Forrester Research (FORR) 10-K 8 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 04, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	FORR
Entity Registrant Name	FORRESTER RESEARCH, INC.
Entity Central Index Key	1,023,313
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		18,411,000
Entity Public Float			$ 424,000,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 140,296	$ 79,790
Marketable investments (Note 4)		54,333
Accounts receivable, net (Note 13)	67,318	70,023
Deferred commissions	15,677	13,731
Prepaid expenses and other current assets	12,802	18,942
Total current assets	236,093	236,819
Property and equipment, net (Note 13)	22,005	25,249
Goodwill (Note 3)	85,165	76,169
Intangible assets, net (Note 3)	4,951	732
Other assets	5,310	6,231
Total assets	353,524	345,200
Current Liabilities:
Accounts payable	588	217
Accrued expenses and other current liabilities (Note 13)	54,065	49,629
Deferred revenue	135,332	145,207
Total current liabilities	189,985	195,053
Non-current liabilities	11,939	8,958
Total liabilities	201,924	204,011
Commitments (Note 8)
Stockholders' Equity (Note 9):
Preferred stock, $0.01 par value Authorized - 500 shares; issued and outstanding - none
Common stock, $0.01 par value Authorized - 125,000 shares Issued - 22,951 and 22,432 shares as of December 31, 2018 and 2017, respectively Outstanding - 18,320 and 18,041 shares as of December 31, 2018 and 2017, respectively	230	224
Additional paid-in capital	200,696	181,910
Retained earnings	127,717	123,010
Treasury stock - 4,631 and 4,391 shares as of December 31, 2018 and 2017, respectively, at cost	(171,889)	(161,943)
Accumulated other comprehensive loss	(5,154)	(2,012)
Total stockholders’ equity	151,600	141,189
Total liabilities and stockholders’ equity	$ 353,524	$ 345,200

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	500,000	500,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	22,951,000	22,432,000
Common stock, shares outstanding	18,320,000	18,041,000
Treasury stock, shares	4,631,000	4,391,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total revenues	$ 357,575	$ 337,673	$ 326,095
Operating expenses:
Selling and marketing	131,824	123,917	116,898
General and administrative	43,920	41,906	40,579
Depreciation	7,955	6,648	7,812
Amortization of intangible assets	1,162	781	831
Acquisition and integration costs	3,787
Reorganization costs			1,026
Total operating expenses	335,150	310,124	295,321
Income from operations	22,425	27,549	30,774
Other income, net	674	301	740
Gains (losses) on investments, net	426	(479)	(805)
Income before income taxes	23,525	27,371	30,709
Income tax provision	8,145	12,231	13,058
Net income	$ 15,380	$ 15,140	$ 17,651
Basic income per common share	$ 0.85	$ 0.84	$ 0.98
Diluted income per common share	$ 0.84	$ 0.83	$ 0.97
Basic weighted average common shares outstanding	18,091	17,919	17,984
Diluted weighted average common shares outstanding	18,380	18,240	18,269
Research Services [Member]
Revenues:
Total revenues	$ 228,399	$ 216,471	$ 215,216
Advisory Services and Events [Member]
Revenues:
Total revenues	129,176	121,202	110,879
Cost of Services and Fulfillment [Member]
Operating expenses:
Cost of services and fulfillment	$ 146,502	$ 136,872	$ 128,175

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 15,380	$ 15,140	$ 17,651
Other comprehensive income (loss), net of taxes:
Foreign currency translation	(3,257)	5,593	(2,764)
Net change in market value of investments	141	(32)	17
Other comprehensive income (loss)	(3,116)	5,561	(2,747)
Comprehensive income	$ 12,264	$ 20,701	$ 14,904

Consolidated Statement of Share

Consolidated Statement of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2015	$ 127,302	$ 211	$ 134,967	$ 117,135	$ (120,185)	$ (4,826)
Beginning Balance, Shares at Dec. 31, 2015		21,063			3,311
Issuance of common stock under stock plans, including tax effects	14,632	$ 6	14,626
Issuance of common stock under stock plans, including tax effects, Shares		656
Stock-based compensation expense	7,976		7,976
Repurchases of common stock	(1,791)				$ (1,791)
Repurchase of common stock, Shares					47
Dividends paid on common shares	(12,987)			(12,987)
Net income	17,651			17,651
Net change in marketable investments, net of tax	17					17
Foreign currency translation	(2,764)					(2,764)
Ending Balance at Dec. 31, 2016	150,036	$ 217	157,569	121,799	$ (121,976)	(7,573)
Ending Balance, Shares at Dec. 31, 2016		21,719			3,358
Issuance of common stock under stock plans, including tax effects	15,979	$ 7	15,972
Issuance of common stock under stock plans, including tax effects, Shares		713
Cumulative effect adjustment due to adoption of new accounting pronouncements	(419)		(121)	(298)
Stock-based compensation expense	8,490		8,490
Repurchases of common stock	(39,967)				$ (39,967)
Repurchase of common stock, Shares					1,033
Dividends paid on common shares	(13,631)			(13,631)
Net income	15,140			15,140
Net change in marketable investments, net of tax	(32)					(32)
Foreign currency translation	5,593					5,593
Ending Balance at Dec. 31, 2017	141,189	$ 224	181,910	123,010	$ (161,943)	(2,012)
Ending Balance, Shares at Dec. 31, 2017		22,432			4,391
Issuance of common stock under stock plans, including tax effects	10,492	$ 6	10,486
Issuance of common stock under stock plans, including tax effects, Shares		519
Cumulative effect adjustment due to adoption of new accounting pronouncements	3,803			3,829		(26)
Stock-based compensation expense	8,300		8,300
Repurchases of common stock	(9,946)				$ (9,946)
Repurchase of common stock, Shares					240
Dividends paid on common shares	(14,502)			(14,502)
Net income	15,380			15,380
Net change in marketable investments, net of tax	141					141
Foreign currency translation	(3,257)					(3,257)
Ending Balance at Dec. 31, 2018	$ 151,600	$ 230	$ 200,696	$ 127,717	$ (171,889)	$ (5,154)
Ending Balance, Shares at Dec. 31, 2018		22,951			4,631

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 15,380	$ 15,140	$ 17,651
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,955	6,648	7,812
Amortization of intangible assets	1,162	781	831
Net (gains) losses from investments	(426)	479	805
Deferred income taxes	2,931	6,425	2,602
Stock-based compensation	8,300	8,490	7,976
Amortization of premium (discount) on investments	(68)	207	345
Foreign currency (gains) losses	603	632	(81)
Changes in assets and liabilities, net of businesses acquired
Accounts receivable	2,588	(10,327)	7,963
Deferred commissions	(1,077)	(1,679)	1,477
Prepaid expenses and other current assets	285	(4,146)	861
Accounts payable	172	(1,600)	1,317
Accrued expenses and other liabilities	1,217	7,857	58
Deferred revenue	(604)	8,586	(5,140)
Net cash provided by operating activities	38,418	37,493	44,477
Cash flows from investing activities:
Acquisitions, net of cash acquired	(9,250)
Purchases of property and equipment	(5,049)	(7,861)	(4,140)
Purchases of marketable investments	(41,810)	(31,910)	(36,763)
Proceeds from maturities of marketable investments	63,627	31,913	18,271
Proceeds from sales of marketable investments	32,568	6,545	4,815
Other investing activity		343	(48)
Net cash provided by (used in) investing activities	40,086	(970)	(17,865)
Cash flows from financing activities:
Dividends paid on common stock	(14,502)	(13,631)	(12,987)
Repurchases of common stock	(9,946)	(39,967)	(1,791)
Proceeds from issuance of common stock under employee equity incentive plans	13,020	18,506	16,734
Taxes paid related to net share settlements of stock-based compensation awards	(2,526)	(2,527)	(2,069)
Net cash used in financing activities	(13,954)	(37,619)	(113)
Effect of exchange rate changes on cash and cash equivalents	(4,044)	3,928	(2,872)
Net increase in cash and cash equivalents	60,506	2,832	23,627
Cash and cash equivalents, beginning of year	79,790	76,958	53,331
Cash and cash equivalents, end of year	140,296	79,790	76,958
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 4,174	$ 10,443	$ 8,507

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - FeedbackNow [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Non-cash investing activities, total consideration payable	$ 5.7
Non-cash investing activities, contingent consideration	3.4
Non-cash investing activities, indemnity holdback	1.5
Non-cash investing activities, working capital adjustment	$ 0.8

