Gartner (IT) 10-Q 6 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'GARTNER INC	'
Entity Central Index Key	'0000749251	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	88,027,698

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'		'
Cash and cash equivalents	$341,220		$423,990
Fees receivable, net of allowances of $6,900 and $7,000, respectively	449,923		490,923
Deferred commissions	80,599		106,287
Prepaid expenses and other current assets	87,492		63,682
Total current assets	959,234		1,084,882
Property, equipment and leasehold improvements, net	93,625		91,759
Goodwill	593,212		519,203	[1]
Intangible assets, net	33,515		6,107
Other assets	89,367		81,631
Total Assets	1,768,953		1,783,582
Current liabilities:	'		'
Accounts payable and accrued liabilities	266,545		325,059
Deferred revenues	847,327		766,114
Current portion of long-term debt	245,000		68,750
Total current liabilities	1,358,872		1,159,923
Long-term debt	125,000		136,250
Other liabilities	132,558		126,093
Total Liabilities	1,616,430		1,422,266
Stockholders’ Equity	'		'
Preferred stock, $.01 par value, 5,000,000 shares authorized; none issued or outstanding	0		0
Common stock, $.0005 par value, 250,000,000 shares authorized; 156,234,415 shares issued for both periods	78		78
Additional paid-in capital	754,827		718,644
Accumulated other comprehensive income, net	-2,001	[2]	8,345	[2]
Accumulated earnings	1,215,905		1,091,283
Treasury stock, at cost, 68,213,874 and 64,268,863 common shares, respectively	-1,816,286		-1,457,034
Total Stockholders’ Equity	152,523		361,316
Total Liabilities and Stockholders’ Equity	$1,768,953		$1,783,582
[1]	The Company does not have any accumulated goodwill impairment losses.
[2]	Amounts in parentheses represent debits (deferred losses).

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parentheticals) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$6,900	$7,000
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)	$0.00	$0.00
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	156,234,415	156,234,415
Treasury stock, shares (in shares)	68,213,874	64,268,863

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues:	'	'	'	'
Research	$365,334	$316,518	$1,071,943	$938,082
Consulting	82,300	70,149	260,059	228,710
Events	23,306	24,038	105,460	96,714
Total revenues	470,940	410,705	1,437,462	1,263,506
Costs and expenses:	'	'	'	'
Cost of services and product development	188,059	161,735	562,058	503,376
Selling, general and administrative	217,025	181,546	640,179	547,653
Depreciation	7,945	7,258	23,125	21,375
Amortization of intangibles	2,505	1,351	5,763	4,089
Acquisition and integration charges	6,015	72	16,015	278
Total costs and expenses	421,549	351,962	1,247,140	1,076,771
Operating income	49,391	58,743	190,322	186,735
Interest expense, net	-2,656	-2,124	-7,586	-6,704
Other (expense) income, net	-287	5	-341	-64
Income before income taxes	46,448	56,624	182,395	179,967
Provision for income taxes	12,602	18,430	57,773	58,584
Net income	$33,846	$38,194	$124,622	$121,383
Earnings per common share:	'	'	'	'
Basic (in Dollars per share)	$0.38	$0.41	$1.39	$1.30
Diluted (in Dollars per share)	$0.38	$0.40	$1.37	$1.28
Weighted average shares outstanding:	'	'	'	'
Basic (in shares)	88,513	92,689	89,901	93,286
Diluted (in shares)	89,708	94,355	91,273	95,100

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'		'		'		'
Net income	$33,846		$38,194		$124,622		$121,383
Other comprehensive (loss) income, net of tax:	'		'		'		'
Foreign currency translation adjustments	-12,588		4,109		-11,990		-900
Interest rate hedge – gain	619		261		1,600		1,636
Pension – actuarial gain	15		6		44		30
Other comprehensive (loss) income	-11,954	[1]	4,376	[1]	-10,346	[1]	766	[1]
Comprehensive income	$21,892		$42,570		$114,276		$122,149
[1]	Amounts in parentheses represent debits (deferred losses).

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating activities:	'	'
Net income	$124,622	$121,383
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	28,888	25,464
Stock-based compensation expense	29,425	27,049
Excess tax benefits from stock-based compensation	-19,275	-18,412
Deferred taxes	-1,299	4,989
Amortization and write-off of debt issue costs	1,572	2,107
Changes in assets and liabilities, net of acquisitions:	'	'
Fees receivable, net	37,365	69,732
Deferred commissions	24,546	10,055
Prepaid expenses and other current assets	-23,831	-20,840
Other assets	-1,303	-3,064
Deferred revenues	92,593	64,662
Accounts payable, accrued, and other liabilities	-17,694	-41,056
Cash provided by operating activities	275,609	242,069
Investing activities:	'	'
Additions to property, equipment and leasehold improvements	-25,516	-27,772
Acquisitions - cash paid (net of cash acquired)	-107,528	0
Acquisitions - increase in restricted cash (escrow)	-14,363	0
Cash used in investing activities	-147,407	-27,772
Financing activities:	'	'
Proceeds from stock issued under stock plans	6,365	4,539
Proceeds from debt issuance	174,375	203,750
Payments for debt issuance costs	0	-3,553
Payments on debt	-9,375	-203,750
Purchases of treasury stock	-387,126	-157,251
Excess tax benefits from stock-based compensation	19,275	18,412
Cash used in financing activities	-196,486	-137,853
Net (decrease) increase in cash and cash equivalents	-68,284	76,444
Effects of exchange rates on cash and cash equivalents	-14,486	-1,775
Cash and cash equivalents, beginning of period	423,990	299,852
Cash and cash equivalents, end of period	$341,220	$374,521

Business_and_Basis_of_Presenta

Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Business and Basis of Presentation	'
	Business and Basis of Presentation
	Business. Gartner, Inc. is a global information technology research and advisory company with its headquarters in Stamford, Connecticut. Gartner delivers its products and services globally through three business segments: Research, Consulting, and Events. When used in these notes, the terms “Gartner,” “Company,” “we,” “us,” or “our” refer to Gartner, Inc. and its consolidated subsidiaries.
	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 the Financial Accounting Standards Board (FASB) Accounting Standards Codification (“ASC”) Topic 270 for interim financial information and with the applicable instructions of the U.S. Securities & 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 filed in its Annual Report on Form 10-K for the year ended December 31, 2013.
	The fiscal year of Gartner is the twelve-month calendar 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 and nine months ended September 30, 2014 may not be indicative of the results of operations for the remainder of 2014.
	Principles of consolidation. The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly- and majority-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, performance-based compensation expenses, depreciation and amortization, and the allowance for losses. 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 our estimates and actual results could be material and would be reflected in the Company’s consolidated financial statements in future periods.
	Adoption of new accounting rules. Effective January 1, 2014, the Company adopted two new accounting rules issued by the FASB, as follows:
	The Company adopted ASU No. 2013-11, "Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists" ("ASU No. 2013-11"). ASU No. 2013-11 addresses the balance sheet presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. ASU No. 2013-11 requires that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. The balance sheet impact from the adoption of ASU No. 2013-11 was not material to the Company.
	The Company adopted ASU No. 2013-05, Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity ("ASU No. 2013-05"). ASU No. 2013-05 provides updated guidance to resolve diversity in practice concerning the release of the cumulative foreign currency translation adjustment into net income when a parent sells a part or all of its investment in a foreign entity or no longer holds a controlling financial interest in a subsidiary or group of assets within a foreign entity. When a company ceases to have a controlling financial interest, the company should recognize any related cumulative translation adjustment into net income only if the sale or transfer results in the complete or substantially complete liquidation of the foreign entity in which the subsidiary had resided. Upon a partial sale, the company should release into earnings a pro rata portion of the cumulative translation adjustment. The adoption of ASU No. 2013-05 did not impact the Company's financial statements and will only have an impact upon the occurrence of a transaction within its scope.
	Acquisitions. The Company made three acquisitions during the nine months ended September 30, 2014 (the "2014 Acquisitions"), which are discussed below.
	In June 2014, the Company acquired 100% of the outstanding shares of SircleIT Inc., a developer of cloud-based knowledge automation software, for $5.7 million in cash. SircleIT Inc. is a domestic company that conducts its operations principally through Senexx Israel Ltd., its wholly-owned subsidiary in Israel with 2 employees. Gartner paid $4.9 million in cash at close and an additional $0.9 million was placed in escrow as security for certain indemnity claims, which is payable 18 months from the date of close.
	In May 2014, the Company acquired 100% of the outstanding shares of Market-Visio Oy ("Market-Visio"), a privately-owned Finnish company with 68 employees, now named Gartner Finland Oy. Market-Visio was previously an independent sales agent of Gartner research products, as well as locally-created research content, in Finland and Russia. Gartner Finland Oy conducts its operations in Russia through a wholly-owned operating subsidiary. The Company paid a total of $6.5 million in cash for Market-Visio, which included $4.1 million paid at close and $2.5 million paid in October 2014 for working capital adjustments.
	In March 2014, the Company acquired Software Advice, Inc., (“Software Advice”), a privately-owned company based in Austin, Texas with 120 employees. Software Advice assists customers with software purchases. At closing, the Company paid $103.2 million in cash for 100% of the outstanding shares of Software Advice. The Company is also obligated to pay up to an additional $31.9 million in cash related to the acquisition. This includes $13.5 million placed in escrow as security for potential losses. Release of the escrowed funds is also subject to the achievement of certain employment conditions. The escrow amount is considered restricted cash and is recorded in Other Assets in the Condensed Consolidated Balance Sheets. An additional $18.4 million is also payable contingent on the achievement of certain employment conditions. This amount is also subject to any indemnified losses in excess of the escrowed funds. The $31.9 million obligation (adjusted for any indemnified losses) will be recognized as compensation expense over the two-year service period of the relevant employees in Acquisition and integration charges in the Condensed Consolidated Statements of Operations. If the employment conditions are not met, any expense previously accrued will be reversed in the period employment terminates.
	The Company's financial statements include the operating results of these businesses beginning from their respective dates of acquisition. The operating results of these businesses were not material to the Company's consolidated and segment operating results for the three and nine month periods ending September 30, 2014. Had the Company acquired these businesses in prior periods the impact to the Company's operating results for prior periods would not have been material, and as a result pro forma financial information for prior periods has not been presented. The Company recorded $6.0 million and $16.0 million of pre-tax acquisition and integration charges in the three and nine months ended September 30, 2014, respectively, which are classified in Acquisition and integration charges in the Condensed Consolidated Statements of Operations. Included in these charges are legal, consulting, retention, severance, and other direct acquisition and integration costs.
	The Company accounts for acquisitions in accordance with the acquisition method of accounting as prescribed by FASB ASC Topic 805, Business Combinations. The acquisition method of accounting requires the consideration paid to be allocated to the net assets and liabilities acquired based on their estimated fair values as of the acquisition date, and any excess of the purchase price over the estimated fair value of the net assets acquired, including identifiable intangible assets, must be allocated to goodwill.
	The following table summarizes the preliminary allocation of the purchase price to the fair value of the assets acquired and liabilities assumed in the 2014 Acquisitions (in thousands):
		Software Advice		Other Acquisitions (1)		Total
	Assets:
	Cash	$	1,450	$	3,203	$	4,653
	Fees receivable and other current assets	3,606		3,547		7,153
	Property, equipment, and leasehold improvements	235		169		404
	Amortizable intangible assets (2)	26,928		5,047		31,975
	Goodwill (3), (4)	73,663		4,929		78,592
	Total assets	$	105,882	$	16,895	$	122,777
	Liabilities:
	Accounts payable and accrued liabilities	$	2,657	$	4,554	$	7,211
	Total liabilities	$	2,657	$	4,554	$	7,211
	Net assets acquired (5)	$	103,225	$	12,341	$	115,566
	-1	Includes the SircleIT Inc. and Market-Visio acquisitions.
	-2	See Note 6 - Goodwill and Intangible Assets for additional information regarding the types and amounts of amortizable intangibles recorded from the 2014 Acquisitions.
	-3	During the third quarter of 2014 certain tax, working capital and other minor adjustments were recorded which decreased the recorded goodwill resulting from the Market-Visio acquisition by approximately $0.1 million on a net basis.
	-4	During the second quarter of 2014, the recorded amount of an amortizable intangible asset resulting from the Software Advice acquisition was reduced by $2.7 million and goodwill was increased by the same amount. This measurement period adjustment was based on a change in the underlying assumptions used to value the amortizable intangible asset and was due to the consideration of new information.
	-5	The Company paid $112.2 million in cash on a gross basis for the net assets acquired through September 30, 2014. On a net basis, and for cash flow reporting, the Company paid $107.5 million through September 30, which represents the $112.2 million in cash paid on a gross basis minus the $4.7 million of cash acquired from the purchased companies. The Company has also recorded a liability for an additional $3.4 million to be paid for the 2014 Acquisitions, of which $2.5 million was paid in late October 2014.
	The determination of the fair value of the amortizable intangibles required management judgment and the consideration of a number of factors, significant among them the historical financial performance of the acquired businesses and projected performance, estimates surrounding customer turnover, as well as assumptions regarding the level of competition and the cost to reproduce certain assets. In determining the fair value of the intangibles, management primarily relied on income methodologies, in particular the discounted cash flow approach. Establishing the useful lives of the amortizable intangibles also required management judgment and the evaluation of a number of factors, among them projected cash flows and the likelihood of competition.
	The Company considers the allocation of the purchase price for the 2014 Acquisitions to be preliminary with respect to certain tax and other contingencies, as well as the finalization of certain working capital and other adjustments. The majority of the recorded goodwill and intangibles from these transactions will be deductible for tax purposes over 15 years. All of the recorded goodwill from the 2014 Acquisitions was included in the Company’s Research segment. The Company believes the recorded goodwill is supported by the anticipated revenue synergies, customer retention, and cost savings resulting from the combined operations.

