Document and Entity Information Document - USD ($)	12 Months Ended
Document and Entity Information Document - USD ($)	Dec. 31, 2017	Feb. 14, 2018	Jun. 30, 2017
DEI [Abstract]
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-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	1217
Document Fiscal Period Focus	FY
Amendment Flag	false
Trading Symbol	IPG
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		384,469,632
Entity Public Float			$ 9,694,530,139

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
REVENUE	$ 7,882.4	$ 7,846.6	$ 7,613.8
OPERATING EXPENSES:
Salaries and related expenses	5,068.1	5,035.1	4,854.8
Office and general expenses	1,840.7	1,870.5	1,884.2
Total operating expenses	6,908.8	6,905.6	6,739.0
OPERATING INCOME	973.6	941.0	874.8
EXPENSES AND OTHER INCOME:
Interest expense	(90.8)	(90.6)	(85.8)
Interest income	19.4	20.1	22.8
Other expense, net	(26.2)	(40.3)	(49.6)
Total (expenses) and other income	(97.6)	(110.8)	(112.6)
Income before income taxes	876.0	830.2	762.2
Provision for income taxes	281.9	198.0	282.8
Income of consolidated companies	594.1	632.2	479.4
Equity in net income of unconsolidated affiliates	0.9	0.3	1.1
NET INCOME	595.0	632.5	480.5
Net income attributable to noncontrolling interests	(16.0)	(24.0)	(25.9)
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$ 579.0	$ 608.5	$ 454.6
Earnings per share available to IPG common stockholders:
Basic	$ 1.49	$ 1.53	$ 1.11
Diluted	$ 1.46	$ 1.49	$ 1.09
Weighted-average number of common shares outstanding:
Basic	389.6	397.9	408.1
Diluted	397.3	408.0	415.7
Dividends declared per common share	$ 0.72	$ 0.60	$ 0.48

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 595.0	$ 632.5	$ 480.5
Foreign Currency Translation:
Foreign currency translation adjustments	132.2	(55.9)	(256.8)
Reclassification adjustments recognized in net income	1.1	3.7	23.3
Foreign currency translation, net of tax	133.3	(52.2)	(233.5)
Available-for-sale securities:
Changes in fair value of available-for-sale securities	0.0	0.5	0.5
Recognition of previously unrealized gains in net income	(0.7)	(1.3)	0.0
Income tax effect	0.1	0.1	0.0
Available-for-sale securities, net of tax	(0.6)	(0.7)	0.5
Derivatives instruments:
Recognition of previously unrealized losses included in net income	2.1	2.0	2.0
Income tax effect	(0.5)	(0.8)	(0.7)
Derivative instruments, net of tax	1.6	1.2	1.3
Defined benefit pension and other postretirement plans:
Net actuarial (losses) gains for the period	(13.6)	(85.4)	14.2
Amortization of unrecognized losses, transition obligation and prior service cost included in net income	6.9	5.4	10.6
Less: settlement and curtailment losses (gains) included in net income	6.8	0.4	(0.2)
Other	2.7	(2.0)	0.4
Income tax effect	(0.5)	15.3	(6.4)
Defined benefit pension and other postretirement plans, net of tax	2.3	(66.3)	18.6
Other comprehensive income (loss), net of tax	136.6	(118.0)	(213.1)
Total comprehensive income	731.6	514.5	267.4
Less: comprehensive income attributable to noncontrolling interests	17.5	22.9	21.7
Comprehensive Income Attributable to IPG	$ 714.1	$ 491.6	$ 245.7

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
ASSETS:
Cash and cash equivalents	$ 790.9	$ 1,097.6
Accounts receivable, net of allowance of $42.7 and $55.7, respectively	4,585.0	4,389.7
Expenditures billable to clients	1,747.4	1,518.1
Assets held for sale	5.7	203.2
Other current assets	335.1	229.4
Total current assets	7,464.1	7,438.0
Property and equipment, net	650.4	622.0
Deferred income taxes	236.0	220.3
Goodwill	3,820.4	3,674.4
Other non-current assets	524.3	530.5
TOTAL ASSETS	12,695.2	12,485.2
LIABILITIES:
Accounts payable	6,907.8	6,303.6
Accrued liabilities	674.7	794.0
Short-term borrowings	84.9	85.7
Current portion of long-term debt	2.0	323.9
Liabilities held for sale	8.8	198.8
Total current liabilities	7,678.2	7,706.0
Long-term debt	1,285.6	1,280.7
Deferred compensation	476.6	480.7
Other non-current liabilities	766.9	708.3
TOTAL LIABILITIES	10,207.3	10,175.7
Redeemable noncontrolling interests (see Note 4)	252.1	252.8
STOCKHOLDERS' EQUITY:
Common stock, $0.10 par value, shares authorized: 800.0 shares issued: 2017 – 386.2; 2016 – 394.3 shares outstanding: 2017 – 383.2; 2016 – 391.6	38.6	39.4
Additional paid-in capital	955.2	1,199.2
Retained earnings	2,093.6	1,804.3
Accumulated other comprehensive loss, net of tax	(827.4)	(962.5)
Stockholders Equity Subtotal Before Treasury Stock	2,260.0	2,080.4
Less: Treasury stock, at cost: 2017 – 3.0 shares; 2016 – 2.7 shares	(59.0)	(63.3)
Total IPG stockholders' equity	2,201.0	2,017.1
Noncontrolling interests	34.8	39.6
TOTAL STOCKHOLDERS' EQUITY	2,235.8	2,056.7
TOTAL LIABILITIES AND EQUITY	$ 12,695.2	$ 12,485.2

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 42.7	$ 55.7
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	800.0	800.0
Common stock, shares issued	386.2	394.3
Common stock, shares outstanding	383.2	391.6
Treasury stock, shares	3.0	2.7

