Gartner (IT) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-14443
Entity Registrant Name	Gartner, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3099750
Entity Address, Address Line One	P.O. Box 10212
Entity Address, Address Line Two	56 Top Gallant Road
Entity Address, City or Town	Stamford,
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06902-7700
City Area Code	203
Local Phone Number	316-1111
Title of 12(b) Security	Common Stock, $.0005 par value per share
Trading Symbol	IT
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		86,076,529
Entity Central Index Key	0000749251
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 445,995	$ 712,583
Fees receivable, net of allowances of $9,000 and $10,000, respectively	1,175,426	1,241,508
Deferred commissions	257,956	259,755
Prepaid expenses and other current assets	118,479	109,212
Total current assets	1,997,856	2,323,058
Property, equipment and leasehold improvements, net	322,610	336,765
Operating lease right-of-use assets	633,796	647,283
Goodwill	2,943,500	2,945,547
Intangible assets, net	777,441	806,998
Other assets	262,655	256,316
Total Assets	6,937,858	7,315,967
Current liabilities:
Accounts payable and accrued liabilities	703,439	952,431
Deferred revenues	2,088,463	1,974,548
Current portion of long-term debt	20,519	20,515
Total current liabilities	2,812,421	2,947,494
Long-term debt, net of deferred financing fees	1,949,078	1,958,286
Operating lease liabilities	765,125	780,166
Other liabilities	519,640	539,593
Total Liabilities	6,046,264	6,225,539
Stockholders’ Equity
Preferred stock, $0.01 par value, 5,000,000 shares authorized; none issued or outstanding	0	0
Common stock, $0.0005 par value, 250,000,000 shares authorized; 163,602,067 shares issued for both periods	82	82
Additional paid-in capital	2,003,473	1,968,930
Accumulated other comprehensive loss, net	(93,178)	(99,228)
Accumulated earnings	2,419,567	2,255,467
Treasury stock, at cost, 76,519,765 and 74,759,985 common shares, respectively	(3,438,350)	(3,034,823)
Total Stockholders’ Equity	891,594	1,090,428
Total Liabilities and Stockholders’ Equity	$ 6,937,858	$ 7,315,967

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Fees receivable, allowance	$ 9,000	$ 10,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0005	$ 0.0005
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	163,602,067	163,602,067
Treasury stock shares (in shares)	76,519,765	74,759,985

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Total revenues	$ 1,104,038	$ 1,018,891
Costs and expenses:
Cost of services and product development	334,467	341,278
Selling, general and administrative	487,255	496,639
Depreciation	25,750	22,517
Amortization of intangibles	30,514	32,179
Acquisition and integration charges	640	1,560
Total costs and expenses	878,626	894,173
Operating income	225,412	124,718
Interest expense, net	(26,149)	(26,349)
Other income (expense), net	15,490	(1,515)
Income before income taxes	214,753	96,854
Provision for income taxes	50,653	21,757
Net income	$ 164,100	$ 75,097
Net income per share:
Basic (in dollars per share)	$ 1.86	$ 0.84
Diluted (in dollars per share)	$ 1.84	$ 0.83
Weighted average shares outstanding:
Basic (in shares)	88,352	89,219
Diluted (in shares)	89,139	90,066
Research
Revenues:
Total revenues	$ 979,732	$ 909,291
Conferences
Revenues:
Total revenues	24,802	13,870
Consulting
Revenues:
Total revenues	$ 99,504	$ 95,730

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 164,100	$ 75,097
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	677	(46,381)
Interest rate swaps – net change in deferred gain or loss	5,270	(44,732)
Pension plans – net change in deferred actuarial loss	103	79
Other comprehensive income (loss), net of tax	6,050	(91,034)
Comprehensive income (loss)	$ 170,150	$ (15,937)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss, Net	Accumulated Earnings	Treasury Stock
Beginning balance at Dec. 31, 2019	$ 938,593	$ 82	$ 1,899,273	$ (77,938)	$ 1,988,722	$ (2,871,546)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	75,097				75,097
Other comprehensive income (loss)	(91,034)			(91,034)
Issuances under stock plans	5,654		(1,794)			7,448
Common share repurchases	(63,164)					(63,164)
Stock-based compensation expense	25,129		25,129
Ending balance at Mar. 31, 2020	890,275	82	1,922,608	(168,972)	2,063,819	(2,927,262)
Beginning balance at Dec. 31, 2020	1,090,428	82	1,968,930	(99,228)	2,255,467	(3,034,823)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	164,100				164,100
Other comprehensive income (loss)	6,050			6,050
Issuances under stock plans	5,380		(1,543)			6,923
Common share repurchases	(410,450)					(410,450)
Stock-based compensation expense	36,086		36,086
Ending balance at Mar. 31, 2021	$ 891,594	$ 82	$ 2,003,473	$ (93,178)	$ 2,419,567	$ (3,438,350)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net income	$ 164,100	$ 75,097
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	56,264	54,696
Stock-based compensation expense	36,086	25,129
Deferred taxes	3,883	25,537
Reduction in the carrying amount of operating lease right-of-use assets	18,575	22,862
Amortization and write-off of deferred financing fees	923	1,637
Gain on de-designated swaps	(15,765)	0
Changes in assets and liabilities:
Fees receivable, net	54,192	135,661
Deferred commissions	(237)	17,520
Prepaid expenses and other current assets	(9,933)	(12,656)
Other assets	(10,081)	5,961
Deferred revenues	131,786	(26,228)
Accounts payable and accrued and other liabilities	(272,495)	(269,467)
Cash provided by operating activities	157,298	55,749
Investing activities:
Additions to property, equipment and leasehold improvements	(12,521)	(24,536)
Cash used in investing activities	(12,521)	(24,536)
Financing activities:
Proceeds from employee stock purchase plan	5,357	5,641
Proceeds from revolving credit facility	0	27,000
Payments on revolving credit facility	(5,000)	0
Payments on borrowings	(5,127)	(27,967)
Purchases of treasury stock	(398,450)	(73,164)
Cash used in financing activities	(403,220)	(68,490)
Net decrease in cash and cash equivalents	(258,443)	(37,277)
Effects of exchange rates on cash and cash equivalents	(8,145)	(15,709)
Cash and cash equivalents, beginning of period	712,583	280,836
Cash and cash equivalents, end of period	$ 445,995	$ 227,850

Business and Basis of Presentat

Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Business. Gartner, Inc. (NYSE: IT) is the world’s leading research and advisory company and a member of the S&P 500. We equip business leaders with indispensable insights, advice and tools to achieve their mission–critical priorities today and build the successful organizations of tomorrow. We believe our unmatched combination of expert-led, practitioner-sourced and data-driven research steers clients toward the right decisions on the issues that matter most. We are a trusted advisor and an objective resource for more than 14,000 enterprises in more than 100 countries — across all major functions, in every industry and enterprise size. Segments . Gartner delivers its products and services globally through three business segments: Research, Conferences and Consulting. Revenues and other financial information for our segments are discussed in Note 5 — Segment Information. Basis of presentation . The accompanying interim Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”), as defined in Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 270 for interim financial information and with the applicable instructions of U.S. Securities and Exchange Commission (“SEC”) Rule 10-01 of Regulation S-X on Form 10-Q, and should be read in conjunction with the consolidated financial statements and related notes of the Company in its Annual Report on Form 10-K for the year ended December 31, 2020. The fiscal year of Gartner is the twelve-month period from January 1 through December 31. In the opinion of management, all normal recurring accruals and adjustments considered necessary for a fair presentation of financial position, results of operations and cash flows at the dates and for the periods presented herein have been included. The results of operations for the three months ended March 31, 2021 may not be indicative of the results of operations for the remainder of 2021 or beyond. When used in these notes, the terms “Gartner,” the “Company,” “we,” “us,” or “our” refer to Gartner, Inc. and its consolidated subsidiaries. Principles of consolidation . The accompanying interim Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances have been eliminated. Use of estimates . The preparation of the accompanying interim Condensed Consolidated Financial Statements requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Such estimates include the valuation of fees receivable, goodwill, intangible assets and other long-lived assets, as well as tax accruals and other liabilities. In addition, estimates are used in revenue recognition, income tax expense or benefit, performance-based compensation charges, depreciation and amortization. Management believes its use of estimates in these interim Condensed Consolidated Financial Statements to be reasonable. Management continually evaluates and revises its estimates using historical experience and other factors, including the general economic environment and actions it may take in the future. Management adjusts these estimates when facts and circumstances dictate. However, these estimates may involve significant uncertainties and judgments and cannot be determined with precision. In addition, these estimates are based on management’s best judgment at a point in time. As a result, differences between estimates and actual results could be material and would be reflected in the Company’s consolidated financial statements in future periods. Revenue recognition. Revenue is recognized in accordance with the requirements of FASB ASC Topic 606, Revenue from Contracts with Customers (“ASC Topic 606”). Revenue is only recognized when all of the required criteria for revenue recognition have been met. The accompanying Condensed Consolidated Statements of Operations present revenue net of any sales or value-added taxes that we collect from customers and remit to government authorities. ASC Topic 270 requires certain disclosures in interim financial statements around the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Note 2 — Revenue and Related Matters provides additional information regarding the Company’s revenues. Adoption of new accounting standards. The Company adopted the accounting standard described below during the three months ended March 31, 2021. Simplifying the Accounting for Income Taxes — In December 2019, the FASB issued ASU No. 2019-12, Income Taxes—Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”). ASU No. 2019-12 provides new guidance to simplify the accounting for income taxes in certain areas, changes the accounting for select income tax transactions and makes minor ASC improvements. Gartner adopted ASU No. 2019-12 on January 1, 2021. The adoption of ASU No. 2019-12 did not have a material impact on the Company’s Condensed Consolidated Financial Statements. Accounting standards issued but not yet adopted. The FASB has issued accounting standards that have not yet become effective and may impact the Company’s consolidated financial statements or related disclosures in future periods. Those standards and their potential impact are discussed below. Accounting standard effective immediately upon voluntary election by Gartner Reference Rate Reform — In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform—Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU No. 2020-04”). ASU No. 2020-04 provides that an entity can elect not to apply certain required modification accounting in U.S. GAAP to contracts where all changes to the critical terms relate to reference rate reform (e.g., the expected discontinuance of LIBOR and the transition to an alternative reference interest rate, etc.). In addition, the rule provides optional expedients and exceptions that enable entities to continue to apply hedge accounting for hedging relationships where one or more of the critical terms change due to reference rate reform. The rule became effective for all entities as of March 12, 2020 and will generally no longer be available to apply after December 31, 2022. The Company is currently evaluating the potential impact of ASU No. 2020-04 on its consolidated financial statements, including the rule’s potential impact on any debt modifications or other contractual changes in the future that may result from reference rate reform.