Comprehensive_Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Comprehensive Income	'
	Comprehensive Income
	The following tables disclose information about changes in accumulated other comprehensive income (“AOCI") by component and amounts reclassified out of AOCI to income during the periods indicated (net of tax, in thousands) (1):
	For the three months ended September 30, 2014:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – June 30, 2014	$	(2,922	)	$	(1,782	)	$	14,657		$	9,953
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(1		)	—			(12,588		)	(12,589		)
	Reclassifications from AOCI to income (2), (3)	620			15			—			635
	Other comprehensive income (loss) for the period	619			15			(12,588		)	(11,954		)
	Balance – September 30, 2014	$	(2,303	)	$	(1,767	)	$	2,069		$	(2,001	)
	For the three months ended September 30, 2013:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – June 30, 2013	$	(4,635	)	$	(1,554	)	$	8,547		$	2,358
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(360		)	—			4,109			3,749
	Reclassifications from AOCI to income (2), (3)	621			6			—			627
	Other comprehensive income (loss) for the period	261			6			4,109			4,376
	Balance – September 30, 2013	$	(4,374	)	$	(1,548	)	$	12,656		$	6,734
	For the nine months ended September 30, 2014:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – December 31, 2013	$	(3,903	)	$	(1,811	)	$	14,059		$	8,345
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(236		)	—			(11,990		)	(12,226		)
	Reclassifications from AOCI to income (2), (3)	1,836			44			—			1,880
	Other comprehensive income (loss) for the period	1,600			44			(11,990		)	(10,346		)
	Balance – September 30, 2014	$	(2,303	)	$	(1,767	)	$	2,069		$	(2,001	)
	For the nine months ended September 30, 2013:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – December 31, 2012	$	(6,010	)	$	(1,578	)	$	13,556		$	5,968
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(153		)	17			(900		)	(1,036		)
	Reclassifications from AOCI to income (2), (3)	1,789			13			—			1,802
	Other comprehensive income (loss) for the period	1,636			30			(900		)	766
	Balance – September 30, 2013	$	(4,374	)	$	(1,548	)	$	12,656		$	6,734
	-1	Amounts in parentheses represent debits (deferred losses).
	-2	The reclassifications related to the interest rate swap (cash flow hedge) were recorded in Interest expense and exclude a related tax benefit reflected in the Provision for income taxes. See Note 10 – Derivatives and Hedging for information regarding the hedge.
	-3	The reclassifications related to defined benefit pension plans were recorded in Selling, general and administrative expense and had an immaterial tax effect for both periods. See Note 12 – Employee Benefits for information regarding the Company’s defined benefit pension plans.

Earnings_per_Share

Earnings per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings per Share	'
	Earnings per Share
	The following table sets forth the calculations of basic and diluted earnings per share (in thousands, except per share data):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Numerator:
	Net income used for calculating basic and diluted earnings per share	$	33,846	$	38,194	$	124,622	$	121,383
	Denominator:
	Weighted average number of common shares used in the calculation of basic earnings per share	88,513		92,689		89,901		93,286
	Common stock equivalents associated with stock-based compensation plans (1)	1,195		1,666		1,372		1,814
	Shares used in the calculation of diluted earnings per share	89,708		94,355		91,273		95,100
	Basic earnings per share	$	0.38	$	0.41	$	1.39	$	1.3
	Diluted earnings per share	$	0.38	$	0.4	$	1.37	$	1.28
	-1	Certain common stock equivalents were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive. These shares totaled less than 0.4 million in each of the periods presented.

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation	'
	Stock-Based Compensation
	The 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. On May 29, 2014, the Company's shareholders approved the 2014 Long-Term Incentive Plan (the "2014 Plan") which replaces the 2003 Long-Term Incentive Plan (the "2003 Plan"). All 5.8 million shares remaining available under the 2003 Plan were transferred to the 2014 Plan, and an additional 2.2 million shares were made available for awards under the 2014 Plan, for a total availability of 8.0 million shares. At September 30, 2014, the Company had a total of 7.96 million shares of its common stock, par value $.0005 per share (the “Common Stock”), remaining available for awards of stock-based compensation under its 2014 Plan.
	The Company accounts for stock-based compensation awards in accordance with FASB ASC Topics 505 and 718, as interpreted by SEC Staff Accounting Bulletins No. 107 (“SAB No. 107”) and No. 110 (“SAB No. 110”). Stock-based compensation expense is based on the fair value of the award on the date of grant, which is then recognized as expense over the related service period, net of estimated forfeitures. The service period is the period over which the related service is performed, which is generally the same as the vesting period. The Company currently issues treasury shares upon the exercise, release or settlement of stock-based compensation awards.
	Determining the appropriate fair value model and calculating the fair value of stock-based compensation awards requires the input of certain complex and subjective assumptions, including the expected life of the stock compensation awards and the Common Stock price volatility. In addition, determining the appropriate amount of associated periodic expense requires management to estimate the amount of employee forfeitures and the likelihood of the achievement of certain performance targets. The assumptions used in calculating the fair value of stock-based compensation awards and the associated periodic expense represent management’s best estimates, but these estimates involve inherent uncertainties and the application of judgment. As a result, if factors change and the Company deems it necessary in the future to modify the assumptions it made or to use different assumptions, or if the quantity and nature of the Company’s stock-based compensation awards changes, then the amount of expense may need to be adjusted and future stock-based compensation expense could be materially different from what has been recorded in the current period.
	Stock-Based Compensation Expense
	The Company recognized the following amounts of stock-based compensation expense by award type and expense category in the periods indicated (in millions):
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Award type:		2014				2013				2014			2013
	Stock appreciation rights		$	1			$	1.1			$	3.9		$	4.1
	Common stock equivalents		0.2				0.1				0.5			0.4
	Restricted stock units		7.6				6.2				25			22.5
	Total stock-based compensation expense (1), (2)		$	8.8			$	7.4			$	29.4		$	27
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Amount recorded in:		2014				2013				2014			2013
	Cost of services and product development		$	4			$	3.2			$	13.5		$	12
	Selling, general and administrative		4.8				4.2				15.9			15
	Total stock-based compensation expense (1), (2)		$	8.8			$	7.4			$	29.4		$	27
	-1	Includes charges of $2.9 million and $1.8 million for the three months ended September 30, 2014 and 2013, respectively, and $12.7 million and $10.6 million for the nine months ended September 30, 2014 and 2013, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis.
	-2	The nine months ended September 30, 2014 includes a reversal of $1.9 million of expense from forfeited awards related to the departure of the Company's former chief financial officer.
	As of September 30, 2014, the Company had $51.7 million of total unrecognized stock-based compensation cost, which is expected to be expensed over the remaining weighted-average service period of approximately 2.3 years.
	Stock-Based Compensation Awards
	The following disclosures provide information regarding the Company’s stock-based compensation awards, all of which are classified as equity awards in accordance with FASB ASC Topic 505:
	Stock Appreciation Rights
	Stock-settled stock appreciation rights (SARs) permit the holder to participate in the appreciation of the Common Stock. SARs are settled in shares of Common Stock once the applicable vesting criteria have been met. SARs vest ratably over a four-year service period and expire seven years from the grant date. The fair value of SARs awards is determined on the date of grant and is recognized as compensation expense on a straight-line basis over four years. SARs have only been awarded to the Company’s executive officers.
	When SARs are exercised, the number of shares of Common Stock issued is calculated as follows: (1) the total proceeds from the SARs exercise (calculated as the closing price of the Common Stock on the date of exercise less the exercise price of the SARs, multiplied by the number of SARs exercised) is divided by (2) the closing price of the Common Stock as reported on the New York Stock Exchange on the exercise date. The Company withholds a portion of the shares of Common Stock issued upon exercise to satisfy minimum statutory tax withholding requirements. SARs recipients do not have any stockholder rights until after actual shares of Common Stock are issued in respect of the award, which is subject to the prior satisfaction of the vesting and other criteria relating to such grants.
	The following table summarizes changes in SARs outstanding during the nine months ended September 30, 2014:
		SARs			Per Share				Per Share				Weighted
		(in millions)			Weighted-				Weighted-				Average
					Average				Average				Remaining
					Exercise Price				Grant Date				Contractual
									Fair Value				Term
	Outstanding at December 31, 2013	1.6			$	34.14			$	11.63			4.34 years
	Granted	0.4			64.64				14.99				6.36 years
	Forfeited	(0.1	)		52.15				n/a				n/a
	Exercised	(0.4	)		23.72				8.73				n/a
	Outstanding at September 30, 2014 (1), (2)	1.5			$	44.01			$	13.17			4.48 years
	Vested and exercisable at September 30, 2014 (2)	0.6			$	33.05			$	11.51			3.27 years
	n/a=t applicable.
	-1	As of September 30, 2014, 0.9 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.
	-2	Total SARs outstanding had an intrinsic value of $43.2 million. SARs vested and exercisable had an intrinsic value of $25.5 million.
	The fair value of the SARs was estimated on the date of grant using the Black-Scholes-Merton valuation model with the following weighted-average assumptions:
		Nine Months Ended
		September 30,
		2014			2013
	Expected dividend yield (1)	—	%		—	%
	Expected stock price volatility (2)	25	%		35	%
	Risk-free interest rate (3)	1.3	%		0.8	%
	Expected life in years (4)	4.4			4.5
	-1	The dividend yield assumption is based on the history and expectation of the Company’s dividend payouts. Historically, Gartner has not paid cash dividends on its Common Stock.
	-2	The determination of expected stock price volatility was based on both historical Common Stock prices and implied volatility from publicly traded options in the Common Stock.
	-3	The risk-free interest rate is based on the yield of a U.S. Treasury security with a maturity similar to the expected life of the award.
	-4	The expected life represents the Company’s weighted-average estimate of the period of time the SARs are expected to be outstanding (defined as the period between the service inception date and the expected exercise date), which is based on historical exercise data.
	Restricted Stock Units
	Restricted stock units (RSUs) give the awardee the right to receive shares of Common Stock when the vesting conditions are met and the restrictions lapse, and each RSU that vests entitles the awardee to one common share. RSU awardees do not have any of the rights of a Gartner stockholder, including voting rights and the right to receive dividends and distributions, until the shares are released. The fair value of RSUs is determined on the date of grant based on the closing price of the Common Stock as reported by the New York Stock Exchange on that date. Service-based RSUs vest ratably over four years and are expensed on a straight-line basis over four years. Performance-based RSUs are subject to the satisfaction of both performance and service conditions, vest ratably over four years, and are expensed on an accelerated basis.
	The following table summarizes the changes in RSUs outstanding during the nine months ended September 30, 2014:
		Restricted			Per Share
		Stock Units			Weighted
		(RSUs)			Average
		(in millions)			Grant Date
					Fair Value
	Outstanding at December 31, 2013	1.8			$	38.83
Granted (1)	0.5			65.3
Vested and released	(0.8	)		34.15
Forfeited	(0.1	)		—
Outstanding at September 30, 2014 (2), (3)	1.4			$	50.67
-1	The 0.5 million RSUs granted consisted of 0.2 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.2 million performance-based RSUs represents the target amount of the grant for the year, which is tied to an increase in the Company’s subscription-based research contract value (“CV”) for 2014. The final number of performance-based RSUs that will ultimately be awarded for 2014 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2014 as measured on December 31, 2014. If the specified minimum level of achievement is not met, the performance-based RSUs will be forfeited in their entirety, and any compensation expense previously recorded will be reversed.
-2	The Company expects that substantially all of the outstanding awards will vest in future periods.
-3	The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.3 years.
Common Stock Equivalents
Common stock equivalents (CSEs) are convertible into Common Stock and each CSE entitles the holder to one common share. CSEs are only awarded to members of our Board of Directors who receive directors’ fees payable in CSEs unless they opt to receive up to 50% of the directors' fees in cash. Generally, the CSEs have no defined term and are converted into common shares when service as a director terminates, unless the director has elected an accelerated release. The number of CSEs awarded is determined by dividing directors' fees owing for the quarter and not payable in cash by the closing price of the Common Stock as reported by the New York Stock Exchange on that date. CSEs vest immediately and as a result are recorded as expense on the date of grant.
The following table summarizes the changes in CSEs outstanding during the nine months ended September 30, 2014:
	Common			Per Share
	Stock			Weighted
	Equivalents			Average
	(CSEs)			Grant Date
				Fair Value
Outstanding at December 31, 2013	102,479			$	17.71
Granted	6,614			71.86
Converted to common shares	(5,274	)		71.86
Outstanding at September 30, 2014	103,819			$	18.41
Employee Stock Purchase Plan
The Company has an employee stock purchase plan (the “ESP Plan”) under which eligible employees are permitted to purchase Common Stock through payroll deductions, which may not exceed 10% of an employee’s compensation (or a maximum of $23,750 in any calendar year), at a price equal to 95% of the closing price of the Common Stock as reported by the New York Stock Exchange at the end of each offering period.
At September 30, 2014, the Company had 1.1 million shares available for purchase under the ESP Plan. The ESP Plan is considered non-compensatory under FASB ASC Topic 718, and as a result the Company does not record stock-based compensation expense for employee share purchases. The Company received $6.4 million and $4.5 million in cash from purchases under the ESP Plan and exercises of stock options during the nine months ended September 30, 2014 and 2013, respectively.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	The Company manages its business through three reportable segments: Research, Consulting and Events. Research consists primarily of subscription-based research products, access to research inquiry, peer networking services, and membership programs. Consulting consists primarily of consulting, measurement engagements, and strategic advisory services. Events consists of various symposia, conferences, and exhibitions.
	The Company evaluates reportable segment performance and allocates resources based on gross contribution margin. Gross contribution, as presented in the table below, is defined as operating income excluding certain Cost of services and product development expenses, Selling, general and administrative expense, 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 in the allocation of resources.
	The following tables present information about the Company’s reportable segments for the periods indicated (in thousands):
	Three Months Ended September 30, 2014	Research			Consulting			Events		Consolidated
	Revenues	$	365,334		$	82,300		$	23,306	$	470,940
	Gross contribution	251,113			24,774			6,946		282,833
	Corporate and other expenses									(233,442		)
	Operating income									$	49,391
	Three Months Ended September 30, 2013	Research			Consulting			Events		Consolidated
	Revenues	$	316,518		$	70,149		$	24,038	$	410,705
	Gross contribution	220,329			21,114			7,095		248,538
	Corporate and other expenses									(189,795		)
	Operating income									$	58,743
	Nine Months Ended September 30, 2014	Research			Consulting			Events		Consolidated
	Revenues	$	1,071,943		$	260,059		$	105,460	$	1,437,462
	Gross contribution	745,477			91,347			44,141		880,965
	Corporate and other expenses									(690,643		)
	Operating income									$	190,322
	Nine Months Ended September 30, 2013	Research			Consulting			Events		Consolidated
	Revenues	$	938,082		$	228,710		$	96,714	$	1,263,506
	Gross contribution	648,954			76,836			37,318		763,108
	Corporate and other expenses									(576,373		)
	Operating income									$	186,735
	The following table provides a reconciliation of total segment gross contribution to net income for the periods indicated (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Total segment gross contribution	$	282,833		$	248,538		$	880,965	$	763,108
	Costs and expenses:
	Cost of services and product development - unallocated (1), (2)	(48		)	(432		)	5,561		2,978
	Selling, general and administrative	217,025			181,546			640,179		547,653
	Depreciation and amortization	10,450			8,609			28,888		25,464
	Acquisition and integration charges	6,015			72			16,015		278
	Operating income	49,391			58,743			190,322		186,735
	Interest expense and other	2,943			2,119			7,927		6,768
	Provision for income taxes	12,602			18,430			57,773		58,584
	Net income	$	33,846		$	38,194		$	124,622	$	121,383
	-1	The unallocated amounts consist of certain bonus and related fringe expenses recorded in Consolidated cost of services and product development expense that are not allocated to segment expense. The Company's policy is to only allocate bonus and related fringe charges to segments for up to 100% of the segment employee's target bonus. Amounts above 100% are absorbed by corporate.
	-2	Amounts in parentheses in the three months ended periods result from adjustments to the year-to-date balances.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2014
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 value of the tangible and identifiable intangible net assets acquired. Goodwill is not amortized but is periodically evaluated for impairment in accordance with FASB ASC Topic 350, which requires an annual assessment of potential goodwill impairment at the reporting unit level, which the Company completes each year in the third quarter. A reporting unit can be an operating segment or a business if discrete financial information is prepared and reviewed by management.
	The following table presents changes to the carrying amount of goodwill by reportable segment during the nine months ended September 30, 2014 (in thousands):
		Research				Consulting				Events				Total
	Balance, December 31, 2013 (1)	$	376,568			$	100,677			$	41,958			$	519,203
	Additions due to acquisitions (2)	78,592				—				—				78,592
	Foreign currency translation adjustments	(4,111		)		(383		)		(89		)		(4,583		)
	Balance, September 30, 2014	$	451,049			$	100,294			$	41,869			$	593,212
	-1	The Company does not have any accumulated goodwill impairment losses.
	-2	The Company made three acquisitions during the nine months ended September 30, 2014 (See Note 1 for additional discussion). All of the recorded goodwill from these acquisitions has been included in the Research segment.
	Amortizable Intangible Assets
	The following tables present reconciliations of the carrying amounts of amortizable intangible assets as of the dates indicated (in thousands):
	September 30, 2014		Trade				Customer				Content				Software			Non-Compete			Total
			Name				Relationships
	Gross cost, December 31, 2013		$	6,023			10,146				3,496				2,143			$	—		$	21,808
	Additions due to acquisitions (1)		915				18,054				206				5,000			7,800			31,975
	Non-competition agreement (2)		—				—				—				—			1,500			1,500
	Foreign currency translation adjustments		(9		)		(35		)		(82		)		(290		)	(14		)	(430		)
	Gross cost		6,929				28,165				3,620				6,853			9,286			54,853
	Accumulated amortization (3)		(5,859		)		(10,371		)		(2,041		)		(2,103		)	(964		)	(21,338		)
	Balance, September 30, 2014		$	1,070			$	17,794			$	1,579			$	4,750		$	8,322		$	33,515
	December 31, 2013		Trade				Customer				Content				Software			Total
			Name				Relationships
	Gross cost, December 31, 2012		$	6,023			$	10,146			$	3,496			$	2,143		$	21,808
	Accumulated amortization (3)		(4,817		)		(8,372		)		(1,388		)		(1,124		)	(15,701		)
	Balance, December 31, 2013		$	1,206			$	1,774			$	2,108			$	1,019		$	6,107
	-1	See Note 1 for additional disclosure.
	-2	The non-competition intangible relates to a separation agreement with the Company's former chief financial officer which was entered into in June 2014.
	-3	Intangible assets are being amortized against earnings over the following periods: Trade name—2 to 5 years; Customer relationships—4 to 7 years; Content—1.5 to 4 years; Software—3 years; Non-compete—4 to 5 years.
	Aggregate amortization expense related to intangible assets was $2.5 million and $1.4 million for the three months ended September 30, 2014 and 2013, respectively, and $5.8 million and $4.1 million for the nine months ended September 30, 2014 and 2013, respectively.
	The estimated future amortization expense by year from amortizable intangibles is as follows (in thousands):
	2014 (remaining three months)	$	2,475
	2015	8,345
	2016	6,990
	2017	5,570
	2018	4,330
	After 2018	5,805
		$	33,515