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 595.0	$ 632.5	$ 480.5
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of fixed assets and intangible assets	157.1	160.2	157.0
Provision for uncollectible receivables	9.5	16.7	11.4
Amortization of restricted stock and other non-cash compensation	82.0	85.6	70.3
Net amortization of bond discounts and deferred financing costs	5.8	5.6	5.8
Deferred income tax provision	1.1	45.7	49.5
Net losses on sales of businesses	24.1	41.4	50.1
Other	12.7	35.5	24.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	37.6	(220.7)	(236.1)
Expenditures billable to clients	(165.5)	(2.2)	(237.8)
Other current assets	27.4	(4.8)	(9.7)
Accounts payable	311.9	(126.1)	419.0
Accrued liabilities	(241.3)	(61.1)	(35.3)
Other non-current assets and liabilities	24.4	(95.5)	(60.4)
Net cash provided by operating activities	881.8	512.8	688.5
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(155.9)	(200.7)	(161.1)
Acquisitions, net of cash acquired	(30.6)	(52.0)	(28.6)
Other investing activities	(9.7)	(11.2)	(10.0)
Net cash used in investing activities	(196.2)	(263.9)	(199.7)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt	(324.6)	(1.8)	(2.0)
Repurchases of common stock	(300.1)	(303.3)	(285.2)
Common stock dividends	(280.3)	(238.4)	(195.5)
Acquisition-related payments	(53.7)	(40.8)	(53.1)
Tax payments for employee shares withheld	(38.8)	(23.1)	(17.6)
Distributions to noncontrolling interests	(20.4)	(13.7)	(15.9)
Exercise of stock options	13.1	10.2	13.5
Net increase (decrease) in short-term borrowings	3.0	(56.2)	51.8
Excess tax benefit on share-based compensation	0.0	0.0	10.2
Other financing activities	(3.1)	0.7	2.9
Net cash used in financing activities	(1,004.9)	(666.4)	(490.9)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	16.8	11.6	(156.2)
Net decrease in cash, cash equivalents and restricted cash	(302.5)	(405.9)	(158.3)
Cash, cash equivalents and restricted cash at beginning of period	1,100.2	1,506.1	1,664.4
Cash, cash equivalents and restricted cash at end of period	$ 797.7	$ 1,100.2	$ 1,506.1

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock	Total IPG Stockholders' Equity	Noncontrolling Interests
Balance at Dec. 31, 2014	$ 2,151.2	$ 41.2	$ 1,547.5	$ 1,183.3	$ (636.7)	$ (19.0)	$ 2,116.3	$ 34.9
Balance, shares at Dec. 31, 2014		412.8
Net income	480.5			454.6			454.6	25.9
Other comprehensive income	(213.1)				(208.9)		(208.9)	(4.2)
Reclassifications related to redeemable noncontrolling interests	(6.0)							(6.0)
Distributions to noncontrolling interests	(15.9)							(15.9)
Change in redemption value of redeemable noncontrolling interests	(3.9)			(3.9)			(3.9)
Repurchases of common stock	(285.2)					(285.2)	(285.2)
Retirement of treasury stock, shares		(11.3)
Retirement of treasury stock	0.0	$ (1.2)	(232.0)			233.2	0.0
Common stock dividends	(195.5)			(195.5)			(195.5)
Stock-based compensation, shares		2.4
Stock-based compensation, Value	83.4	$ 0.3	83.1				83.4
Exercise of stock options, shares		1.3
Exercise of stock options, Value	13.7	$ 0.2	13.5				13.7
Shares withheld for taxes, shares		(0.8)
Shares withheld for taxes, Value	(17.8)	$ (0.1)	(17.7)				(17.8)
Excess tax benefit from stock-based compensation	10.2		10.2				10.2
Other	0.2		(0.5)	(0.9)			(1.4)	1.6
Balance, shares at Dec. 31, 2015		404.4
Balance at Dec. 31, 2015	2,001.8	$ 40.4	1,404.1	1,437.6	(845.6)	(71.0)	1,965.5	36.3
Net income	632.5			608.5			608.5	24.0
Other comprehensive income	(118.0)				(116.9)		(116.9)	(1.1)
Reclassifications related to redeemable noncontrolling interests	(5.8)							(5.8)
Distributions to noncontrolling interests	(13.7)							(13.7)
Change in redemption value of redeemable noncontrolling interests	(2.1)			(2.1)			(2.1)
Repurchases of common stock	(303.3)					(303.3)	(303.3)
Retirement of treasury stock, shares		(13.7)
Retirement of treasury stock	0.0	$ (1.4)	(309.6)			311.0	0.0
Common stock dividends	(238.4)			(238.4)			(238.4)
Stock-based compensation, shares		3.5
Stock-based compensation, Value	117.1	$ 0.4	116.7				117.1
Exercise of stock options, shares		1.2
Exercise of stock options, Value	10.3	$ 0.1	10.2				10.3
Shares withheld for taxes, shares		(1.1)
Shares withheld for taxes, Value	(23.3)	$ (0.1)	(23.2)				(23.3)
Other	(0.4)		(1.0)	(1.3)			(0.3)	(0.1)
Balance, shares at Dec. 31, 2016		394.3
Balance at Dec. 31, 2016	2,056.7	$ 39.4	1,199.2	1,804.3	(962.5)	(63.3)	2,017.1	39.6
Net income	595.0			579.0			579.0	16.0
Other comprehensive income	136.6				135.1		135.1	1.5
Reclassifications related to redeemable noncontrolling interests	0.6		(0.3)				(0.3)	0.9
Distributions to noncontrolling interests	(20.9)							(20.9)
Change in redemption value of redeemable noncontrolling interests	(7.9)			(7.9)			(7.9)
Repurchases of common stock	(300.1)					(300.1)	(300.1)
Retirement of treasury stock, shares		(13.4)
Retirement of treasury stock	0.0	$ (1.3)	(303.1)			304.4	0.0
Common stock dividends	(280.3)			(280.3)			(280.3)
Stock-based compensation, shares		5.7
Stock-based compensation, Value	87.0	$ 0.6	86.4				87.0
Exercise of stock options, shares		1.2
Exercise of stock options, Value	13.2	$ 0.1	13.1				13.2
Shares withheld for taxes, shares		(1.6)
Shares withheld for taxes, Value	(39.0)	$ (0.2)	(38.8)				(39.0)
Other	(5.1)		(1.3)	(1.5)			(2.8)	(2.3)
Balance, shares at Dec. 31, 2017		386.2
Balance at Dec. 31, 2017	$ 2,235.8	$ 38.6	$ 955.2	$ 2,093.6	$ (827.4)	$ (59.0)	$ 2,201.0	$ 34.8

Significant Accounting Policies (Notes)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Business Description

The Interpublic Group of Companies, Inc. and subsidiaries (the “Company,” “IPG,” “we,” “us” or “our”) is one of the world’s premier global advertising and marketing services companies. Our agencies create customized marketing programs for clients that range in scale from large global marketers to regional and local clients. Comprehensive global services are critical to effectively serve our multinational and local clients in markets throughout the world, as they seek to build brands, increase sales of their products and services and gain market share.

Principles of Consolidation

The Consolidated Financial Statements include the accounts of the Company and its consolidated subsidiaries, some of which are not wholly owned. Investments in companies over which we do not have control, but have the ability to exercise significant influence, are accounted for using the equity method of accounting. Investments in companies over which we have neither control nor have the ability to exercise significant influence are accounted for under the cost method. All intercompany accounts and transactions have been eliminated in consolidation.