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1 - Summary of Significant Accounting Policies Basis of Presentation Principles of Consolidation Forrester Research, Inc. (“Forrester” or the “Company”) is a global independent research, data, and advisory services firm. Forrester works with business and technology leaders to help them develop customer-obsessed strategies that drive growth. Forrester’s unique insights are grounded in annual surveys of more than 675,000 consumers and business leaders worldwide, rigorous and objective research methodologies, and the shared wisdom of our clients. Through proprietary research and data, custom consulting, exclusive executive peer groups and events, Forrester challenges the thinking of its clients and positions them to lead change in their organizations in an era of powerful customers. The accompanying consolidated financial statements include the accounts of Forrester and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Business Acquisitions In 2018, Forrester acquired SocialGlimpz, Inc. and S.NOW SA. Refer to Note 2 – Acquisitions On January 3, 2019, Forrester acquired 100% of the issued and outstanding shares of SiriusDecisions, Inc., a privately-held company based in Wilton, Connecticut for $247.3 million in cash. Refer to Note 15 – Subsequent Events Management Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Forrester considers the more significant of these estimates to be revenue recognition, non-marketable investments, valuation of goodwill, intangible assets and acquired assets and liabilities from business combinations, ongoing impairment reviews of Reclassifications The line item “proceeds from sales and maturities of marketable investments” within the investing activities section of the statement of cash flows has changed from the prior years’ consolidated financial statements to reflect the separate presentation of proceeds from sales and maturities of marketable investments. Adoption of New Accounting Pronouncements The Company adopted the guidance in Accounting Standards Update (“ASU”) No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, The Company adopted the guidance in ASU No. 2016-18, Statement of Cash Flows: Restricted Cash, The Company adopted the guidance in ASU No. 2017-01, Business Combinations (ASC 805) – Clarifying the Definition of a Business The Company elected to adopt the guidance in ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606) Other Assets and Deferred Costs-Contracts with Customers On January 1, 2018, the Company adopted ASC 606 using the modified retrospective method. Under this method, the reported results for 2018 reflect the application of ASC 606, while the reported results for 2017 were prepared under the guidance of ASC 605, Revenue Recognition The effect of adopting ASC 606 included a $7.8 million reduction in deferred revenue, primarily related to prepaid performance obligations that are expected to expire in 2018 and 2019 that would have been recognized in 2017 under the new guidance; a decrease of $5.5 million in prepaid expenses and other current assets related to deferred survey costs that would have been expensed as incurred in 2017 under the new guidance and the current tax impact of the cumulative effect; an increase of $0.9 million in deferred commissions related to the capitalization of fringe benefits as incremental costs to obtain customer contracts under the new guidance; and an increase of $0.6 million in other assets for the deferred tax effect of the cumulative effect. Retained earnings increased by $3.8 million as a net result of these adjustments. The following tables summarize the effect of adopting ASC 606 on the Company’s financial statements during and as of the year ended December 31, 2018 (in thousands): Consolidated Balance Sheet As of December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Accounts receivable, net $ 67,318 $ 71,858 Deferred commissions 15,677 14,725 Prepaid expenses and other current assets 12,802 18,587 Total current assets 236,093 245,467 Other assets 5,310 4,748 Total assets 353,524 362,336 Deferred revenue $ 135,332 $ 149,344 Total current liabilities 189,985 203,997 Total liabilities 201,924 215,936 Retained earnings 127,717 122,517 Total stockholders’ equity 151,600 146,400 Total liabilities and stockholders’ equity 353,524 362,336 Total assets were $8.8 million less than if the previous guidance remained in effect, largely due to the following changes: • Accounts receivable, net was lower due to the Company excluding invoices issued on cancellable contracts in excess of revenue recognized. • Deferred commissions were higher due to the capitalization of fringe benefits costs. • Prepaid expenses and other current assets were lower due to expensing survey costs as incurred and the current period tax effect of the adjustments. Deferred revenue was $14.0 million lower due to the accelerated recognition of revenue for estimated unexercised rights, which would have been deferred under the previous guidance until the right expired, and the exclusion of invoices issued on cancellable contracts in excess of revenue recognized. Consolidated Statement of Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Revenues: Research services $ 228,399 $ 227,059 Advisory services and events 129,176 128,872 Total revenues 357,575 355,931 Operating expenses: Cost of services and fulfillment 146,502 146,666 Selling and marketing 131,824 131,907 Total operating expenses 335,150 335,397 Income from operations 22,425 20,534 Income before income taxes 23,525 21,634 Income tax provision 8,145 7,652 Net income 15,380 13,982 Basic income per common share $ 0.85 $ 0.77 Diluted income per common share $ 0.84 $ 0.76 The $1.6 million increase in total revenues for year ended December 31, 2018 is for estimated future unexercised customer rights that were previously recognized when they occurred. The net impact, including the tax effect, of accounting for revenue and costs to obtain and fulfill customer contracts under the new guidance increased net income and diluted net income per share for the year ended December 31, 2018 by $1.4 million and $0.08, respectively. Consolidated Statement of Comprehensive Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Net income $ 15,380 $ 13,982 Comprehensive income 12,264 10,866 Consolidated Statement of Cash Flows Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Cash flows from operating activities: Net income $ 15,380 $ 13,982 Accounts receivable 2,588 (1,952 ) Deferred commissions (1,077 ) (994 ) Prepaid expenses and other current assets 285 (43 ) Deferred revenue (604 ) 5,580 The impact to comprehensive income and cash flows from operating activities are driven by the consolidated balance sheet and income statement changes previously discussed. Fair Value Measurements The carrying amounts reflected in the Consolidated Balance Sheets for cash, cash equivalents, accounts receivable, accounts payable, and accrued expenses approximate fair value due to their short-term maturities. The Company has certain financial assets and liabilities recorded at fair value at each balance sheet date in accordance with the accounting standards for fair value measurements. Refer to Note 6 – Fair Value Measurements Cash, Cash Equivalents, and Marketable Investments Forrester considers all short-term, highly liquid investments with original maturities at the time of purchase of 90 days or less to be cash equivalents. The Company liquidated its entire portfolio of marketable investments in December of 2018 to fund the acquisition of SiriusDecisions on January 3, 2019. Forrester previously accounted for all marketable investments as available-for-sale securities and as such, the marketable investments were carried at fair value with unrealized gains and losses (not related to credit losses) recorded in accumulated other comprehensive loss in the Consolidated Balance Sheets. Realized gains and losses on securities are included in earnings and were determined using the specific identification method. The Company conducted periodic reviews to identify and evaluate each investment that had an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments, as required under current accounting standards. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive loss. The determination of whether a loss is considered temporary is based in part on whether the Company intends to sell the security or whether the Company would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. During the years ended December 31, 2018, 2017 and 2016, the Company did not record any other-than-temporary impairment losses on its available-for-sale securities. Concentrations of Credit Risk Forrester has no off-balance sheet or significant concentration of credit risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially subject Forrester to concentrations of credit risk are principally cash, cash equivalents, and accounts receivable. No single customer accounted for greater than 3% of revenues or 6% of accounts receivable in any of the periods presented. Goodwill Goodwill is not amortized; however, it is required to be tested for impairment annually. Furthermore, testing for impairment is required on an interim basis if an event or circumstance indicates that it is more likely than not an impairment loss has been incurred. An impairment loss would be recognized to the extent that the carrying amount of goodwill exceeds its implied fair value. Absent an event that indicates a specific impairment may exist, the Company has selected November 30th as the date for performing the annual goodwill impairment test. Goodwill impairment charges have not been required for the years ended December 31, 2018, 2017 and 2016. Impairment of Other Long-Lived Tangible and Intangible Assets Forrester continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of long-lived assets and intangible assets may warrant revision or if events or circumstances indicate that the carrying value of these assets may be impaired. To compute whether assets have been impaired, the estimated undiscounted future cash flows for the estimated remaining useful life of the assets are compared to the carrying value. To the extent that the future cash flows are less than the carrying value, the assets are written down to the estimated fair value of the asset. Impairment charges have not been required for the years ended December 31, 2018, 2017 and 2016. Non-Current Liabilities The Company records certain liabilities that are expected to be settled over a period that exceeds one year as non-current liabilities. The Company also records as a non-current liability the portion of the deferred rent liability that is expected to be recognized over a period greater than one year. The non-current deferred rent liability at December 31, 2018 and 2017 was $6.6 million and $7.5 million, respectively, and results from the difference between cash payments and the straight-line recognition of rent expense under the Company’s facility leases. Foreign Currency The functional currency of Forrester’s wholly-owned subsidiaries is their respective local currency. These subsidiary financial statements are translated to U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates during the corresponding period for revenues and expenses, with translation gains and losses accumulated as a component of accumulated other comprehensive loss in the Consolidated Balance Sheets. Gains and losses related to the remeasurement of monetary assets and liabilities denominated in a currency other than an entity’s functional currency are included in other income, net in the Consolidated Statements of Income. For each of the years ended December 31, 2018 and 2017, Forrester recorded $0.6 million of foreign exchange losses in other income, net. For the year ended December 31, 2016, Forrester recorded $0.1 million of foreign exchange gains. Accumulated Other Comprehensive Loss The components of accumulated other comprehensive loss are as follows (in thousands): Total Net Unrealized Gain Cumulative Accumulated (Loss) on Marketable Translation Other Comprehensive Investments Adjustment Income (Loss) Balance at December 31, 2015 $ (100 ) $ (4,726 ) $ (4,826 ) Foreign currency translation before reclassification — (2,764 ) (2,764 ) Unrealized gain on investments, net of tax of $(14) 17 — 17 Balance at December 31, 2016 (83 ) (7,490 ) (7,573 ) Foreign currency translation — 5,593 5,593 Unrealized loss on investments, net of tax of $22 (32 ) — (32 ) Balance at December 31, 2017 (115 ) (1,897 ) (2,012 ) Foreign currency translation — (3,257 ) (3,257 ) Reclassification of stranded tax effects from tax reform (26 ) — (26 ) Unrealized gain on investments before reclassification, net of tax of $(4) 12 — 12 Reclassification adjustment for net losses realized in net income, net of tax of $(75) 129 — 129 Balance at December 31, 2018 $ — $ (5,154 ) $ (5,154 ) Revenue The Company recognizes revenue when a customer obtains control of promised products or services, in an amount that reflects the consideration expected to be received in exchange for those products or services. The Company follows the five-step model prescribed under ASC 606: (i) identify contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies the performance obligation. Revenues are presented net of any sales or value added taxes collected from customers and remitted to the government. The Company accounts for a contract when it has approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance and collectability of the consideration expected to be transferred is probable. The Company applies judgment in determining the customer’s ability and intention to pay for services expected to be transferred, which is based on factors including the customer’s payment history, management’s ability to mitigate exposure to credit risk (for example, requiring payment in advance of the transfer of products or services, or the ability to stop transferring promised products or services in the event a customer fails to pay consideration when due) and experience selling to similarly situated customers. Since the transaction price is fixed and defined as part of entering into a contract, and generally does not change, variable consideration is insignificant. Performance obligations within a contract are identified based on the products and services promised to be transferred in the contract. When a contract includes more than one promised product or service, the Company must apply judgment to determine whether the promises represent multiple performance obligations or a single, combined performance obligation. This evaluation requires the Company to determine if the promises are both capable of being distinct, where the customer can benefit from the product or service on its own or together with other resources readily available, and are distinct within the context of the contract, where the transfer of products or services is separately identifiable from other promises in the contract. When both criteria are met, each promised product or service is accounted for as a separate performance obligation. In cases where the promises are distinct, the Company is further required to evaluate if the promises are a series of products and services that are substantially the same and have the same pattern of transfer to the customer (referred to as the “series” guidance). When the Company determines that promises meet the series guidance, they are accounted for as a single, combined performance obligation. The number of performance obligations in the Company’s arrangements is not different under ASC 606 than the number of separate units of accounting under pervious guidance, as discussed further below. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative basis according to their standalone selling prices. The Company continues to determine standalone selling price based on the price at which the performance obligation is sold separately. If the Company does not have a history of selling a performance obligation, management applies judgment to estimate the standalone selling price, taking into consideration available information, including market conditions, factors considered to set list price, pricing of similar products, and internal pricing objectives. The corresponding allocated revenues are recognized as the performance obligations are satisfied, as discussed below. Research services revenues Research services revenues consist primarily of memberships to Research, Connect, and Analytics products. The majority of the Research revenues are annual subscriptions to our research, including access to all or a designated portion of our research and, depending on the type of license, unlimited phone or email analyst inquiry and unlimited participation in Forrester webinars, all of which are delivered throughout the contract period. The Company has concluded that the promises represent a stand ready obligation to provide a daily information service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these subscriptions meet the requirements of the series guidance and are each accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. Research revenues also include sales of electronic reprints, which are written research documents prepared by Forrester’s analysts and hosted via an on-line platform. Reprints include a promise to deliver a customer-selected research document and certain usage data provided through the on-line platform, which represents two performance obligations. The Company satisfies the performance obligation for the research document by providing access to the electronic reprint and accordingly recognizes revenue at that point in time. The Company satisfies the performance obligation for the data portion of the reprint on a daily basis and accordingly recognizes revenue over time. The majority of the Connect revenues are the Company’s Leadership Board product which includes access to the Research offering, access to a private forum with other Leadership Board member peers, access to a Forrester advisor, member-generated content, and one Event ticket. The Company has concluded that all promises, other than the Event ticket, represent a stand ready obligation to provide a daily information and peer service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these promises meet the requirements of the series guidance and are accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. The Event ticket is accounted for as a separate performance obligation and is recognized when the Event occurs. Analytics revenues are primarily annual subscriptions to access designated survey data products and typically include a data advisor, all of which are delivered throughout the contract period. For Analytics subscriptions, the Company has concluded that the promises represent a stand ready obligation to provide a daily data service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these subscriptions meet the requirements of the series guidance and are accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. Certain of the Analytics products include advisory services which are accounted for as a separate performance obligation and are recognized at the point in time the service is completed or the final deliverable is transferred to the customer. Advisory services and events revenues Advisory services and events revenues consists of sales of advisory services, consulting projects, and Events. Advisory services revenues are short-term presentations or knowledge sharing sessions (which can range from one hour to two days), such as workshops, speeches and advisory days. Each is a promise for a Forrester analyst to deliver a deeper understanding of Forrester’s published research and represents a single performance obligation. Revenue is recognized at the point in time the service is completed or the final deliverable is transferred to the customer. Consulting project revenues consists of the delivery of focused insights and recommendations that assist customers with their challenges in developing and executing strategies around technology, customer experience and digital transformation. Projects are fixed-fee arrangements that are generally completed within two weeks to three months. The Company concluded that each project represents a single performance obligation as they are a single promise to deliver a customized engagement and deliverable. For the majority of these services, either practically or contractually, the work performed and delivered to the customer has no alternative use to the Company. Additionally, Forrester maintains an enforceable right to payment at all times throughout the contract. The Company utilizes an input method and recognizes revenue over time, based on hours expended relative to the total estimated hours required to satisfy the performance obligation. This input method was chosen since it closely aligns with how control of interim deliverables is transferred to the customer throughout the engagement and is also the method used internally to price the project and assess operational performance. If the Company were to enter into an agreement where it does not have an enforceable right to payment at all times, revenue would be recognized at the point in time the project is completed. Events revenues consist of either ticket or sponsorship sales for a Forrester-hosted event. Each is a single promise that either allows entry to, or grants the right to, promote a product or service at, a specific event. The Company concluded that each of these represents a single performance obligation. The Company recognizes revenue at the completion of the Event, which is the point in time when the customer has received the benefit(s) from attending or sponsoring the Event. Prepaid performance obligations, including Event tickets, reprints, advisory and consulting hours, on non-cancellable contracts that the Company estimates will expire unused are recognized in proportion to the pattern of related rights exercised by the customer. This assessment requires judgment, including estimating the percentage of prepaid rights that will go unexercised and anticipating the impact that future changes to products, pricing, and customer engagement will have on actual expirations. The Company periodically updates the rates used to recognize unexercised rights. Refer to Note 12, Operating Segment and Enterprise Wide Reporting Contract Modifications The Company considers a contract modification to exist when a mutually agreed upon change creates new, or updates existing, enforceable rights and obligations. ASC 606 introduced three specific methods to account for contract modifications depending on the nature of the change(s) in scope or price to the original contract. The new guidance is consistent with how the Company has historically accounted for contract modifications and as a result, does not have an impact on the Company’s results of operations. The majority of the Company’s contract modifications result in additional or remaining distinct products and services and are treated on a prospective basis. Under the prospective method, the transaction price is updated to combine the unrecognized amount as of the modification date plus the additional transaction price from the modification. This amount is then re-allocated to the remaining distinct performance obligations and recognized accordingly. Consulting services contracts can be modified to update the scope of the services purchased. Since a consulting project is a single performance obligation that is only partially satisfied at the modification date, the updated project requirements are not distinct and the modification is accounted for as part of the existing contract. The effect of the modification on the transaction price and the Company’s measure of progress for the performance obligation to which it relates, is recognized as an adjustment to revenue (either an increase or decrease) on a cumulative catch-up basis. For the year ended December 31, 2018, the Company recorded an immaterial amount of cumulative catch-up adjustments. Contract Assets and Liabilities Accounts Receivable Accounts receivable includes amounts billed and currently due from customers. Since the only condition for payment of our invoices is the passage of time, the Company records a receivable on the date the invoice is issued. Also included in accounts receivable are unbilled amounts resulting from revenue exceeding the amount billed to the customer, where the right to payment is unconditional. If the right to payment for services performed was conditional on something other than the passage of time, the unbilled amount would be recorded as a separate contract asset. There were no contract assets as of December 31, 2018. The majority of the Company’s contracts are non-cancellable. However, for contracts that are cancellable by the customer, the Company does not record a receivable when it issues an invoice. The Company records accounts receivable on these contracts only up to the amount of revenue earned but not yet collected. In addition, since the majority of the Company’s contracts are for a duration of one year and payment is expected within one year from the transfer of products and services, the Company does not adjust its receivables or transaction price for the effects of a significant financing component. Deferred Revenue The Company refers to contract liabilities as deferred revenue on the Consolidated Balance Sheets. Payment terms in the Company’s customer contracts vary, but generally require payment in advance of fully satisfying the performance obligation(s). Deferred revenue consists of billings in excess of revenue recognized. Similar to accounts receivable, the Company does not record deferred revenue for invoices issued on a cancellable contract. During the year ended December 31, 2018, the Company recognized approximately $134.7 million of revenue related to its deferred revenue balance at January 1, 2018. To determine revenue recognized in the current period from deferred revenue at the beginning of the period, the Company first allocates revenue to the individual deferred revenue balance outstanding at the beginning of the period, until the revenue equals that balance. Approximately $262.6 million of revenue is expected to be recognized during the next 12 to 24 months from remaining performance obligations as of December 31, 2018. Cost to Obtain and Fulfill Contracts The Company capitalizes commissions paid to internal sales representatives and related fringe benefits costs that are incremental to obtaining customer contracts. These costs are included in deferred commissions on the Consolidated Balance Sheets. The judgments made in determining the amount of costs incurred include the types of costs to capitalize and whether the costs are in fact incremental. The Company elected the practical expedient to account for these costs at a portfolio level as the Company’s contracts are similar in nature and the amortization model used closely matches the amortization expense that would be recognized on a contract-by-contract basis. Costs to obtain a contract are amortized to operations as the related revenue is recognized over the initial contract term. Amortization expense related to deferred commissions was $32.2 million for the year ended December 31, 2018. The Company evaluates the recoverability of deferred commissions at each balance sheet date. Costs to fulfill the Company’s contracts, such as our survey costs for our Analytics product line, do not meet the specified capitalization criteria as defined in the guidance and as such are expensed as incurred. Allowance for Doubtful Accounts Forrester maintains an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make contractually obligated payments. When evaluating the adequacy of the allowance for doubtful accounts, the Company makes judgments regarding the collectability of accounts receivable by specifically analyzing historical bad debts, customer concentrations, current economic trends, and changes in the customer payment terms. If the financial condition of the Company’s customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required and if the financial condition of the Company’s customers were to improve, the allowances may be reduced accordingly. Stock-Based Compensation The Company recognizes the fair value of stock-based compensation expense over the requisite service period of the individual grantee, which generally equals the vesting period. The Company adopted the guidance in Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation Improvements to Employee Share-Based Payment Accounting Stock-based compensation expense was recorded in the following expense categories (in thousands): Years Ended December 31, 2018 2017 2016 Cost of services and fulfillment $ 4,329 $ 4,538 $ 4,431 Selling and marketing 1,065 717 1,054 General and administrative 2,906 3,235 2,491 Total $ 8,300 $ 8,490 $ 7,976 The options granted under the equity incentive plan and shares subject to the employee stock purchase plan were valued utilizing the Black-Scholes model using the following assumptions and had the following fair values (no options were granted in 2017 and 2018): Years Ended December 31, 2018 2017 2016 Employee Stock Purchase Plan Employee Stock Purchase Plan Equity Incentive Plans Employee Stock Purchase Plan Average risk-free interest rate 1.90 % 0.90 % 1.30 % 0.32 % Expected dividend yield 1.9 % 1.9 % 2.2 % 2.1 % Expected life 0.5 Years 0.5 Years 5.0 Years 0.5 Years Expected volatility 23 % 24 % 24 % 24 % Weighted average fair value $ 9.13 $ 8.36 $ 6.16 $ 6.69 Prior to the suspension of the quarterly dividend program in November 2018, dividend yields were based on the regular quarterly dividend program approved by the Board of Directors in February 2012. Expected volatility is based, in part, on the historical volatility of Forrester’s common stock as well as management’s expectations of fut