Debt

Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	2013 Credit Agreement
	The Company has a credit arrangement (the “2013 Credit Agreement”) that provides for a five-year, $150.0 million term loan and a $600.0 million revolving credit facility. In addition, the 2013 Credit Agreement contains an expansion feature by which the term loan and revolving credit facility may be increased, at the Company’s option and under certain conditions, by up to an additional $250.0 million in the aggregate. The term loan will be repaid in 16 consecutive quarterly installments which commenced on June 30, 2013, plus a final payment due on March 7, 2018, and may be prepaid at any time without penalty or premium (other than applicable breakage costs) at the Company’s option. The revolving credit facility may be used for loans, and up to $40.0 million may be used for letters of credit. The revolving loans may be borrowed, repaid and re-borrowed until March 7, 2018, at which time all amounts borrowed must be repaid.
	Amounts borrowed under the 2013 Credit Agreement bear interest at a rate equal to, at Gartner’s option, either (i) the greatest of: the Administrative Agent’s prime rate; the average rate on overnight federal funds plus 1/2 of 1%; and the Eurodollar rate (adjusted for statutory reserves) plus 1%, in each case plus a margin equal to between 0.25% and 0.75% depending on Gartner’s leverage ratio as of the end of the four consecutive fiscal quarters most recently ended, or (ii) the Eurodollar rate (adjusted for statutory reserves) plus a margin equal to between 1.25% and 1.75%, depending on Gartner’s leverage ratio as of the end of the four consecutive fiscal quarters most recently ended.
	The 2013 Credit Agreement contains certain customary restrictive loan covenants, including, among others, financial covenants requiring a maximum leverage ratio, a minimum interest expense coverage ratio, and covenants limiting Gartner’s ability to incur indebtedness, grant liens, make acquisitions, be acquired, dispose of assets, pay dividends, repurchase stock, make capital expenditures, make investments and enter into certain transactions with affiliates. The 2013 Credit Agreement contains customary events of default that include, among others, non-payment of principal, interest or fees, inaccuracy of representations and warranties, violation of covenants, cross defaults to certain other indebtedness, bankruptcy and insolvency events, ERISA defaults, material judgments, and events constituting a change of control. The occurrence of an event of default will increase the applicable rate of interest by 2.0%, allows the lenders to terminate their obligations to lend under the 2013 Credit Agreement and could result in the acceleration of Gartner’s obligations under the credit facility and an obligation of any or all of the guarantors to pay the full amount of Gartner’s obligations under the credit facility. As of September 30, 2014, the Company was in full compliance with the loan covenants.
	The following table provides information regarding the Company’s total outstanding borrowings (in thousands):
			Balance		Balance
			September 30,		December 31,
	Description:		2014		2013
	Term loans (1)		$	135,000	$	144,375
	Revolver loans (1), (2)		230,000		55,625
	Other (3)		5,000		5,000
	Total		$	370,000	$	205,000
	-1	The contractual annualized interest rates as of September 30, 2014 on the term loan and the revolver ranged from 1.53% to 1.61%, which consists of a floating Eurodollar base rate ranging from 0.15% to 0.23% plus a margin of 1.38%. However, the Company has an interest rate swap contract which converts the floating Eurodollar base rates to a 2.26% fixed base rate on the first $200.0 million of Company borrowings (see below) and, combined with the 1.38% margin, results in an effective rate of approximately 3.63% on the first $200.0 million of borrowings.
	The annual effective rate on the Company's total debt outstanding as of September 30, 2014, including the effect of the swap, was approximately 3.64%.
	-2	The Company had $366.6 million of available borrowing capacity on the revolver (not including the expansion feature) as of September 30, 2014.
	-3	The Company borrowed $5.0 million in 2012 through a State of Connecticut economic development program. The loan has a 10 year maturity and bears a 3.0% fixed rate of interest. Principal payments are deferred for the first five years and the loan may be repaid at any point by the Company without penalty. The loan has a principal forgiveness provision in which up to $2.5 million of the loan may be forgiven if the Company meets certain employment targets in Connecticut during the first five years of the loan.
	Interest Rate Swap
	The Company has a $200.0 million notional fixed-for-floating interest rate swap contract which it designates as a hedge of the forecasted interest payments on the Company’s variable rate borrowings. Under the swap terms, the Company pays a base fixed rate of 2.26% and in return receives a floating Eurodollar base rate on $200.0 million of notional borrowings. The swap matures in late 2015.
	The Company accounts for the interest rate swap as a cash flow hedge in accordance with FASB ASC Topic 815. Since the swap is hedging forecasted interest payments, changes in the fair value of the swap are recorded in OCI as long as the swap continues to be a highly effective hedge of the designated interest rate risk. Any ineffective portion of change in the fair value of the hedge is recorded in earnings. The swap continued to be a highly effective hedge of the forecasted interest payments as of September 30, 2014. The interest rate swap had a negative fair value to the Company of $3.8 million at September 30, 2014, which is deferred and classified in OCI, net of tax effect.
	Letters of Credit
	The Company had $9.6 million of letters of credit and related guarantees outstanding at September 30, 2014. The Company enters into these instruments in the ordinary course of business to facilitate transactions with customers and others.

Equity

Equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Equity	'
	Equity
	Share Repurchase Program
	On February 4, 2014, the Company’s Board of Directors authorized $800.0 million to repurchase the Company's common stock. This authorization succeeds the Company’s prior $500.0 million share repurchase authorization, which was substantially utilized. The Company may repurchase its common stock from time to time in amounts and at prices 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, private transactions or other transactions and will be funded from cash on hand and borrowings under the Company’s credit agreement.
	The Company’s recent share repurchase activity is presented in the following table:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Number of shares repurchased (1)	1,124,117		1,016,978		5,350,915		2,859,246
	Cost of repurchased shares (in thousands) (2)	$	79,678	$	59,252	$	387,126	$	157,251
	-1	The average purchase price for the shares was $72.94 and $70.67 for the three and nine months ended September 30, 2014, respectively, and $58.26 and $55.00 for the three and nine months ended September 30, 2013, respectively.
	-2	The cost of repurchased shares for the nine months ended September 30, 2014 includes payment for share repurchase transactions that occurred in late December 2013 but were paid in early January 2014.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The provision for income taxes was $12.6 million for the three months ended September 30, 2014 compared to $18.4 million in the three months ended September 30, 2013. The effective income tax rate was 27.1% for the three months ended September 30, 2014 and 32.5% for the same period in 2013. The quarter-over-quarter decrease in the effective income tax rate was primarily due to the recognition of benefits associated with tax credits.
	The provision for income taxes was $57.8 million for the nine months ended September 30, 2014 compared to $58.6 million in the nine months ended September 30, 2013. The effective income tax rate was 31.7% for the nine months ended September 30, 2014 and 32.6% for the same period in 2013. The decrease in the effective income tax rate was primarily due to the recognition of benefits associated with tax credits partially offset by a favorable retroactive tax law change enacted in the first quarter of 2013.
	As of September 30, 2014 and December 31, 2013, the Company had gross unrecognized tax benefits of $18.9 million and $14.5 million, respectively. It is reasonably possible that gross unrecognized tax benefits will decrease by approximately $5.0 million within the next 12 months, due to the anticipated closure of audits and the expiration of certain statutes of limitation. These unrecognized tax benefits relate primarily to the utilization of tax attributes, as well as certain other unrecognized tax positions, each of which are individually insignificant.
	In 2013, the Internal Revenue Service commenced an audit of the Company's federal income tax returns for the 2010 and 2011 tax years. The audits are substantially complete and the Company believes the ultimate disposition will not have a material adverse effect on its consolidated financial position, cash flows, or results of operations.

Derivatives_and_Hedging

Derivatives and Hedging	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives and Hedging	'
	Derivatives and Hedging
	The Company enters into a limited number of derivative contracts to offset the potentially negative economic effects of interest rate and foreign exchange movements. 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 following tables provide information regarding the Company’s outstanding derivatives contracts as of the dates indicated (in thousands, except for number of outstanding contracts):
	30-Sep-14
	Derivative Contract Type		Number of			Notional				Fair Value				Balance		Unrealized
			Outstanding			Amounts				Asset				Sheet		Loss Recorded
			Contracts							(Liability), Net (3)				Line Item		in OCI
	Interest rate swap (1)		1			$	200,000			$	(3,839	)		Other liabilities		$	(2,303	)
	Foreign currency forwards (2)		19			6,630				(19		)		Accrued liabilities		—
	Total		20			$	206,630			$	(3,858	)				$	(2,303	)
	31-Dec-13
	Derivative Contract Type		Number of			Notional				Fair Value				Balance		Unrealized
			Outstanding			Amounts				Asset				Sheet		Loss Recorded
			Contracts							(Liability), Net (3)				Line Item		in OCI
	Interest rate swap (1)		1			$	200,000			$	(6,505	)		Other liabilities		$	(3,903	)
	Foreign currency forwards (2)		89			61,325				(60		)		Accrued liabilities		—
	Total		90			$	261,325			$	(6,565	)				$	(3,903	)
	-1	This swap has been designated, and is accounted for, as a cash flow hedge of the forecasted interest payments on borrowings (see Note 7 — Debt). As a result, changes in fair value of this swap are deferred and are recorded in OCI, net of tax effect.
	-2	The Company has foreign exchange transaction risk since 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 offset the economic effects of these foreign currency transaction risks. These forward exchange contracts are accounted for at fair value with realized and unrealized gains and losses recognized in Other expense, net. All of the contracts outstanding at September 30, 2014 matured by the end of October 2014.
	-3	See Note 11 — Fair Value Disclosures for the determination of the fair value of these instruments.
	The Company’s derivative counterparties are all large 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 guarantees.
	The following table provides information regarding derivative gains and losses that have been recognized in the Condensed Consolidated Statements of Operations for the periods indicated (in thousands):
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Amount recorded in:		2014				2013				2014				2013
	Interest expense, net (1)		$	1,034			$	1,034			$	3,059			$	2,981
	Other expense (income), net (2)		(12		)		(20		)		(110		)		138
	Total expense, net		$	1,022			$	1,014			$	2,949			$	3,119
	-1	Consists of interest expense from an interest rate swap contract.
	-2	Consists of realized and unrealized gains and losses on foreign currency forward contracts.