We have consolidated certain entities meeting the definition of variable interest entities, and the inclusion of these entities does not have a material impact on our Consolidated Financial Statements.

Reclassifications

Certain reclassifications and immaterial revisions have been made to the prior period financial statements to conform to the current-year presentation.

We plan to adopt a new presentation for our Consolidated Statements of Operations beginning the first quarter of 2018 which will separately present Cost of services; Selling, general and administrative expenses; and Depreciation and amortization within our Operating expenses. For the years ended December 31, 2017 and 2016, our Selling, general and administrative expenses were $118.6 and $138.8, respectively, which are primarily the expenses of our “Corporate and other” group, as disclosed further in Note 12, excluding depreciation and amortization. For the years ended December 31, 2017 and 2016, Depreciation and amortization were $157.1 and $160.2, respectively, which is also presented on the Consolidated Statements of Cash Flows. This change in presentation of expenses does not impact total operating expenses or operating income.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires us to make judgments, assumptions and estimates that affect the amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the reporting date and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates and assumptions.

Revenue Recognition

Our revenues are primarily derived from the planning and execution of multi-channel advertising, marketing and communications programs 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. Our revenue is typically lowest in the first quarter and highest in the fourth quarter. This reflects the seasonal spending of our clients, incentives earned at year end on various contracts and project work that is typically completed during the fourth quarter.

Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the bases on which we earn commissions and fees vary significantly. As is customary in the industry, our contracts generally provide for termination by either party on relatively short notice, usually 90 days.

Our client contracts are complex arrangements that 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.

Revenue for our services is recognized when all of the following criteria are satisfied: (i) persuasive evidence of an arrangement exists; (ii) the price is fixed or determinable; (iii) collectability is reasonably assured; and (iv) services have been performed. Depending on the terms of a client contract, fees for services performed can be recognized in three principal ways: proportional performance (input or output), straight-line (or monthly basis) or completed contract.

•

Fees are generally recognized as earned based on the proportional performance input method of revenue recognition in situations where our fee is reconcilable to the actual hours incurred to service the client as detailed in a contractual staffing plan, where the fee is earned on a per hour basis or where actual hours incurred are provided to the client on a periodic basis (whether or not the fee is reconcilable), with the amount of revenue recognized in these situations limited to the amount realizable under the client contract. We believe an input-based measure (the ‘hour’) is appropriate in situations where the client arrangement essentially functions as a time and out-of-pocket expense contract and the client receives the benefit of the services provided throughout the contract term.


•	Fees are recognized on a straight-line or monthly basis when service is provided essentially on a pro-rata basis and the terms of the contract support monthly basis accounting.

•

Certain fees (such as for major marketing events) are deferred until contract completion if the final act is so significant in relation to the service transaction taken as a whole or if any of the terms of the contract do not otherwise qualify for proportional performance or monthly basis recognition. Fees may also be deferred and recognized upon delivery of a project if the terms of the client contract identify individual discrete projects.

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. Commissions are generally earned on the date of the broadcast or publication. 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 goals, or both. Performance incentives are recognized as revenue for quantitative targets when the target has been achieved and for qualitative targets when confirmation of the incentive is received from the client.

The majority of our revenue is recorded as the net amount of our gross billings less pass-through expenses charged to a client. In most cases, the amount that is billed to clients significantly exceeds the amount of revenue that is earned and reflected in our Consolidated Financial Statements because of various pass-through expenses, such as production and media costs. We assess whether our agency or the third-party supplier is the primary obligor, and we evaluate the terms of our client agreements as part of this assessment. In addition, we give appropriate consideration to other key indicators such as latitude in establishing price, discretion in supplier selection and credit risk to the vendor. Because we operate broadly as an advertising agency, based on our primary lines of business and given the industry practice to generally record revenue on a net versus gross basis, we believe that there must be strong evidence in place to overcome the presumption of net revenue accounting. Accordingly, we generally record revenue net of pass-through charges as we believe the key indicators of the business suggest we generally act as an agent on behalf of our clients in our primary lines of business. In those businesses where the key indicators suggest we act as a principal (primarily sales promotion and event, sports and entertainment marketing), we record the gross amount billed to the client as revenue and the related incremental direct costs incurred as office and general expenses. In general, we also report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions.

As we provide services as part of our core operations, we generally incur incidental expenses, which, in practice, are commonly referred to as “out-of-pocket” expenses. These expenses often include expenses related to airfare, mileage, hotel stays, out-of-town meals and telecommunication charges. We record the reimbursements received for such incidental expenses as revenue with a corresponding offset to office and general expense.

We receive credits from our vendors and media outlets for transactions entered into on behalf of our clients that, based on the terms of our contracts and local law, are either remitted to our clients or retained by us. 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.

Cash and Cash Equivalents

Cash equivalents are highly liquid investments, which include certificates of deposit, government securities, commercial paper and time deposits with original maturities of three months or less at the time of purchase and are stated at estimated fair value, which approximates cost. Cash is maintained at multiple high-credit-quality financial institutions.

Allowance for Doubtful Accounts

The allowance for doubtful accounts is estimated based on the aging of accounts receivable, reviews of client credit reports, industry trends and economic indicators, as well as reviews of recent payment history for specific customers. The estimate is based largely on a formula-driven calculation but is supplemented with economic indicators and knowledge of potential write-offs of specific client accounts.

Expenditures Billable to Clients

Expenditures billable to clients are primarily comprised of production and media costs that have been incurred but have not yet been billed to clients, as well as fees that have been earned which have not yet been billed to clients. Unbilled amounts are presented in expenditures billable to clients regardless of whether they relate to our fees or production and media costs. A provision is made for unrecoverable costs as deemed appropriate.

Accounts Payable

Accounts payable includes all operating payables, including those related to all media and production costs. These payables are due within one year.

Investments

Our investments in short-term marketable securities include investment-grade time deposits, commercial paper, government securities with maturities greater than three months but less than twelve months and publicly traded companies over which we do not exert a significant influence. These investments are classified as available-for-sale and reported at fair value based on quoted market prices with net unrealized gains and losses reported as a component of accumulated other comprehensive loss. Our non-publicly traded investments and all other publicly traded investments, including investments to fund certain deferred compensation and retirement obligations, are accounted for using the equity method or cost method. We do not disclose the fair value for all equity method investments or investments held at cost as it is not practical to estimate fair value since there is no readily available market data and it is cost prohibitive to obtain independent valuations. We regularly review our equity and cost method investments to determine whether a significant event or change in circumstances has occurred that may impact the fair value of each investment. In the event a decline in fair value of an investment occurs, we determine if the decline has been other-than-temporary. We consider our investments strategic and long-term in nature, so we determine if the fair value decline is recoverable within a reasonable period. For our investments, we evaluate fair value based on specific information (valuation methodologies, estimates of appraisals, financial statements, etc.) in addition to quoted market price, if available. We consider all known quantitative and qualitative factors in determining if an other-than-temporary decline in value of an investment has occurred.