Revenue and Related Matters

Revenue and Related Matters	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue and Related Matters	Revenue and Related Matters Disaggregated Revenue — The Company’s disaggregated revenue by reportable segment is presented in the tables below for the periods indicated (in thousands). By Primary Geographic Market (1) Three Months Ended March 31, 2021 Primary Geographic Market Research Conferences Consulting Total United States and Canada $ 631,333 $ 19,599 $ 57,486 $ 708,418 Europe, Middle East and Africa 230,201 2,713 30,362 263,276 Other International 118,198 2,490 11,656 132,344 Total revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Three Months Ended March 31, 2020 Primary Geographic Market Research Conferences Consulting Total United States and Canada $ 590,156 $ 5,980 $ 54,163 $ 650,299 Europe, Middle East and Africa 205,939 2,147 30,082 238,168 Other International 113,196 5,743 11,485 130,424 Total revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 (1) Revenue is reported based on where the sale is fulfilled. The Company’s revenue is generated primarily through direct sales to clients by domestic and international sales forces and a network of independent international sales agents. Most of the Company’s products and services are provided on an integrated worldwide basis and, because of this integrated delivery approach, it is not practical to precisely separate the Company's revenue by geographic location. Accordingly, revenue information presented in the above tables is based on internal allocations, which involve certain management estimates and judgments. By Timing of Revenue Recognition Three Months Ended March 31, 2021 Timing of Revenue Recognition Research Conferences Consulting Total Transferred over time (1) $ 894,087 $ — $ 84,342 $ 978,429 Transferred at a point in time (2) 85,645 24,802 15,162 125,609 Total revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Three Months Ended March 31, 2020 Timing of Revenue Recognition Research Conferences Consulting Total Transferred over time (1) $ 829,212 $ — $ 81,408 $ 910,620 Transferred at a point in time (2) 80,079 13,870 14,322 108,271 Total revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 (1) Research revenues were recognized in connection with performance obligations that were satisfied over time using a time-elapsed output method to measure progress. Consulting revenues were recognized over time using labor hours as an input measurement basis. (2) The revenues in this category were recognized in connection with performance obligations that were satisfied at the point in time that the contractual deliverables were provided to the customer. Performance Obligations — For customer contracts that are greater than one year in duration, the aggregate amount of the transaction price allocated to performance obligations that are unsatisfied (or partially unsatisfied) as of March 31, 2021 was approximately $3.6 billion. The Company expects to recognize $1,705.5 million, $1,443.1 million and $424.5 million of this revenue (most of which pertains to Research) during the remainder of 2021, the year ending December 31, 2022 and thereafter, respectively. The Company applies a practical expedient that is permitted under ASC Topic 606 and, accordingly, it does not disclose such performance obligation information for customer contracts that have original durations of one year or less. The Company’s performance obligations for contracts meeting this ASC Topic 606 disclosure exclusion primarily include: (i) stand-ready services under Research subscription contracts; (ii) holding conferences and meetings where attendees and exhibitors can participate; and (iii) providing customized Consulting solutions for clients under fixed fee and time and materials engagements. The remaining duration of these performance obligations is generally less than one year, which aligns with the period that the parties have enforceable rights and obligations under the affected contracts. Customer Contract Assets and Liabilities — The timing of the recognition of revenue and the amount and timing of the Company’s billings and cash collections, including upfront customer payments, result in the recognition of both assets and liabilities on the Company’s consolidated balance sheet. The table below provides information regarding certain of the Company’s balance sheet accounts that pertain to its contracts with customers (in thousands). March 31, December 31, 2021 2020 Assets: Fees receivable, gross (1) $ 1,184,426 $ 1,251,508 Contract assets recorded in Prepaid expenses and other current assets (2) $ 19,883 $ 14,440 Contract liabilities: Deferred revenues (current liability) (3) $ 2,088,463 $ 1,974,548 Non-current deferred revenues recorded in Other liabilities (3) 25,852 26,754 Total contract liabilities $ 2,114,315 $ 2,001,302 (1) Fees receivable represent an unconditional right to payment from the Company’s customers and include both billed and unbilled amounts. (2) Contract assets represent recognized revenue for which the Company does not have an unconditional right to payment as of the balance sheet date because the project may be subject to a progress billing milestone or some other billing restriction. (3) Deferred revenues represent amounts (i) for which the Company has received an upfront customer payment or (ii) that pertain to recognized fees receivable. Both situations occur before the completion of the Company’s performance obligation(s). The Company recognized revenue of $726.7 million and $658.4 million during the three months ended March 31, 2021 and 2020, respectively, that was attributable to deferred revenues that were recorded at the beginning of each such period. Those amounts primarily consisted of (i) Research revenues that were recognized ratably as control of the goods or services passed to the customer and (ii) Conferences revenue pertaining to conferences and meetings that occurred during the reporting periods. During each of the three months ended March 31, 2021 and 2020, the Company did not record any material impairments related to its contract assets. The Company does not typically recognize revenue from performance obligations satisfied in prior periods.

Computation of Earnings Per Sha

Computation of Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation of Earnings Per Share	Computation of Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income by the weighted average number of shares of Common Stock outstanding during the period. Diluted EPS reflects the potential dilution of securities that could share in earnings. Potential shares of common stock are excluded from the computation of diluted earnings per share when their effect would be anti-dilutive. The table below sets forth the calculation of basic and diluted income per share for the periods indicated (in thousands, except per share data). Three Months Ended March 31, 2021 2020 Numerator: Net income used for calculating basic and diluted income per share $ 164,100 $ 75,097 Denominator: Weighted average common shares used in the calculation of basic income per share 88,352 89,219 Dilutive effect of outstanding awards associated with stock-based compensation plans (1) 787 847 Shares used in the calculation of diluted income per share 89,139 90,066 Basic income per share $ 1.86 $ 0.84 Diluted income per share $ 1.84 $ 0.83 (1) Certain potential shares of common stock were not included in the computation of diluted income per share because the effect would have been anti-dilutive. These potential shares of common stock totaled approximately 0.4 million and 0.7 million for the three months ended March 31, 2021, and 2020, respectively.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based CompensationThe Company grants stock-based compensation awards as an incentive for employees and directors to contribute to the Company’s long-term success. The Company currently awards stock-settled stock appreciation rights, service-based and performance-based restricted stock units, and common stock equivalents. As of March 31, 2021, the Company had 4.0 million shares of its common stock, par value $0.0005 per share, (the “Common Stock”) available for stock-based compensation awards under its current Long-Term Incentive Plan as amended and restated in January 2019 (the “Plan”). The tables below summarize the Company’s stock-based compensation expense by award type and expense category line item during the periods indicated (in millions). Three Months Ended March 31, Award type 2021 2020 Stock appreciation rights $ 2.0 $ 1.7 Restricted stock units (2) 33.9 23.2 Common stock equivalents 0.2 0.2 Total (1) $ 36.1 $ 25.1 Three Months Ended March 31, Expense category line item 2021 2020 Cost of services and product development $ 13.7 $ 12.1 Selling, general and administrative 22.4 13.0 Total (1) (2) $ 36.1 $ 25.1 (1) Includes charges of $21.5 million and $11.6 million during the three months ended March 31, 2021 and 2020, respectively, for awards to retirement-eligible employees. Those awards vest on an accelerated basis.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s products and services are delivered through three segments – Research, Conferences and Consulting, as described below. • Research provides trusted, objective insights and advice on the mission-critical priorities of leaders across all functional areas of an enterprise through reports, briefings, proprietary tools, access to our research experts, peer networking services and membership programs that enable our clients to drive organizational performance. • Conferences provides business professionals across an organization the opportunity to learn, share and network. From our Gartner Symposium/Xpo series, to industry-leading conferences focused on specific business roles and topics, to peer-driven sessions, our offerings enable attendees to experience the best of Gartner insight and advice. • Consulting combines the power of Gartner market-leading research with custom analysis and on-the-ground support to help chief information officers and other senior executives driving technology-related strategic initiatives move confidently from insight to action. The Company evaluates segment performance and allocates resources based on gross contribution margin. Gross contribution, as presented in the tables below, is defined as operating income or loss excluding certain Cost of services and product development expenses, Selling, general and administrative expenses, Depreciation, Amortization of intangibles, and Acquisition and integration charges. Certain bonus and fringe benefit costs included in consolidated Cost of services and product development are not allocated to segment expense. The accounting policies used by the reportable segments are the same as those used by the Company. There are no intersegment revenues. The Company does not identify or allocate assets, including capital expenditures, by reportable segment. Accordingly, assets are not reported by segment because the information is not available by segment and is not reviewed in the evaluation of segment performance or in making decisions regarding the allocation of resources. The tables below present information about the Company’s reportable segments for the periods indicated (in thousands). Three Months Ended March 31, 2021 Research Conferences Consulting Consolidated Revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Gross contribution 724,372 13,896 39,098 777,366 Corporate and other expenses (551,954) Operating income $ 225,412 Three Months Ended March 31, 2020 Research Conferences Consulting Consolidated Revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 Gross contribution 653,469 (6,060) 29,382 676,791 Corporate and other expenses (552,073) Operating income $ 124,718 The table below provides a reconciliation of total segment gross contribution to net income for the periods indicated (in thousands). Three Months Ended March 31, 2021 2020 Total segment gross contribution $ 777,366 $ 676,791 Costs and expenses: Cost of services and product development - unallocated (1) 7,795 (822) Selling, general and administrative 487,255 496,639 Depreciation and amortization 56,264 54,696 Acquisition and integration charges 640 1,560 Operating income 225,412 124,718 Interest expense and other, net (10,659) (27,864) Less: Provision for income taxes 50,653 21,757 Net income $ 164,100 $ 75,097 (1) The unallocated amounts consist of certain bonus and fringe costs recorded in consolidated Cost of services and product development that are not allocated to segment expense. The Company’s policy is to allocate bonuses to segments at 100% of a segment employee’s target bonus. Amounts above or below 100% are absorbed by corporate.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill Goodwill represents the excess of the purchase price of acquired businesses over the estimated fair values of the tangible and identifiable intangible net assets acquired. Evaluations of the recoverability of goodwill are performed in accordance with FASB ASC Topic 350, which requires an annual assessment of potential goodwill impairment at the reporting unit level and whenever events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. When performing the annual assessment of the recoverability of goodwill, the Company initially performs a qualitative analysis evaluating whether any events or circumstances occurred or exist that provide evidence that it is more likely than not that the fair value of any of the Company’s reporting units is less than the related carrying amount. If the Company does not believe that it is more likely than not that the fair value of any of the Company’s reporting units is less than the related carrying amount, then no quantitative impairment test is performed. However, if the results of the qualitative assessment indicate that it is more likely than not that the fair value of a reporting unit is less than its respective carrying amount, then a quantitative impairment test is performed. Evaluating the recoverability of goodwill requires judgments and assumptions regarding future trends and events. As a result, both the precision and reliability of the estimates are subject to uncertainty. The Company’s most recent annual impairment test of goodwill was a qualitative analysis conducted during the quarter ended September 30, 2020 that indicated no impairment. Subsequent to completing the 2020 annual impairment test, there were no events or changes in circumstances noted that required an interim impairment test. The table below presents changes to the carrying amount of goodwill by segment during the three months ended March 31, 2021 (in thousands). Research Conferences Consulting Total Balance at December 31, 2020 (1) $ 2,664,732 $ 184,091 $ 96,724 $ 2,945,547 Foreign currency translation impact (1,917) (38) (92) (2,047) Balance at March 31, 2021 $ 2,662,815 $ 184,053 $ 96,632 $ 2,943,500 (1) The Company does not have any accumulated goodwill impairment losses. Finite-Lived Intangible Assets The tables below present reconciliations of the carrying amounts of the Company’s finite-lived intangible assets as of the dates indicated (in thousands). March 31, 2021 Customer Software Content Other Total Gross cost at December 31, 2020 $ 1,154,210 $ 110,597 $ 3,965 $ 10,614 $ 1,279,386 Foreign currency translation impact 948 53 — — 1,001 Gross cost 1,155,158 110,650 3,965 10,614 1,280,387 Accumulated amortization (1) (406,074) (88,933) (3,965) (3,974) (502,946) Balance at March 31, 2021 $ 749,084 $ 21,717 $ — $ 6,640 $ 777,441 December 31, 2020 Customer Software Content Other Total Gross cost $ 1,154,210 $ 110,597 $ 3,965 $ 10,614 $ 1,279,386 Accumulated amortization (1) (381,776) (83,320) (3,595) (3,697) (472,388) Balance at December 31, 2020 $ 772,434 $ 27,277 $ 370 $ 6,917 $ 806,998 (1) Finite-lived intangible assets are amortized using the straight-line method over the following periods: Customer relationships—6 to 13 years; Software—3 to 7 years; Content—2 to 3 years; and Other—2 to 11 years. Amortization expense related to finite-lived intangible assets was $30.5 million and $32.2 million during the three months ended March 31, 2021 and 2020, respectively. The estimated future amortization expense by year for finite-lived intangible assets is presented in the table below (in thousands). 2021 (remaining nine months) $ 75,546 2022 96,169 2023 96,154 2024 90,819 2025 82,150 Thereafter 336,603 $ 777,441

