

$ 14.8

Cost of investment: prior-year acquisitions

16.2

37.1

Less: net cash acquired

(0.4)

(3.0)

Total cost of investment

24.5

48.9

Operating payments

^[1]

18.2

34.7

Total cash paid for acquisitions

^[2]

42.7

83.6

Payments for initial acquisitions, Investing Cash Flows

8.5

12.6

Payments for previous acquisitions, Financing Cash Flows

$ 16.0

$ 36.3

[1]

[2]

Acquisitions Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Redeemable Noncontrolling Interests
Balance at beginning of period	$ 252.1	$ 252.8
Change in related noncontrolling interests balance	(14.6)	(6.5)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0	3.0
Redemptions	(32.2)	(13.2)
Redemption value adjustments	(39.5)	7.3
Balance at end of period	$ 165.8	$ 243.4

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 145.8	$ 107.7	$ 131.7	$ 132.4
Weighted-average number of common shares outstanding, Basic	383.6	392.3	383.5	392.0
Dilutive effect of stock options and restricted shares	5.9	8.0	5.4	7.6
Weighted-average number of common shares outstanding, Diluted	389.5	400.3	388.9	399.6
Earnings per share, Basic	$ 0.38	$ 0.27	$ 0.34	$ 0.34
Earnings per share, Diluted	$ 0.37	$ 0.27	$ 0.34	$ 0.33

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1337-109256

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=109256448&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1252-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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-Publisher FASB
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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Supplementary Data Accrued Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accrued Liabilities [Abstract]
Salaries, benefits and related expenses	$ 310.7	$ 441.7
Acquisition obligations	65.7	42.0
Office and related expenses	48.8	53.2
Interest	16.9	16.4
Other	109.4	121.4
Total accrued liabilities	$ 551.5	$ 674.7

Supplementary Data Other (Expense) Income, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Net losses on sales of businesses	$ (19.8)	$ (13.1)	$ (44.2)	$ (12.2)
Other	3.5	(2.3)	3.5	(2.4)
Total other expense, net	$ (16.3)	$ (15.4)	$ (40.7)	$ (14.6)

Supplementary Data Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Feb. 14, 2018	Feb. 10, 2017
Disclosure of Repurchase Agreements [Abstract]
Stock repurchase program, authorized amount			$ 300.0	$ 300.0
Number of shares repurchased	5.0	4.8
Aggregate cost, including fees	$ 114.5	$ 115.0
Average price per share, including fees	$ 23.02	$ 24.13
Stock repurchase program, remaining authorized repurchase amount, excluding fees	$ 341.0

Income Taxes Change in Unrecognized Tax Benefits (Details) $ in Millions	Jun. 30, 2018 USD ($)
Maximum [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	$ 40.0
Minimum [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	$ 30.0

Incentive Compensation Plans Stock-based Compensation Awards (Details) shares in Millions	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Restricted stock (shares or units)
Incentive Compensation Plans
Granted awards	1.8
Weighted average grant date fair value \| $ / shares	$ 23.62
Performance-based stock (shares)
Incentive Compensation Plans
Granted awards	2.9
Weighted average grant date fair value \| $ / shares	$ 21.13
Restricted stock units (settled in cash)
Incentive Compensation Plans
Granted awards	0.1
Weighted average grant date fair value \| $ / shares	$ 23.63
Total stock-based compensation awards
Incentive Compensation Plans
Granted awards	4.8

Incentive Compensation Plans Plan Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Performance cash awards granted during the period target value	$ 55.7
Restricted cash awards granted during the period target value	$ 19.8
Cash awards vesting period	3 years

Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Foreign currency translation adjustment:
Balance at beginning of period	$ (585.3)	$ (718.6)
Other comprehensive income before reclassifications	(92.2)	85.2
Amount reclassified from accumulated other comprehensive loss, net of tax	13.4	0.3
Balance at end of period	(664.1)	(633.1)
Available-for-sale securities:
Balance at beginning of period		0.6
Other comprehensive income before reclassifications		0.1
Amount reclassified from accumulated other comprehensive loss, net of tax		0.0
Balance at end of period		0.7
Derivative instruments:
Balance at beginning of period	(6.8)	(8.4)
Other comprehensive income before reclassifications	0.0	0.0
Amount reclassified from accumulated other comprehensive loss, net of tax	0.8	0.7
Balance at end of period	(6.0)	(7.7)
Defined benefit pension and other postretirement plans:
Balance at beginning of period	(235.7)	(238.0)
Other comprehensive income before reclassifications	(0.9)	0.4
Amount reclassified from accumulated other comprehensive loss,net of tax	3.3	2.7
Balance at end of period	(233.3)	(234.9)
Total:
Balance at beginning of period	(827.8)	(964.4)
Other comprehensive income before reclassifications	(93.1)	85.7
Amount reclassified from accumulated other comprehensive loss, net of tax	17.5	3.7
Balance at end of period	$ (903.4)	$ (875.0)

Accumulated Other Comprehensive Loss, Net of Tax Reclassification of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	$ 0.9	$ 0.7	$ 13.4	$ 0.3
Losses on derivative instruments	0.6	0.6	1.1	1.1
Amortization of defined benefit pension and postretirement plans items	2.0	1.8	4.1	3.5
Tax effect	(0.5)	(0.6)	(1.1)	(1.2)
Reclassifications from accumulated other comprehensive loss to earnings, net of tax	$ (3.0)	$ (2.5)	$ (17.5)	$ (3.7)

Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Employee Benefits (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Domestic Plan [Member]
Defined Pension and Postretirement Benefit Plans
Service cost	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Interest cost	1.1	1.2	2.2	2.5
Expected return on plan assets	(1.5)	(1.5)	(3.3)	(3.1)
Amortization of:
Prior service cost (credit)	0.0	0.0	0.0	0.0
Unrecognized actuarial losses	0.4	0.4	0.8	0.8
Net periodic cost	0.0	0.1	(0.3)	0.2
Pension plan - employer contributions			1.9
Pension plan - estimated employer contributions for remainder of current fiscal year	8.0		8.0
Foreign Plan [Member]
Defined Pension and Postretirement Benefit Plans
Service cost	0.9	1.0	2.0	1.9
Interest cost	3.4	3.3	6.8	6.6
Expected return on plan assets	(4.8)	(4.4)	(9.7)	(8.7)
Settlement and curtailments			0.2
Amortization of:
Prior service cost (credit)	0.1	0.0	0.1	0.0
Unrecognized actuarial losses	1.5	1.4	3.0	2.7
Net periodic cost	1.1	1.3	2.4	2.5
Pension plan - employer contributions			9.9
Pension plan - estimated employer contributions for remainder of current fiscal year	9.0		9.0
Domestic Postretirement Benefit Plan
Defined Pension and Postretirement Benefit Plans
Service cost	0.0	0.0	0.0	0.0
Interest cost	0.2	0.3	0.5	0.6
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of:
Prior service cost (credit)	(0.1)	0.0	(0.1)	0.0
Unrecognized actuarial losses	0.1	0.0	0.1	0.0
Net periodic cost	$ 0.2	$ 0.3	$ 0.5	$ 0.6

Segment Information Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segments:
Total revenue	$ 2,391.8	$ 2,185.8	$ 4,560.9	$ 4,249.6
Net Revenue	1,948.2	1,834.6	3,722.2	3,509.9
Segment operating income (loss):	249.2	225.7	288.0	260.4
Interest Income (Expense), Net	(21.4)	(21.0)	(37.3)	(36.7)
Interest Expense	26.1	25.7	46.0	46.6
Other expense, net	(16.3)	(15.4)	(40.7)	(14.6)
Income before income taxes	211.5	189.3	210.0	209.1
Depreciation and amortization	44.0	41.3	90.0	82.3
Capital expenditures	38.7	44.1	61.5	68.9
IAN
Segments:
Total revenue	1,812.5	1,711.3	3,498.0	3,279.1
Net Revenue	1,629.1	1,534.0	3,110.4	2,925.1
Segment operating income (loss):	238.2	195.9	295.2	246.0
Depreciation and amortization	35.8	33.9	73.2	66.6
Capital expenditures	31.9	31.4	47.7	48.6
CMG
Segments:
Total revenue	579.3	474.5	1,062.9	970.5
Net Revenue	319.1	300.6	611.8	584.8
Segment operating income (loss):	42.0	51.5	61.4	73.6
Depreciation and amortization	6.0	6.0	12.1	12.0
Capital expenditures	1.9	4.0	3.0	6.7
Corporate and Other
Segments:
Segment operating income (loss):	(31.0)	(21.7)	(68.6)	(59.2)
Depreciation and amortization	2.2	1.4	4.7	3.7
Capital expenditures	$ 4.9	$ 8.7	$ 10.8	$ 13.6

Segment Information Balance Sheet (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segments:
Interest Income (Expense), Net	$ (21.4)	$ (21.0)	$ (37.3)	$ (36.7)
Assets	12,357.6		12,357.6		$ 12,704.7
IAN
Segments:
Assets	10,840.0		10,840.0		10,978.0
CMG
Segments:
Assets	1,476.8		1,476.8		1,427.4
Corporate and Other
Segments:
Assets	$ 40.8		$ 40.8		$ 299.3

Fair Value on a Recurring Basis (Details) - USD ($)
$ in Millions

6 Months Ended

Jun. 30, 2018

Dec. 31, 2017

Fair value assets and liabilities measured on recurring basis

Contingent acquisition liability, total change

$ 0.2

Level 1

Fair value assets and liabilities measured on recurring basis

Cash equivalents

111.8

$ 201.6

Contingent acquisition obligations

^[1]

0.0

Level 2

Fair value assets and liabilities measured on recurring basis

Cash equivalents

0.0

Contingent acquisition obligations

^[1]

0.0

Level 3

Fair value assets and liabilities measured on recurring basis

Cash equivalents

0.0

Contingent acquisition obligations

^[1]

147.2

147.0

Fair Value, Total [Member]

Fair value assets and liabilities measured on recurring basis

Cash equivalents

111.8

201.6

Contingent acquisition obligations

^[1]

$ 147.2

$ 147.0

[1]

Fair Value Measurements Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Level 1
Fair value assets and liabilities measured on nonrecurring basis
Total long-term debt	$ 0.0	$ 0.0
Level 2
Fair value assets and liabilities measured on nonrecurring basis
Total long-term debt	1,250.5	1,296.4
Level 3
Fair value assets and liabilities measured on nonrecurring basis
Total long-term debt	40.5	46.2
Fair Value, Total [Member]
Fair value assets and liabilities measured on nonrecurring basis
Total long-term debt	$ 1,291.0	$ 1,342.6

Commitments and Contingencies (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Lease guarantees	$ 823.6	$ 829.2
Credit facility guarantees	322.7	308.8
Cash pooling guarantees	$ 193.0	$ 182.2

Subsequent Events (Details)	3 Months Ended
Subsequent Events (Details)	Jun. 30, 2018 USD ($)
Subsequent Events [Abstract]
Agreed Consideration	$ 2,300,000,000.0