Fair_Value_Disclosures

Fair Value Disclosures	9 Months Ended
	Sep. 30, 2014
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 accruals which are normally short-term in nature. The Company believes the carrying amounts of these financial instruments reasonably approximate their fair value due to their short-term nature. The Company’s financial instruments also include its outstanding borrowings. The Company believes the carrying amount of the outstanding borrowings reasonably approximates their fair value since the rate of interest on the borrowings reflect current market rates of interest for similar instruments with comparable maturities.
	FASB ASC Topic 820 provides a framework for the measurement of fair value and a valuation hierarchy based upon the transparency of inputs used in the valuation of assets and liabilities. Classification within the hierarchy is based upon 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 has a limited number of assets and liabilities recorded in its Consolidated Balance Sheets that are remeasured to fair value on a recurring basis, and the Company does not currently utilize Level 3 valuation inputs to remeasure any of its assets or liabilities. In addition, the Company typically does not transfer assets or liabilities between different levels of the fair value hierarchy.
	The Company’s assets and liabilities that are remeasured to fair value are presented in the following table for the periods indicated (in thousands):
			Fair Value		Fair Value
	Description:		September 30,		December 31,
			2014		2013
	Assets:
	Values based on Level 1 inputs:
	Deferred compensation plan assets (1)		$	7,525	$	7,775
	Total Level 1 inputs		$	7,525	$	7,775
	Values based on Level 2 inputs:
	Deferred compensation plan assets (1)		$	26,185	$	24,780
	Foreign currency forward contracts (2)		7		116
	Total Level 2 inputs		$	26,192	$	24,896
	Total Assets		$	33,717	$	32,671
	Liabilities:
	Values based on level 2 inputs:
	Deferred compensation plan liabilities (1)		$	38,150	$	36,410
	Foreign currency forward contracts (2)		26		176
	Interest rate swap contract (3)		3,839		6,505
	Total Level 2 inputs		$	42,015	$	43,091
	Total Liabilities		$	42,015	$	43,091
	-1	The Company has a deferred compensation plan for the benefit of certain highly compensated employees. The assets consist of investments in money market and mutual funds, and company-owned life insurance contracts, all of which are valued based on Level 1 or Level 2 valuation 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 based on 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. Valuation of the foreign currency forward contracts is based on observable foreign currency exchange rates in active markets, which the Company considers a Level 2 input.
	-3	The Company has an interest rate swap contract which hedges the forecasted interest payments on its borrowings (see Note 7 — Debt). To determine the fair value of this over-the-counter financial instrument, the Company relies on a mark-to-market valuation prepared by a third-party broker. The valuation is based on observable interest rates from recently executed market transactions or broker quotes corroborated by other observable market data. Accordingly, the fair value of the swap is determined under a Level 2 input. The Company independently corroborates the reasonableness of the swap valuation prepared by the third-party broker through the use of an electronic quotation service.

Employee_Benefits

Employee Benefits	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Employee Benefits	'
	Employee Benefits
	Defined Benefit Pension Plans
	The Company has defined-benefit pension plans in several of its international locations. Benefits paid under these plans are based on years of service and level of employee compensation. The Company’s defined benefit pension plans are accounted for in accordance with FASB ASC Topics 715 and 960. Net periodic pension expense was $0.8 million and $2.3 million for the three and nine months ended September 30, 2014, respectively, and $0.8 million and $2.4 million for the three and nine months ended September 30, 2013, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Contingencies
	The Company is involved in legal proceedings and litigation arising in the ordinary course of business. We believe 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 our financial position, cash flows, or results of operations when resolved in a future period.
	The Company has various agreements that may obligate us 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 we customarily agree to hold the other party harmless against losses arising from a breach of representations related to such matters 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 us under these agreements have not been material. As of September 30, 2014, the Company did not have any material payment obligations under any such indemnification agreements.

Business_and_Basis_of_Presenta1

Business and Basis of Presentation Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
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 the Financial Accounting Standards Board (FASB) Accounting Standards Codification (“ASC”) Topic 270 for interim financial information and with the applicable instructions of the U.S. Securities & 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 filed in its Annual Report on Form 10-K for the year ended December 31, 2013.
	The fiscal year of Gartner is the twelve-month calendar 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 and nine months ended September 30, 2014 may not be indicative of the results of operations for the remainder of 2014.
Principles of consolidation	'
	Principles of consolidation. The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly- and majority-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, performance-based compensation expenses, depreciation and amortization, and the allowance for losses. 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 our estimates and actual results could be material and would be reflected in the Company’s consolidated financial statements in future periods.
Adoption of new accounting rules	'
	Adoption of new accounting rules. Effective January 1, 2014, the Company adopted two new accounting rules issued by the FASB, as follows:
	The Company adopted ASU No. 2013-11, "Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists" ("ASU No. 2013-11"). ASU No. 2013-11 addresses the balance sheet presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. ASU No. 2013-11 requires that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. The balance sheet impact from the adoption of ASU No. 2013-11 was not material to the Company.
	The Company adopted ASU No. 2013-05, Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity ("ASU No. 2013-05"). ASU No. 2013-05 provides updated guidance to resolve diversity in practice concerning the release of the cumulative foreign currency translation adjustment into net income when a parent sells a part or all of its investment in a foreign entity or no longer holds a controlling financial interest in a subsidiary or group of assets within a foreign entity. When a company ceases to have a controlling financial interest, the company should recognize any related cumulative translation adjustment into net income only if the sale or transfer results in the complete or substantially complete liquidation of the foreign entity in which the subsidiary had resided. Upon a partial sale, the company should release into earnings a pro rata portion of the cumulative translation adjustment. The adoption of ASU No. 2013-05 did not impact the Company's financial statements and will only have an impact upon the occurrence of a transaction within its scope.

Business_and_Basis_of_Presenta2

Business and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Schedule of preliminary allocation of the purchase price to the fair value of the assets acquired and liabilities assumed in the acquisition	'
	The following table summarizes the preliminary allocation of the purchase price to the fair value of the assets acquired and liabilities assumed in the 2014 Acquisitions (in thousands):
		Software Advice		Other Acquisitions (1)		Total
	Assets:
	Cash	$	1,450	$	3,203	$	4,653
	Fees receivable and other current assets	3,606		3,547		7,153
	Property, equipment, and leasehold improvements	235		169		404
	Amortizable intangible assets (2)	26,928		5,047		31,975
	Goodwill (3), (4)	73,663		4,929		78,592
	Total assets	$	105,882	$	16,895	$	122,777
	Liabilities:
	Accounts payable and accrued liabilities	$	2,657	$	4,554	$	7,211
	Total liabilities	$	2,657	$	4,554	$	7,211
	Net assets acquired (5)	$	103,225	$	12,341	$	115,566
	-1	Includes the SircleIT Inc. and Market-Visio acquisitions.
	-2	See Note 6 - Goodwill and Intangible Assets for additional information regarding the types and amounts of amortizable intangibles recorded from the 2014 Acquisitions.
	-3	During the third quarter of 2014 certain tax, working capital and other minor adjustments were recorded which decreased the recorded goodwill resulting from the Market-Visio acquisition by approximately $0.1 million on a net basis.
	-4	During the second quarter of 2014, the recorded amount of an amortizable intangible asset resulting from the Software Advice acquisition was reduced by $2.7 million and goodwill was increased by the same amount. This measurement period adjustment was based on a change in the underlying assumptions used to value the amortizable intangible asset and was due to the consideration of new information.
	-5	The Company paid $112.2 million in cash on a gross basis for the net assets acquired through September 30, 2014. On a net basis, and for cash flow reporting, the Company paid $107.5 million through September 30, which represents the $112.2 million in cash paid on a gross basis minus the $4.7 million of cash acquired from the purchased companies. The Company has also recorded a liability for an additional $3.4 million to be paid for the 2014 Acquisitions, of which $2.5 million was paid in late October 2014.

Comprehensive_Income_Tables

Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Schedule of the changes in AOCI by component (net of tax)	'
	The following tables disclose information about changes in accumulated other comprehensive income (“AOCI") by component and amounts reclassified out of AOCI to income during the periods indicated (net of tax, in thousands) (1):
	For the three months ended September 30, 2014:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – June 30, 2014	$	(2,922	)	$	(1,782	)	$	14,657		$	9,953
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(1		)	—			(12,588		)	(12,589		)
	Reclassifications from AOCI to income (2), (3)	620			15			—			635
	Other comprehensive income (loss) for the period	619			15			(12,588		)	(11,954		)
	Balance – September 30, 2014	$	(2,303	)	$	(1,767	)	$	2,069		$	(2,001	)
	For the three months ended September 30, 2013:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – June 30, 2013	$	(4,635	)	$	(1,554	)	$	8,547		$	2,358
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(360		)	—			4,109			3,749
	Reclassifications from AOCI to income (2), (3)	621			6			—			627
	Other comprehensive income (loss) for the period	261			6			4,109			4,376
	Balance – September 30, 2013	$	(4,374	)	$	(1,548	)	$	12,656		$	6,734
	For the nine months ended September 30, 2014:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – December 31, 2013	$	(3,903	)	$	(1,811	)	$	14,059		$	8,345
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(236		)	—			(11,990		)	(12,226		)
	Reclassifications from AOCI to income (2), (3)	1,836			44			—			1,880
	Other comprehensive income (loss) for the period	1,600			44			(11,990		)	(10,346		)
	Balance – September 30, 2014	$	(2,303	)	$	(1,767	)	$	2,069		$	(2,001	)
	For the nine months ended September 30, 2013:
		Interest Rate			Defined			Foreign			Total
		Swap			Benefit			Currency
					Pension Plans			Translation
								Adjustments
	Balance – December 31, 2012	$	(6,010	)	$	(1,578	)	$	13,556		$	5,968
	Changes during the period:
	Other comprehensive income (loss) before reclassifications	(153		)	17			(900		)	(1,036		)
	Reclassifications from AOCI to income (2), (3)	1,789			13			—			1,802
	Other comprehensive income (loss) for the period	1,636			30			(900		)	766
	Balance – September 30, 2013	$	(4,374	)	$	(1,548	)	$	12,656		$	6,734
	-1	Amounts in parentheses represent debits (deferred losses).
	-2	The reclassifications related to the interest rate swap (cash flow hedge) were recorded in Interest expense and exclude a related tax benefit reflected in the Provision for income taxes. See Note 10 – Derivatives and Hedging for information regarding the hedge.
	-3	The reclassifications related to defined benefit pension plans were recorded in Selling, general and administrative expense and had an immaterial tax effect for both periods. See Note 12 – Employee Benefits for information regarding the Company’s defined benefit pension plans.

Earnings_per_Share_Tables

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule of earnings per share reconciliation	'
	The following table sets forth the calculations of basic and diluted earnings per share (in thousands, except per share data):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Numerator:
	Net income used for calculating basic and diluted earnings per share	$	33,846	$	38,194	$	124,622	$	121,383
	Denominator:
	Weighted average number of common shares used in the calculation of basic earnings per share	88,513		92,689		89,901		93,286
	Common stock equivalents associated with stock-based compensation plans (1)	1,195		1,666		1,372		1,814
	Shares used in the calculation of diluted earnings per share	89,708		94,355		91,273		95,100
	Basic earnings per share	$	0.38	$	0.41	$	1.39	$	1.3
	Diluted earnings per share	$	0.38	$	0.4	$	1.37	$	1.28
	-1	Certain common stock equivalents were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive. These shares totaled less than 0.4 million in each of the periods presented.