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt The Company’s total outstanding borrowings are summarized in the table below (in thousands). March 31, December 31, Description 2021 2020 2020 Credit Agreement - Term loan facility (1) $ 390,000 $ 395,000 2020 Credit Agreement - Revolving credit facility (1), (2) — 5,000 2028 Notes (3) 800,000 800,000 2030 Notes (4) 800,000 800,000 Other (5) 5,919 6,046 Principal amount outstanding (6) 1,995,919 2,006,046 Less: deferred financing fees (7) (26,322) (27,245) Net balance sheet carrying amount $ 1,969,597 $ 1,978,801 (1) The contractual annualized interest rate as of March 31, 2021 on the 2020 Credit Agreement Term loan facility and the revolving credit facility was 1.50%, which consisted of a floating Eurodollar base rate of 0.125% plus a margin of 1.375%. However, the Company has interest rate swap contracts that effectively convert the floating Eurodollar base rates on outstanding amounts to a fixed base rate. (2) The Company had approximately $1.0 billion of available borrowing capacity on the 2020 Credit Agreement revolver (not including the expansion feature) as of March 31, 2021. (3) Consists of $800.0 million principal amount of 2028 Notes outstanding. The 2028 Notes bear interest at a fixed rate of 4.50% and mature on July 1, 2028. (4) Consists of $800.0 million principal amount of 2030 Notes outstanding. The 2030 Notes bear interest at a fixed rate of 3.75% and mature on October 1, 2030. (5) Consists of two State of Connecticut economic development loans. One of the loans originated in 2012, has a 10-year maturity and the outstanding balance of $0.9 million as of March 31, 2021 bears interest at a fixed rate of 3.00%. The second loan, originated in 2019, has a 10-year maturity and bears interest at a fixed rate of 1.75%. Both of these loans may be repaid at any time by the Company without penalty. (6) The weighted average annual effective rate on the Company’s outstanding debt for the three months ended March 31, 2021, including the effects of its interest rate swaps discussed below, was 5.02%. (7) Deferred financing fees are being amortized to Interest expense, net over the term of the related debt obligation. 2030 Notes On September 28, 2020, the Company issued $800.0 million aggregate principal amount of 3.75% Senior Notes due 2030 (the “2030 Notes”). The 2030 Notes were issued pursuant to an indenture, dated as of September 28, 2020 (the “2030 Note Indenture”), among the Company, the guarantors party thereto and U.S. Bank National Association, as trustee. The 2030 Notes were issued at an issue price of 100.0% and bear interest at a rate of 3.75% per annum. Interest on the 2030 Notes is payable on April 1 and October 1 of each year, beginning on April 1, 2021. The 2030 Notes will mature on October 1, 2030. The Company may redeem some or all of the 2030 Notes at any time on or after October 1, 2025 for cash at the redemption prices set forth in the 2030 Note Indenture, plus accrued and unpaid interest to, but excluding, the redemption date. Prior to October 1, 2025, the Company may redeem up to 40% of the aggregate principal amount of the 2030 Notes in connection with certain equity offerings, or some or all of the 2030 Notes with a “make-whole” premium, in each case subject to the terms set forth in the 2030 Indenture. 2028 Notes On June 22, 2020, the Company issued $800.0 million aggregate principal amount of 4.50% Senior Notes due 2028 (the “2028 Notes”). The 2028 Notes were issued pursuant to an indenture, dated as of June 22, 2020 (the “2028 Note Indenture”), among the Company, the guarantors party thereto and U.S. Bank National Association, as trustee. The 2028 Notes were issued at an issue price of 100.0% and bear interest at a rate of 4.50% per annum. Interest on the 2028 Notes is payable on January 1 and July 1 of each year, beginning on January 1, 2021. The Notes will mature on July 1, 2028. The Company may redeem some or all of the 2028 Notes at any time on or after July 1, 2023 for cash at the redemption prices set forth in the 2028 Note Indenture, plus accrued and unpaid interest to, but excluding, the redemption date. Prior to July 1, 2023, the Company may redeem up to 40% of the aggregate principal amount of the 2028 Notes in connection with certain equity offerings, or some or all of the 2028 Notes with a “make-whole” premium, in each case subject to the terms set forth in the 2028 Indenture. 2020 Credit Agreement On September 28, 2020, the Company entered into an agreement among the Company, as borrower, the lenders party thereto and JPMorgan Chase Bank, N.A., as administrative agent (the “Administrative Agent,” and such agreement, the “2020 Credit Agreement”), which amended and restated the Company’s existing credit facility, dated as of June 17, 2016 (as amended, supplemented or otherwise modified from time to time, the “2016 Credit Agreement”). The 2020 Credit Agreement provides for a $400.0 million senior secured five-year term loan facility and a $1.0 billion senior secured five-year revolving facility. The term and revolving facilities may be increased, at the Company’s option and under certain conditions, by up to an additional $1.0 billion in the aggregate plus additional amounts subject to the satisfaction of certain conditions, including a maximum secured leverage ratio. The term loan will be repaid in consecutive quarterly installments commencing December 31, 2020, plus a final payment due on September 28, 2025, and may be prepaid at any time without penalty or premium (other than applicable breakage costs) at the option of the Company. The revolving credit facility may be used for loans, and up to $75.0 million may be used for letters of credit. The revolving loans may be borrowed, repaid and re-borrowed until September 28, 2025, at which time all amounts borrowed must be repaid. On September 28, 2020, the Company drew down $400.0 million in term loans. The initial drawdown was used to refinance the outstanding amounts under the 2016 Credit Agreement. Additional amounts drawn down under the 2020 Credit Agreement will be used for general corporate purposes, including the funding of acquisitions, payment of capital expenditures and the repurchase of shares. The Company’s obligations under the 2020 Credit Agreement are guaranteed, on a secured basis, by certain existing and future direct and indirect U.S. subsidiaries. The Company’s obligations under the 2020 Credit Agreement and the guarantees of the subsidiary guarantors are secured by first priority security interests in substantially all of the assets of the Company and the subsidiary guarantors. The security and pledges are subject to certain exceptions. Loans under the 2020 Credit Agreement bear interest at a rate equal to, at the Company’s option, either (i) the greatest of: (x) the Wall Street Journal prime rate; (y) the average rate on Federal Reserve Board of New York rate plus 1/2 of 1%; and (z) and the adjusted LIBO rate (adjusted for statutory reserves) for a one-month interest period plus 1%, in each case plus a margin equal to between 0.125% and 1.25% depending on the Company’s consolidated leverage ratio as of the end of the four consecutive fiscal quarters most recently ended, or (ii) the adjusted LIBO rate (adjusted for statutory reserves) plus a margin equal to between 1.125% and 2.25%, depending on the Company’s leverage ratio as of the end of the four consecutive fiscal quarters most recently ended. The commitment fee payable on the unused portion of the revolving credit facility is equal to between 0.175% and 0.40% based on utilization of the revolving credit facility. The Company has also agreed to pay customary letter of credit fees. Interest Rate Swaps As of March 31, 2021, the Company had four fixed-for-floating interest rate swap contracts with a total notional value of $1.4 billion that mature through 2025. The Company pays base fixed rates on these swaps ranging from 2.13% to 3.04% and in return receives a floating Eurodollar base rate on 30-day notional borrowings. As a result of the payment under the then outstanding 2016 Credit Agreement term loan and revolving credit facility, the Company de-designated all of its interest rate swaps effective June 30, 2020. Accordingly, hedge accounting is not applicable, and subsequent changes to the fair value of the interest rate swaps are recorded in Other income (expense), net. The amounts previously recorded in Accumulated other comprehensive loss are amortized into Interest expense, net over the terms of the hedged forecasted interest payments. As of March 31, 2021, $97.0 million is remaining in Accumulated other comprehensive loss, net. The interest rate swaps had negative unrealized fair values (liabilities) of $84.8 million and $109.2 million as of March 31, 2021 and December 31, 2020, respectively, of which $72.8 million and $78.1 million were recorded in Accumulated other comprehensive loss, net of tax effect, as of March 31, 2021 and December 31, 2020, respectively. See Note 11 — Fair Value Disclosures for the determination of the fair values of Company’s interest rate swaps.

Equity

Equity	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Equity	Equity Share Repurchase Authorization In 2015, the Company’s Board of Directors (the “Board”) authorized a share repurchase program to repurchase up to $1.2 billion of the Company’s common stock. On February 4, 2021, the Board authorized incremental share repurchases of up to an additional $300 million of the Company’s common stock. $0.5 billion remained available under the share repurchase program as of March 31, 2021. The Company may repurchase its common stock from time-to-time in amounts, at prices and in the manner that the Company deems appropriate, subject to the availability of stock, prevailing market conditions, the trading price of the stock, the Company’s financial performance and other conditions. Repurchases may be made through open market purchases (which may include repurchase plans designed to comply with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended), accelerated share repurchases, private transactions or other transactions and will be funded by cash on hand and borrowings. Repurchases may also be made from time-to-time in connection with the settlement of the Company’s stock-based compensation awards. See Note 14 — Subsequent Event for a discussion regarding an increase in the Company’s share repurchase authorization. The Company’s share repurchase activity is presented in the table below for the periods indicated. Three Months Ended March 31, 2021 2020 Number of shares repurchased (1) 2,274,710 417,707 Cash paid for repurchased shares (in thousands) (2) $ 398,450 $ 73,164 (1) The average purchase price for repurchased shares was $180.44 and $151.22 for the three months ended March 31, 2021 and 2020, respectively. The repurchased shares during the three months ended March 31, 2021 and 2020 included purchases for both stock-based compensation awards and open market purchases. (2) The cash paid for repurchased shares during the three months ended March 31, 2021 included $8.0 million of open market purchases with trade dates in December 2020 that settled in January 2021. There were $20.0 million of open market purchases with trade dates in March 2021 that settled in April 2021. The cash paid for repurchased shares during the three months ended March 31, 2020 included open market purchases with trade dates in December 2019 that settled in January 2020. Accumulated Other Comprehensive Income (Loss), net (“AOCI/L”) The tables below provide information about the changes in AOCI/L by component and the related amounts reclassified out of AOCI/L to income during the periods indicated (net of tax, in thousands) (1). Three Months Ended March 31, 2021 Interest Rate Defined Foreign Total Balance – December 31, 2020 $ (78,104) $ (9,309) $ (11,815) $ (99,228) Other comprehensive income (loss) activity during the period: Change in AOCI/L before reclassifications to income — — 677 677 Reclassifications from AOCI/L to income (2), (3) 5,270 103 — 5,373 Other comprehensive income (loss) for the period 5,270 103 677 6,050 Balance – March 31, 2021 $ (72,834) $ (9,206) $ (11,138) $ (93,178) Three Months Ended March 31, 2020 Interest Rate Defined Foreign Total Balance – December 31, 2019 $ (47,164) $ (8,584) $ (22,190) $ (77,938) Other comprehensive income (loss) activity during the period: Change in AOCI/L before reclassifications to income (47,054) — (46,381) (93,435) Reclassifications from AOCI/L to income (2), (3) 2,322 79 — 2,401 Other comprehensive income (loss) for the period (44,732) 79 (46,381) (91,034) Balance – March 31, 2020 $ (91,896) $ (8,505) $ (68,571) $ (168,972) (1) Amounts in parentheses represent debits (deferred losses). (2) $7.0 million and $3.2 million of the reclassifications related to interest rate swaps (cash flow hedges) were recorded in Interest expense, net, for the three months ended March 31, 2021 and 2020, respectively. See Note 7 — Debt and Note 10 — Derivatives and Hedging for information regarding the cash flow hedges. (3) The reclassifications related to defined benefit pension plans were recorded in Other income (expense), net.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The provision for income taxes for the three months ended March 31, 2021 and 2020 was an expense of $50.7 million and $21.8 million, respectively. The effective income tax rate was 23.6% and of 22.5% for the three months ended March 31, 2021 and 2020, respectively. The quarter-over-quarter increase in the effective income tax rate was primarily due to the shifts in estimated geographical mix of earnings as well as the relative impact of tax benefits from stock-based compensation. The Company had gross unrecognized tax benefits of $125.0 million on March 31, 2021 and $127.1 million on December 31, 2020. It is reasonably possible that gross unrecognized tax benefits will decrease by approximately $8.9 million within the next twelve months due to the anticipated closure of audits and the expiration of certain statutes of limitation.