Derivatives

We are exposed to market risk related to interest rates, foreign currency rates and certain balance sheet items. From time to time we enter into derivative instruments for risk management purposes, and not for speculative purposes. All derivative instruments are recorded at fair value on our balance sheet. Changes in fair value are immediately included in earnings if the derivatives are not designated as a hedge instrument or if the derivatives do not qualify as effective hedges. For derivatives designated as hedge instruments, we evaluate for hedge accounting both at inception and throughout the hedge period. If a derivative is designated as a fair value hedge, then changes in the fair value of the derivative are offset against the changes in the fair value of the underlying hedged item. If a derivative is designated as a cash flow hedge, then the effective portion of the changes in the fair value of the derivative is recognized as a component of accumulated other comprehensive income and subsequently reclassified to earnings in our Consolidated Statement of Operations in the same period as the underlying hedged transaction affects earnings.

Property and Equipment

Furniture, equipment, leasehold improvements and buildings are stated at cost, net of accumulated depreciation. Furniture and equipment are depreciated generally using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years for furniture and equipment, 10 to 35 years for buildings and the shorter of the useful life or the remaining lease term for leasehold improvements. Land is stated at cost and is not depreciated.

We capitalize certain internal and external costs incurred to acquire or create internal use software, principally related to our enterprise resource planning (“ERP”) systems. Our ERP systems are stated at cost, net of accumulated amortization, and are amortized using the straight-line method over 10 years. All other internal use computer software are stated at cost, net of accumulated amortization and are amortized using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years.

Goodwill and Other Intangible Assets

We account for our business combinations using the acquisition accounting method, which requires us to determine the fair value of net assets acquired and the related goodwill and other intangible assets. Determining the fair value of assets acquired and liabilities assumed requires management's judgment and involves the use of significant estimates, including projections of future cash inflows and outflows, discount rates, asset lives and market multiples. Considering the characteristics of advertising, specialized marketing and communication services companies, our acquisitions usually do not have significant amounts of tangible assets, as the principal asset we typically acquire is creative talent. As a result, a substantial portion of the purchase price is allocated to goodwill and other intangible assets.

We review goodwill and other intangible assets with indefinite lives not subject to amortization as of October 1^st each year and whenever events or significant changes in circumstances indicate that the carrying value may not be recoverable. We evaluate the recoverability of goodwill at a reporting unit level. We have 11 reporting units that were subject to the 2017 annual impairment testing. Our annual impairment review as of October 1, 2017 did not result in an impairment charge for any of our reporting units.

For reporting units not included in the qualitative assessment, or for any reporting units identified in the qualitative assessment as "more likely than not" that the fair value is less than its carrying value, the quantitative impairment test is performed. For our annual impairment test, we compare the respective fair value of our reporting units' equity to the carrying value of their net assets. The sum of the fair values of all our reporting units is also reconciled to our current market capitalization plus an estimated control premium. Goodwill allocated to a reporting unit whose fair value is equal to or greater than its carrying value is not impaired, and no further testing is required. Should the carrying amount for a reporting unit exceed its fair value, then the quantitative impairment test is failed and impaired goodwill is written down to its fair value with a charge to expense in the period the impairment is identified.

The fair value of each reporting unit for 2017 and 2016 was estimated using a combination of the income approach, which incorporates the use of the discounted cash flow method, and the market approach, which incorporates the use of earnings and revenue multiples based on market data.

We review intangible assets with definite lives subject to amortization whenever events or circumstances indicate that a carrying amount of an asset may not be recoverable. Recoverability of these assets is determined by comparing the carrying value of these assets to the estimated undiscounted future cash flows expected to be generated by these assets. These assets are impaired when their carrying value exceeds their fair value. Impaired intangible assets with definite lives subject to amortization are written down to their fair value with a charge to expense in the period the impairment is identified. Intangible assets with definite lives are amortized on a straight-line basis with estimated useful lives generally between 7 and 15 years. Events or circumstances that might require impairment testing include the loss of a significant client, the identification of other impaired assets within a reporting unit, loss of key personnel, the disposition of a significant portion of a reporting unit, significant decline in stock price or a significant adverse change in business climate or regulations.

Foreign Currencies

The functional currency of our foreign operations is generally their respective local currency. Assets and liabilities are translated at the exchange rates in effect at the balance sheet date, and revenues and expenses are translated at the average exchange rates during the period presented. The resulting translation adjustments are recorded as a component of accumulated other comprehensive loss in the stockholders’ equity section of our Consolidated Balance Sheets. Currency transaction gains or losses primarily arising from transactions in currencies other than the functional currency are included in office and general expenses. Foreign currency transactions resulted in pre-tax gains of $1.9, $2.1 and $2.0 in for the years ended December 31, 2017, 2016 and 2015, respectively.

We monitor the currencies of countries in which we operate in order to determine if the country should be considered a highly inflationary environment. A currency is determined to be highly inflationary when there is cumulative inflation of approximately 100% or more over a three-year period. If this occurs the functional currency of that country would be changed to our reporting currency, the U.S. Dollar, and foreign exchange gains or losses would be recognized on all monetary transactions, assets and liabilities in currencies other than the U.S. Dollar until the currency is no longer considered highly inflationary.

Income Taxes

The provision for income taxes includes U.S. federal, state, local and foreign taxes. Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences of temporary differences between the financial statement carrying amounts and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be reversed. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is “more likely than not” that all or a portion of the deferred tax assets will not be realized. We evaluate our tax positions using the “more likely than not” recognition threshold and then apply a measurement assessment to those positions that meet the recognition threshold. The factors used in assessing valuation allowances include all available evidence, such as past operating results, estimates of future taxable income and the feasibility of tax planning strategies. We have established tax reserves that we believe to be 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 adjust our reserves as additional information or events require.

In response to the enactment of the Tax Act, the SEC issued SAB 118 on December 22, 2017, which acknowledges that the information necessary to determine such income tax effects may not be sufficiently available, prepared or analyzed in reasonable detail to complete the accounting under U.S. GAAP. SAB 118 allows for the reporting of provisional amounts for those specific tax effects for which a reasonable estimate can be made, and for no amounts to be recorded where a reasonable estimate cannot be made. Any subsequent adjustments to reported amounts will be made over the measurement period, which begins in the reporting period that includes the Tax Act's enactment date and ends when an entity has obtained, prepared and analyzed the information that is needed in order to complete the accounting requirements under U.S. GAAP, not to exceed one year from the enactment date. We have reasonably estimated and recorded provisional amounts resulting from the enactment of the Tax Act. Refer to Note 7 to our Consolidated Financial Statements for further information.