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Schedule of stock-based compensation expense by award type	'
	The Company recognized the following amounts of stock-based compensation expense by award type and expense category in the periods indicated (in millions):
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Award type:		2014				2013				2014			2013
	Stock appreciation rights		$	1			$	1.1			$	3.9		$	4.1
	Common stock equivalents		0.2				0.1				0.5			0.4
	Restricted stock units		7.6				6.2				25			22.5
	Total stock-based compensation expense (1), (2)		$	8.8			$	7.4			$	29.4		$	27
Schedule of stock-based compensation expense by expense category	'
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Amount recorded in:		2014				2013				2014			2013
	Cost of services and product development		$	4			$	3.2			$	13.5		$	12
	Selling, general and administrative		4.8				4.2				15.9			15
	Total stock-based compensation expense (1), (2)		$	8.8			$	7.4			$	29.4		$	27
	-1	Includes charges of $2.9 million and $1.8 million for the three months ended September 30, 2014 and 2013, respectively, and $12.7 million and $10.6 million for the nine months ended September 30, 2014 and 2013, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis.
	-2	The nine months ended September 30, 2014 includes a reversal of $1.9 million of expense from forfeited awards related to the departure of the Company's former chief financial officer.
Schedule of fair value assumptions of SARs	'
	The fair value of the SARs was estimated on the date of grant using the Black-Scholes-Merton valuation model with the following weighted-average assumptions:
		Nine Months Ended
		September 30,
		2014			2013
	Expected dividend yield (1)	—	%		—	%
	Expected stock price volatility (2)	25	%		35	%
	Risk-free interest rate (3)	1.3	%		0.8	%
	Expected life in years (4)	4.4			4.5
	-1	The dividend yield assumption is based on the history and expectation of the Company’s dividend payouts. Historically, Gartner has not paid cash dividends on its Common Stock.
	-2	The determination of expected stock price volatility was based on both historical Common Stock prices and implied volatility from publicly traded options in the Common Stock.
	-3	The risk-free interest rate is based on the yield of a U.S. Treasury security with a maturity similar to the expected life of the award.
	-4	The expected life represents the Company’s weighted-average estimate of the period of time the SARs are expected to be outstanding (defined as the period between the service inception date and the expected exercise date), which is based on historical exercise data.
Stock appreciation rights (SARs)	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Schedule of summary of the changes in SARS, RSUs, and CSEs outstanding	'
	The following table summarizes changes in SARs outstanding during the nine months ended September 30, 2014:
		SARs			Per Share				Per Share				Weighted
		(in millions)			Weighted-				Weighted-				Average
					Average				Average				Remaining
					Exercise Price				Grant Date				Contractual
									Fair Value				Term
	Outstanding at December 31, 2013	1.6			$	34.14			$	11.63			4.34 years
	Granted	0.4			64.64				14.99				6.36 years
	Forfeited	(0.1	)		52.15				n/a				n/a
	Exercised	(0.4	)		23.72				8.73				n/a
	Outstanding at September 30, 2014 (1), (2)	1.5			$	44.01			$	13.17			4.48 years
	Vested and exercisable at September 30, 2014 (2)	0.6			$	33.05			$	11.51			3.27 years
	n/a=t applicable.
	-1	As of September 30, 2014, 0.9 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.
	-2	Total SARs outstanding had an intrinsic value of $43.2 million. SARs vested and exercisable had an intrinsic value of $25.5 million.
Restricted stock units (RSUs)	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Schedule of summary of the changes in SARS, RSUs, and CSEs outstanding	'
	The following table summarizes the changes in RSUs outstanding during the nine months ended September 30, 2014:
		Restricted			Per Share
		Stock Units			Weighted
		(RSUs)			Average
		(in millions)			Grant Date
					Fair Value
	Outstanding at December 31, 2013	1.8			$	38.83
	Granted (1)	0.5			65.3
	Vested and released	(0.8	)		34.15
	Forfeited	(0.1	)		—
	Outstanding at September 30, 2014 (2), (3)	1.4			$	50.67
	-1	The 0.5 million RSUs granted consisted of 0.2 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.2 million performance-based RSUs represents the target amount of the grant for the year, which is tied to an increase in the Company’s subscription-based research contract value (“CV”) for 2014. The final number of performance-based RSUs that will ultimately be awarded for 2014 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2014 as measured on December 31, 2014. If the specified minimum level of achievement is not met, the performance-based RSUs will be forfeited in their entirety, and any compensation expense previously recorded will be reversed.
	-2	The Company expects that substantially all of the outstanding awards will vest in future periods.
	-3	The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.3 years.
Common stock equivalents (CSEs)	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Schedule of summary of the changes in SARS, RSUs, and CSEs outstanding	'
	The following table summarizes the changes in CSEs outstanding during the nine months ended September 30, 2014:
		Common			Per Share
		Stock			Weighted
		Equivalents			Average
		(CSEs)			Grant Date
					Fair Value
	Outstanding at December 31, 2013	102,479			$	17.71
	Granted	6,614			71.86
	Converted to common shares	(5,274	)		71.86
	Outstanding at September 30, 2014	103,819			$	18.41

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Schedule of segment reporting information, by segment	'
	The following tables present information about the Company’s reportable segments for the periods indicated (in thousands):
	Three Months Ended September 30, 2014	Research			Consulting			Events		Consolidated
	Revenues	$	365,334		$	82,300		$	23,306	$	470,940
	Gross contribution	251,113			24,774			6,946		282,833
	Corporate and other expenses									(233,442		)
	Operating income									$	49,391
	Three Months Ended September 30, 2013	Research			Consulting			Events		Consolidated
	Revenues	$	316,518		$	70,149		$	24,038	$	410,705
	Gross contribution	220,329			21,114			7,095		248,538
	Corporate and other expenses									(189,795		)
	Operating income									$	58,743
	Nine Months Ended September 30, 2014	Research			Consulting			Events		Consolidated
	Revenues	$	1,071,943		$	260,059		$	105,460	$	1,437,462
	Gross contribution	745,477			91,347			44,141		880,965
	Corporate and other expenses									(690,643		)
	Operating income									$	190,322
	Nine Months Ended September 30, 2013	Research			Consulting			Events		Consolidated
	Revenues	$	938,082		$	228,710		$	96,714	$	1,263,506
	Gross contribution	648,954			76,836			37,318		763,108
	Corporate and other expenses									(576,373		)
	Operating income									$	186,735
Schedule of reconciliation of segment gross contribution to net income	'
	The following table provides a reconciliation of total segment gross contribution to net income for the periods indicated (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Total segment gross contribution	$	282,833		$	248,538		$	880,965	$	763,108
	Costs and expenses:
	Cost of services and product development - unallocated (1), (2)	(48		)	(432		)	5,561		2,978
	Selling, general and administrative	217,025			181,546			640,179		547,653
	Depreciation and amortization	10,450			8,609			28,888		25,464
	Acquisition and integration charges	6,015			72			16,015		278
	Operating income	49,391			58,743			190,322		186,735
	Interest expense and other	2,943			2,119			7,927		6,768
	Provision for income taxes	12,602			18,430			57,773		58,584
	Net income	$	33,846		$	38,194		$	124,622	$	121,383
	-1	The unallocated amounts consist of certain bonus and related fringe expenses recorded in Consolidated cost of services and product development expense that are not allocated to segment expense. The Company's policy is to only allocate bonus and related fringe charges to segments for up to 100% of the segment employee's target bonus. Amounts above 100% are absorbed by corporate.
	-2	Amounts in parentheses in the three months ended periods result from adjustments to the year-to-date balances.

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of changes to the carrying amount of goodwill by reporting unit	'
	The following table presents changes to the carrying amount of goodwill by reportable segment during the nine months ended September 30, 2014 (in thousands):
		Research				Consulting				Events				Total
	Balance, December 31, 2013 (1)	$	376,568			$	100,677			$	41,958			$	519,203
	Additions due to acquisitions (2)	78,592				—				—				78,592
	Foreign currency translation adjustments	(4,111		)		(383		)		(89		)		(4,583		)
	Balance, September 30, 2014	$	451,049			$	100,294			$	41,869			$	593,212
	-1	The Company does not have any accumulated goodwill impairment losses.
	-2	The Company made three acquisitions during the nine months ended September 30, 2014 (See Note 1 for additional discussion). All of the recorded goodwill from these acquisitions has been included in the Research segment.
Schedule of amortizable intangible assets	'
	The following tables present reconciliations of the carrying amounts of amortizable intangible assets as of the dates indicated (in thousands):
	September 30, 2014		Trade				Customer				Content				Software			Non-Compete			Total
			Name				Relationships
	Gross cost, December 31, 2013		$	6,023			10,146				3,496				2,143			$	—		$	21,808
	Additions due to acquisitions (1)		915				18,054				206				5,000			7,800			31,975
	Non-competition agreement (2)		—				—				—				—			1,500			1,500
	Foreign currency translation adjustments		(9		)		(35		)		(82		)		(290		)	(14		)	(430		)
	Gross cost		6,929				28,165				3,620				6,853			9,286			54,853
	Accumulated amortization (3)		(5,859		)		(10,371		)		(2,041		)		(2,103		)	(964		)	(21,338		)
	Balance, September 30, 2014		$	1,070			$	17,794			$	1,579			$	4,750		$	8,322		$	33,515
	December 31, 2013		Trade				Customer				Content				Software			Total
			Name				Relationships
	Gross cost, December 31, 2012		$	6,023			$	10,146			$	3,496			$	2,143		$	21,808
	Accumulated amortization (3)		(4,817		)		(8,372		)		(1,388		)		(1,124		)	(15,701		)
	Balance, December 31, 2013		$	1,206			$	1,774			$	2,108			$	1,019		$	6,107
	-1	See Note 1 for additional disclosure.
	-2	The non-competition intangible relates to a separation agreement with the Company's former chief financial officer which was entered into in June 2014.
	-3	Intangible assets are being amortized against earnings over the following periods: Trade name—2 to 5 years; Customer relationships—4 to 7 years; Content—1.5 to 4 years; Software—3 years; Non-compete—4 to 5 years.
Schedule of estimated future amortization expense by year	'
	The estimated future amortization expense by year from amortizable intangibles is as follows (in thousands):
	2014 (remaining three months)	$	2,475
	2015	8,345
	2016	6,990
	2017	5,570
	2018	4,330
	After 2018	5,805
		$	33,515

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of debt	'
	The following table provides information regarding the Company’s total outstanding borrowings (in thousands):
			Balance		Balance
			September 30,		December 31,
	Description:		2014		2013
	Term loans (1)		$	135,000	$	144,375
	Revolver loans (1), (2)		230,000		55,625
	Other (3)		5,000		5,000
	Total		$	370,000	$	205,000
	-1	The contractual annualized interest rates as of September 30, 2014 on the term loan and the revolver ranged from 1.53% to 1.61%, which consists of a floating Eurodollar base rate ranging from 0.15% to 0.23% plus a margin of 1.38%. However, the Company has an interest rate swap contract which converts the floating Eurodollar base rates to a 2.26% fixed base rate on the first $200.0 million of Company borrowings (see below) and, combined with the 1.38% margin, results in an effective rate of approximately 3.63% on the first $200.0 million of borrowings.
	The annual effective rate on the Company's total debt outstanding as of September 30, 2014, including the effect of the swap, was approximately 3.64%.
	-2	The Company had $366.6 million of available borrowing capacity on the revolver (not including the expansion feature) as of September 30, 2014.
	-3	The Company borrowed $5.0 million in 2012 through a State of Connecticut economic development program. The loan has a 10 year maturity and bears a 3.0% fixed rate of interest. Principal payments are deferred for the first five years and the loan may be repaid at any point by the Company without penalty. The loan has a principal forgiveness provision in which up to $2.5 million of the loan may be forgiven if the Company meets certain employment targets in Connecticut during the first five years of the loan.

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Schedule of share repurchase activity	'
	The Company’s recent share repurchase activity is presented in the following table:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Number of shares repurchased (1)	1,124,117		1,016,978		5,350,915		2,859,246
	Cost of repurchased shares (in thousands) (2)	$	79,678	$	59,252	$	387,126	$	157,251
	-1	The average purchase price for the shares was $72.94 and $70.67 for the three and nine months ended September 30, 2014, respectively, and $58.26 and $55.00 for the three and nine months ended September 30, 2013, respectively.
	-2	The cost of repurchased shares for the nine months ended September 30, 2014 includes payment for share repurchase transactions that occurred in late December 2013 but were paid in early January 2014.

Derivatives_and_Hedging_Tables

Derivatives and Hedging (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of notional amounts of outstanding derivative positions	'
	The following tables provide information regarding the Company’s outstanding derivatives contracts as of the dates indicated (in thousands, except for number of outstanding contracts):
	30-Sep-14
	Derivative Contract Type		Number of			Notional				Fair Value				Balance		Unrealized
			Outstanding			Amounts				Asset				Sheet		Loss Recorded
			Contracts							(Liability), Net (3)				Line Item		in OCI
	Interest rate swap (1)		1			$	200,000			$	(3,839	)		Other liabilities		$	(2,303	)
	Foreign currency forwards (2)		19			6,630				(19		)		Accrued liabilities		—
	Total		20			$	206,630			$	(3,858	)				$	(2,303	)
	31-Dec-13
	Derivative Contract Type		Number of			Notional				Fair Value				Balance		Unrealized
			Outstanding			Amounts				Asset				Sheet		Loss Recorded
			Contracts							(Liability), Net (3)				Line Item		in OCI
	Interest rate swap (1)		1			$	200,000			$	(6,505	)		Other liabilities		$	(3,903	)
	Foreign currency forwards (2)		89			61,325				(60		)		Accrued liabilities		—
	Total		90			$	261,325			$	(6,565	)				$	(3,903	)
	-1	This swap has been designated, and is accounted for, as a cash flow hedge of the forecasted interest payments on borrowings (see Note 7 — Debt). As a result, changes in fair value of this swap are deferred and are recorded in OCI, net of tax effect.
	-2	The Company has foreign exchange transaction risk since 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 offset the economic effects of these foreign currency transaction risks. These forward exchange contracts are accounted for at fair value with realized and unrealized gains and losses recognized in Other expense, net. All of the contracts outstanding at September 30, 2014 matured by the end of October 2014.
	-3	See Note 11 — Fair Value Disclosures for the determination of the fair value of these instruments.
Schedule of derivative instruments, gain (loss) in statement of financial performance	'
	The following table provides information regarding derivative gains and losses that have been recognized in the Condensed Consolidated Statements of Operations for the periods indicated (in thousands):
			Three Months Ended								Nine Months Ended
			September 30,								September 30,
	Amount recorded in:		2014				2013				2014				2013
	Interest expense, net (1)		$	1,034			$	1,034			$	3,059			$	2,981
	Other expense (income), net (2)		(12		)		(20		)		(110		)		138
	Total expense, net		$	1,022			$	1,014			$	2,949			$	3,119
	-1	Consists of interest expense from an interest rate swap contract.
	-2	Consists of realized and unrealized gains and losses on foreign currency forward contracts.