Derivatives and Hedging

Derivatives and Hedging	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging	Derivatives and Hedging The Company enters into a limited number of derivative contracts to mitigate the cash flow risk associated with changes in interest rates on variable-rate debt and changes in foreign exchange rates on forecasted foreign currency transactions. The Company accounts for its outstanding derivative contracts in accordance with FASB ASC Topic 815, which requires all derivatives, including derivatives designated as accounting hedges, to be recorded on the balance sheet at fair value. The tables below provide information regarding the Company’s outstanding derivative contracts as of the dates indicated (in thousands, except for number of contracts). March 31, 2021 Derivative Contract Type Number of Notional Fair Value Balance Unrealized Interest rate swaps (1) 4 $ 1,400,000 $ (50,096) Other liabilities $ (72,834) (34,710) Accrued liabilities Foreign currency forwards (2) 33 196,038 (220) Accrued liabilities — Total 37 $ 1,596,038 $ (85,026) $ (72,834) December 31, 2020 Derivative Contract Type Number of Contracts Notional Fair Value Balance Unrealized Interest rate swaps (1) 4 $ 1,400,000 $ (74,289) Other liabilities $ (78,104) (34,886) Accrued liabilities Foreign currency forwards (2) 163 430,063 (1,514) Accrued liabilities — Total 167 $ 1,830,063 $ (110,689) $ (78,104) (1) As a result of the payment under the then outstanding 2016 Credit Agreement term loan and revolving credit facility, the Company de-designated all of its interest rate swaps effective June 30, 2020. Accordingly, hedge accounting is not applicable, and subsequent changes to fair value of the interest rate swaps are recorded in Other income (expense), net. The amounts previously recorded in Accumulated other comprehensive loss are amortized into Interest expense, net over the terms of the hedged forecasted interest payments. See Note 7 — Debt provides additional information regarding the Company’s interest rate swap contracts. (2) The Company has foreign exchange transaction risk because it typically enters into transactions in the normal course of business that are denominated in foreign currencies that differ from the local functional currency. The Company enters into short-term foreign currency forward exchange contracts to mitigate the cash flow risk associated with changes in foreign currency rates on forecasted foreign currency transactions. These contracts are accounted for at fair value with realized and unrealized gains and losses recognized in Other income (expense), net because the Company does not designate these contracts as hedges for accounting purposes. All of the outstanding foreign currency forward exchange contracts at March 31, 2021 matured before April 30, 2021. (3) See Note 11 — Fair Value Disclosures for the determination of the fair values of these instruments. At March 31, 2021, all of the Company’s derivative counterparties were investment grade financial institutions. The Company did not have any collateral arrangements with its derivative counterparties and none of the derivative contracts contained credit-risk related contingent features. The table below provides information regarding amounts recognized in the accompanying Condensed Consolidated Statements of Operations for derivative contracts for the periods indicated (in thousands). Three Months Ended March 31, Amount recorded in: 2021 2020 Interest expense, net (1) $ 7,032 $ 3,192 Other (income) expense, net (2) (15,823) 12,599 Total (income) expense, net $ (8,791) $ 15,791 (1) Consists of interest expense from interest rate swap contracts. (2) Consists of net realized and unrealized gains and losses on foreign currency forward contracts, and gains and losses on de-designated interest rate swaps.

Fair Value Disclosures

Fair Value Disclosures	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair Value Disclosures The Company’s financial instruments include cash equivalents, fees receivable from customers, accounts payable and accrued liabilities, all of which are normally short-term in nature. The Company believes that the carrying amounts of these financial instruments reasonably approximate their fair values due to their short-term nature. The Company’s financial instruments also include its outstanding variable-rate borrowings under the 2020 Credit Agreement. The Company believes that the carrying amounts of its variable-rate borrowings reasonably approximate their fair values because the rates of interest on those borrowings reflect current market rates of interest for similar instruments with comparable maturities. The Company enters into a limited number of derivatives transactions but does not enter into repurchase agreements, securities lending transactions or master netting arrangements. Receivables or payables that result from derivatives transactions are recorded gross in the Company’s consolidated balance sheets. FASB ASC Topic 820 provides a framework for the measurement of fair value and a valuation hierarchy based on the transparency of inputs used in the valuation of assets and liabilities. Classification within the valuation hierarchy is based on the lowest level of input that is significant to the resulting fair value measurement. The valuation hierarchy contains three levels. Level 1 measurements consist of quoted prices in active markets for identical assets or liabilities. Level 2 measurements include significant other observable inputs such as quoted prices for similar assets or liabilities in active markets; identical assets or liabilities in inactive markets; observable inputs such as interest rates and yield curves; and other market-corroborated inputs. Level 3 measurements include significant unobservable inputs such as internally-created valuation models. The Company does not currently utilize Level 3 valuation inputs to remeasure any of its assets or liabilities. However, Level 3 inputs may be used by the Company in its required annual impairment review of goodwill. Information regarding the periodic assessment of the Company’s goodwill is included in Note 6 — Goodwill and Intangible Assets. The Company does not typically transfer assets or liabilities between different levels of the valuation hierarchy. The table below presents the fair values of certain financial assets and liabilities (in thousands). Description March 31, December 31, Assets: Values based on Level 1 inputs: Deferred compensation plan assets (1) $ 6,980 $ 2,589 Total Level 1 inputs 6,980 2,589 Values based on Level 2 inputs: Deferred compensation plan assets (1) 89,059 85,932 Foreign currency forward contracts (2) 41 885 Total Level 2 inputs 89,100 86,817 Total Assets $ 96,080 $ 89,406 Liabilities: Values based on Level 2 inputs: Deferred compensation plan liabilities (1) $ 99,397 $ 94,538 Foreign currency forward contracts (2) 261 2,399 Interest rate swap contracts (3) 84,806 109,175 Total Level 2 inputs 184,464 206,112 Total Liabilities $ 184,464 $ 206,112 (1) The Company has a deferred compensation plan for the benefit of certain highly compensated officers, managers and other key employees. The assets consist of investments in money market funds, mutual funds and company-owned life insurance contracts, which are valued based on Level 1 or Level 2 inputs. The related deferred compensation plan liabilities are recorded at fair value, or the estimated amount needed to settle the liability, which the Company considers to be a Level 2 input. (2) The Company enters into foreign currency forward exchange contracts to hedge the effects of adverse fluctuations in foreign currency exchange rates (see Note 10 — Derivatives and Hedging). Valuation of these contracts is based on observable foreign currency exchange rates in active markets, which the Company considers to be a Level 2 input. (3) The Company has interest rate swap contracts that hedge the risk of variability from interest payments on its borrowings (see Note 7 — Debt). The fair values of interest rate swaps are based on mark-to-market valuations prepared by a third-party broker. Those valuations are based on observable interest rates from recently executed market transactions and other observable market data, which the Company considers to be Level 2 inputs. The Company independently corroborates the reasonableness of the valuations prepared by the third-party broker by using an electronic quotation service. The table below presents the carrying amounts and fair values of financial instruments that are not recorded at fair value in the Company’s Condensed Consolidated Balance Sheets (in thousands). The estimated fair value of the financial instruments was derived from quoted market prices provided by an independent dealer, which the Company considers to be a Level 2 input. Carrying Amount Fair Value March 31, December 31, March 31, December 31, Description 2021 2020 2021 2020 2028 Senior Notes $ 791,041 $ 790,783 $ 823,208 $ 846,296 2030 Senior Notes 790,888 790,690 792,624 843,800 Total $ 1,581,929 $ 1,581,473 $ 1,615,832 $ 1,690,096

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Legal Matters. The Company is involved in legal proceedings and litigation arising in the ordinary course of business. A provision is recorded for pending litigation in the Company’s consolidated financial statements when it is determined that an unfavorable outcome is probable and the amount of the loss can be reasonably estimated. The Company believes that the potential liability, if any, in excess of amounts already accrued from all proceedings, claims and litigation will not have a material effect on the its financial position, cash flows or results of operations when resolved in a future period. Indemnifications. The Company has various agreements that may obligate it to indemnify the other party with respect to certain matters. Generally, these indemnification clauses are included in contracts arising in the normal course of business under which the Company customarily agrees to hold the other party harmless against losses arising from a breach of representations related to matters such as title to assets sold and licensed or certain intellectual property rights. It is not possible to predict the maximum potential amount of future payments under these indemnification agreements due to the conditional nature of the Company’s obligations and the unique facts of each particular agreement. Historically, payments made by the Company under these agreements have not been material. As of March 31, 2021, the Company did not have any material payment obligations under any such indemnification agreements.