Redeemable Noncontrolling Interests

Many of our acquisitions include provisions under which the noncontrolling equity owners can require us to purchase additional interests in a subsidiary at their discretion. Payments for these redeemable noncontrolling interests may be contingent on projected operating performance and satisfying other conditions specified in the related agreements. These payments are also subject to revision in accordance with the terms of the agreements. We record these redeemable noncontrolling interests in “mezzanine equity” in our Consolidated Balance Sheets. Each reporting period, redeemable noncontrolling interests are reported at their estimated redemption value, but not less than their initial fair value. Any adjustment to the redemption value above initial value prior to exercise will also impact retained earnings or additional paid-in capital (“APIC”), but will not impact net income. Adjustments as a result of currency translation will affect the redeemable noncontrolling interest balance, but do not impact retained earnings or additional paid-in capital.

Earnings Per Share (“EPS”)

Basic EPS available to IPG common stockholders equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding for the applicable period. Diluted EPS equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding, plus any additional common shares that would have been outstanding if potentially dilutive shares had been issued.

Diluted EPS reflect the potential dilution that would occur if certain potentially dilutive securities were exercised. The potential issuance of common stock is assumed to occur at the beginning of the year (or at the time of issuance of the potentially dilutive instrument, if later) and the incremental shares are included using the treasury stock method. The proceeds utilized in applying the treasury stock method consist of the amount, if any, to be paid upon exercise and, as it relates to stock-based compensation, the amount of compensation cost attributed to future service not yet recognized. These proceeds are then assumed to be used to purchase common stock at the average market price of our stock during the period. The incremental shares (difference between the shares assumed to be issued and the shares assumed to be purchased), to the extent they would have been dilutive, are included in the denominator of the diluted EPS calculation.

We may be required to calculate basic EPS using the two-class method as a result of our redeemable noncontrolling interests. To the extent that the redemption value increases and exceeds the then-current fair value of a redeemable noncontrolling interest, net income available to IPG common stockholders (used to calculate EPS) could be negatively impacted by that increase, subject to certain limitations. The partial or full recovery of any reductions to net income available to IPG common stockholders (used to calculate EPS) is limited to any cumulative prior-period reductions. For the years ended December 31, 2017, 2016 and 2015, there was no impact to EPS for adjustments related to our redeemable noncontrolling interests.

Pension and Postretirement Benefits

We have pension and postretirement benefit plans covering certain domestic and international employees. We use various actuarial methods and assumptions in determining our net pension and postretirement benefit costs and obligations, including the discount rate used to determine the present value of future benefits, expected long-term rate of return on plan assets and healthcare cost trend rates. The overfunded or underfunded status of our pension and postretirement benefit plans is recorded on our Consolidated Balance Sheet.

Stock-Based Compensation

Compensation costs related to share-based transactions, including employee stock options, are recognized in the Consolidated Financial Statements based on fair value. Stock-based compensation expense is generally recognized ratably over the requisite service period based on the estimated grant-date fair value, net of estimated forfeitures.

Treasury Stock

We account for repurchased common stock under the cost method and include such treasury stock as a component of our Consolidated Statements of Stockholders' Equity. Upon retirement, we reduce common stock for the par value of the shares being retired and the excess of the cost of the shares over par value as a reduction to APIC, to the extent there is APIC in the same class of stock, and any remaining amount to retained earnings. These retired shares remain authorized but unissued.

In October and November 2017, we retired 13.4 shares of our treasury stock, which resulted in a reduction in common stock of $1.3, treasury stock of $304.4 and APIC of $303.1. In October 2016, we retired 13.7 shares of our treasury stock, which resulted in a reduction in common stock of $1.4, treasury stock of $311.0 and APIC of $309.6. In October 2015, we retired 11.3 shares of our treasury stock, which resulted in a reduction in common stock of $1.2, treasury stock of $233.2 and APIC of $232.0. There was no effect on total stockholders' equity as a result of these retirements.

Debt and Credit Agreements (Notes)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

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		December 31,
			2017				2016
			Book Value		Fair Value ¹		Book Value		Fair Value ¹
2.25% Senior Notes due 2017	2.30	%	$	0.0	$	0.0	$	299.4	$	301.4
4.00% Senior Notes due 2022 (less unamortized discount and issuance costs of $1.3 and $1.1, respectively)	4.13	%	247.6		259.0		247.0		258.4
3.75% Senior Notes due 2023 (less unamortized discount and issuance costs of $0.8 and $2.1, respectively)	4.32	%	497.1		513.2		496.6		503.3
4.20% Senior Notes due 2024 (less unamortized discount and issuance costs of $0.7 and $2.6, respectively)	4.24	%	496.7		524.2		496.2		511.6
Other notes payable and capitalized leases			46.2		46.2		65.4		65.4
Total long-term debt			1,287.6				1,604.6
Less: current portion			2.0				323.9
Long-term debt, excluding current portion			$	1,285.6			$	1,280.7


1	See Note 10 for information on the fair value measurement of our long-term debt.

Annual maturities are scheduled as follows based on the book value as of December 31, 2017.



2018	$	2.0
2019	3.1
2020	1.0
2021	0.0
2022	247.6
Thereafter	1,033.9
Total long-term debt	$	1,287.6

For those debt securities that have a premium or discount at the time of issuance, we amortize the amount through interest expense based on the maturity date or the first date the holders may require us to repurchase the debt securities, if applicable. A premium would result in a decrease in interest expense, and a discount would result in an increase in interest expense in future periods. Additionally, we have debt issuance costs related to certain financing transactions which are also amortized through interest expense. As of December 31, 2017 and 2016, we had total unamortized debt issuance costs of $13.0 and $12.3, respectively.

Our debt securities include covenants that, among other things, limit our liens and the liens of certain of our consolidated subsidiaries, but do not require us to maintain any financial ratios or specified levels of net worth or liquidity.

Long-Term Debt Transactions

2.25% Senior Notes due 2017

In November 2017, we redeemed all $300.0 in aggregate principal amount of the 2.25% Senior Notes due 2017 (the "2.25% Notes"). Total cash paid to redeem the 2.25% Notes was $303.4, which included accrued and unpaid interest of $3.4.