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions	Note 2 – Acquisitions The Company accounts for business combinations in accordance with the acquisition method of accounting as prescribed by ASC 805, Business Combinations GlimpzIt On June 22, 2018, Forrester acquired substantially all of the assets of SocialGlimpz Inc. (“GlimpzIt”), an artificial intelligence and machine-learning provider based in San Francisco. The acquisition is part of Forrester's plan to build a real-time customer experience or CX cloud solution, integrating a range of inputs to help companies monitor and improve customer experience. Forrester intends to deploy the GlimpzIt technology to extend the analytics engine in Forrester’s planned real-time CX cloud . FeedbackNow On July 6, 2018, Forrester acquired 100% of the shares of S.NOW SA, a Switzerland-based business that operates as FeedbackNow. FeedbackNow is a maker of physical buttons and monitoring software that companies deploy to measure, analyze, and improve customer experience. The acquisition is part of Forrester's plan to build a real-time CX cloud solution. FeedbackNow provides a high-volume input source for the real-time CX cloud solution. The acquisition of FeedbackNow was determined to be an acquisition of a business under the provisions of ASC 805. The Company paid $8.4 million on the closing date. An additional $1.5 million is payable during a two-year period from the closing date and is subject to typical indemnity provisions from the seller. The Company is also required to pay additional purchase price based on the acquired working capital of $0.8 million and the sellers may earn up to $4.2 million based on the financial performance of FeedbackNow during the two-year period following the closing date. Total Consideration Transferred The following table summarizes the fair value of the aggregate consideration paid or payable for FeedbackNow (in thousands): Cash paid at close (1) $ 8,425 Working capital adjustment (2) 798 Indemnity holdback (3) 1,485 Contingent purchase price (4) 3,388 Total $ 14,096 (1) The cash paid at close represents the gross contractual amount paid. Net cash paid, which accounts for the cash acquired of $0.5 million, was $8.0 million and is reflected as an investing activity in the Consolidated Statements of Cash Flows. (2) Represents the amount payable to the sellers based upon working capital as defined, which was paid to the sellers during the first quarter of 2019. (3) Approximately $0.5 million and $1.0 million of the holdback is expected to be paid during 2019 and 2020, respectively. (4) The acquisition of FeedbackNow includes a contingent consideration arrangement that requires additional consideration to be paid to the sellers based on the financial performance of FeedbackNow during the two-year period subsequent to the closing date. Up to $1.7 million and $2.5 million could be payable during 2019 and 2020, respectively, if the financial targets are met. The range of undiscounted amounts that could be payable under this arrangement is zero to $4.2 million. This range of amounts payable has not changed since the acquisition. The provisional fair value of the contingent consideration recognized on the acquisition date, which represents purchase price, was $3.0 million. During the fourth quarter of 2018, the Company recorded a $0.4 million increase to the initial value of the contingent consideration representing additional purchase price, as a result of finalizing its acquisition date fair value assessment during the measurement period. This adjustment resulted in a final acquisition date fair value of $3.4 million for the contingent consideration. The fair value was based on a Monte Carlo simulation and included significant Level 3 inputs not observable in the market including projected contract bookings, a discount rate of 23.7%, and revenue volatility of 20.8%. See further discussion in Note 6 – Fair Value Measurements Preliminary Allocation of Purchase Price The following table summarizes the preliminary allocation of the purchase price to the fair value of the assets acquired and liabilities assumed for the acquisition of FeedbackNow (in thousands): Assets: Cash $ 463 Accounts receivable 738 Prepaids and other current assets 487 Goodwill (1) 9,513 Acquired intangible assets (2) 4,780 Other assets 75 Total assets 16,056 Liabilities: Accounts payable and accrued liabilities 837 Contract liabilities 298 Deferred tax liability 825 Total liabilities 1,960 Net assets acquired $ 14,096 (1) Goodwill represents the expected synergies from combining FeedbackNow with Forrester as well as the value of the acquired workforce. (2) All of the acquired intangible assets are finite-lived. The determination of the fair value of the finite-lived intangible assets required management judgment and the consideration of a number of factors. In determining the fair values, management primarily relied on income valuation methodologies, in particular discounted cash flow models. The use of discounted cash flow models required the use of estimates, including projected cash flows related to the particular asset; the useful lives of the particular assets; the selection of royalty and discount rates used in the models; and certain published industry benchmark data. In establishing the estimated useful lives of the acquired intangible assets, the Company relied primarily on the duration of the cash flows utilized in the valuation model. Of the $4.8 million assigned to acquired intangible assets, $3.0 million was assigned to the technology asset class with a useful life of 6.5 years, $1.3 million to customer relationships with useful lives of 4.5 years to 7.5 years (with a weighted average amortization period of 6.1 years), and $0.5 million to trade names with a useful life of 8.5 years. The weighted-average amortization period for the total acquired intangible assets is 4.8 years. Amortization of acquired intangible assets was $0.4 million for the year ended December 31, 2018. During the fourth quarter of 2018, the Company recognized a $0.4 million increase to goodwill primarily as a result of finalizing the fair value assessment of the contingent purchase price during the measurement period. The allocation of the purchase price for FeedbackNow is preliminary with respect to certain working capital items. The Company expects to obtain the remainder of the information to complete the allocation of the purchase price during the first half of 2019. The Company's financial statements include the operating results of FeedbackNow beginning on July 6, 2018, the date of acquisition. FeedbackNow's operating results and the related goodwill are being reported as part of the Company's Product segment. The goodwill is not deductible for income tax purposes. The acquisition of FeedbackNow added approximately $1.2 million and $1.9 million of revenue and direct expenses, respectively, for the year ended December 31, 2018. For the year ended December 31, 2018, goodwill increased by $9.0 million with $10.2 million of the increase attributable to the acquisitions of GlimpzIt and FeedbackNow and a $1.2 million decrease due to foreign currency fluctuations. The Company recognized $1.8 million of acquisition costs during the year ended December 31, 2018. The costs primarily consisted of legal fees, regulatory costs and accounting and tax professional fees.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 3 - Goodwill and Other Intangible Assets A summary of the goodwill by segment and the changes in the carrying amount of goodwill is shown in the following table (in thousands). Project Product Research Consulting Total Balance at January 1, 2017 $ 2,343 $ 70,850 $ — $ 73,193 Translation adjustments 95 2,881 — 2,976 Balance at December 31, 2017 2,438 73,731 — 76,169 Acquisitions 10,178 — — 10,178 Translation adjustments (98 ) (1,084 ) — (1,182 ) Balance at December 31, 2018 $ 12,518 $ 72,647 $ — $ 85,165 As of December 31, 2018, the Company had no accumulated goodwill impairment losses. During the year ending December 31, 2018, $4.8 million and $0.6 million of intangible assets were added as a result of the acquisitions of FeedbackNow and GlimpzIt, respectively. A summary of Forrester’s intangible assets is as follows (in thousands): December 31, 2018 Gross Net Carrying Accumulated Carrying Amount Amortization Amount Amortizable intangible assets: Customer relationships $ 32,823 $ 31,604 $ 1,219 Technology 3,610 295 3,315 Trade name 443 26 417 Total $ 36,876 $ 31,925 $ 4,951 December 31, 2017 Gross Net Carrying Accumulated Carrying Amount Amortization Amount Amortizable intangible assets: Customer relationships $ 31,735 $ 31,003 $ 732 Research content 1,083 1,083 — Total $ 32,818 $ 32,086 $ 732 Amortization expense related to intangible assets was approximately $1.2 million, $0.8 million and $0.8 million during the years ended December 31, 2018, 2017 and 2016, respectively. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows (in thousands): Year ending December 31, 2019 $ 865 Year ending December 31, 2020 865 Year ending December 31, 2021 865 Year ending December 31, 2022 865 Year ending December 31, 2023 693 Thereafter 798 Total $ 4,951

Marketable Investments

Marketable Investments	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Marketable Investments	Note 4 - Marketable Investments The Company liquidated all of its marketable investments in December of 2018 to finance the acquisition of SiriusDecisions on January 3, 2019. The following table summarizes the Company’s marketable investments, all of which are classified as available-for-sale (in thousands): As of December 31, 2017 Gross Gross Amortized Unrealized Unrealized Market Cost Gains Losses Value Federal agency obligations $ 1,800 $ — $ (7 ) $ 1,793 Corporate obligations 52,721 — (181 ) 52,540 Total $ 54,521 $ — $ (188 ) $ 54,333 The following table shows the gross unrealized losses and market value of Forrester’s available-for-sale securities with unrealized losses that are not deemed to be other-than-temporary, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands): As of December 31, 2017 Less Than 12 Months 12 Months or Greater Market Unrealized Market Unrealized Value Losses Value Losses Federal agency obligations $ — $ — $ 1,793 $ 7 Corporate obligations 31,723 149 20,817 32 Total $ 31,723 $ 149 $ 22,610 $ 39 Realized gains and losses are recognized into earnings at the time of the sale based on specific identification of the cost basis of each security. Realized losses on sales of the Company’s available-for-sale securities were $0.2 million for the year ended December 31, 2018 and were recorded in other income, net. Realized gains or losses on sales of the Company’s available-for-sale securities were not significant for the year ended December 31, 2017.