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	Leases The Company’s leasing activities are primarily for facilities under cancelable and non-cancelable lease agreements expiring during 2021 and through 2038. These facilities support our executive and administrative activities, sales, systems support, operations, and other functions. The Company also has leases for office equipment and other assets, which are not significant. Certain of these lease agreements include (i) renewal options to extend the lease term for up to five years and/or (ii) options to terminate the agreement within one year. Additionally, certain of the Company’s lease agreements provide standard recurring escalations of lease payments for, among other things, increases in a lessor’s maintenance costs and taxes. Under some lease agreements, the Company may be entitled to allowances, free rent, lessor-financed tenant improvements and other incentives. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company subleases certain office space that it does not intend to occupy. Such sublease arrangements expire during 2021 and through 2032 and primarily relate to facilities in Arlington, Virginia. Certain of the Company’s sublease agreements: (i) include renewal and termination options; (ii) provide for customary escalations of lease payments in the normal course of business; and (iii) grant the subtenant certain allowances, free rent, Gartner-financed tenant improvements and other incentives. All of the Company’s leasing and subleasing activity is recognized in Selling, general and administrative expense in the accompanying Condensed Consolidated Statements of Operations. The table below presents the Company’s net lease cost and certain other information related to the Company’s leasing activities as of and for the periods indicated (dollars in thousands). Three Months Ended March 31, Description: 2021 2020 Operating lease cost (1) $ 32,865 $ 37,961 Variable lease cost (2) 4,302 4,403 Sublease income (10,339) (11,090) Total lease cost, net (3) $ 26,828 $ 31,274 Cash paid for amounts included in the measurement of operating lease $ 34,927 $ 34,936 Cash receipts from sublease arrangements $ 10,095 $ 9,417 Right-of-use assets obtained in exchange for new operating lease $ 7,046 $ 14,919 (1) Included in operating lease cost was $10.4 million and $10.6 million for the three months ended March 31, 2021 and 2020, respectively, for costs related to subleasing activities. (2) These amounts are primarily variable lease and nonlease costs that were not fixed at the lease commencement date or are dependent on something other than an index or a rate. (3) The Company did not capitalize any operating lease costs during each of the three months ended March 31, 2021 and 2020. The table below indicates where the discounted operating lease payments from the above table are classified in the accompanying Condensed Consolidated Balance Sheets (in thousands). March 31, December 31, Description: 2021 2020 Accounts payable and accrued liabilities $ 85,150 $ 83,995 Operating leases - liabilities 765,125 780,166 Total operating lease liabilities per the Condensed Consolidated Balance Sheets $ 850,275 $ 864,161
Leases	Leases The Company’s leasing activities are primarily for facilities under cancelable and non-cancelable lease agreements expiring during 2021 and through 2038. These facilities support our executive and administrative activities, sales, systems support, operations, and other functions. The Company also has leases for office equipment and other assets, which are not significant. Certain of these lease agreements include (i) renewal options to extend the lease term for up to five years and/or (ii) options to terminate the agreement within one year. Additionally, certain of the Company’s lease agreements provide standard recurring escalations of lease payments for, among other things, increases in a lessor’s maintenance costs and taxes. Under some lease agreements, the Company may be entitled to allowances, free rent, lessor-financed tenant improvements and other incentives. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company subleases certain office space that it does not intend to occupy. Such sublease arrangements expire during 2021 and through 2032 and primarily relate to facilities in Arlington, Virginia. Certain of the Company’s sublease agreements: (i) include renewal and termination options; (ii) provide for customary escalations of lease payments in the normal course of business; and (iii) grant the subtenant certain allowances, free rent, Gartner-financed tenant improvements and other incentives. All of the Company’s leasing and subleasing activity is recognized in Selling, general and administrative expense in the accompanying Condensed Consolidated Statements of Operations. The table below presents the Company’s net lease cost and certain other information related to the Company’s leasing activities as of and for the periods indicated (dollars in thousands). Three Months Ended March 31, Description: 2021 2020 Operating lease cost (1) $ 32,865 $ 37,961 Variable lease cost (2) 4,302 4,403 Sublease income (10,339) (11,090) Total lease cost, net (3) $ 26,828 $ 31,274 Cash paid for amounts included in the measurement of operating lease $ 34,927 $ 34,936 Cash receipts from sublease arrangements $ 10,095 $ 9,417 Right-of-use assets obtained in exchange for new operating lease $ 7,046 $ 14,919 (1) Included in operating lease cost was $10.4 million and $10.6 million for the three months ended March 31, 2021 and 2020, respectively, for costs related to subleasing activities. (2) These amounts are primarily variable lease and nonlease costs that were not fixed at the lease commencement date or are dependent on something other than an index or a rate. (3) The Company did not capitalize any operating lease costs during each of the three months ended March 31, 2021 and 2020. The table below indicates where the discounted operating lease payments from the above table are classified in the accompanying Condensed Consolidated Balance Sheets (in thousands). March 31, December 31, Description: 2021 2020 Accounts payable and accrued liabilities $ 85,150 $ 83,995 Operating leases - liabilities 765,125 780,166 Total operating lease liabilities per the Condensed Consolidated Balance Sheets $ 850,275 $ 864,161

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	Subsequent EventOn April 29, 2021, the Company’s Board of Directors authorized incremental share repurchases of up to an additional $500 million of Gartner’s common stock. This authorization is in addition to the previously authorized repurchases of up to $1.5 billion, which as of the end of April 2021 had approximately $290 million remaining.

Business and Basis of Present_2

Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Segments	Segments . Gartner delivers its products and services globally through three business segments: Research, Conferences and Consulting. Revenues and other financial information for our segments are discussed in Note 5 — Segment Information.
Basis of presentation	Basis of presentation . The accompanying interim Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”), as defined in Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 270 for interim financial information and with the applicable instructions of U.S. Securities and Exchange Commission (“SEC”) Rule 10-01 of Regulation S-X on Form 10-Q, and should be read in conjunction with the consolidated financial statements and related notes of the Company in its Annual Report on Form 10-K for the year ended December 31, 2020.
Principles of consolidation	Principles of consolidation . The accompanying interim Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances have been eliminated.
Use of estimates	Use of estimates . The preparation of the accompanying interim Condensed Consolidated Financial Statements requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Such estimates include the valuation of fees receivable, goodwill, intangible assets and other long-lived assets, as well as tax accruals and other liabilities. In addition, estimates are used in revenue recognition, income tax expense or benefit, performance-based compensation charges, depreciation and amortization. Management believes its use of estimates in these interim Condensed Consolidated Financial Statements to be reasonable. Management continually evaluates and revises its estimates using historical experience and other factors, including the general economic environment and actions it may take in the future. Management adjusts these estimates when facts and circumstances dictate. However, these estimates may involve significant uncertainties and judgments and cannot be determined with precision. In addition, these estimates are based on management’s best judgment at a point in time. As a result, differences between estimates and actual results could be material and would be reflected in the Company’s consolidated financial statements in future periods.
Revenue recognition	Revenue recognition. Revenue is recognized in accordance with the requirements of FASB ASC Topic 606, Revenue from Contracts with Customers
Adoption of new accounting standards	Adoption of new accounting standards. The Company adopted the accounting standard described below during the three months ended March 31, 2021. Simplifying the Accounting for Income Taxes — In December 2019, the FASB issued ASU No. 2019-12, Income Taxes—Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”). ASU No. 2019-12 provides new guidance to simplify the accounting for income taxes in certain areas, changes the accounting for select income tax transactions and makes minor ASC improvements. Gartner adopted ASU No. 2019-12 on January 1, 2021. The adoption of ASU No. 2019-12 did not have a material impact on the Company’s Condensed Consolidated Financial Statements. Accounting standards issued but not yet adopted. The FASB has issued accounting standards that have not yet become effective and may impact the Company’s consolidated financial statements or related disclosures in future periods. Those standards and their potential impact are discussed below. Accounting standard effective immediately upon voluntary election by Gartner Reference Rate Reform — In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform—Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU No. 2020-04”). ASU No. 2020-04 provides that an entity can elect not to apply certain required modification accounting in U.S. GAAP to contracts where all changes to the critical terms relate to reference rate reform (e.g., the expected discontinuance of LIBOR and the transition to an alternative reference interest rate, etc.). In addition, the rule provides optional expedients and exceptions that enable entities to continue to apply hedge accounting for hedging relationships where one or more of the critical terms change due to reference rate reform. The rule became effective for all entities as of March 12, 2020 and will generally no longer be available to apply after December 31, 2022. The Company is currently evaluating the potential impact of ASU No. 2020-04 on its consolidated financial statements, including the rule’s potential impact on any debt modifications or other contractual changes in the future that may result from reference rate reform.

Revenue and Related Matters (Ta

Revenue and Related Matters (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue by Reportable Segment	Disaggregated Revenue — The Company’s disaggregated revenue by reportable segment is presented in the tables below for the periods indicated (in thousands). By Primary Geographic Market (1) Three Months Ended March 31, 2021 Primary Geographic Market Research Conferences Consulting Total United States and Canada $ 631,333 $ 19,599 $ 57,486 $ 708,418 Europe, Middle East and Africa 230,201 2,713 30,362 263,276 Other International 118,198 2,490 11,656 132,344 Total revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Three Months Ended March 31, 2020 Primary Geographic Market Research Conferences Consulting Total United States and Canada $ 590,156 $ 5,980 $ 54,163 $ 650,299 Europe, Middle East and Africa 205,939 2,147 30,082 238,168 Other International 113,196 5,743 11,485 130,424 Total revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 (1) Revenue is reported based on where the sale is fulfilled.
Schedule of Disaggregation of Revenue	By Timing of Revenue Recognition Three Months Ended March 31, 2021 Timing of Revenue Recognition Research Conferences Consulting Total Transferred over time (1) $ 894,087 $ — $ 84,342 $ 978,429 Transferred at a point in time (2) 85,645 24,802 15,162 125,609 Total revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Three Months Ended March 31, 2020 Timing of Revenue Recognition Research Conferences Consulting Total Transferred over time (1) $ 829,212 $ — $ 81,408 $ 910,620 Transferred at a point in time (2) 80,079 13,870 14,322 108,271 Total revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 (1) Research revenues were recognized in connection with performance obligations that were satisfied over time using a time-elapsed output method to measure progress. Consulting revenues were recognized over time using labor hours as an input measurement basis. (2) The revenues in this category were recognized in connection with performance obligations that were satisfied at the point in time that the contractual deliverables were provided to the customer.
Schedule for Contract with Customer, Asset and Liability	The table below provides information regarding certain of the Company’s balance sheet accounts that pertain to its contracts with customers (in thousands). March 31, December 31, 2021 2020 Assets: Fees receivable, gross (1) $ 1,184,426 $ 1,251,508 Contract assets recorded in Prepaid expenses and other current assets (2) $ 19,883 $ 14,440 Contract liabilities: Deferred revenues (current liability) (3) $ 2,088,463 $ 1,974,548 Non-current deferred revenues recorded in Other liabilities (3) 25,852 26,754 Total contract liabilities $ 2,114,315 $ 2,001,302 (1) Fees receivable represent an unconditional right to payment from the Company’s customers and include both billed and unbilled amounts. (2) Contract assets represent recognized revenue for which the Company does not have an unconditional right to payment as of the balance sheet date because the project may be subject to a progress billing milestone or some other billing restriction. (3) Deferred revenues represent amounts (i) for which the Company has received an upfront customer payment or (ii) that pertain to recognized fees receivable. Both situations occur before the completion of the Company’s performance obligation(s).

Computation of Earnings Per S_2

Computation of Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of basic and diluted (loss) earnings per share calculations	The table below sets forth the calculation of basic and diluted income per share for the periods indicated (in thousands, except per share data). Three Months Ended March 31, 2021 2020 Numerator: Net income used for calculating basic and diluted income per share $ 164,100 $ 75,097 Denominator: Weighted average common shares used in the calculation of basic income per share 88,352 89,219 Dilutive effect of outstanding awards associated with stock-based compensation plans (1) 787 847 Shares used in the calculation of diluted income per share 89,139 90,066 Basic income per share $ 1.86 $ 0.84 Diluted income per share $ 1.84 $ 0.83 (1) Certain potential shares of common stock were not included in the computation of diluted income per share because the effect would have been anti-dilutive. These potential shares of common stock totaled approximately 0.4 million and 0.7 million for the three months ended March 31, 2021, and 2020, respectively.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of stock-based compensation expense by award type	The tables below summarize the Company’s stock-based compensation expense by award type and expense category line item during the periods indicated (in millions). Three Months Ended March 31, Award type 2021 2020 Stock appreciation rights $ 2.0 $ 1.7 Restricted stock units (2) 33.9 23.2 Common stock equivalents 0.2 0.2 Total (1) $ 36.1 $ 25.1
Schedule of stock-based compensation expense by expense category	Three Months Ended March 31, Expense category line item 2021 2020 Cost of services and product development $ 13.7 $ 12.1 Selling, general and administrative 22.4 13.0 Total (1) (2) $ 36.1 $ 25.1 (1) Includes charges of $21.5 million and $11.6 million during the three months ended March 31, 2021 and 2020, respectively, for awards to retirement-eligible employees. Those awards vest on an accelerated basis.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	The tables below present information about the Company’s reportable segments for the periods indicated (in thousands). Three Months Ended March 31, 2021 Research Conferences Consulting Consolidated Revenues $ 979,732 $ 24,802 $ 99,504 $ 1,104,038 Gross contribution 724,372 13,896 39,098 777,366 Corporate and other expenses (551,954) Operating income $ 225,412 Three Months Ended March 31, 2020 Research Conferences Consulting Consolidated Revenues $ 909,291 $ 13,870 $ 95,730 $ 1,018,891 Gross contribution 653,469 (6,060) 29,382 676,791 Corporate and other expenses (552,073) Operating income $ 124,718
Schedule of reconciliation of segment gross contribution to net income (loss)	The table below provides a reconciliation of total segment gross contribution to net income for the periods indicated (in thousands). Three Months Ended March 31, 2021 2020 Total segment gross contribution $ 777,366 $ 676,791 Costs and expenses: Cost of services and product development - unallocated (1) 7,795 (822) Selling, general and administrative 487,255 496,639 Depreciation and amortization 56,264 54,696 Acquisition and integration charges 640 1,560 Operating income 225,412 124,718 Interest expense and other, net (10,659) (27,864) Less: Provision for income taxes 50,653 21,757 Net income $ 164,100 $ 75,097 (1) The unallocated amounts consist of certain bonus and fringe costs recorded in consolidated Cost of services and product development that are not allocated to segment expense. The Company’s policy is to allocate bonuses to segments at 100% of a segment employee’s target bonus. Amounts above or below 100% are absorbed by corporate.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes to the carrying amount of goodwill by reporting unit	The table below presents changes to the carrying amount of goodwill by segment during the three months ended March 31, 2021 (in thousands). Research Conferences Consulting Total Balance at December 31, 2020 (1) $ 2,664,732 $ 184,091 $ 96,724 $ 2,945,547 Foreign currency translation impact (1,917) (38) (92) (2,047) Balance at March 31, 2021 $ 2,662,815 $ 184,053 $ 96,632 $ 2,943,500 (1) The Company does not have any accumulated goodwill impairment losses.
Schedule of amortizable intangible assets	The tables below present reconciliations of the carrying amounts of the Company’s finite-lived intangible assets as of the dates indicated (in thousands). March 31, 2021 Customer Software Content Other Total Gross cost at December 31, 2020 $ 1,154,210 $ 110,597 $ 3,965 $ 10,614 $ 1,279,386 Foreign currency translation impact 948 53 — — 1,001 Gross cost 1,155,158 110,650 3,965 10,614 1,280,387 Accumulated amortization (1) (406,074) (88,933) (3,965) (3,974) (502,946) Balance at March 31, 2021 $ 749,084 $ 21,717 $ — $ 6,640 $ 777,441 December 31, 2020 Customer Software Content Other Total Gross cost $ 1,154,210 $ 110,597 $ 3,965 $ 10,614 $ 1,279,386 Accumulated amortization (1) (381,776) (83,320) (3,595) (3,697) (472,388) Balance at December 31, 2020 $ 772,434 $ 27,277 $ 370 $ 6,917 $ 806,998 (1) Finite-lived intangible assets are amortized using the straight-line method over the following periods: Customer relationships—6 to 13 years; Software—3 to 7 years; Content—2 to 3 years; and Other—2 to 11 years.
Schedule of estimated future amortization expense by year	The estimated future amortization expense by year for finite-lived intangible assets is presented in the table below (in thousands). 2021 (remaining nine months) $ 75,546 2022 96,169 2023 96,154 2024 90,819 2025 82,150 Thereafter 336,603 $ 777,441