Credit Agreements

We maintain a committed corporate credit facility, which has been amended and restated from time to time (the "Credit Agreement"). The Credit Agreement is a revolving facility, 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. On October 25, 2017, we amended and restated our committed credit agreement, originally dated as of July 18, 2008 (as amended and restated, the "Credit Agreement"), increasing the revolving commitments from $1,000.0 to $1,500.0, or the equivalent in other specified currencies, and extending the Credit Agreement's expiration to October 25, 2022.

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 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 December 31, 2017 and 2016, there were no borrowings under the Credit Agreement; however, we had $8.4 and $4.9 of letters of credit under the Credit Agreement, which reduced our total availability to $1,491.6 and $995.1, respectively.

Under the Credit Agreement, we can elect to receive advances bearing interest based on either the base rate or the Eurocurrency rate (each as defined in the Credit Agreement) plus an applicable margin that is determined based on our credit ratings. As of December 31, 2017, the applicable margin was 0.10% for base rate advances and 1.10% for Eurocurrency rate advances. Letter of credit fees accrue on the average daily aggregate amount of letters of credit outstanding, at a rate equal to the applicable margin for Eurocurrency rate advances, and fronting fees accrue on the aggregate amount of letters of credit outstanding at an annual rate of 0.25%. We also pay a facility fee at an annual rate that is determined based on our credit ratings, which as of December 31, 2017, was 0.15% on the aggregate lending commitment under the Credit Agreement.

In addition to other and customary covenants, the Credit Agreement requires that we maintain the financial covenants listed below as of the end of each fiscal quarter for the period of four fiscal quarters then ended. We were in compliance with all of our covenants in the Credit Agreement as of December 31, 2017.



Interest coverage ratio (not less than): ¹		5.00x
Leverage ratio (not greater than): ²		3.50x


1	The interest coverage ratio is defined as EBITDA, as defined in the Credit Agreement, to net interest expense for the four quarters then ended.

The leverage ratio is defined as debt as of the last day of such fiscal quarter to EBITDA, as defined in the Credit Agreement, for the four quarters then ended. The leverage ratio may be changed to not more than 4.00 to 1 at our election for four consecutive fiscal quarters, beginning with the fiscal quarter in which there is an occurrence of one or more acquisitions with an aggregate purchase price of at least $200.0.

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 December 31, 2017 and 2016, the Company had uncommitted lines of credit in an aggregate amount of $926.2 and $856.6, under which we had outstanding borrowings of $84.9 and $85.7 classified as short-term borrowings on our Consolidated Balance Sheets, respectively. The average amounts outstanding during 2017 and 2016 were $223.8 and $216.0, respectively, with weighted-average interest rates of approximately 2.9% for both periods.

Commercial Paper

In June 2017, the Company established a commercial paper program under which the Company was authorized to issue unsecured commercial paper up to a maximum aggregate amount outstanding at any time of $1,000.0, which was increased to $1,500.0 on October 25, 2017. 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 December 31, 2017, there was no commercial paper outstanding. From the date the program was first utilized through December 31, 2017, the average amount outstanding under the program was $477.4, with a weighted-average interest rate of 1.5% and a weighted-average maturity of seventeen days.

Cash Pooling

We aggregate our domestic cash position on a daily basis. Outside the United States, we use cash pooling arrangements with banks to help manage our liquidity requirements. In these pooling arrangements, several IPG agencies agree with a single bank that the cash balances of any of the agencies with the bank will be subject to a full right of set-off against amounts other agencies owe the bank, and the bank provides for overdrafts as long as the net balance for all agencies does not exceed an agreed-upon level. Typically, each agency pays interest on outstanding overdrafts and receives interest on cash balances. Our Consolidated Balance Sheets reflect cash, net of bank overdrafts, under all of our pooling arrangements, and as of December 31, 2017 and 2016 the amounts netted were $1,412.0 and $1,300.6, respectively.

Acquisitions (Notes)

12 Months Ended

Dec. 31, 2017

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 technological capabilities and improve 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, changes in foreign currency exchange rates and other factors.

During 2017, we completed ten acquisitions, eight of which were included in the Integrated Agency Networks ("IAN") operating segment, and two of which were included in the Constituency Management Group ("CMG") operating segment. These acquisitions included a digital marketing agency based in the U.S., a data science and business intelligence firm based in the U.S. with operations in China, an advertising and consulting company based in Indonesia, a strategic communications agency based in the U.K., an independent creative agency based in the U.K., a retail branding and design firm based in the U.S., 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. During 2017, we recorded approximately $62.0 of goodwill and intangible assets related to our acquisitions.

During 2016, we completed ten acquisitions, three of which were included in the IAN operating segment, and seven of which were included in the CMG operating segment. The most significant acquisitions included a product and service design consultancy based in the U.S., an integrated healthcare marketing communications agency based in the U.S., a content creation and digital agency with offices in the U.S. and the U.K., a mobile consultancy and application development agency based in the U.K., a full-service public relations and digital agency based in China, a search engine optimization and digital content marketing agency based in the U.K., and a mobile focused digital agency based in the U.K. During 2016, we recorded approximately $149.0 of goodwill and intangible assets related to these acquisitions.

During 2015, we completed five acquisitions, four of which were included in the IAN operating segment, and one of which was included in the CMG operating segment. The most significant acquisitions included a full-service digital agency in the U.K., a group of creative marketing agencies based in Russia, and a media planning and buying agency with significant digital capabilities in Canada. During 2015, we recorded approximately $61.0 of goodwill and intangible assets related to these acquisitions.

The results of operations of our acquired companies were included in our consolidated results from the closing date of each acquisition. We did not make any payments in stock related to our acquisitions in 2017, 2016 or 2015.

Details of cash paid for current and prior years' acquisitions are listed below.



	Years ended December 31,
	2017			2016			2015
Cost of investment: current-year acquisitions	$	36.8		$	65.7		$	37.8
Cost of investment: prior-year acquisitions	54.6			40.7			53.1
Less: net cash acquired	(7.1		)	(13.6		)	(9.2		)
Total cost of investment	84.3			92.8			81.7
Operating payments¹	47.1			19.1			18.4
Total cash paid for acquisitions ²	$	131.4		$	111.9		$	100.1

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 Consolidated Statements of Cash Flows.

Of the total cash paid for acquisitions, $30.6, $52.0 and $28.6 for the years ended December 31, 2017, 2016 and 2015, respectively, are classified under the investing section of the 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, $53.7, $40.8 and $53.1 for the years ended December 31, 2017, 2016 and 2015, respectively, are classified under the financing section of the Consolidated Statements of Cash Flows as acquisition-related payments. These amounts relate to deferred payments and increases in our ownership interest for prior acquisitions.