Fair_Value_Disclosures_Tables

Fair Value Disclosures (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Schedule of fair value, assets and liabilities measured on recurring basis	'
	The Company’s assets and liabilities that are remeasured to fair value are presented in the following table for the periods indicated (in thousands):
			Fair Value		Fair Value
	Description:		September 30,		December 31,
			2014		2013
	Assets:
	Values based on Level 1 inputs:
	Deferred compensation plan assets (1)		$	7,525	$	7,775
	Total Level 1 inputs		$	7,525	$	7,775
	Values based on Level 2 inputs:
	Deferred compensation plan assets (1)		$	26,185	$	24,780
	Foreign currency forward contracts (2)		7		116
	Total Level 2 inputs		$	26,192	$	24,896
	Total Assets		$	33,717	$	32,671
	Liabilities:
	Values based on level 2 inputs:
	Deferred compensation plan liabilities (1)		$	38,150	$	36,410
	Foreign currency forward contracts (2)		26		176
	Interest rate swap contract (3)		3,839		6,505
	Total Level 2 inputs		$	42,015	$	43,091
	Total Liabilities		$	42,015	$	43,091
	-1	The Company has a deferred compensation plan for the benefit of certain highly compensated employees. The assets consist of investments in money market and mutual funds, and company-owned life insurance contracts, all of which are valued based on Level 1 or Level 2 valuation 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 based on 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. Valuation of the foreign currency forward contracts is based on observable foreign currency exchange rates in active markets, which the Company considers a Level 2 input.
	-3	The Company has an interest rate swap contract which hedges the forecasted interest payments on its borrowings (see Note 7 — Debt). To determine the fair value of this over-the-counter financial instrument, the Company relies on a mark-to-market valuation prepared by a third-party broker. The valuation is based on observable interest rates from recently executed market transactions or broker quotes corroborated by other observable market data. Accordingly, the fair value of the swap is determined under a Level 2 input. The Company independently corroborates the reasonableness of the swap valuation prepared by the third-party broker through the use of an electronic quotation service.

Business_and_Basis_of_Presenta3

Business and Basis of Presentation (Detail) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

1 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Mar. 07, 2014

Mar. 31, 2014

Jun. 30, 2014

Sep. 30, 2014

31-May-14

Sep. 30, 2014

Jun. 30, 2014

Sep. 30, 2014

Oct. 31, 2014

segment

Software Advice, Inc.

Software Advice, Inc.

Software Advice, Inc.

Software Advice, Inc.

Market-Visio Oy

Market-Visio Oy

Senexx, Ltd.

Total

Subsequent event

business

employee

employee

employee

Market-Visio Oy

Organization, Consolidation and Presentation of Financial Statements [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of reportable segments

'

'

3

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of businesses acquired

'

'

3

'

'

'

'

'

'

'

'

'

'

Payments to acquired business, gross, including cash placed in escrow

'

'

'

'

'

'

'

'

'

'

$5,700,000

'

'

Number of employees

'

'

'

'

'

120

'

'

68

'

2

'

'

Business combination consideration

'

'

'

'

'

'

'

'

6,500,000

'

'

'

'

Cash payment to acquire business

'

'

112,200,000

'

'

103,200,000

'

'

4,100,000

'

4,900,000

'

'

Decrease in contingent liability

'

'

'

'

'

'

'

'

'

'

'

'

2,500,000

Escrow balance payment period

'

'

'

'

'

'

'

'

'

'

'18 months

'

'

Percentage of voting interests acquired

'

'

'

'

'

100.00%

'

'

100.00%

'

100.00%

'

'

Acquisitions cash placed in escrow

'

'

14,363,000

0

'

13,500,000

'

'

'

'

900,000

'

'

Business combination, additional obligated amount

'

'

'

'

'

31,900,000

'

'

'

'

'

'

'

Expensed liability time period

'

'

'

'

'

'2 years

'

'

'

'

'

'

'

Acquisition and integration charges

6,015,000

72,000

16,015,000

278,000

'

'

'

'

'

'

'

'

'

Goodwill adjustment increase (decrease)

'

'

'

'

'

'

2,700,000

'

'

-100,000

'

'

'

Intangible asset decrease adjustment

'

'

'

'

'

'

2,700,000

'

'

'

'

'

'

Cash acquired

'

'

'

'

'

'

'

1,450,000

'

'

'

4,653,000

'

Contingent consideration amount, maximum

3,400,000

'

3,400,000

'

'

18,400,000

'

'

'

'

'

'

'

Acquisitions - cash paid (net of cash acquired)

'

'

$107,528,000

$0

'

'

'

'

'

'

'

'

'

Goodwill deductible period

'

'

'

'

'15 years

'

'

'

'

'

'

'

'

Business_and_Basis_of_Presenta4

Business and Basis of Presentation (Detail) - Preliminary Allocation of Purchase Price) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'		'
Goodwill	$593,212		$519,203	[1]
Software Advice, Inc.	'		'
Assets:	'		'
Cash	1,450		'
Fees receivable and other current assets	3,606		'
Property, equipment, and leasehold improvements	235		'
Amortizable intangible assets	26,928	[2]	'
Goodwill	73,663	[3],[4]	'
Total assets	105,882		'
Liabilities:	'		'
Accounts payable and accrued liabilities	2,657		'
Total liabilities	2,657		'
Net assets acquired	103,225	[5]	'
Other Acquisitions	'		'
Assets:	'		'
Cash	3,203	[6]	'
Fees receivable and other current assets	3,547	[6]	'
Property, equipment, and leasehold improvements	169	[6]	'
Amortizable intangible assets	5,047	[2],[6]	'
Goodwill	4,929	[3],[4],[6]	'
Total assets	16,895	[6]	'
Liabilities:	'		'
Accounts payable and accrued liabilities	4,554	[6]	'
Total liabilities	4,554	[6]	'
Net assets acquired	12,341	[5],[6]	'
Total	'		'
Assets:	'		'
Cash	4,653		'
Fees receivable and other current assets	7,153		'
Property, equipment, and leasehold improvements	404		'
Amortizable intangible assets	31,975	[2]	'
Goodwill	78,592	[3],[4]	'
Total assets	122,777		'
Liabilities:	'		'
Accounts payable and accrued liabilities	7,211		'
Total liabilities	7,211		'
Net assets acquired	$115,566	[5]	'
[1]	The Company does not have any accumulated goodwill impairment losses.
[2]	See Note 6 - Goodwill and Intangible Assets for additional information regarding the types and amounts of amortizable intangibles recorded from the 2014 Acquisitions.
[3]	During the second quarter of 2014, the recorded amount of an amortizable intangible asset resulting from the Software Advice acquisition was reduced by $2.7 million and goodwill was increased by the same amount. This measurement period adjustment was based on a change in the underlying assumptions used to value the amortizable intangible asset and was due to the consideration of new information.
[4]	During the third quarter of 2014 certain tax, working capital and other minor adjustments were recorded which decreased the recorded goodwill resulting from the Market-Visio acquisition by approximately $0.1 million on a net basis.
[5]	The Company paid $112.2 million in cash on a gross basis for the net assets acquired through September 30, 2014. On a net basis, and for cash flow reporting, the Company paid $107.5 million through September 30, which represents the $112.2 million in cash paid on a gross basis minus the $4.7 million of cash acquired from the purchased companies. The Company has also recorded a liability for an additional $3.4 million to be paid for the 2014 Acquisitions, of which $2.5 million was paid in late October 2014.
[6]	Includes the SircleIT Inc. and Market-Visio acquisitions.

Comprehensive_Income_Detail_Ch

Comprehensive Income (Detail) - Changes in AOCI by Component (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Beginning balance	$9,953	[1]	$2,358	[1]	$8,345	[1]	$5,968	[1]
Other comprehensive income (loss) before reclassifications	-12,589	[1]	3,749	[1]	-12,226	[1]	-1,036	[1]
Reclassifications from AOCI to income	635	[1],[2],[3]	627	[1],[2],[3]	1,880	[1],[2],[3]	1,802	[1],[2],[3]
Other comprehensive (loss) income	-11,954	[1]	4,376	[1]	-10,346	[1]	766	[1]
Ending balance	-2,001	[1]	6,734	[1]	-2,001	[1]	6,734	[1]
Interest Rate Swap	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Beginning balance	-2,922	[1]	-4,635	[1]	-3,903	[1]	-6,010	[1]
Other comprehensive income (loss) before reclassifications	-1	[1]	-360	[1]	-236	[1]	-153	[1]
Reclassifications from AOCI to income	620	[1],[2],[3]	621	[1],[2],[3]	1,836	[1],[2],[3]	1,789	[1],[2],[3]
Other comprehensive (loss) income	619	[1]	261	[1]	1,600	[1]	1,636	[1]
Ending balance	-2,303	[1]	-4,374	[1]	-2,303	[1]	-4,374	[1]
Defined Benefit Pension Plans	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Beginning balance	-1,782	[1]	-1,554	[1]	-1,811	[1]	-1,578	[1]
Other comprehensive income (loss) before reclassifications	0	[1]	0	[1]	0	[1]	17	[1]
Reclassifications from AOCI to income	15	[1],[2],[3]	6	[1],[2],[3]	44	[1],[2],[3]	13	[1],[2],[3]
Other comprehensive (loss) income	15	[1]	6	[1]	44	[1]	30	[1]
Ending balance	-1,767	[1]	-1,548	[1]	-1,767	[1]	-1,548	[1]
Foreign Currency Translation Adjustments	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Beginning balance	14,657	[1]	8,547	[1]	14,059	[1]	13,556	[1]
Other comprehensive income (loss) before reclassifications	-12,588	[1]	4,109	[1]	-11,990	[1]	-900	[1]
Reclassifications from AOCI to income	0	[1],[2],[3]	0	[1],[2],[3]	0	[1],[2],[3]	0	[1],[2],[3]
Other comprehensive (loss) income	-12,588	[1]	4,109	[1]	-11,990	[1]	-900	[1]
Ending balance	$2,069	[1]	$12,656	[1]	$2,069	[1]	$12,656	[1]
[1]	Amounts in parentheses represent debits (deferred losses).
[2]	The reclassifications related to defined benefit pension plans were recorded in Selling, general and administrative expense and had an immaterial tax effect for both periods. See Note 12 – Employee Benefits for information regarding the Company’s defined benefit pension plans.
[3]	The reclassifications related to the interest rate swap (cash flow hedge) were recorded in Interest expense and exclude a related tax benefit reflected in the Provision for income taxes. See Note 10 – Derivatives and Hedging for information regarding the hedge.

Earnings_per_Share_Detail

Earnings per Share (Detail)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share (less than .4 million in all periods)	0.4	0.4	0.4	0.4

Earnings_per_Share_Detail_Calc

Earnings per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share (USD $)	3 Months Ended				9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Numerator:	'		'		'		'
Net income used for calculating basic and diluted earnings per share	$33,846		$38,194		$124,622		$121,383
Denominator:	'		'		'		'
Weighted average number of common shares used in the calculation of basic earnings per share	88,513		92,689		89,901		93,286
Common stock equivalents associated with stock-based compensation plans	1,195	[1]	1,666	[1]	1,372	[1]	1,814	[1]
Shares used in the calculation of diluted earnings per share	89,708		94,355		91,273		95,100
Basic earnings per share (in Dollars per share)	$0.38		$0.41		$1.39		$1.30
Diluted earnings per share (in Dollars per share)	$0.38		$0.40		$1.37		$1.28
[1]	Certain common stock equivalents were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive. These shares totaled less than 0.4 million in each of the periods presented.

StockBased_Compensation_Detail

Stock-Based Compensation (Detail) (USD $)

9 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

29-May-14

29-May-14

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Stock appreciation rights (SARs)

Stock appreciation rights (SARs)

Restricted stock units (RSUs)

Restricted stock units (RSUs)

Restricted stock units (RSUs)

Restricted stock units (RSUs)

Performance-based RSUs

Common stock equivalents (CSEs)

Common stock equivalents (CSEs)

Target amount

Target amount

2014 Long-Term Incentive Plan

2014 Long-Term Incentive Plan

Unvested

Employee stock purchase plan

Employee stock purchase plan

Executive officer

Non executive

Restricted stock units (RSUs)

Restricted stock units (RSUs)

Stock appreciation rights (SARs)

Executive officer

Executive officer

Minimum

Maximum

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of transferred shares authorized

'

'

'

'

'

'

'

'

'

'

'

'

'

5,800,000

'

'

'

'

Number of additional shares authorized

'

'

'

'

'

'

'

'

'

'

'

'

'

2,200,000

'

'

'

'

Number of shares authorized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8,000,000

'

'

'

Number of shares available for grant

7,960,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock par value (in Dollars per share)

$0.00

$0.00

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total share-based compensation cost not yet recognized

$51,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Award vesting period

'

'

'4 years

'

'4 years

'

'

'

'4 years

'

'

'

'

'

'

'

'

'

Award expiry period from date of grant

'

'

'7 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total compensation cost not yet recognized, period for recognition

'2 years 3 months 18 days

'

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding shares unvested

'

'

1,500,000

[1],[2]

1,600,000

1,400,000

[3],[4]

1,800,000

'

'

'

103,819

102,479

'

'

'

'

900,000

'

'

Aggregate Intrinsic value of outstanding shares

'

'

43,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate intrinsic value of shares vested and exercisable

'

'

25,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock grants during period

'

'

400,000

'

500,000

[5]

'

200,000

300,000

'

6,614

'

'

'

'

'

'

'

'

Percentage of shares authorized for grant

'

'

'

'

'

'

'

'

'

'

'

0.00%

200.00%

'

'

'

'

'

Weighted average remaining contractual terms

'

'

'4 years 4 months 53 days

[1],[2]

'4 years 4 months 2 days

'1 year 4 months 3 days

'

'

'

'

'

'

'

'

'

'

'

'

'

Base fee percentage

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

'

'

'

'

Employee stock purchase plan, stock purchases as percentage of employee compensation maximum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

Maximum share value authorized for purchase under employee stock purchase plan

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

23,750

'

Exercisable price percentage of closing price of another class of stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

95.00%

'

Maximum number of shares that may be purchased by eligible participants

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,100,000

'

Proceeds from stock plans

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$6,400,000

$4,500,000

[1]

As of September 30, 2014, 0.9 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.

[2]

Total SARs outstanding had an intrinsic value of $43.2 million. SARs vested and exercisable had an intrinsic value of $25.5 million.

[3]

The Company expects that substantially all of the outstanding awards will vest in future periods.

[4]

The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.3 years.