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of debt	The Company’s total outstanding borrowings are summarized in the table below (in thousands). March 31, December 31, Description 2021 2020 2020 Credit Agreement - Term loan facility (1) $ 390,000 $ 395,000 2020 Credit Agreement - Revolving credit facility (1), (2) — 5,000 2028 Notes (3) 800,000 800,000 2030 Notes (4) 800,000 800,000 Other (5) 5,919 6,046 Principal amount outstanding (6) 1,995,919 2,006,046 Less: deferred financing fees (7) (26,322) (27,245) Net balance sheet carrying amount $ 1,969,597 $ 1,978,801 (1) The contractual annualized interest rate as of March 31, 2021 on the 2020 Credit Agreement Term loan facility and the revolving credit facility was 1.50%, which consisted of a floating Eurodollar base rate of 0.125% plus a margin of 1.375%. However, the Company has interest rate swap contracts that effectively convert the floating Eurodollar base rates on outstanding amounts to a fixed base rate. (2) The Company had approximately $1.0 billion of available borrowing capacity on the 2020 Credit Agreement revolver (not including the expansion feature) as of March 31, 2021. (3) Consists of $800.0 million principal amount of 2028 Notes outstanding. The 2028 Notes bear interest at a fixed rate of 4.50% and mature on July 1, 2028. (4) Consists of $800.0 million principal amount of 2030 Notes outstanding. The 2030 Notes bear interest at a fixed rate of 3.75% and mature on October 1, 2030. (5) Consists of two State of Connecticut economic development loans. One of the loans originated in 2012, has a 10-year maturity and the outstanding balance of $0.9 million as of March 31, 2021 bears interest at a fixed rate of 3.00%. The second loan, originated in 2019, has a 10-year maturity and bears interest at a fixed rate of 1.75%. Both of these loans may be repaid at any time by the Company without penalty. (6) The weighted average annual effective rate on the Company’s outstanding debt for the three months ended March 31, 2021, including the effects of its interest rate swaps discussed below, was 5.02%. (7) Deferred financing fees are being amortized to Interest expense, net over the term of the related debt obligation.

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Schedule of share repurchase activity	The Company’s share repurchase activity is presented in the table below for the periods indicated. Three Months Ended March 31, 2021 2020 Number of shares repurchased (1) 2,274,710 417,707 Cash paid for repurchased shares (in thousands) (2) $ 398,450 $ 73,164 (1) The average purchase price for repurchased shares was $180.44 and $151.22 for the three months ended March 31, 2021 and 2020, respectively. The repurchased shares during the three months ended March 31, 2021 and 2020 included purchases for both stock-based compensation awards and open market purchases. (2) The cash paid for repurchased shares during the three months ended March 31, 2021 included $8.0 million of open market purchases with trade dates in December 2020 that settled in January 2021. There were $20.0 million of open market purchases with trade dates in March 2021 that settled in April 2021. The cash paid for repurchased shares during the three months ended March 31, 2020 included open market purchases with trade dates in December 2019 that settled in January 2020.
Schedule of the changes in Accumulated Other Comprehensive (Loss) Income by component (net of tax)	The tables below provide information about the changes in AOCI/L by component and the related amounts reclassified out of AOCI/L to income during the periods indicated (net of tax, in thousands) (1). Three Months Ended March 31, 2021 Interest Rate Defined Foreign Total Balance – December 31, 2020 $ (78,104) $ (9,309) $ (11,815) $ (99,228) Other comprehensive income (loss) activity during the period: Change in AOCI/L before reclassifications to income — — 677 677 Reclassifications from AOCI/L to income (2), (3) 5,270 103 — 5,373 Other comprehensive income (loss) for the period 5,270 103 677 6,050 Balance – March 31, 2021 $ (72,834) $ (9,206) $ (11,138) $ (93,178) Three Months Ended March 31, 2020 Interest Rate Defined Foreign Total Balance – December 31, 2019 $ (47,164) $ (8,584) $ (22,190) $ (77,938) Other comprehensive income (loss) activity during the period: Change in AOCI/L before reclassifications to income (47,054) — (46,381) (93,435) Reclassifications from AOCI/L to income (2), (3) 2,322 79 — 2,401 Other comprehensive income (loss) for the period (44,732) 79 (46,381) (91,034) Balance – March 31, 2020 $ (91,896) $ (8,505) $ (68,571) $ (168,972) (1) Amounts in parentheses represent debits (deferred losses). (2) $7.0 million and $3.2 million of the reclassifications related to interest rate swaps (cash flow hedges) were recorded in Interest expense, net, for the three months ended March 31, 2021 and 2020, respectively. See Note 7 — Debt and Note 10 — Derivatives and Hedging for information regarding the cash flow hedges.

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of information regarding outstanding derivative contracts	The tables below provide information regarding the Company’s outstanding derivative contracts as of the dates indicated (in thousands, except for number of contracts). March 31, 2021 Derivative Contract Type Number of Notional Fair Value Balance Unrealized Interest rate swaps (1) 4 $ 1,400,000 $ (50,096) Other liabilities $ (72,834) (34,710) Accrued liabilities Foreign currency forwards (2) 33 196,038 (220) Accrued liabilities — Total 37 $ 1,596,038 $ (85,026) $ (72,834) December 31, 2020 Derivative Contract Type Number of Contracts Notional Fair Value Balance Unrealized Interest rate swaps (1) 4 $ 1,400,000 $ (74,289) Other liabilities $ (78,104) (34,886) Accrued liabilities Foreign currency forwards (2) 163 430,063 (1,514) Accrued liabilities — Total 167 $ 1,830,063 $ (110,689) $ (78,104) (1) As a result of the payment under the then outstanding 2016 Credit Agreement term loan and revolving credit facility, the Company de-designated all of its interest rate swaps effective June 30, 2020. Accordingly, hedge accounting is not applicable, and subsequent changes to fair value of the interest rate swaps are recorded in Other income (expense), net. The amounts previously recorded in Accumulated other comprehensive loss are amortized into Interest expense, net over the terms of the hedged forecasted interest payments. See Note 7 — Debt provides additional information regarding the Company’s interest rate swap contracts. (2) The Company has foreign exchange transaction risk because it typically enters into transactions in the normal course of business that are denominated in foreign currencies that differ from the local functional currency. The Company enters into short-term foreign currency forward exchange contracts to mitigate the cash flow risk associated with changes in foreign currency rates on forecasted foreign currency transactions. These contracts are accounted for at fair value with realized and unrealized gains and losses recognized in Other income (expense), net because the Company does not designate these contracts as hedges for accounting purposes. All of the outstanding foreign currency forward exchange contracts at March 31, 2021 matured before April 30, 2021. (3) See Note 11 — Fair Value Disclosures for the determination of the fair values of these instruments.
Schedule of amounts recognized in statement of operations	The table below provides information regarding amounts recognized in the accompanying Condensed Consolidated Statements of Operations for derivative contracts for the periods indicated (in thousands). Three Months Ended March 31, Amount recorded in: 2021 2020 Interest expense, net (1) $ 7,032 $ 3,192 Other (income) expense, net (2) (15,823) 12,599 Total (income) expense, net $ (8,791) $ 15,791 (1) Consists of interest expense from interest rate swap contracts. (2) Consists of net realized and unrealized gains and losses on foreign currency forward contracts, and gains and losses on de-designated interest rate swaps.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities that are remeasured to fair value	The table below presents the fair values of certain financial assets and liabilities (in thousands). Description March 31, December 31, Assets: Values based on Level 1 inputs: Deferred compensation plan assets (1) $ 6,980 $ 2,589 Total Level 1 inputs 6,980 2,589 Values based on Level 2 inputs: Deferred compensation plan assets (1) 89,059 85,932 Foreign currency forward contracts (2) 41 885 Total Level 2 inputs 89,100 86,817 Total Assets $ 96,080 $ 89,406 Liabilities: Values based on Level 2 inputs: Deferred compensation plan liabilities (1) $ 99,397 $ 94,538 Foreign currency forward contracts (2) 261 2,399 Interest rate swap contracts (3) 84,806 109,175 Total Level 2 inputs 184,464 206,112 Total Liabilities $ 184,464 $ 206,112 (1) The Company has a deferred compensation plan for the benefit of certain highly compensated officers, managers and other key employees. The assets consist of investments in money market funds, mutual funds and company-owned life insurance contracts, which are valued based on Level 1 or Level 2 inputs. The related deferred compensation plan liabilities are recorded at fair value, or the estimated amount needed to settle the liability, which the Company considers to be a Level 2 input. (2) The Company enters into foreign currency forward exchange contracts to hedge the effects of adverse fluctuations in foreign currency exchange rates (see Note 10 — Derivatives and Hedging). Valuation of these contracts is based on observable foreign currency exchange rates in active markets, which the Company considers to be a Level 2 input. (3) The Company has interest rate swap contracts that hedge the risk of variability from interest payments on its borrowings (see Note 7 — Debt). The fair values of interest rate swaps are based on mark-to-market valuations prepared by a third-party broker. Those valuations are based on observable interest rates from recently executed market transactions and other observable market data, which the Company considers to be Level 2 inputs. The Company independently corroborates the reasonableness of the valuations prepared by the third-party broker by using an electronic quotation service.
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The table below presents the carrying amounts and fair values of financial instruments that are not recorded at fair value in the Company’s Condensed Consolidated Balance Sheets (in thousands). The estimated fair value of the financial instruments was derived from quoted market prices provided by an independent dealer, which the Company considers to be a Level 2 input. Carrying Amount Fair Value March 31, December 31, March 31, December 31, Description 2021 2020 2021 2020 2028 Senior Notes $ 791,041 $ 790,783 $ 823,208 $ 846,296 2030 Senior Notes 790,888 790,690 792,624 843,800 Total $ 1,581,929 $ 1,581,473 $ 1,615,832 $ 1,690,096