Non-Marketable Investments

Non-Marketable Investments	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Non-Marketable Investments	Note 5 - Non-Marketable Investments At December 31, 2018 and 2017, the carrying value of the Company’s non-marketable investments, which were composed primarily of interests in technology-related private equity funds, was $2.5 million and $1.9 million, respectively, and are included in other assets in the Consolidated Balance Sheets. The Company’s investments are being accounted for using the equity method as the investments are limited partnerships and the Company has an ownership interest in excess of 5% and, accordingly, the Company records its share of the investee’s operating results each period. At December 31, 2016, the Company’s investments also included an investment with a book value of $0.4 million, which was accounted for using the cost method. This investment was fully liquidated during 2017. During the year ended December 31, 2018, the Company recorded a gain from its non-marketable investments of $0.6 million, which is included in gains (losses) on investments, net in the Consolidated Statement of Income. During the years ended December 31, 2017 and 2016, the Company recorded losses from its non-marketable investments of $0.5 million and $0.8 million, respectively. During the years ended December 31, 2018 and 2016, no distributions were received from the funds. During the year ended December 31, 2017, a gross distribution of $0.4 million was received from the investment fund that the Company accounted for under the cost method.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 6 - Fair Value Measurements The Company has certain financial assets and liabilities which have been classified as either Level 1, 2 or 3 within the fair value hierarchy as described below. Level 1 — Fair value based on quoted prices in active markets for identical assets or liabilities. Level 2 — Fair value based on inputs other than Level 1 inputs that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Fair value based on unobservable inputs that are supported by little or no market activity and such inputs are significant to the fair value of the assets or liabilities. The following table represents the Company’s fair value hierarchy for its financial assets and liabilities that are measured at fair value on a recurring basis (in thousands): Fair Value Measurements As of December 31, 2018 Level 1 Level 2 Level 3 Total Assets: Money market funds (1) $ 255 $ — $ — $ 255 Total Assets $ 255 $ — $ — $ 255 Liabilities: Contingent purchase price (2) $ — $ — $ (4,196 ) $ (4,196 ) Total Liabilities $ — $ — $ (4,196 ) $ (4,196 ) Fair Value Measurements As of December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Money market funds (1) $ 492 $ — $ — $ 492 Federal agency obligations — 1,793 — 1,793 Corporate obligations (3) — 52,540 — 52,540 Total Assets $ 492 $ 54,333 $ — $ 54,825 (1) Included in cash and cash equivalents. (2) $1.8 million is included in accrued expenses and other current liabilities and $2.4 million is included in non-current liabilities in the Consolidated Balance Sheet. (3) All corporate obligations were sold in December 2018, resulting in a loss of $0.2 million that was recorded in other income, net in the Consolidated Statements of Income. These investments were sold to fund a portion of the purchase of SiriusDecisions (refer to Note 15 – Subsequent Events During the years ended December 31, 2018 and 2017, the Company did not transfer assets or liabilities between levels of the fair value hierarchy. Level 2 assets consist of the Company’s entire portfolio of marketable investments at December 31, 2017. Level 2 assets have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, typically utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation methods, including both income and market based approaches and observable market inputs to determine value. These observable market inputs include reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates and other industry and economic events. Level 3 liabilities at December 31, 2018 consist entirely of the contingent purchase price related to the acquisition of FeedbackNow. Changes in the fair value of Level 3 contingent consideration for the year ended December 31, 2018 were as follows (in thousands): Contingent Consideration Acquisition of FeedbackNow (1) $ (3,388 ) Fair value adjustment of FeedbackNow (2) (3) (780 ) Foreign exchange effect (28 ) Balance at December 31, 2018 $ (4,196 ) (1) See Note 2 – Acquisitions, (2) In the period subsequent to the acquisition of FeedbackNow on July 6, 2018, the fair value of the contingent consideration increased by $0.8 million due primarily to the achievement of contract bookings during this period. This amount was recognized as acquisition and integration costs within the Consolidated Statements of Income. (3) As of December 31, 2018, the significant unobservable inputs used in the Monte Carlo simulation to fair value the contingent consideration included projected contract bookings, a discount rate of 23.8%, and revenue volatility of 21.9%. Increases or decreases in the inputs would result in a higher or lower fair value measurement.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 7 - Income Taxes Income before income taxes consists of the following (in thousands): Years Ended December 31, 2018 2017 2016 Domestic $ 17,718 $ 20,061 $ 22,303 Foreign 5,807 7,310 8,406 Total $ 23,525 $ 27,371 $ 30,709 The components of the income tax provision are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Current: Federal $ 2,278 $ 2,587 $ 6,094 State 1,173 1,060 2,330 Foreign 1,763 2,159 2,032 Total current 5,214 5,806 10,456 Deferred: Federal 2,111 5,550 2,719 State 667 700 59 Foreign 153 175 (176 ) Total deferred 2,931 6,425 2,602 Income tax provision $ 8,145 $ 12,231 $ 13,058 A reconciliation of the federal statutory rate to Forrester’s effective tax rate is as follows: Years Ended December 31, 2018 2017 2016 Income tax provision at federal statutory rate 21.0 % 35.0 % 35.0 % Increase (decrease) in tax resulting from: State tax provision, net of federal benefit 6.2 4.0 5.0 Foreign tax rate differential (0.2 ) (3.4 ) (4.4 ) Stock option compensation deduction (1.1 ) 0.1 0.6 Withholding taxes 2.1 1.7 0.5 Non-deductible expenses 5.3 1.8 1.5 Change in valuation allowance — 3.9 3.2 Change in tax legislation 1.9 5.8 — Audit settlements — (4.0 ) — Other, net (0.6 ) (0.2 ) 1.1 Effective tax rate 34.6 % 44.7 % 42.5 % On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a decrease in the corporate tax rate from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S international taxation from a worldwide tax system to a modified territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. In December 2017, Staff Accounting Bulletin No. 118 (“SAB 118”) was issued to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete the accounting for certain income tax effects of the Act. SAB 118 provided a measurement period of one year from the enactment date of the Act for companies to complete the accounting for the income tax effects of the Act. During 2017, the Company recorded provisional income tax for the remeasurement of federal deferred tax assets and liabilities of $1.2 million and the one-time transition tax on the mandatory deemed repatriation of foreign earnings was $0.4 million based on cumulative foreign earnings of $22.6 million. The Company completed its analysis of the effect of the Act during 2018 in accordance with SAB 118 and recorded additional tax expense of $0.4 million in the fourth quarter of 2018 relating to the one-time transition tax on the mandatory repatriation of foreign earnings. In July 2015, the U.S. Tax Court issued an opinion in Altera Corp. v. Commissioner related to the treatment of stock-based compensation expense in an intercompany cost-sharing arrangement. The opinion invalidates part of a treasury regulation requiring stock-based compensation to be included in any qualified intercompany cost-sharing arrangement. The Company previously recorded a tax benefit based on the opinion in the case. Currently the U.S. Court of Appeals for the Ninth Circuit is reviewing the case and a final decision is yet to be issued. The Company will continue to monitor ongoing developments and potential impacts to its consolidated financial statements. The components of deferred income taxes are as follows (in thousands): As of December 31, 2018 2017 Non-deductible reserves and accruals $ 3,835 $ 4,936 Net operating loss and other carryforwards 7,954 8,528 Stock compensation 2,125 2,644 Depreciation and amortization 727 402 Other assets — 46 Gross deferred tax asset 14,641 16,556 Less - valuation allowance (2,574 ) (2,686 ) Sub-total 12,067 13,870 Other liabilities (1,249 ) (911 ) Goodwill and intangible assets (6,201 ) (5,677 ) Deferred commissions (4,479 ) (3,873 ) Net deferred tax asset $ 138 $ 3,409 As of December 31, 2018 and 2017, long-term net deferred tax assets were $1.1 million and $3.5 million, respectively, and are included in other assets in the Consolidated Balance Sheets. Long-term net deferred tax liabilities were $1.0 million and $0.1 million, respectively, at December 31, 2018 and 2017, and are included in non-current liabilities in the Consolidated Balance Sheets. The Company considers all available evidence, both positive and negative, to determine whether, based on the weight of that evidence, a valuation allowance is needed for some portion or all of a net deferred income tax asset. Judgment is required in considering the relative impact of negative and positive evidence. In arriving at these judgments, the weight given to the potential effect of negative and positive evidence is commensurate with the extent to which it can be objectively verified. Although realization is not assured, based upon the Company’s historical taxable income and projections of the Company’s future taxable income over the periods during which the deferred tax assets are deductible and the carryforwards expire, management believes it is more likely than not that the Company will realize the benefits of these deductible differences, net of the existing valuation allowances, as discussed below. As of December 31, 2018 and 2017, the Company maintained a valuation allowance of approximately $2.6 million and $2.7 million, respectively, primarily relating to U.S. capital losses from the Company’s investment in technology-related private equity funds, and from foreign net operating loss carryforwards from an acquisition. The Company has foreign net operating loss carryforwards of approximately $20.8 million, which can be carried forward indefinitely. Approximately $3.2 million of the foreign net operating loss carryforwards relate to a prior acquisition, the utilization of which is subject to limitation under the tax law of the United Kingdom. As of December 31, 2018, the Company had U.S. federal and state capital loss carryforwards of $6.2 million, of which $1.6 million expires in 2020, $1.4 million expires in 2021, and $3.2 million expires in 2022. The following table provides a summary of the changes in the deferred tax valuation allowance for the years ended December 31, 2018, 2017 and 2016 (in thousands): 2018 2017 2016 Deferred tax valuation allowance at January 1 $ 2,686 $ 2,193 $ 1,534 Additions 74 1,439 1,256 Deductions (139 ) (70 ) (455 ) Change in tax legislation — (954 ) — Translation adjustments (47 ) 78 (142 ) Deferred tax valuation allowance at December 31 $ 2,574 $ 2,686 $ 2,193 T h A c i n c l ud e a nd a t o r on e - ti t a o acc u u l a t e ea r n i ng o f o r e i g ub i d i a r i e a n a r e u lt a l p r e v i ou l un r e itt e ea r n i ng f o w h i c n U . S d e f e rr e t a li a b ilit h a b ee acc r u e h a v no b ee ub j ec t U . S t a x N o t w it h t a nd i n t h U . S t a x a ti o o t h e a oun t the Company i n t e n t c on ti nu t i nv e all of their unremitted earnings of $13.8 million a w e l a the ca p it a i t h e ub i d i a r i e i nd e f i n it e l ou t i d o t h U . S d no e xp ec t i n c u a n a dd iti on a r e l a t e t u c a oun t The Company utilizes a two-step process for the measurement of uncertain tax positions that have been taken or are expected to be taken on a tax return. The first step is a determination of whether the tax position should be recognized in the financial statements. The second step determines the measurement of the tax position. A reconciliation of the beginning and ending amount of unrecognized tax benefits is summarized as follows for the years ended December 31, 2018, 2017 and 2016 (in thousands): 2018 2017 2016 Unrecognized tax benefits at January 1 $ 806 $ 1,774 $ 1,910 Reductions for tax positions of prior years — — (31 ) Additions for tax positions of current year — — 75 Settlements — (986 ) (163 ) Translation adjustments (7 ) 18 (17 ) Unrecognized tax benefits at December 31 $ 799 $ 806 $ 1,774 As of December 31, 2018, the total amount of unrecognized tax benefits totaled approximately $0.8 million, all of which if recognized, would decrease our effective tax rate in a future period. Subsequent to December 31, 2018, the Company was notified that the U.S. Competent Authority claim was in the process of being finalized. This would result in the reversal of $0.4 million of unrecognized tax benefits and additional tax expense of approximately $0.5 million during 2019. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense and such amounts were not significant in the years ended December 31, 2018, 2017 and 2016. Accrued interest and penalties were insignificant at December 31, 2018 and 2017. At December 31, 2016, the Company had $0.1 million of accrued interest and penalties related to uncertain tax positions. The Company files income tax returns in the U.S. and in foreign jurisdictions. Generally, the Company is no longer subject to U.S., state, local and foreign income tax examinations by tax authorities in its major jurisdictions for years before 2013, except to the extent of net operating loss and tax credit carryforwards from those years. Major taxing jurisdictions include the U.S., the Netherlands, the United Kingdom, Germany and Switzerland. As of December 31, 2018, the Company was not under any audits.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments	Note 8 - Commitments As of December 31, 2018, Forrester had future contractual obligations as follows for operating leases (in thousands): 2019 $ 12,498 2020 11,762 2021 10,145 2022 8,552 2023 7,856 Thereafter 22,222 Total minimum lease payments $ 73,035 The cost of these operating leases, including any contractual rent increases, rent concessions, and landlord incentives, are recognized ratably over the life of the related lease agreement. Aggregate rent expense was $17.5 million, $17.4 million and $16.1 million for the years ended December 31, 2018, 2017, and 2016, respectively.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Note 9 - Stockholders’ Equity Preferred Stock Forrester has authorized 500,000 shares of $0.01 par value preferred stock. The Board of Directors has full authority to issue this stock and to fix the voting powers, preferences, rights, qualifications, limitations, or restrictions thereof, including dividend rights, conversion rights, redemption privileges and liquidation preferences and the number of shares constituting any series or designation of such series. Treasury Stock Through 2018, Forrester’s Board of Directors has authorized an aggregate $535.0 million to purchase common stock under the Company’s stock repurchase program including $50.0 million authorized in February 2018. The shares repurchased may be used, among other things, in connection with Forrester’s equity incentive and purchase plans. As of December 31, 2018, the Company had repurchased approximately 16.3 million shares of common stock at an aggregate cost of $474.9 million. Dividends During the years ended December 31, 2018, 2017 and 2016, the Company declared and paid four quarterly dividends of $0.20, $0.19 and $0.18 per share each quarter, respectively, amounting to $0.80 per share or $14.5 million, $0.76 per share or $13.6 million and $0.72 per share or $13.0 million, respectively. Equity Plans Forrester maintains the following two equity incentive plans: the Forrester Research, Inc. Amended and Restated Equity Incentive Plan (the “Equity Incentive Plan” and previously the “2006 Plan”) and the 2006 Stock Option Plan for Directors, as amended (the “2006 Directors’ Plan”). Upon approval of an amendment to the 2006 Plan by stockholders in 2012, no future awards under the 2006 Directors’ Plan could be granted or issued. In May 2016, the stockholders of the Company approved an amendment and restatement of the Company’s 2006 Plan. The amendment and restatement resulted in (1) extending the term of the plan for 10 years until May 2026, (2) increasing the number of shares issuable under the plan by 2,000,000 shares, (3) establishing a maximum amount of awards issuable under the plan to the Company’s non-employee directors, and (4) changing the name of the plan to the Forrester Research, Inc. Amended and Restated Equity Incentive Plan The Equity Incentive Plan provides for the issuance of stock-based awards, including incentive stock options (“ISOs”), non-qualified stock options (“NSOs”), and restricted stock units (“RSUs”) to purchase up to 6,350,000 shares authorized in the plan, 80,000 shares returned from the 2006 Directors’ Plan and 713,275 shares returned from a prior plan. Under the terms of the Equity Incentive Plan, ISOs may not be granted at less than fair market value on the date of grant (and in no event less than par value). Options and RSUs generally vest annually over four years and options expire after 10 years. Beginning in 2017, RSUs granted to non-employee directors vest quarterly over one year. Options and RSUs granted under the Equity Incentive Plan immediately vest upon certain events, as described in the plan. As of December 31, 2018, approximately 2.5 million shares were available for future grant of awards under the Equity Incentive Plan. The 2006 Directors’ Plan provided for the issuance of options to purchase up to 450,000 shares of common stock. As of December 31, 2018, approximately 36,000 options remain outstanding and are fully vested under the 2006 Directors’ Plan. Restricted Stock Units Restricted stock units (“RSUs”) represent the right to receive one share of Forrester common stock when the restrictions lapse and the vesting conditions are met, and are valued on the date of grant based upon the value of the Company’s stock on the date of grant less the present value of dividends expected to be paid during the requisite service period. Shares of Forrester’s common stock will be delivered to the grantee upon vesting, subject to a reduction of shares for payment of withholding taxes. The weighted average grant date fair value for RSUs granted in 2018, 2017 and 2016 was $43.71, $39.73 and $37.87, respectively. The value of RSUs vested and converted to common stock, based on the value of Forrester’s common stock on the date of vesting, was $9.1 million, $8.7 million and $6.6 million during 2018, 2017 and 2016, respectively. RSU activity for the year ended December 31, 2018 is presented below (in thousands, except per share data): Weighted- Average Number of Grant Date Shares Fair Value Unvested at December 31, 2017 509 $ 37.59 Granted 261 43.71 Vested (198 ) 37.12 Forfeited (75 ) 38.31 Unvested at December 31, 2018 497 $ 40.89 Stock Options Stock option activity for the year ended December 31, 2018 is presented below (in thousands, except per share data and contractual term): Weighted - Weighted - Average Average Exercise Remaining Aggregate Number Price Per Contractual Intrinsic of Shares Share Term (in years) Value Outstanding at December 31, 2017 937 $ 35.10 Granted — — Exercised (319 ) 34.83 Forfeited (35 ) 34.78 Outstanding at December 31, 2018 583 $ 35.27 4.82 $ 5,496 Exercisable at December 31, 2018 488 $ 35.40 4.44 $ 4,545 Vested and expected to vest at December 31, 2018 583 $ 35.27 4.82 $ 5,496 The total intrinsic value of options exercised during 2018, 2017 and 2016 was $3.3 million, $4.5 million and $3.7 million, respectively. Employee Stock Purchase Plan In May 2018, stockholders of the Company approved an amendment to the Company’s Amended and Restated Employee Stock Purchase Plan (the “Stock Purchase Plan”) The Stock Purchase Plan provides for the issuance of up to 1.1 million shares of common stock and as of December 31, 2018, approximately 0.5 million shares remain available for issuance. With certain limited exceptions, all employees of Forrester whose customary employment is more than 20 hours per week, including officers and directors who are employees, are eligible to participate in the Stock Purchase Plan. Purchase periods under the Stock Purchase Plan are six months in length and commence on each successive March 1 and September 1. Stock purchased under the Stock Purchase Plan is required to be held for one year before it is able to be sold. During each purchase period the maximum number of shares of common stock that may be purchased by an employee is limited to the number of shares equal to $12,500 divided by the fair market value of a share of common stock on the first day of the purchase period. An employee may elect to have up to 10% deducted from his or her compensation for the purpose of purchasing shares under the Stock Purchase Plan. The price at which the employee’s shares are purchased is the lower of: (a) 85% of the closing price of the common stock on the day that the purchase period commences, or (b) 85% of the closing price of the common stock on the day that the purchase period terminates Shares purchased by employees under the Stock Purchase Plan are as follows (in thousands, except per share data): Shares Purchase Purchase Period Ended Purchased Price February 28, 2018 27 $ 34.43 August 31, 2018 28 $ 34.21 February 28, 2017 24 $ 31.03 August 31, 2017 26 $ 31.71

Employee Pension Plans

Employee Pension Plans	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Pension Plans	Note 10 - Employee Pension Plans Forrester sponsors several defined contribution plans for eligible employees. Generally, the defined contribution plans have funding provisions which, in certain situations, require contributions based upon formulas relating to employee wages or the level of elective participant contributions, as well as allow for additional discretionary contributions. Further, certain plans contain vesting provisions. Forrester’s contributions to these plans totaled approximately $5.0 million, $5.2 million and $4.3 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Reorganization

Reorganization	12 Months Ended
	Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Reorganization	Note 11 – Reorganization In the first quarter of 2016, the Company implemented and completed a reduction in its workforce of approximately 2% of its employees across various geographies and functions. The Company incurred $1.0 million of severance and related costs for this action, all of which was paid before December 31, 2016.

Operating Segment and Enterpris

Operating Segment and Enterprise Wide Reporting	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Operating Segment and Enterprise Wide Reporting	Note 12 - Operating Segment and Enterprise Wide Reporting The Product segment includes the costs of the product management organization that is responsible for pricing and packaging and the launch of new products. In addition, this segment includes the costs of the Company’s Analytics, Connect and Events organizations. Revenue in this segment includes all of the Company’s revenue (including Research and Connect) except for revenue from advisory services and project consulting services that are delivered by personnel in the Research and Project Consulting segments. The Research segment includes the costs of the Company’s research personnel who are responsible for writing the research and performing the webinars and inquiries for its Research and Connect products. In addition, the research personnel deliver advisory services (such as workshops, speeches and advisory days) and a portion of the project consulting services. Revenue in this segment includes only revenue from advisory services and project consulting services that are delivered by the research personnel in this segment. The Project Consulting segment includes the costs of the consultants that deliver the majority of the Company’s project consulting services. Revenue in this segment includes the project consulting revenue delivered by the consultants in this segment. The Company evaluates reportable segment performance and allocates resources based on segment revenues and expenses. Segment expenses include the direct expenses of each segment organization and exclude selling and marketing expenses, general and administrative expenses, stock-based compensation expense, depreciation expense, adjustments to incentive bonus compensation from target amounts, amortization of intangible assets, other income and gains (losses) on investments. The accounting policies used by the segments are the same as those used in the consolidated financial statements. The Company does not identify or allocate assets, including capital expenditures, by operating segment. Accordingly, assets are not being reported by segment because the information is not available by segment and is not reviewed in the evaluation of performance or making decisions in the allocation of resources. In 2018, as part of the adoption of ASC 606, the Company updated its segment disclosures to present disaggregated revenue by product line within all of its reportable segments. The Company did not make any changes to the number or type of reporting segments themselves. Accordingly, the 2017 and 2016 amounts have been reclassified to conform to the current presentation. The following tables present information about reportable segments (in thousands): Project Product Research Consulting Consolidated Year Ended December 31, 2018 Research services revenues Research $ 157,669 $ — $ — $ 157,669 Connect 50,820 — — 50,820 Analytics 19,910 — — 19,910 Total research services revenues 228,399 — — 228,399 Advisory services and events revenues Advisory services — 41,086 478 41,564 Consulting services 8,649 10,027 55,465 74,141 Events 13,471 — — 13,471 Total advisory services and events revenues 22,120 51,113 55,943 129,176 Total segment revenues 250,519 51,113 55,943 357,575 Segment expenses 50,551 51,129 27,981 129,661 Contribution margin (loss) 199,968 (16 ) 27,962 227,914 Selling, marketing, administrative and other expenses (200,540 ) Amortization of intangible assets (1,162 ) Acquisition and integration costs (3,787 ) Reorganization costs — Other income and gains (losses) on investments 1,100 Income before income taxes $ 23,525 Project Product Research Consulting Consolidated Year Ended December 31, 2017 Research services revenues Research $ 148,935 $ — $ — $ 148,935 Connect 48,798 — — 48,798 Analytics 18,738 — — 18,738 Total research services revenues 216,471 — — 216,471 Advisory services and events revenues Advisory services — 36,074 320 36,394 Consulting services 10,132 8,980 53,941 73,053 Events 11,755 — — 11,755 Total advisory services and events revenues 21,887 45,054 54,261 121,202 Total segment revenues 238,358 45,054 54,261 337,673 Segment expenses 45,205 48,812 25,477 119,494 Contribution margin (loss) 193,153 (3,758 ) 28,784 218,179 Selling, marketing, administrative and other expenses (189,849 ) Amortization of intangible assets (781 ) Acquisition and integration costs — Reorganization costs — Other income and gains (losses) on investments (178 ) Income before income taxes $ 27,371 Project Product Research Consulting Consolidated Year Ended December 31, 2016 Research services revenues Research $ 147,576 $ — $ — $ 147,576 Connect 47,291 — — 47,291 Analytics 20,349 — — 20,349 Total research services revenues 215,216 — — 215,216 Advisory services and events revenues Advisory services — 34,392 590 34,982 Consulting services 9,547 10,239 45,284 65,070 Events 10,827 — — 10,827 Total advisory services and events revenues 20,374 44,631 45,874 110,879 Total segment revenues 235,590 44,631 45,874 326,095 Segment expenses 41,528 47,496 23,141 112,165 Contribution margin (loss) 194,062 (2,865 ) 22,733 213,930 Selling, marketing, administrative and other expenses (181,299 ) Amortization of intangible assets (831 ) Acquisition and integration costs — Reorganization costs (1,026 ) Other income and gains (losses) on investments (65 ) Income before income taxes $ 30,709 Net long-lived tangible assets by location as of December 31, 2018 and 2017 are as follows (in thousands): 2018 2017 United States $ 20,880 $ 23,943 United Kingdom 522 727 Europe (excluding United Kingdom) 83 163 Asia Pacific 517 413 Other 3 3 Total $ 22,005 $ 25,249 Revenues by geographic destination, based on the location products and services are consumed, and as a percentage of total revenues for the years ended December 31, 2018, 2017, and 2016 are as follows (dollars in thousands): 2018 2017 2016 United States 77 % 77 % 77 % Europe (excluding United Kingdom) 8 9 8 United Kingdom 4 4 5 Canada 4 4 4 Asia Pacific 5 4 4 Other 2 2 2 Total 100 % 100 % 100 % 2018 2017 2016 United States $ 274,151 $ 260,077 $ 252,222 Europe (excluding United Kingdom) 29,741 28,525 27,061 United Kingdom 15,273 13,651 14,808 Canada 15,569 14,523 13,806 Asia Pacific 17,839 15,952 13,686 Other 5,002 4,945 4,512 Total $ 357,575 $ 337,673 $ 326,095