[5]

The 0.5 million RSUs granted consisted of 0.2 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.2 million performance-based RSUs represents the target amount of the grant for the year, which is tied to an increase in the Company’s subscription-based research contract value (“CV”) for 2014. The final number of performance-based RSUs that will ultimately be awarded for 2014 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2014 as measured on December 31, 2014. If the specified minimum level of achievement is not met, the performance-based RSUs will be forfeited in their entirety, and any compensation expense previously recorded will be reversed.

StockBased_Compensation_Detail1

Stock-Based Compensation (Detail) - Stock-Based Compensation Expense By Award Type (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	$8,800,000	[1],[2]	$7,400,000	[1],[2]	$29,400,000	[1],[2]	$27,049,000	[1],[2]
Stock-based compensation expense reversal forfeited awards	'		'		1,900,000		'
Retirement eligible employees equity award	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	2,900,000		1,800,000		12,700,000		10,600,000
Stock appreciation rights (SARs)	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	1,000,000		1,100,000		3,900,000		4,100,000
Common stock equivalents (CSEs)	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	200,000		100,000		500,000		400,000
Restricted stock units (RSUs)	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	$7,600,000		$6,200,000		$25,000,000		$22,500,000
[1]	Includes charges of $2.9 million and $1.8 million for the three months ended September 30, 2014 and 2013, respectively, and $12.7 million and $10.6 million for the nine months ended September 30, 2014 and 2013, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis.
[2]	The nine months ended September 30, 2014 includes a reversal of $1.9 million of expense from forfeited awards related to the departure of the Company's former chief financial officer.

StockBased_Compensation_Detail2

Stock-Based Compensation (Detail) - Stock-Based Compensation Expense Recognized In Consolidated Statements Of Operations (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	$8,800	[1],[2]	$7,400	[1],[2]	$29,400	[1],[2]	$27,049	[1],[2]
Cost of services and product development	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	4,000		3,200		13,500		12,000
Selling, general and administrative	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Total stock-based compensation expense	$4,800		$4,200		$15,900		$15,000
[1]	Includes charges of $2.9 million and $1.8 million for the three months ended September 30, 2014 and 2013, respectively, and $12.7 million and $10.6 million for the nine months ended September 30, 2014 and 2013, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis.
[2]	The nine months ended September 30, 2014 includes a reversal of $1.9 million of expense from forfeited awards related to the departure of the Company's former chief financial officer.

StockBased_Compensation_Detail3

Stock-Based Compensation (Detail) - Summary Of Changes In SARs Outstanding (Stock appreciation rights (SARs), USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
Stock appreciation rights (SARs)	'		'
SARs [Roll Forward]	'		'
Outstanding at December 31, 2013 (in shares)	1,600,000		'
Granted (in shares)	400,000		'
Forfeited (in shares)	-100,000		'
Exercised (in shares)	-400,000		'
Outstanding at June 30, 2014 (in shares)	1,500,000	[1],[2]	1,600,000
Vested and exercisable at March 31, 2014 (in shares)	600,000	[2]	'
Per Share Weighted- Average Exercise Price [Roll Forward]	'		'
Outstanding at December 31, 2013 (in Dollars per share)	$34.14		'
Granted (in Dollars per share)	$64.64		'
Forfeited (in Dollars per share)	$52.15		'
Exercised (in Dollars per share)	$23.72		'
Outstanding at June 30, 2014 (in Dollars per share)	$44.01	[1],[2]	$34.14
Vested and exercisable at June 30, 2014 (in Dollars per share)	$33.05	[2]	'
Per Share Weighted Average Grant Date Fair Value [Roll Forward]	'		'
Outstanding at December 31, 2013 (in Dollars per share)	$11.63		'
Granted (in Dollars per share)	$14.99		'
Exercised (in Dollars per share)	$8.73		'
Outstanding at June 30, 2014 (in Dollars per share)	$13.17	[1],[2]	$11.63
Vested and exercisable at June 30, 2014 (in Dollars per share)	$11.51	[2]	'
Weighted Average Remaining Contractual Term [Roll Forward]	'		'
Outstanding at December 31, 2013	'4 years 4 months 53 days	[1],[2]	'4 years 4 months 2 days
Granted	'6 years 3 months 39 days		'
Outstanding at June 30, 2014	'4 years 4 months 53 days	[1],[2]	'4 years 4 months 2 days
Vested and exercisable at June 30, 2014	'2 years 12 months 98 days	[2]	'
[1]	As of September 30, 2014, 0.9 million of the SARs outstanding were unvested. The Company expects that substantially all of these unvested awards will vest in future periods.
[2]	Total SARs outstanding had an intrinsic value of $43.2 million. SARs vested and exercisable had an intrinsic value of $25.5 million.

StockBased_Compensation_Detail4

Stock-Based Compensation (Detail) - Weighted-Average Assumptions Used To Determine Fair Value Of SARs Grants On Date Of Grant Using Black-Scholes-Merton Valuation Model (Stock appreciation rights (SARs))	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Stock appreciation rights (SARs)	'		'
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]	'		'
Expected dividend yield	0.00%	[1]	0.00%	[1]
Expected stock price volatility	25.00%	[2]	35.00%	[2]
Risk-free interest rate	1.30%	[3]	0.80%	[3]
Expected life in years	'4 years 5 months	[4]	'4 years 6 months	[4]
[1]	The dividend yield assumption is based on the history and expectation of the Company’s dividend payouts. Historically, Gartner has not paid cash dividends on its Common Stock.
[2]	The determination of expected stock price volatility was based on both historical Common Stock prices and implied volatility from publicly traded options in the Common Stock.
[3]	The risk-free interest rate is based on the yield of a U.S. Treasury security with a maturity similar to the expected life of the award.
[4]	The expected life represents the Company’s weighted-average estimate of the period of time the SARs are expected to be outstanding (defined as the period between the service inception date and the expected exercise date), which is based on historical exercise data.

StockBased_Compensation_Detail5

Stock-Based Compensation (Detail) - Summary Of Changes In RSUs Outstanding (Restricted stock units (RSUs), USD $)	9 Months Ended
	Sep. 30, 2014
Restricted stock units (RSUs)	'
Restricted Stock Units (RSUs) [Roll Forward]	'
Outstanding at December 31, 2013 (in shares)	1,800,000
Granted (in shares)	500,000	[1]
Vested and released (in shares)	-800,000
Forfeited (in shares)	-100,000
Outstanding at June 30, 2014 (in shares)	1,400,000	[2],[3]
Per Share Weighted Average Grant Date Fair Value [Roll Forward]	'
Outstanding at December 31, 2013 (in Dollars per share)	$38.83
Granted (in Dollars per share)	$65.30	[1]
Vested and released (in Dollars per share)	$34.15
Forfeited (in Dollars per share)	$0
Outstanding at June 30, 2014 (in Dollars per share)	$50.67	[2],[3]
[1]	The 0.5 million RSUs granted consisted of 0.2 million performance-based RSUs awarded to executives and 0.3 million service-based RSUs awarded to non-executive employees and certain board members. The 0.2 million performance-based RSUs represents the target amount of the grant for the year, which is tied to an increase in the Company’s subscription-based research contract value (“CV”) for 2014. The final number of performance-based RSUs that will ultimately be awarded for 2014 ranges from 0% to 200% of the target amount, with the final number dependent on the actual increase in CV for 2014 as measured on December 31, 2014. If the specified minimum level of achievement is not met, the performance-based RSUs will be forfeited in their entirety, and any compensation expense previously recorded will be reversed.
[2]	The Company expects that substantially all of the outstanding awards will vest in future periods.
[3]	The weighted-average remaining contractual term of the outstanding RSUs is approximately 1.3 years.

StockBased_Compensation_Detail6

Stock-Based Compensation (Detail) - Summary Of Changes In CSEs Outstanding (Common stock equivalents (CSEs), USD $)	9 Months Ended
	Sep. 30, 2014
Common stock equivalents (CSEs)	'
Common Stock Equivalents (CSEs) [Roll Forward]	'
Outstanding at December 31, 2013 (in shares)	102,479
Granted (in shares)	6,614
Converted to common shares (in shares)	-5,274
Outstanding at June 30, 2014 (in shares)	103,819
Per Share Weighted Average Grant Date Fair Value [Roll Forward]	'
Outstanding at December 31, 2013 (in Dollars per share)	$17.71
Granted (in Dollars per share)	$71.86
Converted to common shares (in Dollars per share)	$71.86
Outstanding at June 30, 2014 (in Dollars per share)	$18.41

Segment_Information_Details_In

Segment Information (Details) - Information About Reportable Segments (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
			segment
Segment Reporting Information [Line Items]	'	'	'	'
Number of reportable segments	'	'	3	'
Revenues	$470,940	$410,705	$1,437,462	$1,263,506
Gross contribution	282,833	248,538	880,965	763,108
Corporate and other expenses	-233,442	-189,795	-690,643	-576,373
Operating income	49,391	58,743	190,322	186,735
Research	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	365,334	316,518	1,071,943	938,082
Gross contribution	251,113	220,329	745,477	648,954
Consulting	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	82,300	70,149	260,059	228,710
Gross contribution	24,774	21,114	91,347	76,836
Events	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	23,306	24,038	105,460	96,714
Gross contribution	$6,946	$7,095	$44,141	$37,318

Segment_Information_Details_Re

Segment Information (Details) - Reconciliation of Segment Gross Contribution to Net Income (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Total segment gross contribution	$282,833		$248,538		$880,965		$763,108
Costs and expenses:	'		'		'		'
Selling, general and administrative	217,025		181,546		640,179		547,653
Acquisition and integration charges	6,015		72		16,015		278
Operating income	49,391		58,743		190,322		186,735
Provision for income taxes	12,602		18,430		57,773		58,584
Net income	33,846		38,194		124,622		121,383
Reportable segments	'		'		'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Total segment gross contribution	282,833		248,538		880,965		763,108
Costs and expenses:	'		'		'		'
Selling, general and administrative	217,025		181,546		640,179		547,653
Depreciation and amortization	10,450		8,609		28,888		25,464
Acquisition and integration charges	6,015		72		16,015		278
Operating income	49,391		58,743		190,322		186,735
Interest expense and other	2,943		2,119		7,927		6,768
Provision for income taxes	12,602		18,430		57,773		58,584
Net income	33,846		38,194		124,622		121,383
Reportable segments | Maximum	'		'		'		'
Costs and expenses:	'		'		'		'
Percent of target bonus allocated to segments	'		'		100.00%		'
Unallocated amount to segments	'		'		'		'
Costs and expenses:	'		'		'		'
Cost of services and product development - unallocated	($48)	[1],[2]	($432)	[1],[2]	$5,561	[1],[2]	$2,978	[1],[2]
[1]	The unallocated amounts consist of certain bonus and related fringe expenses recorded in Consolidated cost of services and product development expense that are not allocated to segment expense. The Company's policy is to only allocate bonus and related fringe charges to segments for up to 100% of the segment employee's target bonus. Amounts above 100% are absorbed by corporate.
[2]	Amounts in parentheses in the three months ended periods result from adjustments to the year-to-date balances.

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
			business
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of businesses acquired	'	'	3	'
Amortization of intangibles	$2,505	$1,351	$5,763	$4,089
Software	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'3 years	'
Minimum | Trade Name	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'2 years	'
Minimum | Customer Relationships	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'4 years	'
Minimum | Content	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'1 year 6 months	'
Minimum | Non-Compete	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'4 years	'
Maximum | Trade Name	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'5 years	'
Maximum | Customer Relationships	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'7 years	'
Maximum | Content	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'4 years	'
Maximum | Non-Compete	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Finite-lived intangible assets useful life	'	'	'5 years	'

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets (Detail) - Changes to Carrying Amount of Goodwill by Reporting Unit (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014
Goodwill [Roll Forward]	'
Balance, December 31, 2013	$519,203	[1]
Addition due to acquisition	78,592	[2]
Foreign currency translation adjustments and other	-4,583
Balance, September 30, 2014	593,212
Research	'
Goodwill [Roll Forward]	'
Balance, December 31, 2013	376,568	[1]
Foreign currency translation adjustments and other	-4,111
Balance, September 30, 2014	451,049
Consulting	'
Goodwill [Roll Forward]	'
Balance, December 31, 2013	100,677	[1]
Addition due to acquisition	0	[2]
Foreign currency translation adjustments and other	-383
Balance, September 30, 2014	100,294
Events	'
Goodwill [Roll Forward]	'
Balance, December 31, 2013	41,958	[1]
Addition due to acquisition	0	[2]
Foreign currency translation adjustments and other	-89
Balance, September 30, 2014	$41,869
[1]	The Company does not have any accumulated goodwill impairment losses.
[2]	The Company made three acquisitions during the nine months ended September 30, 2014 (See Note 1 for additional discussion). All of the recorded goodwill from these acquisitions has been included in the Research segment.

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets (Detail) - Carrying Amounts of Amortizable Intangible Assets (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	$21,808		'
Additions due to acquisition	31,975	[1]	'
Amortization of intangibles	1,500	[2]	'
Foreign currency translation adjustments	-430		'
Gross carrying amount	54,853		'
Accumulated amortization	-21,338	[3]	-15,701	[3]
Finite-lived intangible assets, net	33,515		6,107
Trade Name	'		'
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	6,023		'
Additions due to acquisition	915	[1]	'
Amortization of intangibles	0	[2]	'
Foreign currency translation adjustments	-9		'
Gross carrying amount	6,929		'
Accumulated amortization	-5,859	[3]	-4,817	[3]
Finite-lived intangible assets, net	1,070		1,206
Customer Relationships	'		'
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	10,146		'
Additions due to acquisition	18,054	[1]	'
Amortization of intangibles	0	[2]	'
Foreign currency translation adjustments	-35		'
Gross carrying amount	28,165		'
Accumulated amortization	-10,371	[3]	-8,372	[3]
Finite-lived intangible assets, net	17,794		1,774
Content	'		'
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	3,496		'
Additions due to acquisition	206	[1]	'
Amortization of intangibles	0	[2]	'
Foreign currency translation adjustments	-82		'
Gross carrying amount	3,620		'
Accumulated amortization	-2,041	[3]	-1,388	[3]
Finite-lived intangible assets, net	1,579		2,108
Software	'		'
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	2,143		'
Additions due to acquisition	5,000	[1]	'
Amortization of intangibles	0	[2]	'
Foreign currency translation adjustments	-290		'
Gross carrying amount	6,853		'
Accumulated amortization	-2,103	[3]	-1,124	[3]
Finite-lived intangible assets, net	4,750		1,019
Non-Compete	'		'
Finite-lived Intangible Assets [Roll Forward]	'		'
Gross carrying amount	0		'
Additions due to acquisition	7,800	[1]	'
Amortization of intangibles	1,500	[2]	'
Foreign currency translation adjustments	-14		'
Gross carrying amount	9,286		'
Accumulated amortization	-964	[3]	'
Finite-lived intangible assets, net	$8,322		'
[1]	See Note 1 for additional disclosure.
[2]	The non-competition intangible relates to a separation agreement with the Company's former chief financial officer which was entered into in June 2014.
[3]	Intangible assets are being amortized against earnings over the following periods: Trade name—2 to 5 years; Customer relationships—4 to 7 years; Content—1.5 to 4 years; Software—3 years; Non-compete—4 to 5 years.