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lease costs	The table below presents the Company’s net lease cost and certain other information related to the Company’s leasing activities as of and for the periods indicated (dollars in thousands). Three Months Ended March 31, Description: 2021 2020 Operating lease cost (1) $ 32,865 $ 37,961 Variable lease cost (2) 4,302 4,403 Sublease income (10,339) (11,090) Total lease cost, net (3) $ 26,828 $ 31,274 Cash paid for amounts included in the measurement of operating lease $ 34,927 $ 34,936 Cash receipts from sublease arrangements $ 10,095 $ 9,417 Right-of-use assets obtained in exchange for new operating lease $ 7,046 $ 14,919 (1) Included in operating lease cost was $10.4 million and $10.6 million for the three months ended March 31, 2021 and 2020, respectively, for costs related to subleasing activities. (2) These amounts are primarily variable lease and nonlease costs that were not fixed at the lease commencement date or are dependent on something other than an index or a rate. (3) The Company did not capitalize any operating lease costs during each of the three months ended March 31, 2021 and 2020.
Supplemental balance sheet information	The table below indicates where the discounted operating lease payments from the above table are classified in the accompanying Condensed Consolidated Balance Sheets (in thousands). March 31, December 31, Description: 2021 2020 Accounts payable and accrued liabilities $ 85,150 $ 83,995 Operating leases - liabilities 765,125 780,166 Total operating lease liabilities per the Condensed Consolidated Balance Sheets $ 850,275 $ 864,161

Business and Basis of Present_3

Business and Basis of Presentation - Narrative (Details)	3 Months Ended
	Mar. 31, 2021enterprisecountrysegment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of organizations Company serves | enterprise	14,000
Number of countries in which entity operates | country	100
Number of reportable segments | segment	3

Revenue and Related Matters - D

Revenue and Related Matters - Disaggregation of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,104,038	$ 1,018,891
Research
Disaggregation of Revenue [Line Items]
Total revenues	979,732	909,291
Conferences
Disaggregation of Revenue [Line Items]
Total revenues	24,802	13,870
Consulting
Disaggregation of Revenue [Line Items]
Total revenues	99,504	95,730
United States and Canada
Disaggregation of Revenue [Line Items]
Total revenues	708,418	650,299
United States and Canada | Research
Disaggregation of Revenue [Line Items]
Total revenues	631,333	590,156
United States and Canada | Conferences
Disaggregation of Revenue [Line Items]
Total revenues	19,599	5,980
United States and Canada | Consulting
Disaggregation of Revenue [Line Items]
Total revenues	57,486	54,163
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	263,276	238,168
Europe, Middle East and Africa | Research
Disaggregation of Revenue [Line Items]
Total revenues	230,201	205,939
Europe, Middle East and Africa | Conferences
Disaggregation of Revenue [Line Items]
Total revenues	2,713	2,147
Europe, Middle East and Africa | Consulting
Disaggregation of Revenue [Line Items]
Total revenues	30,362	30,082
Other International
Disaggregation of Revenue [Line Items]
Total revenues	132,344	130,424
Other International | Research
Disaggregation of Revenue [Line Items]
Total revenues	118,198	113,196
Other International | Conferences
Disaggregation of Revenue [Line Items]
Total revenues	2,490	5,743
Other International | Consulting
Disaggregation of Revenue [Line Items]
Total revenues	$ 11,656	$ 11,485

Revenue and Related Matters - T

Revenue and Related Matters - Timing Of Revenue Recognition Liabilities per Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,104,038	$ 1,018,891
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	978,429	910,620
Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	125,609	108,271
Research
Disaggregation of Revenue [Line Items]
Total revenues	979,732	909,291
Research | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	894,087	829,212
Research | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	85,645	80,079
Conferences
Disaggregation of Revenue [Line Items]
Total revenues	24,802	13,870
Conferences | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Conferences | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	24,802	13,870
Consulting
Disaggregation of Revenue [Line Items]
Total revenues	99,504	95,730
Consulting | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	84,342	81,408
Consulting | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	$ 15,162	$ 14,322

Revenue and Related Matters - R

Revenue and Related Matters - Revenue Remaining Performance Obligation (Details) $ in Millions	Mar. 31, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation, amount	$ 3,600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation, amount	$ 1,705.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation, amount	$ 1,443.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation, amount	$ 424.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction

Revenue and Related Matters - S

Revenue and Related Matters - Schedule of Contract with Customer, Asset and Liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Assets:
Fees receivable, gross	$ 1,184,426		$ 1,251,508
Contract assets recorded in Prepaid expenses and other current assets	19,883		14,440
Contract liabilities:
Deferred revenues (current liability)	2,088,463		1,974,548
Non-current deferred revenues recorded in Other liabilities	25,852		26,754
Total contract liabilities	2,114,315		$ 2,001,302
Revenue recognized previously attributable to deferred revenues	$ 726,700	$ 658,400

Computation of Earnings Per S_3

Computation of Earnings Per Share - Calculations Of Basic And Diluted (Loss) Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income used for calculating basic and diluted income per share	$ 164,100	$ 75,097
Denominator:
Weighted average number of common shares used in the calculation of basic income per share (in shares)	88,352	89,219
Dilutive effect of outstanding awards associated with stock-based compensation plans (in shares)	787	847
Shares used in the calculation of diluted income per share (in shares)	89,139	90,066
Basic income per share (in dollars per share)	$ 1.86	$ 0.84
Diluted income per share (in dollars per share)	$ 1.84	$ 0.83

Computation of Earnings Per S_4

Computation of Earnings Per Share - Additional information (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of (loss) income per share (in shares)	0.4	0.7

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - $ / shares shares in Millions	Mar. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Number of shares available for grant (in shares)	4
Common stock par value (in dollars per share)	$ 0.0005	$ 0.0005

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-based Compensation Expense by Award Type and Expense Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Feb. 03, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	$ 36.1	$ 25.1
Cost of services and product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	13.7	12.1
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	22.4	13
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	2	1.7
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	33.9	23.2
Common stock equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	0.2	0.2
Retirement eligible employees equity award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense (credit)	$ 21.5	$ 11.6
Performance-based RSUs | Executive officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance percentage	50.00%		95.00%
Total stock-based compensation expense (credit)	$ 6.5

Segment Information - Informati

Segment Information - Information About Reportable Segments (Details)	3 Months Ended
	Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3
Operating income	$ 225,412,000	$ 124,718,000
Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	0	0
Reportable segments
Segment Reporting Information [Line Items]
Revenues	1,104,038,000	1,018,891,000
Operating income	777,366,000	676,791,000
Corporate and other expenses
Segment Reporting Information [Line Items]
Operating income	(551,954,000)	(552,073,000)
Research | Reportable segments
Segment Reporting Information [Line Items]
Revenues	979,732,000	909,291,000
Operating income	724,372,000	653,469,000
Conferences | Reportable segments
Segment Reporting Information [Line Items]
Revenues	24,802,000	13,870,000
Operating income	13,896,000	(6,060,000)
Consulting | Reportable segments
Segment Reporting Information [Line Items]
Revenues	99,504,000	95,730,000
Operating income	$ 39,098,000	$ 29,382,000

Segment Information - Reconcili

Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Costs and expenses:
Cost of services and product development	$ 334,467	$ 341,278
Selling, general and administrative	487,255	496,639
Acquisition and integration charges	640	1,560
Operating income	225,412	124,718
Interest expense and other, net	(10,659)	(27,864)
Less: Provision for income taxes	50,653	21,757
Net income	164,100	75,097
Reportable segments
Costs and expenses:
Operating income	$ 777,366	676,791
Reportable segments | Maximum
Costs and expenses:
Percent of target bonus allocated to segments	100.00%
Corporate and other expenses
Costs and expenses:
Cost of services and product development	$ 7,795	(822)
Selling, general and administrative	487,255	496,639
Depreciation and amortization	56,264	54,696
Acquisition and integration charges	640	1,560
Operating income	$ (551,954)	$ (552,073)

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Changes to Carrying Amount of Goodwill by Reporting Unit (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Goodwill [Line Items]
Goodwill impairment		$ 0
Goodwill [Roll Forward]
Beginning balance	$ 2,945,547,000
Foreign currency translation impact	(2,047,000)
Ending balance	2,943,500,000
Goodwill, accumulated impairment losses	0
Research
Goodwill [Roll Forward]
Beginning balance	2,664,732,000
Foreign currency translation impact	(1,917,000)
Ending balance	2,662,815,000
Conferences
Goodwill [Roll Forward]
Beginning balance	184,091,000
Foreign currency translation impact	(38,000)
Ending balance	184,053,000
Consulting
Goodwill [Roll Forward]
Beginning balance	96,724,000
Foreign currency translation impact	(92,000)
Ending balance	$ 96,632,000

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Carrying Amounts of Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	$ 1,279,386
Foreign currency translation impact	1,001
Gross cost, ending balance	1,280,387
Accumulated amortization	(502,946)		$ (472,388)
Finite-lived intangible assets, net	777,441		806,998
Amortization of intangibles	30,514	$ 32,179
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	1,154,210
Foreign currency translation impact	948
Gross cost, ending balance	1,155,158
Accumulated amortization	(406,074)		(381,776)
Finite-lived intangible assets, net	$ 749,084		772,434
Customer Relationships | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	6 years
Customer Relationships | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	13 years
Software
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	$ 110,597
Foreign currency translation impact	53
Gross cost, ending balance	110,650
Accumulated amortization	(88,933)		(83,320)
Finite-lived intangible assets, net	$ 21,717		27,277
Software | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	3 years
Software | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	7 years
Content
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	$ 3,965
Foreign currency translation impact	0
Gross cost, ending balance	3,965
Accumulated amortization	(3,965)		(3,595)
Finite-lived intangible assets, net	$ 0		370
Content | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	2 years
Content | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	3 years
Other
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	$ 10,614
Foreign currency translation impact	0
Gross cost, ending balance	10,614
Accumulated amortization	(3,974)		(3,697)
Finite-lived intangible assets, net	$ 6,640		$ 6,917
Other | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	2 years
Other | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life	11 years

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Estimated Future Amortization Expense By Year From Amortizable Intangibles (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2021 (remaining nine months)	$ 75,546
2022	96,169
2023	96,154
2024	90,819
2025	82,150
Thereafter	336,603
Finite-lived intangible assets, net	$ 777,441	$ 806,998

Debt - Borrowings (Details)

Debt - Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Principal amount outstanding	$ 1,995,919	$ 2,006,046
Less: deferred financing fees	(26,322)	(27,245)
Net balance sheet carrying amount	1,969,597	1,978,801
Term Loan Facility | 2020 Credit Agreement
Debt Instrument [Line Items]
Principal amount outstanding	390,000	395,000
Line of Credit | Revolving credit facility | 2020 Credit Agreement
Debt Instrument [Line Items]
Principal amount outstanding	0	5,000
Senior Notes | Senior Notes Due 2028
Debt Instrument [Line Items]
Principal amount outstanding	800,000	800,000
Senior Notes | Senior Notes Due 2030
Debt Instrument [Line Items]
Principal amount outstanding	800,000	800,000
Other
Debt Instrument [Line Items]
Principal amount outstanding	$ 5,919	$ 6,046