For companies acquired, we estimate the fair values of the assets and liabilities based on 100% of the business for consolidation. The purchase price in excess of the estimated fair value of the tangible net assets acquired is allocated to identifiable intangible assets and then to goodwill. Due to the characteristics of advertising, specialized marketing and communication services companies, our acquisitions typically do not have significant amounts of tangible assets since the principal assets we acquire are client relationships and talent. As a result, a substantial portion of the purchase price is primarily allocated to customer lists, trade names and goodwill.

For acquisitions we record deferred payment and redeemable noncontrolling interest amounts on our Consolidated Balance Sheets based on their acquisition-date fair value. Deferred payments are recorded on a discounted basis and adjusted quarterly, if necessary, through operating income or net interest expense, depending on the nature of the arrangement, for both changes in estimate and accretion between the acquisition date and the final payment date. See Note 13 for further information on contingent acquisition obligations. 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.



	Years ended December 31,
	2017			2016			2015
Balance at beginning of period	$	252.8		$	251.9		$	257.4
Change in related noncontrolling interests balance	(2.8		)	4.9			0.8
Changes in redemption value of redeemable noncontrolling interests:
Additions	7.7			6.8			16.5
Redemptions and other	(18.5		)	(14.8		)	(25.1		)
Redemption value adjustments	12.9			4.0			2.3
Balance at end of period	$	252.1		$	252.8		$	251.9

For all acquisitions, if a portion of the deferred payments and purchases of additional interests after the effective date of purchase are contingent upon employment terms, then that amount is accounted for separately from the business combination and recognized as compensation expense over the required earn-out period. Payments deemed as compensation are excluded from the fair value purchase price allocation to tangible net assets and intangible assets acquired.

Supplementary Data (Notes)

12 Months Ended

Dec. 31, 2017

Supplementary Data [Abstract]

Supplementary Data

Valuation and Qualifying Accounts – Allowance for Uncollectible Accounts Receivable



	Years ended December 31,
	2017			2016			2015
Balance at beginning of period	$	55.7		$	54.2		$	59.5
Charges to costs and expenses	9.5			16.7			11.4
Deductions:
Dispositions	(1.0		)	(2.5		)	(2.8		)
Uncollectible accounts written off	(25.5		)	(9.4		)	(9.8		)
Foreign currency translation adjustments	4.0			(3.3		)	(4.1		)
Balance at end of period	$	42.7		$	55.7		$	54.2

Property and Equipment



	December 31,
	2017			2016
Furniture and equipment	$	634.8		$	604.2
Leasehold improvements	641.5			599.8
Internal-use computer software	331.3			306.5
Land and buildings	79.0			73.1
Gross property and equipment	1,686.6			1,583.6
Less: accumulated depreciation	(1,036.2		)	(961.6		)
Total property and equipment, net	$	650.4		$	622.0

Total depreciation and amortization expense for property and equipment for the years ended December 31, 2017, 2016 and 2015 was $135.9, $138.3 and $130.9, respectively.

Accrued Liabilities

The following table presents the components of accrued liabilities.



	December 31,
	2017		2016
Salaries, benefits and related expenses	$	441.7	$	499.0
Office and related expenses	53.2		46.7
Acquisition obligations	42.0		77.5
Interest	16.4		17.3
Other	121.4		153.5
Total accrued liabilities	$	674.7	$	794.0

Other Expense, net

Results of operations include certain items that are not directly associated with our revenue-producing operations.



	Years ended December 31,
	2017			2016			2015
Net losses on sales of businesses	$	(24.1	)	$	(41.4	)	$	(50.0	)
Other	(2.1		)	1.1			0.4
Total other expense, net	$	(26.2	)	$	(40.3	)	$	(49.6	)

Net losses on sales of businesses – During 2017, the amounts recognized were primarily 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. The businesses held for sale as of year end primarily represent unprofitable, non-strategic agencies which are expected to be sold within the next twelve months. During 2016, the amounts recognized were related to sales of businesses and the classification of certain assets and liabilities, consisting primarily of accounts receivable and accounts payable, as held for sale within both our IAN and CMG operating segments. During 2015, the amounts recognized were related to sales of businesses within both our IAN and CMG operating segments and the classification of certain assets and liabilities, consisting primarily of accounts receivable and accounts payable, as held for sale within our IAN operating segment.

Share Repurchase Program

In February 2017, 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 (the "2017 Share Repurchase Program"), which was in addition to the remaining amount available to be repurchased from the $300.0 authorization made by the Board in February 2016 (the "2016 Share Repurchase Program").

We may effect such repurchases through open market purchases, trading plans established in accordance with U.S. Securities and Exchange Commission ("SEC") rules, derivative transactions or other means. We expect to continue to repurchase our common stock in future periods, although the timing and amount of the repurchases will depend on market conditions and other funding requirements.

The following table presents our share repurchase activity under our share repurchase programs.



	Years ended December 31,
	2017		2016		2015
Number of shares repurchased	13.7		13.3		13.6
Aggregate cost, including fees	$	300.1	$	303.3	$	285.2
Average price per share, including fees	$	21.97	$	22.76	$	20.97

We fully utilized the 2016 Share Repurchase Program in the third quarter of 2017. As of December 31, 2017, $155.5 remained available for repurchase under the 2017 Share Repurchase Program. The 2017 Share Repurchase Program has no expiration date.

Supplemental Cash Flow Information



	Years ended December 31,
	2017		2016		2015
Cash paid for interest	$	82.3	$	78.8	$	74.5
Cash paid for income taxes, net of refunds ¹	228.4		244.1		231.9


1	Refunds of $31.9, $26.6 and $13.0 were received for the years ended December 31, 2017, 2016 and 2015, respectively.

Intangible Assets (Notes)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets [Abstract]

Goodwill and Intangible Assets Disclosure [Text Block]

Intangible Assets

Goodwill

Goodwill is the excess purchase price remaining from an acquisition after an allocation of purchase price has been made to identifiable assets acquired and liabilities assumed based on estimated fair values. The changes in the carrying value of goodwill for our segments, IAN and CMG, for the years ended December 31, 2017 and 2016 are listed below.



	IAN			CMG			Total ¹
Balance as of December 31, 2015	$	3,051.4		$	557.1		$	3,608.5
Acquisitions	32.7			89.3			122.0
Foreign currency and other	(40.3		)	(15.8		)	(56.1		)
Balance as of December 31, 2016	$	3,043.8		$	630.6		$	3,674.4
Acquisitions	39.6			15.5			55.1
Foreign currency and other	78.4			12.5			90.9
Balance as of December 31, 2017	$	3,161.8		$	658.6		$	3,820.4


1	For all periods presented, no goodwill impairment charge has been recorded.

See Note 1 for information regarding our annual impairment methodology.