Goodwill_and_Intangible_Assets5

Goodwill and Intangible Assets (Detail) - Estimated Future Amortization Expense By Year From Amortizable Intangibles (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
2014 (remaining three months)	$2,475	'
2015	8,345	'
2016	6,990	'
2017	5,570	'
2018	4,330	'
After 2018	5,805	'
Finite-lived intangible assets, net	$33,515	$6,107

Debt_Detail

Debt (Detail) (USD $)

9 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Interest rate swap

Federal Funds rate

Term loans

Revolver loans

Revolver loans

Connecticut Economic Development Program

Minimum

Minimum

Maximum

Maximum

Euro Dollar rate

Euro Dollar rate

quarter

Letter of credit

Term loans

Term loans

Federal Funds rate

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instruments, maturity duration

'

'

'

'

'5 years

'

'

'

'

'

'

'

'

'

Line of credit facility, maximum borrowing capacity

'

'

'

'

$150,000,000

$600,000,000

$40,000,000

$5,000,000

'

'

'

'

'

'

Line of credit facility, additional borrowing capacity

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, frequency of payments

'

'

'

'

16

'

'

'

'

'

'

'

'

'

Debt instrument, maturity date

'

'

'

'

7-Mar-18

7-Mar-18

'

'

'

'

'

'

'

'

Debt instrument, interest, additional interest above federal fund rate

'

'

'

0.50%

'

'

'

'

'

'

'

'

'

'

Debt instrument, period principal payments are deferred

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

Debt Instrument, interest, additional interest above eurodollar rate

1.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum applicable margin rate

'

'

'

'

'

'

'

'

'

'

'

'

1.25%

0.25%

Maximum applicable margin rate

'

'

'

'

'

'

'

'

'

'

'

'

1.75%

0.75%

Debt Instrument, interest rate increase

2.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Contractual annualized interest rate

'

'

'

'

'

'

'

'

'

1.53%

[1]

'

1.61%

[1]

'

'

Floating Eurodollar Based Rate

'

'

'

'

'

'

'

'

0.15%

'

0.23%

'

'

'

Debt instrument, interest, additional interest above base rate

'

'

'

'

1.38%

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate, Effective Percentage, Initial $200 million Borrowed

3.63%

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative, fixed interest rate

'

'

2.26%

'

'

'

'

'

'

'

'

'

'

'

Notional amount of interest rate derivatives

206,630,000

261,325,000

200,000,000

'

'

'

'

'

'

'

'

'

'

'

Debt instrument, interest rate at period end

3.64%

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, remaining borrowing capacity

366,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument, maturity period

'

'

'

'

'

'

'

'10 years

'

'

'

'

'

'

Debt instrument, fixed interest rate

'

'

'

'

'

'

'

3.00%

'

'

'

'

'

'

Line of credit facility, decrease, forgiveness

'

'

'

'

'

'

'

2,500,000

'

'

'

'

'

'

Debt instrument, forgiveness period under the terms of the loan

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

Interest rate, fair value hedge derivative at fair value, net (negative fair value)

'

'

3,800,000

'

'

'

'

'

'

'

'

'

'

'

Letters of credit outstanding, amount

$9,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

The contractual annualized interest rates as of September 30, 2014 on the term loan and the revolver ranged from 1.53% to 1.61%, which consists of a floating Eurodollar base rate ranging from 0.15% to 0.23% plus a margin of 1.38%. However, the Company has an interest rate swap contract which converts the floating Eurodollar base rates to a 2.26% fixed base rate on the first $200.0 million of Company borrowings (see below) and, combined with the 1.38% margin, results in an effective rate of approximately 3.63% on the first $200.0 million of borrowings. The annual effective rate on the Company's total debt outstanding as of September 30, 2014, including the effect of the swap, was approximately 3.64%.

Debt_Detail_Borrowings

Debt (Detail) - Borrowings (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'		'
Amount Outstanding	$370,000		$205,000
Term loans	'		'
Debt Instrument [Line Items]	'		'
Amount Outstanding	135,000	[1]	144,375	[1]
Revolver loans	'		'
Debt Instrument [Line Items]	'		'
Amount Outstanding	230,000	[1],[2]	55,625	[1],[2]
Other	'		'
Debt Instrument [Line Items]	'		'
Amount Outstanding	$5,000	[3]	$5,000	[3]
[1]	The contractual annualized interest rates as of September 30, 2014 on the term loan and the revolver ranged from 1.53% to 1.61%, which consists of a floating Eurodollar base rate ranging from 0.15% to 0.23% plus a margin of 1.38%. However, the Company has an interest rate swap contract which converts the floating Eurodollar base rates to a 2.26% fixed base rate on the first $200.0 million of Company borrowings (see below) and, combined with the 1.38% margin, results in an effective rate of approximately 3.63% on the first $200.0 million of borrowings. The annual effective rate on the Company's total debt outstanding as of September 30, 2014, including the effect of the swap, was approximately 3.64%.
[2]	The Company had $366.6 million of available borrowing capacity on the revolver (not including the expansion feature) as of September 30, 2014.
[3]	The Company borrowed $5.0 million in 2012 through a State of Connecticut economic development program. The loan has a 10 year maturity and bears a 3.0% fixed rate of interest. Principal payments are deferred for the first five years and the loan may be repaid at any point by the Company without penalty. The loan has a principal forgiveness provision in which up to $2.5 million of the loan may be forgiven if the Company meets certain employment targets in Connecticut during the first five years of the loan.

Equity_Detail

Equity (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Feb. 04, 2014	Feb. 03, 2014
Stockholders' Equity Note [Abstract]	'	'	'	'	'	'
Stock repurchase program, authorized amount	'	'	'	'	$800,000,000	$500,000,000
Treasury stock, average price paid per share (in Dollars per share)	$72.94	$58.26	$70.67	$55	'	'

Equity_Detail_Share_Repurchase

Equity (Detail) - Share Repurchase Activity (USD $)	3 Months Ended				9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Stockholders' Equity Note [Abstract]	'		'		'		'
Number of shares repurchased	1,124,117	[1]	1,016,978	[1]	5,350,915	[1]	2,859,246	[1]
Cost of repurchased shares	$79,678	[2]	$59,252	[2]	$387,126	[2]	$157,251	[2]
[1]	The average purchase price for the shares was $72.94 and $70.67 for the three and nine months ended September 30, 2014, respectively, and $58.26 and $55.00 for the three and nine months ended September 30, 2013, respectively.
[2]	The cost of repurchased shares for the nine months ended September 30, 2014 includes payment for share repurchase transactions that occurred in late December 2013 but were paid in early January 2014.

Income_Taxes_Detail

Income Taxes (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'	'	'	'	'
Provision for income taxes	$12,602,000	$18,430,000	$57,773,000	$58,584,000	'
Effective income tax rate	27.10%	32.50%	31.70%	32.60%	'
Unrecognized tax benefits	18,900,000	'	18,900,000	'	14,500,000
Unrecognized tax benefits reductions resulting from settlements with taxing authorities and lapse of applicable statute of limitations	'	'	$5,000,000	'	'

Derivatives_and_Hedging_Detail

Derivatives and Hedging (Detail) - Outstanding Derivatives Contracts (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
	outstanding_contract		outstanding_contract
Derivatives, Fair Value [Line Items]	'		'
Number of Outstanding Contracts	20		90
Notional Amounts	$206,630,000		$261,325,000
Fair Value Asset (Liability), Net	-3,858,000	[1]	-6,565,000	[1]
Unrealized Loss Recorded in OCI	-2,303,000		-3,903,000
Interest rate swap	'		'
Derivatives, Fair Value [Line Items]	'		'
Notional Amounts	200,000,000		'
Foreign currency forwards	'		'
Derivatives, Fair Value [Line Items]	'		'
Unrealized Loss Recorded in OCI	0	[2]	0	[2]
Accrued liabilities | Foreign currency forwards	'		'
Derivatives, Fair Value [Line Items]	'		'
Number of Outstanding Contracts	19	[2]	89	[2]
Notional Amounts	6,630,000	[2]	61,325,000	[2]
Fair Value Asset (Liability), Net	-19,000	[1],[2]	-60,000	[1],[2]
Designated as hedging instrument | Interest rate swap	'		'
Derivatives, Fair Value [Line Items]	'		'
Unrealized Loss Recorded in OCI	-2,303,000	[3]	-3,903,000	[3]
Designated as hedging instrument | Other liabilities | Interest rate swap	'		'
Derivatives, Fair Value [Line Items]	'		'
Number of Outstanding Contracts	1	[3]	1	[3]
Notional Amounts	200,000,000	[3]	200,000,000	[3]
Fair Value Asset (Liability), Net	($3,839,000)	[1],[3]	($6,505,000)	[1],[3]
[1]	See Note 11 — Fair Value Disclosures for the determination of the fair value of these instruments.
[2]	The Company has foreign exchange transaction risk since 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 offset the economic effects of these foreign currency transaction risks. These forward exchange contracts are accounted for at fair value with realized and unrealized gains and losses recognized in Other expense, net. All of the contracts outstanding at September 30, 2014 matured by the end of October 2014.
[3]	This swap has been designated, and is accounted for, as a cash flow hedge of the forecasted interest payments on borrowings (see Note 7 — Debt). As a result, changes in fair value of this swap are deferred and are recorded in OCI, net of tax effect.

Derivatives_and_Hedging_Detail1

Derivatives and Hedging (Detail) - Derivative Gains And Losses That Have Been Recognized In Condensed Consolidated Statements Of Operations (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'		'		'		'
Derivative instruments gain (loss) recognized in income, net	$1,022		$1,014		$2,949		$3,119
Interest expense, net	'		'		'		'
Derivative Instruments, Gain (Loss) [Line Items]	'		'		'		'
Derivative instruments gain (loss) recognized in income, net	1,034	[1]	1,034	[1]	3,059	[1]	2,981	[1]
Other expense (income), net	'		'		'		'
Derivative Instruments, Gain (Loss) [Line Items]	'		'		'		'
Derivative instruments gain (loss) recognized in income, net	($12)	[2]	($20)	[2]	($110)	[2]	$138	[2]
[1]	Consists of interest expense from an interest rate swap contract.
[2]	Consists of realized and unrealized gains and losses on foreign currency forward contracts.

Fair_Value_Disclosures_Detail_

Fair Value Disclosures (Detail) - Assets And Liabilities Measured At Fair Value On Recurring Basis (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'		'
Assets measured at fair value on a recurring basis	$33,717		$32,671
Fair Value, Inputs, Level 1 | Deferred compensation plan assets	'		'
Assets:	'		'
Assets measured at fair value on a recurring basis	7,525		7,775
Fair Value, Inputs, Level 2	'		'
Assets:	'		'
Assets measured at fair value on a recurring basis	26,192		24,896
Liabilities:	'		'
Liabilities measured at fair value on a recurring basis	42,015		43,091
Fair Value, Inputs, Level 2 | Foreign currency forward contracts	'		'
Assets:	'		'
Assets measured at fair value on a recurring basis	7	[1]	116	[1]
Liabilities:	'		'
Liabilities measured at fair value on a recurring basis	26	[1]	176	[1]
Fair Value, Inputs, Level 2 | Interest rate swap contract	'		'
Liabilities:	'		'
Liabilities measured at fair value on a recurring basis	3,839	[2]	6,505	[2]
Fair Value, Inputs, Level 2 | Deferred compensation plan assets	'		'
Assets:	'		'
Assets measured at fair value on a recurring basis	26,185	[3]	24,780	[3]
Fair Value, Inputs, Level 2 | Deferred compensation plan liabilities	'		'
Liabilities:	'		'
Liabilities measured at fair value on a recurring basis	$38,150	[3]	$36,410	[3]
[1]	The Company enters into foreign currency forward exchange contracts to hedge the effects of adverse fluctuations in foreign currency exchange rates. Valuation of the foreign currency forward contracts is based on observable foreign currency exchange rates in active markets, which the Company considers a Level 2 input.
[2]	The Company has an interest rate swap contract which hedges the forecasted interest payments on its borrowings (see Note 7 — Debt). To determine the fair value of this over-the-counter financial instrument, the Company relies on a mark-to-market valuation prepared by a third-party broker. The valuation is based on observable interest rates from recently executed market transactions or broker quotes corroborated by other observable market data. Accordingly, the fair value of the swap is determined under a Level 2 input. The Company independently corroborates the reasonableness of the swap valuation prepared by the third-party broker through the use of an electronic quotation service.
[3]	The Company has a deferred compensation plan for the benefit of certain highly compensated employees. The assets consist of investments in money market and mutual funds, and company-owned life insurance contracts, all of which are valued based on Level 1 or Level 2 valuation 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 based on a Level 2 input.

Employee_Benefits_Detail

Employee Benefits (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Compensation and Retirement Disclosure [Abstract]	'	'	'	'
Net periodic pension expense	$0.80	$0.80	$2.30	$2.40