Certain Balance Sheet Accounts

Certain Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Certain Balance Sheet Accounts	Note 13 - Certain Balance Sheet Accounts Property and Equipment: Property and equipment as of December 31, 2018 and 2017 is recorded at cost less accumulated depreciation and consists of the following (in thousands): 2018 2017 Computers and equipment $ 18,621 $ 18,570 Computer software 31,276 29,891 Furniture and fixtures 8,449 9,094 Leasehold improvements 26,610 26,650 Total property and equipment 84,956 84,205 Less accumulated depreciation (62,951 ) (58,956 ) Total property and equipment, net $ 22,005 $ 25,249 The Company incurs costs to develop or obtain internal use computer software used for its operations, and certain of these costs meeting the criteria in ASC 350 – Internal use software Accrued Expenses and Other Current Liabilities: Accrued expenses and other current liabilities as of December 31, 2018 and 2017 consist of the following (in thousands): 2018 2017 Payroll and related benefits $ 35,467 $ 34,809 Taxes 2,991 3,912 Other 15,607 10,908 Total $ 54,065 $ 49,629 Non-Current Liabilities: Non-current liabilities as of December 31, 2018 and 2017 consist of the following (in thousands): 2018 2017 Deferred tax liability $ 969 $ 408 Deferred rent 6,602 7,523 Contingent consideration and indemnity holdback 3,433 — Other 935 1,027 Total $ 11,939 $ 8,958 Allowance for Doubtful Accounts: A roll-forward of the allowance for doubtful accounts as of and for the years ended December 31, 2018, 2017, and 2016 is as follows (in thousands): 2018 2017 2016 Balance, beginning of year $ 155 $ 140 $ 153 Provision for doubtful accounts 567 331 150 Write-offs (363 ) (316 ) (163 ) Balance, end of year $ 359 $ 155 $ 140

Summary Selected Quarterly Fina

Summary Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Summary Selected Quarterly Financial Data (Unaudited)	Note 14 - Summary Selected Quarterly Financial Data (unaudited) The following is a summary of selected unaudited consolidated quarterly financial data for the years ended December 31, 2018 and 2017 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, 2018 2018 2018 2018 Total revenues $ 77,749 $ 96,353 $ 84,890 $ 98,583 Income (loss) from operations $ (2,288 ) $ 11,027 $ 4,942 $ 8,744 Net income (loss) $ (1,733 ) $ 7,788 $ 3,950 $ 5,375 Basic income (loss) per common share $ (0.10 ) $ 0.43 $ 0.22 $ 0.29 Diluted income (loss) per common share $ (0.10 ) $ 0.43 $ 0.21 $ 0.29 Three Months Ended March 31, June 30, September 30, December 31, 2017 2017 2017 2017 Total revenues $ 77,194 $ 89,733 $ 80,369 $ 90,377 Income from operations $ 3,136 $ 10,213 $ 6,749 $ 7,451 Net income $ 3,030 $ 6,064 $ 3,953 $ 2,093 Basic income per common share $ 0.17 $ 0.34 $ 0.22 $ 0.12 Diluted income per common share $ 0.16 $ 0.34 $ 0.22 $ 0.11 Out of Period Adjustment During the quarter ended June 30, 2018, the Company recorded $1.0 million of revenue ($0.7 million after tax) for an out-of-period correction within research services in the Consolidated Statements of Income. The error resulted from an understatement of revenue from the reprint product line of $0.8 million ($0.5 million after tax) during the three months ended March 31, 2018 and $0.2 million ($0.1 million after tax) from the year ended December 31, 2017. The Company has concluded that the error was not material to all annual financial statement periods presented.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Note 15 - Subsequent Events On January 3, 2019, Forrester acquired 100% of the issued and outstanding shares of SiriusDecisions, Inc., a privately-held company based in Wilton, Connecticut with approximately 350 employees globally. We believe that the combination of our expertise in strategy with SiriusDecisions’ focus on operational excellence will enable our clients to know what they should do, why they should do it, and how to do it. The acquisition creates several opportunities for us, including cross-selling services to our respective client bases, extending SiriusDecisions’ platform, methodologies, data, and best-practices tools into new roles, and accelerating international and industry growth. The acquisition of SiriusDecisions was determined to be an acquisition of a business under the provisions of ASC 805, Business Combinations . Total Consideration Transferred Pursuant to the terms of the merger agreement, the Company paid $247.3 million at closing, which included the purchase price of $245.0 million plus an estimate of cash acquired and reduced by certain working capital items, which is subject to adjustment. Net cash paid, which accounts for the cash acquired of $7.2 million, was $240.1 million. At the time of the merger, each vested SiriusDecisions stock option was converted into the right to receive the excess of the per share merger consideration over the exercise price of such stock option. All unvested SiriusDecisions stock options were cancelled without payment of any consideration. The initial accounting for the acquisition was not complete at the time the financial statements were issued due to the timing of the acquisition and the filing of this Annual Report on Form 10-K. As a result, disclosures required under ASC 805-10-50, Business Combinations The Company recognized $1.8 million of acquisition costs in the year ended December 31, 2018 related to the SiriusDecisions acquisition. The costs primarily consisted of legal fees and accounting and tax professional fees and are included in acquisition and integration costs within the Consolidated Statements of Income. In connection with the acquisition of SiriusDecisions, the Company entered into a $200.0 million Credit Agreement on January 3, 2019 (the “Closing Date”). The Credit Agreement provides for: (1) senior secured term loans in an aggregate principal amount of $125.0 million (the “ Term Loans Revolving Credit Facility Facilities Amounts borrowed under the Facilities bear interest, at Forrester’s option, at a rate per annum equal to either (i) the London Interbank Offering Rate (“ LIBOR” The Term Loans require repayment of the outstanding principal balance in equal quarterly installments, commencing on March 31, 2019, in each year below, with the balance repayable on the maturity date, subject to customary exceptions. The amount payable in each year is set forth in the table below: Year Yearly Repayment Amount 1 $ 6,250,000 2 9,375,000 3 12,500,000 4 12,500,000 5 15,625,000 Thereafter $ 68,750,000 The Revolving Credit Facility does not require repayment prior to maturity, subject to customary exceptions. In addition to financing the acquisition, proceeds from the Revolving Credit Facility can also be used towards working capital and general corporate purposes. Up to $5 million of the Revolving Credit Facility is available for the issuance of letters of credit, and any drawings under the letters of credit must be reimbursed within one business day. The Facilities contain certain customary restrictive loan covenants, including among others, financial covenants that apply a maximum leverage ratio and minimum fixed charge coverage ratio. The negative covenants limit, subject to various exceptions, the Company’s ability to incur additional indebtedness, create liens on assets, merge, consolidate, liquidate or dissolve any part of the Company, sell assets, pay dividends or other payments in respect to capital stock, change fiscal year, or enter into certain transactions with affiliates and subsidiaries. The first covenant reporting period is March 31, 2019, and the Company expects to be in full compliance. The Facilities also contain customary events of default, representations, and warranties. The Facilities permit the Company to borrow incremental term loans and / or increase commitments under the Revolving Credit Facility in an aggregate principal amount up to $50.0 million, subject to approval by the administrative agent and certain customary terms and conditions. The Facilities can be repaid early, in part or in whole, at any time and from time to time, without premium or penalty, other than customary breakage reimbursement requirements for LIBOR-based loans. The Term Loans must be prepaid with net cash proceeds of (i) certain debt incurred or issued by Forrester and its restricted subsidiaries and (ii) certain asset sales and condemnation or casualty events, subject to certain reinvestment rights. All obligations under the Facilities are unconditionally guaranteed by each of the Company’s existing and future, direct and indirect material wholly-owned domestic subsidiaries, other than certain excluded subsidiaries, and are collateralized by a first priority lien on substantially all tangible and intangible assets including intellectual property and all of the capital stock of the Company and its subsidiaries (limited to 65% of the voting equity of certain subsidiaries).