Other Intangible Assets

Other intangible assets are comprised of both assets with indefinite lives not subject to amortization and assets with definite lives subject to amortization. Other intangible assets primarily consist of customer lists and trade names, which have definitive lives and are subject to amortization on a straight-line basis with estimated useful lives generally between 7 and 15 years. Amortization expense for other intangible assets for the years ended December 31, 2017, 2016 and 2015 was $21.2, $21.9 and $26.1, respectively. There were no material impairment charges on other intangibles for the years ended December 31, 2017, 2016 and 2015. During 2017 and 2016, we recorded approximately $7.0 and $29.0 of intangible assets related to our acquisitions in the respective year.

The following table provides a summary of other intangible assets, which are included in other assets on our Consolidated Balance Sheets.



	December 31,
	2017							2016
	Gross Amount		Accumulated Amortization			Net Amount		Gross Amount		Accumulated Amortization			Net Amount
Customer lists	$	267.3	$	(172.2	)	$	95.1	$	252.4	$	(151.4	)	$	101.0
Trade names	68.8		(33.8		)	35.0		65.5		(28.9		)	36.6
Other	14.4		(3.8		)	10.6		14.3		(3.8		)	10.5
Total	$	350.5	$	(209.8	)	$	140.7	$	332.2	$	(184.1	)	$	148.1

The estimated annual amortization expense for other intangible assets for the next five years as of December 31, 2017 is listed below.



	2018		2019		2020		2021		2022
Estimated amortization expense	$	23.3	$	22.1	$	20.4	$	19.3	$	16.4

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Income Taxes (Notes)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

Public Law 115-97, commonly referred to as the Tax Cuts and Jobs Act (the "Tax Act"), was enacted on December 22, 2017. The Tax Act legislated many new tax provisions which have impacted our operations, including the reduction of the U.S. federal income tax rate from 35.0% to 21.0%, effective in 2018, a current tax on the deemed repatriation of unremitted foreign earnings and a U.S tax exemption for future distributions of certain foreign earnings.

U.S. GAAP requires the income tax accounting effect of a change in tax law, including the effects on current and deferred income taxes, to be reflected in the period in which such law is enacted. The SEC issued Staff Accounting Bulletin No. 118 ("SAB 118") on December 22, 2017, which acknowledges that the information necessary to determine such income tax effects may not be sufficiently available, prepared or analyzed in reasonable detail to complete the accounting under U.S. GAAP. SAB 118 allows for the reporting of provisional amounts for those specific tax effects for which a reasonable estimate can be made, and for no amounts to be recorded where a reasonable estimate cannot be made. Any subsequent adjustments to reported amounts will be made over the measurement period, which begins in the reporting period that includes the Tax Act's enactment date and ends when an entity has obtained, prepared and analyzed the information that is needed in order to complete the accounting requirements under U.S. GAAP, not to exceed one year from the enactment date.

We have reasonably estimated the tax effect of re-measuring our deferred tax balances and reserves at year end to reflect the tax effect of the reversal of such deferred tax balances in future periods during which the U.S. federal income tax rate will be 21.0%. We have recorded a decrease related to deferred tax assets and deferred tax liabilities, with a corresponding provisional net benefit to our deferred income taxes of $104.7. The Tax Act’s various changes to the treatment of fixed assets and deferred compensation are sufficiently complex to conclude that an adjustment may be necessary.

The Tax Act also imposes a tax on certain unremitted foreign earnings at various tax rates. We have reasonably estimated the tax effect of this deemed repatriation of unremitted foreign earnings and have recorded tax expense of $62.3 as a provisional amount due to the fact that necessary information could not be attained, prepared or analyzed on a timely basis to be able to complete the calculations. The complexity of the rules and the comprehensive data requirements will likely result in some adjustment to the provisional amount. The Company expects to pay this amount over the next eight years, as allowed by the Tax Act.

Additionally, the Tax Act imposes a new tax on certain foreign earnings generated in 2018 and forward. We are continuing to evaluate these global intangible low-taxed income ("GILTI") tax rules, which are extremely complex. U.S. GAAP allows us to choose between 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. We are not able to reasonably estimate the effect of the GILTI rules due to the significant complexity of the rules and the fact that the information necessary could not be attained, prepared or analyzed on a timely basis. Therefore, we have not made any adjustment related to the potential GILTI tax and have not made a policy decision regarding whether to record deferred taxes thereon.

Finally, as per interpretive guidance issued by the U.S. Treasury on February 13, 2018, a tax benefit of $31.2, which was recorded during the third quarter of 2017, was reversed during the fourth quarter of 2017 due to the enactment of the Tax Act.

The components of income before income taxes are listed below.



	Years ended December 31,
	2017		2016		2015
Domestic	$	528.2	$	504.7	$	461.0
Foreign	347.8		325.5		301.2
Total	$	876.0	$	830.2	$	762.2

The provision for income taxes is listed below.



	Years ended December 31,
	2017			2016			2015
U.S. federal income taxes (including foreign withholding taxes):
Current	$	154.1		$	54.3		$	117.8
Deferred	(32.2		)	36.6			46.9
	121.9			90.9			164.7
State and local income taxes:
Current	18.8			8.2			15.1
Deferred	20.4			(1.5		)	13.0
	39.2			6.7			28.1
Foreign income taxes:
Current	107.9			89.8			100.4
Deferred	12.9			10.6			(10.4		)
	120.8			100.4			90.0
Total	$	281.9		$	198.0		$	282.8

A reconciliation of the effective income tax rate as reflected in our Consolidated Statements of Operations to the U.S. federal statutory income tax rate is listed below.



	Years ended December 31,
	2017			2016			2015
U.S. federal statutory income tax rate	35.0		%	35.0		%	35.0		%

Income tax provision at U.S. federal statutory rate	$	306.6		$	290.6		$	266.8
State and local income taxes, net of U.S. federal income tax benefit	23.5			4.3			18.3
Impact of foreign operations, including withholding taxes	(6.7		)	(23.9		)	14.7
Change in net valuation allowance ¹	1.4			(13.4		)	(20.6		)
Divestitures	1.1			9.7			11.9
U.S. federal tax credits	(1.7		)	(44.6		)	0.0
Stock compensation	(15.3		)	(9.0		)	0.0
Increase/(decrease) in unrecognized tax benefits	7.0			(22.2		)	(6.5		)
Net impact of the Tax Act	(36.0		)	0.0			0.0
Statutory tax rate changes	0.0			11.4			1.4
Other	2.0			(4.9		)	(3.2		)
Provision for income taxes	$	281.9