Debt - Footnote to Borrowings (

Debt - Footnote to Borrowings (Details)	Sep. 28, 2020USD ($)	Mar. 31, 2021USD ($)segment	Dec. 31, 2020USD ($)	Jun. 22, 2020USD ($)
Debt Instrument [Line Items]
Long term debt		$ 1,995,919,000	$ 2,006,046,000
Weighted average annual effect rate		5.02%
Term Loan Facility | 2020 Credit Agreement
Debt Instrument [Line Items]
Contractual annualized interest rate		1.50%
Floating eurodollar base rate		0.125%
Additional interest above base rate		1.375%
Aggregate principal amount	$ 400,000,000
Debt term	5 years
Long term debt		$ 390,000,000	395,000,000
Senior Notes | Senior Notes Due 2028
Debt Instrument [Line Items]
Aggregate principal amount		800,000,000		$ 800,000,000
Debt instrument, fixed interest rate				4.50%
Long term debt		800,000,000	800,000,000
Senior Notes | Senior Notes Due 2030
Debt Instrument [Line Items]
Aggregate principal amount	$ 800,000,000	800,000,000
Debt instrument, fixed interest rate	3.75%
Long term debt		$ 800,000,000	800,000,000
Connecticut Economic Development Program
Debt Instrument [Line Items]
Number of loans | segment		2
Connecticut Economic Development Program | Economic Development Loan 1
Debt Instrument [Line Items]
Debt instrument, fixed interest rate		3.00%
Debt term		10 years
Long term debt		$ 900,000
Connecticut Economic Development Program | Economic Development Loan 2
Debt Instrument [Line Items]
Debt instrument, fixed interest rate		1.75%
Debt term		10 years
Revolving credit facility | Line of Credit | 2020 Credit Agreement
Debt Instrument [Line Items]
Remaining borrowing capacity		$ 1,000,000,000
Debt term	5 years
Long term debt		$ 0	$ 5,000,000

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Sep. 28, 2020	Mar. 31, 2021	Jun. 22, 2020
Senior Notes Due 2030 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 800,000,000	$ 800,000,000
Debt instrument, fixed interest rate	3.75%
Debt instrument, issue price, percent	100.00%
Percentage of principal amount redeemed		40.00%
Senior Notes Due 2028 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount		$ 800,000,000	$ 800,000,000
Debt instrument, fixed interest rate			4.50%
Debt instrument, issue price, percent			100.00%
Percentage of principal amount redeemed		40.00%
2020 Credit Agreement | Variable Rate Component, One | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
2020 Credit Agreement | Variable Rate Component, One | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.125%
2020 Credit Agreement | Variable Rate Component, One | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
2020 Credit Agreement | Variable Rate Component, Two | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.125%
2020 Credit Agreement | Variable Rate Component, Two | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
2020 Credit Agreement | Term Loan Facility
Debt Instrument [Line Items]
Aggregate principal amount	$ 400,000,000
Debt term	5 years
Proceeds from borrowings	$ 400,000,000
2020 Credit Agreement | Revolving credit facility | Line of Credit
Debt Instrument [Line Items]
Debt term	5 years
Accordion feature, increase limit	$ 1,000,000,000
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
2020 Credit Agreement | Revolving credit facility | Line of Credit | Minimum
Debt Instrument [Line Items]
Unused borrowing capacity, fee percent	0.175%
2020 Credit Agreement | Revolving credit facility | Line of Credit | Maximum
Debt Instrument [Line Items]
Unused borrowing capacity, fee percent	0.40%
2020 Credit Agreement | Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 75,000,000

Debt - Interest Rate Swaps (Det

Debt - Interest Rate Swaps (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)derivative_instrumentoutstanding_contract	Dec. 31, 2020USD ($)outstanding_contract
Derivative [Line Items]
Number of contracts | outstanding_contract	37	167
Interest rate swap contracts total notional value	$ 1,596,038	$ 1,830,063
Interest rate swaps
Derivative [Line Items]
Number of contracts | derivative_instrument	4
Interest rate swap contracts total notional value	$ 1,400,000
Term of contract	30 days
Loss on release of interest rate swap recognized in AOCI	$ 97,000
Net negative fair value (liability)	(84,800)	(109,200)
Interest rate swaps | Accumulated Other Comprehensive Loss, Net
Derivative [Line Items]
Net negative fair value (liability)	$ (72,800)	$ (78,100)
Interest rate swaps | Minimum
Derivative [Line Items]
Fixed interest rate	2.13%
Interest rate swaps | Maximum
Derivative [Line Items]
Fixed interest rate	3.04%

Equity - Share Repurchase Progr

Equity - Share Repurchase Program and Share Repurchase Activity (Details) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Feb. 04, 2021	May 31, 2015
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 1,200,000,000
Stock repurchase program, additional authorized amount				$ 300,000,000
Stock repurchase program, remaining authorized repurchase amount		$ 500,000,000
Number of shares repurchased (in shares)		2,274,710	417,707
Cash paid for repurchased shares		$ 398,450,000	$ 73,164,000
Treasury stock, average price paid per share (in dollars per share)		$ 180.44	$ 151.22
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, remaining authorized repurchase amount	$ 290,000,000
Open Market Purchases
Equity, Class of Treasury Stock [Line Items]
Cash paid for repurchased shares		$ 8,000,000
Open Market Purchases | Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Cash paid for repurchased shares	$ 20,000,000

Equity - Changes in AOCI_L by C

Equity - Changes in AOCI/L by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,090,428	$ 938,593
Change in AOCI/L before reclassifications to income	677	(93,435)
Reclassifications from AOCL/I to income	5,373	2,401
Other comprehensive income (loss), net of tax	6,050	(91,034)
Ending balance	891,594	890,275
Derivative reclassifications	8,791	(15,791)
Interest (income) expense, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Derivative reclassifications	(7,032)	(3,192)
Interest rate swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Loss to be reclassified within twelve months	29,200
Interest rate swaps | Interest (income) expense, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Derivative reclassifications	7,000	3,200
Interest Rate Swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(78,104)	(47,164)
Change in AOCI/L before reclassifications to income	0	(47,054)
Reclassifications from AOCL/I to income	5,270	2,322
Other comprehensive income (loss), net of tax	5,270	(44,732)
Ending balance	(72,834)	(91,896)
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(9,309)	(8,584)
Change in AOCI/L before reclassifications to income	0	0
Reclassifications from AOCL/I to income	103	79
Other comprehensive income (loss), net of tax	103	79
Ending balance	(9,206)	(8,505)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(11,815)	(22,190)
Change in AOCI/L before reclassifications to income	677	(46,381)
Reclassifications from AOCL/I to income	0	0
Other comprehensive income (loss), net of tax	677	(46,381)
Ending balance	(11,138)	(68,571)
Accumulated Other Comprehensive Loss, Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(99,228)	(77,938)
Other comprehensive income (loss), net of tax	6,050	(91,034)
Ending balance	$ (93,178)	$ (168,972)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 50,653	$ 21,757
Effective income tax rate	23.60%	22.50%
Unrecognized tax benefits	$ 125,000		$ 127,100
Decrease in unrecognized tax benefits is reasonably possible	$ 8,900

Derivatives and Hedging - Outst

Derivatives and Hedging - Outstanding Derivatives Contracts (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)outstanding_contractderivative_instrument	Dec. 31, 2020USD ($)outstanding_contract
Derivatives, Fair Value [Line Items]
Number of Contracts | outstanding_contract	37	167
Notional Amounts	$ 1,596,038	$ 1,830,063
Fair Value Asset (Liability), Net	(85,026)	(110,689)
Unrealized Loss Recorded in AOCI/L, net of tax	$ (72,834)	$ (78,104)
Interest rate swaps
Derivatives, Fair Value [Line Items]
Number of Contracts | derivative_instrument	4
Notional Amounts	$ 1,400,000
Not Designated as Hedging Instrument | Other liabilities | Interest rate swaps
Derivatives, Fair Value [Line Items]
Number of Contracts | outstanding_contract	4	4
Notional Amounts	$ 1,400,000	$ 1,400,000
Fair Value Asset (Liability), Net	(50,096)	(74,289)
Unrealized Loss Recorded in AOCI/L, net of tax	(72,834)	(78,104)
Not Designated as Hedging Instrument | Accrued liabilities | Interest rate swaps
Derivatives, Fair Value [Line Items]
Fair Value Asset (Liability), Net	$ (34,710)	$ (34,886)
Not Designated as Hedging Instrument | Accrued liabilities | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Number of Contracts | outstanding_contract	33	163
Notional Amounts	$ 196,038	$ 430,063
Fair Value Asset (Liability), Net	(220)	(1,514)
Unrealized Loss Recorded in AOCI/L, net of tax	$ 0	$ 0

Derivatives and Hedging - Amoun

Derivatives and Hedging - Amounts Recognized in the Condensed Consolidated Statements of Operations for Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Total (income) expense, net	$ (8,791)	$ 15,791
Interest (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Total (income) expense, net	7,032	3,192
Other expense (income), net
Derivative Instruments, Gain (Loss) [Line Items]
Total (income) expense, net	$ (15,823)	$ 12,599

Fair Value Disclosures - Assets

Fair Value Disclosures - Assets And Liabilities Measured At Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets:
Assets measured at fair value on a recurring basis	$ 96,080	$ 89,406
Liabilities:
Liabilities measured at fair value on a recurring basis	184,464	206,112
Fair Value, Inputs, Level 1
Assets:
Assets measured at fair value on a recurring basis	6,980	2,589
Fair Value, Inputs, Level 2
Assets:
Assets measured at fair value on a recurring basis	89,100	86,817
Liabilities:
Liabilities measured at fair value on a recurring basis	184,464	206,112
Fair Value, Inputs, Level 2 | Foreign currency forward contracts
Assets:
Assets measured at fair value on a recurring basis	41	885
Liabilities:
Liabilities measured at fair value on a recurring basis	261	2,399
Fair Value, Inputs, Level 2 | Interest rate swap contracts
Liabilities:
Liabilities measured at fair value on a recurring basis	84,806	109,175
Fair Value, Inputs, Level 2 | Deferred compensation plan assets
Assets:
Assets measured at fair value on a recurring basis	89,059	85,932
Fair Value, Inputs, Level 2 | Deferred compensation plan liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	$ 99,397	$ 94,538

Fair Value Disclosures - Fair V

Fair Value Disclosures - Fair Value of Debt Instruments (Details) - Senior Notes - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 1,581,929	$ 1,581,473
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,615,832	1,690,096
Senior Notes Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	791,041	790,783
Senior Notes Due 2028 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	823,208	846,296
Senior Notes Due 2030
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	790,888	790,690
Senior Notes Due 2030 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 792,624	$ 843,800

Leases - Narrative (Details)

Leases - Narrative (Details)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Renewal term	5 years
Option to terminate, term	1 year

Leases - Net Lease Costs (Detai

Leases - Net Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 32,865	$ 37,961
Variable lease cost	4,302	4,403
Sublease income	(10,339)	(11,090)
Total lease cost, net	26,828	31,274
Cash paid for amounts included in the measurement of operating lease liabilities	34,927	34,936
Cash receipts from sublease arrangements	10,095	9,417
Right-of-use assets obtained in exchange for new operating lease liabilities	7,046	14,919
Cost for subleasing activities	$ 10,400	$ 10,600

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Accounts payable and accrued liabilities	$ 85,150	$ 83,995
Operating leases - liabilities	765,125	780,166
Total operating lease liabilities per the Condensed Consolidated Balance Sheets	$ 850,275	$ 864,161
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accounts payable and accrued liabilities	Accounts payable and accrued liabilities

Subsequent Events - (Details)

Subsequent Events - (Details) - USD ($) $ in Millions	Apr. 30, 2021	Apr. 29, 2021	Mar. 31, 2021
Subsequent Event [Line Items]
Number of shares authorized to be repurchased (in shares)			1,500,000,000
Stock repurchase program, remaining authorized repurchase amount			$ 500
Subsequent Event
Subsequent Event [Line Items]
Additional shares authorized to be repurchased (in shares)		500,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 290