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Principles of Consolidation Forrester Research, Inc. (“Forrester” or the “Company”) is a global independent research, data, and advisory services firm. Forrester works with business and technology leaders to help them develop customer-obsessed strategies that drive growth. Forrester’s unique insights are grounded in annual surveys of more than 675,000 consumers and business leaders worldwide, rigorous and objective research methodologies, and the shared wisdom of our clients. Through proprietary research and data, custom consulting, exclusive executive peer groups and events, Forrester challenges the thinking of its clients and positions them to lead change in their organizations in an era of powerful customers. The accompanying consolidated financial statements include the accounts of Forrester and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Business Acquisitions In 2018, Forrester acquired SocialGlimpz, Inc. and S.NOW SA. Refer to Note 2 – Acquisitions On January 3, 2019, Forrester acquired 100% of the issued and outstanding shares of SiriusDecisions, Inc., a privately-held company based in Wilton, Connecticut for $247.3 million in cash. Refer to Note 15 – Subsequent Events Management Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Forrester considers the more significant of these estimates to be revenue recognition, non-marketable investments, valuation of goodwill, intangible assets and acquired assets and liabilities from business combinations, ongoing impairment reviews of
Reclassifications	Reclassifications The line item “proceeds from sales and maturities of marketable investments” within the investing activities section of the statement of cash flows has changed from the prior years’ consolidated financial statements to reflect the separate presentation of proceeds from sales and maturities of marketable investments.
Adoption of New Accounting Pronouncements	Adoption of New Accounting Pronouncements The Company adopted the guidance in Accounting Standards Update (“ASU”) No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, The Company adopted the guidance in ASU No. 2016-18, Statement of Cash Flows: Restricted Cash, The Company adopted the guidance in ASU No. 2017-01, Business Combinations (ASC 805) – Clarifying the Definition of a Business The Company elected to adopt the guidance in ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606) Other Assets and Deferred Costs-Contracts with Customers On January 1, 2018, the Company adopted ASC 606 using the modified retrospective method. Under this method, the reported results for 2018 reflect the application of ASC 606, while the reported results for 2017 were prepared under the guidance of ASC 605, Revenue Recognition The effect of adopting ASC 606 included a $7.8 million reduction in deferred revenue, primarily related to prepaid performance obligations that are expected to expire in 2018 and 2019 that would have been recognized in 2017 under the new guidance; a decrease of $5.5 million in prepaid expenses and other current assets related to deferred survey costs that would have been expensed as incurred in 2017 under the new guidance and the current tax impact of the cumulative effect; an increase of $0.9 million in deferred commissions related to the capitalization of fringe benefits as incremental costs to obtain customer contracts under the new guidance; and an increase of $0.6 million in other assets for the deferred tax effect of the cumulative effect. Retained earnings increased by $3.8 million as a net result of these adjustments. The following tables summarize the effect of adopting ASC 606 on the Company’s financial statements during and as of the year ended December 31, 2018 (in thousands): Consolidated Balance Sheet As of December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Accounts receivable, net $ 67,318 $ 71,858 Deferred commissions 15,677 14,725 Prepaid expenses and other current assets 12,802 18,587 Total current assets 236,093 245,467 Other assets 5,310 4,748 Total assets 353,524 362,336 Deferred revenue $ 135,332 $ 149,344 Total current liabilities 189,985 203,997 Total liabilities 201,924 215,936 Retained earnings 127,717 122,517 Total stockholders’ equity 151,600 146,400 Total liabilities and stockholders’ equity 353,524 362,336 Total assets were $8.8 million less than if the previous guidance remained in effect, largely due to the following changes: • Accounts receivable, net was lower due to the Company excluding invoices issued on cancellable contracts in excess of revenue recognized. • Deferred commissions were higher due to the capitalization of fringe benefits costs. • Prepaid expenses and other current assets were lower due to expensing survey costs as incurred and the current period tax effect of the adjustments. Deferred revenue was $14.0 million lower due to the accelerated recognition of revenue for estimated unexercised rights, which would have been deferred under the previous guidance until the right expired, and the exclusion of invoices issued on cancellable contracts in excess of revenue recognized. Consolidated Statement of Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Revenues: Research services $ 228,399 $ 227,059 Advisory services and events 129,176 128,872 Total revenues 357,575 355,931 Operating expenses: Cost of services and fulfillment 146,502 146,666 Selling and marketing 131,824 131,907 Total operating expenses 335,150 335,397 Income from operations 22,425 20,534 Income before income taxes 23,525 21,634 Income tax provision 8,145 7,652 Net income 15,380 13,982 Basic income per common share $ 0.85 $ 0.77 Diluted income per common share $ 0.84 $ 0.76 The $1.6 million increase in total revenues for year ended December 31, 2018 is for estimated future unexercised customer rights that were previously recognized when they occurred. The net impact, including the tax effect, of accounting for revenue and costs to obtain and fulfill customer contracts under the new guidance increased net income and diluted net income per share for the year ended December 31, 2018 by $1.4 million and $0.08, respectively. Consolidated Statement of Comprehensive Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Net income $ 15,380 $ 13,982 Comprehensive income 12,264 10,866 Consolidated Statement of Cash Flows Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Cash flows from operating activities: Net income $ 15,380 $ 13,982 Accounts receivable 2,588 (1,952 ) Deferred commissions (1,077 ) (994 ) Prepaid expenses and other current assets 285 (43 ) Deferred revenue (604 ) 5,580 The impact to comprehensive income and cash flows from operating activities are driven by the consolidated balance sheet and income statement changes previously discussed.
Fair Value Measurements	Fair Value Measurements The carrying amounts reflected in the Consolidated Balance Sheets for cash, cash equivalents, accounts receivable, accounts payable, and accrued expenses approximate fair value due to their short-term maturities. The Company has certain financial assets and liabilities recorded at fair value at each balance sheet date in accordance with the accounting standards for fair value measurements. Refer to Note 6 – Fair Value Measurements
Cash, Cash Equivalents, and Marketable Investments	Cash, Cash Equivalents, and Marketable Investments Forrester considers all short-term, highly liquid investments with original maturities at the time of purchase of 90 days or less to be cash equivalents. The Company liquidated its entire portfolio of marketable investments in December of 2018 to fund the acquisition of SiriusDecisions on January 3, 2019. Forrester previously accounted for all marketable investments as available-for-sale securities and as such, the marketable investments were carried at fair value with unrealized gains and losses (not related to credit losses) recorded in accumulated other comprehensive loss in the Consolidated Balance Sheets. Realized gains and losses on securities are included in earnings and were determined using the specific identification method. The Company conducted periodic reviews to identify and evaluate each investment that had an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments, as required under current accounting standards. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive loss. The determination of whether a loss is considered temporary is based in part on whether the Company intends to sell the security or whether the Company would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. During the years ended December 31, 2018, 2017 and 2016, the Company did not record any other-than-temporary impairment losses on its available-for-sale securities.
Concentrations of Credit Risk	Concentrations of Credit Risk Forrester has no off-balance sheet or significant concentration of credit risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially subject Forrester to concentrations of credit risk are principally cash, cash equivalents, and accounts receivable. No single customer accounted for greater than 3% of revenues or 6% of accounts receivable in any of the periods presented.
Goodwill	Goodwill Goodwill is not amortized; however, it is required to be tested for impairment annually. Furthermore, testing for impairment is required on an interim basis if an event or circumstance indicates that it is more likely than not an impairment loss has been incurred. An impairment loss would be recognized to the extent that the carrying amount of goodwill exceeds its implied fair value. Absent an event that indicates a specific impairment may exist, the Company has selected November 30th as the date for performing the annual goodwill impairment test. Goodwill impairment charges have not been required for the years ended December 31, 2018, 2017 and 2016.
Impairment of Other Long-Lived Tangible and Intangible Assets	Impairment of Other Long-Lived Tangible and Intangible Assets Forrester continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of long-lived assets and intangible assets may warrant revision or if events or circumstances indicate that the carrying value of these assets may be impaired. To compute whether assets have been impaired, the estimated undiscounted future cash flows for the estimated remaining useful life of the assets are compared to the carrying value. To the extent that the future cash flows are less than the carrying value, the assets are written down to the estimated fair value of the asset. Impairment charges have not been required for the years ended December 31, 2018, 2017 and 2016.
Non-Current Liabilities	Non-Current Liabilities The Company records certain liabilities that are expected to be settled over a period that exceeds one year as non-current liabilities. The Company also records as a non-current liability the portion of the deferred rent liability that is expected to be recognized over a period greater than one year. The non-current deferred rent liability at December 31, 2018 and 2017 was $6.6 million and $7.5 million, respectively, and results from the difference between cash payments and the straight-line recognition of rent expense under the Company’s facility leases.
Foreign Currency	Foreign Currency The functional currency of Forrester’s wholly-owned subsidiaries is their respective local currency. These subsidiary financial statements are translated to U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates during the corresponding period for revenues and expenses, with translation gains and losses accumulated as a component of accumulated other comprehensive loss in the Consolidated Balance Sheets. Gains and losses related to the remeasurement of monetary assets and liabilities denominated in a currency other than an entity’s functional currency are included in other income, net in the Consolidated Statements of Income. For each of the years ended December 31, 2018 and 2017, Forrester recorded $0.6 million of foreign exchange losses in other income, net. For the year ended December 31, 2016, Forrester recorded $0.1 million of foreign exchange gains.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The components of accumulated other comprehensive loss are as follows (in thousands): Total Net Unrealized Gain Cumulative Accumulated (Loss) on Marketable Translation Other Comprehensive Investments Adjustment Income (Loss) Balance at December 31, 2015 $ (100 ) $ (4,726 ) $ (4,826 ) Foreign currency translation before reclassification — (2,764 ) (2,764 ) Unrealized gain on investments, net of tax of $(14) 17 — 17 Balance at December 31, 2016 (83 ) (7,490 ) (7,573 ) Foreign currency translation — 5,593 5,593 Unrealized loss on investments, net of tax of $22 (32 ) — (32 ) Balance at December 31, 2017 (115 ) (1,897 ) (2,012 ) Foreign currency translation — (3,257 ) (3,257 ) Reclassification of stranded tax effects from tax reform (26 ) — (26 ) Unrealized gain on investments before reclassification, net of tax of $(4) 12 — 12 Reclassification adjustment for net losses realized in net income, net of tax of $(75) 129 — 129 Balance at December 31, 2018 $ — $ (5,154 ) $ (5,154 )
Revenue	Revenue The Company recognizes revenue when a customer obtains control of promised products or services, in an amount that reflects the consideration expected to be received in exchange for those products or services. The Company follows the five-step model prescribed under ASC 606: (i) identify contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies the performance obligation. Revenues are presented net of any sales or value added taxes collected from customers and remitted to the government. The Company accounts for a contract when it has approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance and collectability of the consideration expected to be transferred is probable. The Company applies judgment in determining the customer’s ability and intention to pay for services expected to be transferred, which is based on factors including the customer’s payment history, management’s ability to mitigate exposure to credit risk (for example, requiring payment in advance of the transfer of products or services, or the ability to stop transferring promised products or services in the event a customer fails to pay consideration when due) and experience selling to similarly situated customers. Since the transaction price is fixed and defined as part of entering into a contract, and generally does not change, variable consideration is insignificant. Performance obligations within a contract are identified based on the products and services promised to be transferred in the contract. When a contract includes more than one promised product or service, the Company must apply judgment to determine whether the promises represent multiple performance obligations or a single, combined performance obligation. This evaluation requires the Company to determine if the promises are both capable of being distinct, where the customer can benefit from the product or service on its own or together with other resources readily available, and are distinct within the context of the contract, where the transfer of products or services is separately identifiable from other promises in the contract. When both criteria are met, each promised product or service is accounted for as a separate performance obligation. In cases where the promises are distinct, the Company is further required to evaluate if the promises are a series of products and services that are substantially the same and have the same pattern of transfer to the customer (referred to as the “series” guidance). When the Company determines that promises meet the series guidance, they are accounted for as a single, combined performance obligation. The number of performance obligations in the Company’s arrangements is not different under ASC 606 than the number of separate units of accounting under pervious guidance, as discussed further below. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative basis according to their standalone selling prices. The Company continues to determine standalone selling price based on the price at which the performance obligation is sold separately. If the Company does not have a history of selling a performance obligation, management applies judgment to estimate the standalone selling price, taking into consideration available information, including market conditions, factors considered to set list price, pricing of similar products, and internal pricing objectives. The corresponding allocated revenues are recognized as the performance obligations are satisfied, as discussed below. Research services revenues Research services revenues consist primarily of memberships to Research, Connect, and Analytics products. The majority of the Research revenues are annual subscriptions to our research, including access to all or a designated portion of our research and, depending on the type of license, unlimited phone or email analyst inquiry and unlimited participation in Forrester webinars, all of which are delivered throughout the contract period. The Company has concluded that the promises represent a stand ready obligation to provide a daily information service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these subscriptions meet the requirements of the series guidance and are each accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. Research revenues also include sales of electronic reprints, which are written research documents prepared by Forrester’s analysts and hosted via an on-line platform. Reprints include a promise to deliver a customer-selected research document and certain usage data provided through the on-line platform, which represents two performance obligations. The Company satisfies the performance obligation for the research document by providing access to the electronic reprint and accordingly recognizes revenue at that point in time. The Company satisfies the performance obligation for the data portion of the reprint on a daily basis and accordingly recognizes revenue over time. The majority of the Connect revenues are the Company’s Leadership Board product which includes access to the Research offering, access to a private forum with other Leadership Board member peers, access to a Forrester advisor, member-generated content, and one Event ticket. The Company has concluded that all promises, other than the Event ticket, represent a stand ready obligation to provide a daily information and peer service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these promises meet the requirements of the series guidance and are accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. The Event ticket is accounted for as a separate performance obligation and is recognized when the Event occurs. Analytics revenues are primarily annual subscriptions to access designated survey data products and typically include a data advisor, all of which are delivered throughout the contract period. For Analytics subscriptions, the Company has concluded that the promises represent a stand ready obligation to provide a daily data service, in which the services are the same each day, every day is distinct, and the customer simultaneously receives and consumes the benefits as the Company transfers control throughout the contract period. Accordingly, these subscriptions meet the requirements of the series guidance and are accounted for as a single performance obligation. The Company recognizes revenue ratably over time, using an output measure of time elapsed. Certain of the Analytics products include advisory services which are accounted for as a separate performance obligation and are recognized at the point in time the service is completed or the final deliverable is transferred to the customer. Advisory services and events revenues Advisory services and events revenues consists of sales of advisory services, consulting projects, and Events. Advisory services revenues are short-term presentations or knowledge sharing sessions (which can range from one hour to two days), such as workshops, speeches and advisory days. Each is a promise for a Forrester analyst to deliver a deeper understanding of Forrester’s published research and represents a single performance obligation. Revenue is recognized at the point in time the service is completed or the final deliverable is transferred to the customer. Consulting project revenues consists of the delivery of focused insights and recommendations that assist customers with their challenges in developing and executing strategies around technology, customer experience and digital transformation. Projects are fixed-fee arrangements that are generally completed within two weeks to three months. The Company concluded that each project represents a single performance obligation as they are a single promise to deliver a customized engagement and deliverable. For the majority of these services, either practically or contractually, the work performed and delivered to the customer has no alternative use to the Company. Additionally, Forrester maintains an enforceable right to payment at all times throughout the contract. The Company utilizes an input method and recognizes revenue over time, based on hours expended relative to the total estimated hours required to satisfy the performance obligation. This input method was chosen since it closely aligns with how control of interim deliverables is transferred to the customer throughout the engagement and is also the method used internally to price the project and assess operational performance. If the Company were to enter into an agreement where it does not have an enforceable right to payment at all times, revenue would be recognized at the point in time the project is completed. Events revenues consist of either ticket or sponsorship sales for a Forrester-hosted event. Each is a single promise that either allows entry to, or grants the right to, promote a product or service at, a specific event. The Company concluded that each of these represents a single performance obligation. The Company recognizes revenue at the completion of the Event, which is the point in time when the customer has received the benefit(s) from attending or sponsoring the Event. Prepaid performance obligations, including Event tickets, reprints, advisory and consulting hours, on non-cancellable contracts that the Company estimates will expire unused are recognized in proportion to the pattern of related rights exercised by the customer. This assessment requires judgment, including estimating the percentage of prepaid rights that will go unexercised and anticipating the impact that future changes to products, pricing, and customer engagement will have on actual expirations. The Company periodically updates the rates used to recognize unexercised rights. Refer to Note 12, Operating Segment and Enterprise Wide Reporting Contract Modifications The Company considers a contract modification to exist when a mutually agreed upon change creates new, or updates existing, enforceable rights and obligations. ASC 606 introduced three specific methods to account for contract modifications depending on the nature of the change(s) in scope or price to the original contract. The new guidance is consistent with how the Company has historically accounted for contract modifications and as a result, does not have an impact on the Company’s results of operations. The majority of the Company’s contract modifications result in additional or remaining distinct products and services and are treated on a prospective basis. Under the prospective method, the transaction price is updated to combine the unrecognized amount as of the modification date plus the additional transaction price from the modification. This amount is then re-allocated to the remaining distinct performance obligations and recognized accordingly. Consulting services contracts can be modified to update the scope of the services purchased. Since a consulting project is a single performance obligation that is only partially satisfied at the modification date, the updated project requirements are not distinct and the modification is accounted for as part of the existing contract. The effect of the modification on the transaction price and the Company’s measure of progress for the performance obligation to which it relates, is recognized as an adjustment to revenue (either an increase or decrease) on a cumulative catch-up basis. For the year ended December 31, 2018, the Company recorded an immaterial amount of cumulative catch-up adjustments.
Accounts Receivable	Accounts Receivable Accounts receivable includes amounts billed and currently due from customers. Since the only condition for payment of our invoices is the passage of time, the Company records a receivable on the date the invoice is issued. Also included in accounts receivable are unbilled amounts resulting from revenue exceeding the amount billed to the customer, where the right to payment is unconditional. If the right to payment for services performed was conditional on something other than the passage of time, the unbilled amount would be recorded as a separate contract asset. There were no contract assets as of December 31, 2018. The majority of the Company’s contracts are non-cancellable. However, for contracts that are cancellable by the customer, the Company does not record a receivable when it issues an invoice. The Company records accounts receivable on these contracts only up to the amount of revenue earned but not yet collected. In addition, since the majority of the Company’s contracts are for a duration of one year and payment is expected within one year from the transfer of products and services, the Company does not adjust its receivables or transaction price for the effects of a significant financing component.
Deferred Revenue	Deferred Revenue The Company refers to contract liabilities as deferred revenue on the Consolidated Balance Sheets. Payment terms in the Company’s customer contracts vary, but generally require payment in advance of fully satisfying the performance obligation(s). Deferred revenue consists of billings in excess of revenue recognized. Similar to accounts receivable, the Company does not record deferred revenue for invoices issued on a cancellable contract. During the year ended December 31, 2018, the Company recognized approximately $134.7 million of revenue related to its deferred revenue balance at January 1, 2018. To determine revenue recognized in the current period from deferred revenue at the beginning of the period, the Company first allocates revenue to the individual deferred revenue balance outstanding at the beginning of the period, until the revenue equals that balance. Approximately $262.6 million of revenue is expected to be recognized during the next 12 to 24 months from remaining performance obligations as of December 31, 2018.
Cost to Obtain and Fulfill Contracts	Cost to Obtain and Fulfill Contracts The Company capitalizes commissions paid to internal sales representatives and related fringe benefits costs that are incremental to obtaining customer contracts. These costs are included in deferred commissions on the Consolidated Balance Sheets. The judgments made in determining the amount of costs incurred include the types of costs to capitalize and whether the costs are in fact incremental. The Company elected the practical expedient to account for these costs at a portfolio level as the Company’s contracts are similar in nature and the amortization model used closely matches the amortization expense that would be recognized on a contract-by-contract basis. Costs to obtain a contract are amortized to operations as the related revenue is recognized over the initial contract term. Amortization expense related to deferred commissions was $32.2 million for the year ended December 31, 2018. The Company evaluates the recoverability of deferred commissions at each balance sheet date. Costs to fulfill the Company’s contracts, such as our survey costs for our Analytics product line, do not meet the specified capitalization criteria as defined in the guidance and as such are expensed as incurred.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts Forrester maintains an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make contractually obligated payments. When evaluating the adequacy of the allowance for doubtful accounts, the Company makes judgments regarding the collectability of accounts receivable by specifically analyzing historical bad debts, customer concentrations, current economic trends, and changes in the customer payment terms. If the financial condition of the Company’s customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required and if the financial condition of the Company’s customers were to improve, the allowances may be reduced accordingly.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes the fair value of stock-based compensation expense over the requisite service period of the individual grantee, which generally equals the vesting period. The Company adopted the guidance in Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation Improvements to Employee Share-Based Payment Accounting Stock-based compensation expense was recorded in the following expense categories (in thousands): Years Ended December 31, 2018 2017 2016 Cost of services and fulfillment $ 4,329 $ 4,538 $ 4,431 Selling and marketing 1,065 717 1,054 General and administrative 2,906 3,235 2,491 Total $ 8,300 $ 8,490 $ 7,976 The options granted under the equity incentive plan and shares subject to the employee stock purchase plan were valued utilizing the Black-Scholes model using the following assumptions and had the following fair values (no options were granted in 2017 and 2018): Years Ended December 31, 2018 2017 2016 Employee Stock Purchase Plan Employee Stock Purchase Plan Equity Incentive Plans Employee Stock Purchase Plan Average risk-free interest rate 1.90 % 0.90 % 1.30 % 0.32 % Expected dividend yield 1.9 % 1.9 % 2.2 % 2.1 % Expected life 0.5 Years 0.5 Years 5.0 Years 0.5 Years Expected volatility 23 % 24 % 24 % 24 % Weighted average fair value $ 9.13 $ 8.36 $ 6.16 $ 6.69 Prior to the suspension of the quarterly dividend program in November 2018, dividend yields were based on the regular quarterly dividend program approved by the Board of Directors in February 2012. Expected volatility is based, in part, on the historical volatility of Forrester’s common stock as well as management’s expectations of future volatility over the expected term of the awards granted. The risk-free interest rate is based on the U.S. Treasury Constant Maturity rate with an equivalent remaining term. Where the expected term of a stock-based award does not correspond with a term for which the interest rates are quoted, Forrester uses the rate with the maturity closest to the award’s expected term. The expected term calculation is based upon Forrester’s historical experience of exercise patterns. The unamortized fair value of stock-based awards as of December 31, 2018 was $17.1 million with a weighted average remaining recognition period of 2.5 years.
Depreciation and Amortization	Depreciation and Amortization Forrester provides for depreciation and amortization of property and equipment, computed using the straight-line method, over estimated useful lives of assets as follows: Estimated Useful Life Computers and equipment 3 to 10 Years Computer software 3 to 5 Years Furniture and fixtures 7 Years Leasehold improvements Shorter of asset life or lease term Forrester provides for amortization of intangible assets, computed using an accelerated method according to the expected cash flows to be received from the underlying assets, over the respective lives as follows: Estimated Useful Life Customer relationships 5 to 11 Years Research content 1 to 2 Years Technology 5 to 7 Years Trademarks 8 to 9 Years
Income Taxes	Income Taxes Forrester recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statements and tax basis of assets and liabilities as well as operating loss carryforwards. Forrester’s provision for income taxes is composed of a current and a deferred provision for federal, state and foreign jurisdictions. The current provision is calculated as the estimated taxes payable or refundable on tax returns for the current year. The deferred provision is calculated as the net change during the year in deferred tax assets and liabilities. Valuation allowances are provided if based on the weight of available evidence, it is more likely than not that some or all of the deferred tax asset will not be realized. Forrester accounts for uncertain tax positions using a “more-likely-than-not” threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position. The Company evaluates these tax positions on a quarterly basis. The Company also accrues for potential interest and penalties related to unrecognized tax benefits in income tax expense.
Net Income Per Common Share	Net Income Per Common Share Basic net income per common share is computed by dividing net income by the basic weighted average number of common shares outstanding during the period. Diluted net income per common share is computed by dividing net income by the diluted weighted average number of common shares and common equivalent shares outstanding during the period. The weighted average number of common equivalent shares outstanding has been determined in accordance with the treasury-stock method. Common stock equivalents consist of common stock issuable upon the exercise of outstanding stock options and the vesting of restricted stock units. Basic and diluted weighted average common shares are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Basic weighted average common shares outstanding 18,091 17,919 17,984 Weighted average common equivalent shares 289 321 285 Diluted weighted average common shares outstanding 18,380 18,240 18,269 Options excluded from diluted weighted average share calculation as effect would have been anti-dilutive 8 133 706
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements , which allows for an additional adoption method and for lessors, provides a practical expedient for the separation of lease and non-lease components within a contract. The new standard will be effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. The two permitted transition methods under the new standard are both modified retrospective methods. Under the first method, the standard would be applied to all leases that existed at or subsequently commenced after the beginning of the earliest comparative period presented in the financial statements, with a cumulative effect adjustment recorded at the beginning of the earliest comparative period for all leases that commenced prior to such date. Under the second method, comparative periods are not adjusted and the cumulative effect of applying the standard would be recorded at the date of initial application. The Company will adopt the standard as of January 1, 2019 utilizing the modified retrospective method in which comparative periods are not adjusted. The Company anticipates that it will not be required to record a cumulative effect adjustment upon adoption. The Company expects the standard to have a material impact on its balance sheet as substantially all operating leases longer then 12 months will be recorded as a right-of-use (“ROU”) asset and a lease liability. Adoption of the standard will result in an approximate increase of $50 million to $54 million in total assets and $58 million to $62 million in total liabilities. The Company does not expect the standard to have a material impact on its results of operations. During 2019, ROU assets and lease liabilities for operating leases are expected to increase primarily due to the acquisition of SiriusDecisions. Several practical expedients are permitted under the new standard. The Company expects to elect the package of practical expedients, including the related disclosure requirements, that permits the use of historical lease classification and accounting under the previous guidance for all leases that expired or existed as of the adoption date. A key area still in process includes development of the reports for the various disclosures required during 2019. This area will be completed by the end of the first quarter of 2019. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Summary Of Significant Accounting Policy [Line Items]
Schedule of Components of Accumulated Other Comprehensive Loss	The components of accumulated other comprehensive loss are as follows (in thousands): Total Net Unrealized Gain Cumulative Accumulated (Loss) on Marketable Translation Other Comprehensive Investments Adjustment Income (Loss) Balance at December 31, 2015 $ (100 ) $ (4,726 ) $ (4,826 ) Foreign currency translation before reclassification — (2,764 ) (2,764 ) Unrealized gain on investments, net of tax of $(14) 17 — 17 Balance at December 31, 2016 (83 ) (7,490 ) (7,573 ) Foreign currency translation — 5,593 5,593 Unrealized loss on investments, net of tax of $22 (32 ) — (32 ) Balance at December 31, 2017 (115 ) (1,897 ) (2,012 ) Foreign currency translation — (3,257 ) (3,257 ) Reclassification of stranded tax effects from tax reform (26 ) — (26 ) Unrealized gain on investments before reclassification, net of tax of $(4) 12 — 12 Reclassification adjustment for net losses realized in net income, net of tax of $(75) 129 — 129 Balance at December 31, 2018 $ — $ (5,154 ) $ (5,154 )
Summary of Stock-Based Compensation Expense Recorded in Expense Categories	Stock-based compensation expense was recorded in the following expense categories (in thousands): Years Ended December 31, 2018 2017 2016 Cost of services and fulfillment $ 4,329 $ 4,538 $ 4,431 Selling and marketing 1,065 717 1,054 General and administrative 2,906 3,235 2,491 Total $ 8,300 $ 8,490 $ 7,976
Options Granted Under Equity Incentive Plans and Shares Subject to Employee Stock Purchase Plan Valuation Assumptions	The options granted under the equity incentive plan and shares subject to the employee stock purchase plan were valued utilizing the Black-Scholes model using the following assumptions and had the following fair values (no options were granted in 2017 and 2018): Years Ended December 31, 2018 2017 2016 Employee Stock Purchase Plan Employee Stock Purchase Plan Equity Incentive Plans Employee Stock Purchase Plan Average risk-free interest rate 1.90 % 0.90 % 1.30 % 0.32 % Expected dividend yield 1.9 % 1.9 % 2.2 % 2.1 % Expected life 0.5 Years 0.5 Years 5.0 Years 0.5 Years Expected volatility 23 % 24 % 24 % 24 % Weighted average fair value $ 9.13 $ 8.36 $ 6.16 $ 6.69
Depreciation and Amortization of Property and Equipment, Useful Life	Forrester provides for depreciation and amortization of property and equipment, computed using the straight-line method, over estimated useful lives of assets as follows: Estimated Useful Life Computers and equipment 3 to 10 Years Computer software 3 to 5 Years Furniture and fixtures 7 Years Leasehold improvements Shorter of asset life or lease term
Amortization of Intangible Assets, Useful Life	Forrester provides for amortization of intangible assets, computed using an accelerated method according to the expected cash flows to be received from the underlying assets, over the respective lives as follows: Estimated Useful Life Customer relationships 5 to 11 Years Research content 1 to 2 Years Technology 5 to 7 Years Trademarks 8 to 9 Years
Schedule of Basic and Diluted Weighted Average Common Shares	Basic and diluted weighted average common shares are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Basic weighted average common shares outstanding 18,091 17,919 17,984 Weighted average common equivalent shares 289 321 285 Diluted weighted average common shares outstanding 18,380 18,240 18,269 Options excluded from diluted weighted average share calculation as effect would have been anti-dilutive 8 133 706
ASC 606 [Member]
Summary Of Significant Accounting Policy [Line Items]
Summary of Effect of Adopting ASC 606 on Company's Financial Statements	The following tables summarize the effect of adopting ASC 606 on the Company’s financial statements during and as of the year ended December 31, 2018 (in thousands): Consolidated Balance Sheet As of December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Accounts receivable, net $ 67,318 $ 71,858 Deferred commissions 15,677 14,725 Prepaid expenses and other current assets 12,802 18,587 Total current assets 236,093 245,467 Other assets 5,310 4,748 Total assets 353,524 362,336 Deferred revenue $ 135,332 $ 149,344 Total current liabilities 189,985 203,997 Total liabilities 201,924 215,936 Retained earnings 127,717 122,517 Total stockholders’ equity 151,600 146,400 Total liabilities and stockholders’ equity 353,524 362,336 Consolidated Statement of Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Revenues: Research services $ 228,399 $ 227,059 Advisory services and events 129,176 128,872 Total revenues 357,575 355,931 Operating expenses: Cost of services and fulfillment 146,502 146,666 Selling and marketing 131,824 131,907 Total operating expenses 335,150 335,397 Income from operations 22,425 20,534 Income before income taxes 23,525 21,634 Income tax provision 8,145 7,652 Net income 15,380 13,982 Basic income per common share $ 0.85 $ 0.77 Diluted income per common share $ 0.84 $ 0.76 Consolidated Statement of Comprehensive Income Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Net income $ 15,380 $ 13,982 Comprehensive income 12,264 10,866 Consolidated Statement of Cash Flows Year Ended December 31, 2018 Amounts as if Previous Guidance in As Reported Effect Cash flows from operating activities: Net income $ 15,380 $ 13,982 Accounts receivable 2,588 (1,952 ) Deferred commissions (1,077 ) (994 ) Prepaid expenses and other current assets 285 (43 ) Deferred revenue (604 ) 5,580

Acquisitions (Tables)

Acquisitions (Tables) - FeedbackNow [Member]	12 Months Ended
	Dec. 31, 2018
Summary of Fair Value of Aggregate Consideration Paid or Payable	The following table summarizes the fair value of the aggregate consideration paid or payable for FeedbackNow (in thousands): Cash paid at close (1) $ 8,425 Working capital adjustment (2) 798 Indemnity holdback (3) 1,485 Contingent purchase price (4) 3,388 Total $ 14,096 (1) The cash paid at close represents the gross contractual amount paid. Net cash paid, which accounts for the cash acquired of $0.5 million, was $8.0 million and is reflected as an investing activity in the Consolidated Statements of Cash Flows. (2) Represents the amount payable to the sellers based upon working capital as defined, which was paid to the sellers during the first quarter of 2019. (3) Approximately $0.5 million and $1.0 million of the holdback is expected to be paid during 2019 and 2020, respectively. (4) The acquisition of FeedbackNow includes a contingent consideration arrangement that requires additional consideration to be paid to the sellers based on the financial performance of FeedbackNow during the two-year period subsequent to the closing date. Up to $1.7 million and $2.5 million could be payable during 2019 and 2020, respectively, if the financial targets are met. The range of undiscounted amounts that could be payable under this arrangement is zero to $4.2 million. This range of amounts payable has not changed since the acquisition. The provisional fair value of the contingent consideration recognized on the acquisition date, which represents purchase price, was $3.0 million. During the fourth quarter of 2018, the Company recorded a $0.4 million increase to the initial value of the contingent consideration representing additional purchase price, as a result of finalizing its acquisition date fair value assessment during the measurement period. This adjustment resulted in a final acquisition date fair value of $3.4 million for the contingent consideration. The fair value was based on a Monte Carlo simulation and included significant Level 3 inputs not observable in the market including projected contract bookings, a discount rate of 23.7%, and revenue volatility of 20.8%. See further discussion in Note 6 – Fair Value Measurements
Summary of Preliminary Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed	The following table summarizes the preliminary allocation of the purchase price to the fair value of the assets acquired and liabilities assumed for the acquisition of FeedbackNow (in thousands): Assets: Cash $ 463 Accounts receivable 738 Prepaids and other current assets 487 Goodwill (1) 9,513 Acquired intangible assets (2) 4,780 Other assets 75 Total assets 16,056 Liabilities: Accounts payable and accrued liabilities 837 Contract liabilities 298 Deferred tax liability 825 Total liabilities 1,960 Net assets acquired $ 14,096 (1) Goodwill represents the expected synergies from combining FeedbackNow with Forrester as well as the value of the acquired workforce. (2) All of the acquired intangible assets are finite-lived. The determination of the fair value of the finite-lived intangible assets required management judgment and the consideration of a number of factors. In determining the fair values, management primarily relied on income valuation methodologies, in particular discounted cash flow models. The use of discounted cash flow models required the use of estimates, including projected cash flows related to the particular asset; the useful lives of the particular assets; the selection of royalty and discount rates used in the models; and certain published industry benchmark data. In establishing the estimated useful lives of the acquired intangible assets, the Company relied primarily on the duration of the cash flows utilized in the valuation model. Of the $4.8 million assigned to acquired intangible assets, $3.0 million was assigned to the technology asset class with a useful life of 6.5 years, $1.3 million to customer relationships with useful lives of 4.5 years to 7.5 years (with a weighted average amortization period of 6.1 years), and $0.5 million to trade names with a useful life of 8.5 years. The weighted-average amortization period for the total acquired intangible assets is 4.8 years. Amortization of acquired intangible assets was $0.4 million for the year ended December 31, 2018.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Goodwill by Segment and Changes in Carrying Amount of Goodwill	A summary of the goodwill by segment and the changes in the carrying amount of goodwill is shown in the following table (in thousands). Project Product Research Consulting Total Balance at January 1, 2017 $ 2,343 $ 70,850 $ — $ 73,193 Translation adjustments 95 2,881 — 2,976 Balance at December 31, 2017 2,438 73,731 — 76,169 Acquisitions 10,178 — — 10,178 Translation adjustments (98 ) (1,084 ) — (1,182 ) Balance at December 31, 2018 $ 12,518 $ 72,647 $ — $ 85,165
Summary of Intangible Assets	A summary of Forrester’s intangible assets is as follows (in thousands): December 31, 2018 Gross Net Carrying Accumulated Carrying Amount Amortization Amount Amortizable intangible assets: Customer relationships $ 32,823 $ 31,604 $ 1,219 Technology 3,610 295 3,315 Trade name 443 26 417 Total $ 36,876 $ 31,925 $ 4,951 December 31, 2017 Gross Net Carrying Accumulated Carrying Amount Amortization Amount Amortizable intangible assets: Customer relationships $ 31,735 $ 31,003 $ 732 Research content 1,083 1,083 — Total $ 32,818 $ 32,086 $ 732
Summary of Estimated Intangible Assets Amortization Expense	Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows (in thousands): Year ending December 31, 2019 $ 865 Year ending December 31, 2020 865 Year ending December 31, 2021 865 Year ending December 31, 2022 865 Year ending December 31, 2023 693 Thereafter 798 Total $ 4,951

Marketable Investments (Tables)

Marketable Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Summary of Company's Marketable Investments	The following table summarizes the Company’s marketable investments, all of which are classified as available-for-sale (in thousands): As of December 31, 2017 Gross Gross Amortized Unrealized Unrealized Market Cost Gains Losses Value Federal agency obligations $ 1,800 $ — $ (7 ) $ 1,793 Corporate obligations 52,721 — (181 ) 52,540 Total $ 54,521 $ — $ (188 ) $ 54,333
Summary of Gross Unrealized Losses and Market Value of Available-for-Sale Securities with Unrealized Losses	The following table shows the gross unrealized losses and market value of Forrester’s available-for-sale securities with unrealized losses that are not deemed to be other-than-temporary, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands): As of December 31, 2017 Less Than 12 Months 12 Months or Greater Market Unrealized Market Unrealized Value Losses Value Losses Federal agency obligations $ — $ — $ 1,793 $ 7 Corporate obligations 31,723 149 20,817 32 Total $ 31,723 $ 149 $ 22,610 $ 39

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Company's Fair Value Hierarchy for its Financial Assets and Liabilities	The following table represents the Company’s fair value hierarchy for its financial assets and liabilities that are measured at fair value on a recurring basis (in thousands): Fair Value Measurements As of December 31, 2018 Level 1 Level 2 Level 3 Total Assets: Money market funds (1) $ 255 $ — $ — $ 255 Total Assets $ 255 $ — $ — $ 255 Liabilities: Contingent purchase price (2) $ — $ — $ (4,196 ) $ (4,196 ) Total Liabilities $ — $ — $ (4,196 ) $ (4,196 ) Fair Value Measurements As of December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Money market funds (1) $ 492 $ — $ — $ 492 Federal agency obligations — 1,793 — 1,793 Corporate obligations (3) — 52,540 — 52,540 Total Assets $ 492 $ 54,333 $ — $ 54,825 (1) Included in cash and cash equivalents. (2) $1.8 million is included in accrued expenses and other current liabilities and $2.4 million is included in non-current liabilities in the Consolidated Balance Sheet. (3) All corporate obligations were sold in December 2018, resulting in a loss of $0.2 million that was recorded in other income, net in the Consolidated Statements of Income. These investments were sold to fund a portion of the purchase of SiriusDecisions (refer to Note 15 – Subsequent Events
Summary of Changes in the Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the year ended December 31, 2018 were as follows (in thousands): Contingent Consideration Acquisition of FeedbackNow (1) $ (3,388 ) Fair value adjustment of FeedbackNow (2) (3) (780 ) Foreign exchange effect (28 ) Balance at December 31, 2018 $ (4,196 ) (1) See Note 2 – Acquisitions, (2) In the period subsequent to the acquisition of FeedbackNow on July 6, 2018, the fair value of the contingent consideration increased by $0.8 million due primarily to the achievement of contract bookings during this period. This amount was recognized as acquisition and integration costs within the Consolidated Statements of Income. (3) As of December 31, 2018, the significant unobservable inputs used in the Monte Carlo simulation to fair value the contingent consideration included projected contract bookings, a discount rate of 23.8%, and revenue volatility of 21.9%. Increases or decreases in the inputs would result in a higher or lower fair value measurement.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Before Income Taxes	Income before income taxes consists of the following (in thousands): Years Ended December 31, 2018 2017 2016 Domestic $ 17,718 $ 20,061 $ 22,303 Foreign 5,807 7,310 8,406 Total $ 23,525 $ 27,371 $ 30,709
Components of the Income Tax Provision	The components of the income tax provision are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Current: Federal $ 2,278 $ 2,587 $ 6,094 State 1,173 1,060 2,330 Foreign 1,763 2,159 2,032 Total current 5,214 5,806 10,456 Deferred: Federal 2,111 5,550 2,719 State 667 700 59 Foreign 153 175 (176 ) Total deferred 2,931 6,425 2,602 Income tax provision $ 8,145 $ 12,231 $ 13,058
Reconciliation of the Federal Statutory Rate	A reconciliation of the federal statutory rate to Forrester’s effective tax rate is as follows: Years Ended December 31, 2018 2017 2016 Income tax provision at federal statutory rate 21.0 % 35.0 % 35.0 % Increase (decrease) in tax resulting from: State tax provision, net of federal benefit 6.2 4.0 5.0 Foreign tax rate differential (0.2 ) (3.4 ) (4.4 ) Stock option compensation deduction (1.1 ) 0.1 0.6 Withholding taxes 2.1 1.7 0.5 Non-deductible expenses 5.3 1.8 1.5 Change in valuation allowance — 3.9 3.2 Change in tax legislation 1.9 5.8 — Audit settlements — (4.0 ) — Other, net (0.6 ) (0.2 ) 1.1 Effective tax rate 34.6 % 44.7 % 42.5 %
Components of Deferred Income Taxes	The components of deferred income taxes are as follows (in thousands): As of December 31, 2018 2017 Non-deductible reserves and accruals $ 3,835 $ 4,936 Net operating loss and other carryforwards 7,954 8,528 Stock compensation 2,125 2,644 Depreciation and amortization 727 402 Other assets — 46 Gross deferred tax asset 14,641 16,556 Less - valuation allowance (2,574 ) (2,686 ) Sub-total 12,067 13,870 Other liabilities (1,249 ) (911 ) Goodwill and intangible assets (6,201 ) (5,677 ) Deferred commissions (4,479 ) (3,873 ) Net deferred tax asset $ 138 $ 3,409
Summary of Changes in Deferred Tax Valuation Allowance	The following table provides a summary of the changes in the deferred tax valuation allowance for the years ended December 31, 2018, 2017 and 2016 (in thousands): 2018 2017 2016 Deferred tax valuation allowance at January 1 $ 2,686 $ 2,193 $ 1,534 Additions 74 1,439 1,256 Deductions (139 ) (70 ) (455 ) Change in tax legislation — (954 ) — Translation adjustments (47 ) 78 (142 ) Deferred tax valuation allowance at December 31 $ 2,574 $ 2,686 $ 2,193
Reconciliation of Unrecognized Tax Benefits	. A reconciliation of the beginning and ending amount of unrecognized tax benefits is summarized as follows for the years ended December 31, 2018, 2017 and 2016 (in thousands): 2018 2017 2016 Unrecognized tax benefits at January 1 $ 806 $ 1,774 $ 1,910 Reductions for tax positions of prior years — — (31 ) Additions for tax positions of current year — — 75 Settlements — (986 ) (163 ) Translation adjustments (7 ) 18 (17 ) Unrecognized tax benefits at December 31 $ 799 $ 806 $ 1,774

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Future Contractual Obligations for Operating Leases	As of December 31, 2018, Forrester had future contractual obligations as follows for operating leases (in thousands): 2019 $ 12,498 2020 11,762 2021 10,145 2022 8,552 2023 7,856 Thereafter 22,222 Total minimum lease payments $ 73,035

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Restricted Stock Unit Activity	RSU activity for the year ended December 31, 2018 is presented below (in thousands, except per share data): Weighted- Average Number of Grant Date Shares Fair Value Unvested at December 31, 2017 509 $ 37.59 Granted 261 43.71 Vested (198 ) 37.12 Forfeited (75 ) 38.31 Unvested at December 31, 2018 497 $ 40.89
Schedule of Stock Option Activity	Stock option activity for the year ended December 31, 2018 is presented below (in thousands, except per share data and contractual term): Weighted - Weighted - Average Average Exercise Remaining Aggregate Number Price Per Contractual Intrinsic of Shares Share Term (in years) Value Outstanding at December 31, 2017 937 $ 35.10 Granted — — Exercised (319 ) 34.83 Forfeited (35 ) 34.78 Outstanding at December 31, 2018 583 $ 35.27 4.82 $ 5,496 Exercisable at December 31, 2018 488 $ 35.40 4.44 $ 4,545 Vested and expected to vest at December 31, 2018 583 $ 35.27 4.82 $ 5,496
Summary of Shares Purchased by Employees Under the Stock Purchase Plan	Shares purchased by employees under the Stock Purchase Plan are as follows (in thousands, except per share data): Shares Purchase Purchase Period Ended Purchased Price February 28, 2018 27 $ 34.43 August 31, 2018 28 $ 34.21 February 28, 2017 24 $ 31.03 August 31, 2017 26 $ 31.71

Operating Segment and Enterpr_2

Operating Segment and Enterprise Wide Reporting (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Information about Reportable Segments	The following tables present information about reportable segments (in thousands): Project Product Research Consulting Consolidated Year Ended December 31, 2018 Research services revenues Research $ 157,669 $ — $ — $ 157,669 Connect 50,820 — — 50,820 Analytics 19,910 — — 19,910 Total research services revenues 228,399 — — 228,399 Advisory services and events revenues Advisory services — 41,086 478 41,564 Consulting services 8,649 10,027 55,465 74,141 Events 13,471 — — 13,471 Total advisory services and events revenues 22,120 51,113 55,943 129,176 Total segment revenues 250,519 51,113 55,943 357,575 Segment expenses 50,551 51,129 27,981 129,661 Contribution margin (loss) 199,968 (16 ) 27,962 227,914 Selling, marketing, administrative and other expenses (200,540 ) Amortization of intangible assets (1,162 ) Acquisition and integration costs (3,787 ) Reorganization costs — Other income and gains (losses) on investments 1,100 Income before income taxes $ 23,525 Project Product Research Consulting Consolidated Year Ended December 31, 2017 Research services revenues Research $ 148,935 $ — $ — $ 148,935 Connect 48,798 — — 48,798 Analytics 18,738 — — 18,738 Total research services revenues 216,471 — — 216,471 Advisory services and events revenues Advisory services — 36,074 320 36,394 Consulting services 10,132 8,980 53,941 73,053 Events 11,755 — — 11,755 Total advisory services and events revenues 21,887 45,054 54,261 121,202 Total segment revenues 238,358 45,054 54,261 337,673 Segment expenses 45,205 48,812 25,477 119,494 Contribution margin (loss) 193,153 (3,758 ) 28,784 218,179 Selling, marketing, administrative and other expenses (189,849 ) Amortization of intangible assets (781 ) Acquisition and integration costs — Reorganization costs — Other income and gains (losses) on investments (178 ) Income before income taxes $ 27,371 Project Product Research Consulting Consolidated Year Ended December 31, 2016 Research services revenues Research $ 147,576 $ — $ — $ 147,576 Connect 47,291 — — 47,291 Analytics 20,349 — — 20,349 Total research services revenues 215,216 — — 215,216 Advisory services and events revenues Advisory services — 34,392 590 34,982 Consulting services 9,547 10,239 45,284 65,070 Events 10,827 — — 10,827 Total advisory services and events revenues 20,374 44,631 45,874 110,879 Total segment revenues 235,590 44,631 45,874 326,095 Segment expenses 41,528 47,496 23,141 112,165 Contribution margin (loss) 194,062 (2,865 ) 22,733 213,930 Selling, marketing, administrative and other expenses (181,299 ) Amortization of intangible assets (831 ) Acquisition and integration costs — Reorganization costs (1,026 ) Other income and gains (losses) on investments (65 ) Income before income taxes $ 30,709
Schedule of Net Long-lived Tangible Assets by Location	Net long-lived tangible assets by location as of December 31, 2018 and 2017 are as follows (in thousands): 2018 2017 United States $ 20,880 $ 23,943 United Kingdom 522 727 Europe (excluding United Kingdom) 83 163 Asia Pacific 517 413 Other 3 3 Total $ 22,005 $ 25,249
Schedule of Revenues by Geographic Destination, Based on Location Products and Services and as a Percentage of Total Revenues	Revenues by geographic destination, based on the location products and services are consumed, and as a percentage of total revenues for the years ended December 31, 2018, 2017, and 2016 are as follows (dollars in thousands): 2018 2017 2016 United States 77 % 77 % 77 % Europe (excluding United Kingdom) 8 9 8 United Kingdom 4 4 5 Canada 4 4 4 Asia Pacific 5 4 4 Other 2 2 2 Total 100 % 100 % 100 % 2018 2017 2016 United States $ 274,151 $ 260,077 $ 252,222 Europe (excluding United Kingdom) 29,741 28,525 27,061 United Kingdom 15,273 13,651 14,808 Canada 15,569 14,523 13,806 Asia Pacific 17,839 15,952 13,686 Other 5,002 4,945 4,512 Total $ 357,575 $ 337,673 $ 326,095

Certain Balance Sheet Accounts

Certain Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Property and Equipment	Property and equipment as of December 31, 2018 and 2017 is recorded at cost less accumulated depreciation and consists of the following (in thousands): 2018 2017 Computers and equipment $ 18,621 $ 18,570 Computer software 31,276 29,891 Furniture and fixtures 8,449 9,094 Leasehold improvements 26,610 26,650 Total property and equipment 84,956 84,205 Less accumulated depreciation (62,951 ) (58,956 ) Total property and equipment, net $ 22,005 $ 25,249
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities as of December 31, 2018 and 2017 consist of the following (in thousands): 2018 2017 Payroll and related benefits $ 35,467 $ 34,809 Taxes 2,991 3,912 Other 15,607 10,908 Total $ 54,065 $ 49,629
Summary of Non-Current Liabilities	Non-current liabilities as of December 31, 2018 and 2017 consist of the following (in thousands): 2018 2017 Deferred tax liability $ 969 $ 408 Deferred rent 6,602 7,523 Contingent consideration and indemnity holdback 3,433 — Other 935 1,027 Total $ 11,939 $ 8,958
Summary of Allowance for Doubtful Accounts	A roll-forward of the allowance for doubtful accounts as of and for the years ended December 31, 2018, 2017, and 2016 is as follows (in thousands): 2018 2017 2016 Balance, beginning of year $ 155 $ 140 $ 153 Provision for doubtful accounts 567 331 150 Write-offs (363 ) (316 ) (163 ) Balance, end of year $ 359 $ 155 $ 140

Summary Selected Quarterly Fi_2

Summary Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Summary of Selected Consolidated Quarterly Financial Data	The following is a summary of selected unaudited consolidated quarterly financial data for the years ended December 31, 2018 and 2017 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, 2018 2018 2018 2018 Total revenues $ 77,749 $ 96,353 $ 84,890 $ 98,583 Income (loss) from operations $ (2,288 ) $ 11,027 $ 4,942 $ 8,744 Net income (loss) $ (1,733 ) $ 7,788 $ 3,950 $ 5,375 Basic income (loss) per common share $ (0.10 ) $ 0.43 $ 0.22 $ 0.29 Diluted income (loss) per common share $ (0.10 ) $ 0.43 $ 0.21 $ 0.29 Three Months Ended March 31, June 30, September 30, December 31, 2017 2017 2017 2017 Total revenues $ 77,194 $ 89,733 $ 80,369 $ 90,377 Income from operations $ 3,136 $ 10,213 $ 6,749 $ 7,451 Net income $ 3,030 $ 6,064 $ 3,953 $ 2,093 Basic income per common share $ 0.17 $ 0.34 $ 0.22 $ 0.12 Diluted income per common share $ 0.16 $ 0.34 $ 0.22 $ 0.11

Subsequent Events (Tables)

Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Schedule of Maturities of Long-term Debt	The amount payable in each year is set forth in the table below: Year Yearly Repayment Amount 1 $ 6,250,000 2 9,375,000 3 12,500,000 4 12,500,000 5 15,625,000 Thereafter $ 68,750,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail)	Jan. 03, 2019USD ($)	Jan. 02, 2018USD ($)	Dec. 31, 2018USD ($)$ / shares	Sep. 30, 2018USD ($)$ / shares	Jun. 30, 2018USD ($)$ / shares	Mar. 31, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Sep. 30, 2017USD ($)$ / shares	Jun. 30, 2017USD ($)$ / shares	Mar. 31, 2017USD ($)$ / shares	Dec. 31, 2018USD ($)ConsumerandBusinessLeaderCustomer$ / sharesshares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares
Summary Of Significant Accounting Policy [Line Items]
Reclassification adjustment to retained earnings for tax effects											$ 3,803,000	$ (419,000)
Deferred revenue			$ 135,332,000				$ 145,207,000				135,332,000	145,207,000
Prepaid expenses and other current assets			12,802,000				18,942,000				12,802,000	18,942,000
Deferred commissions			15,677,000				13,731,000				15,677,000	13,731,000
Other assets			5,310,000				6,231,000				5,310,000	6,231,000
Retained earnings			127,717,000				123,010,000				127,717,000	123,010,000
Total assets			353,524,000				345,200,000				353,524,000	345,200,000
Total revenues			98,583,000	$ 84,890,000	$ 96,353,000	$ 77,749,000	90,377,000	$ 80,369,000	$ 89,733,000	$ 77,194,000	357,575,000	337,673,000	$ 326,095,000
Net income			$ 5,375,000	$ 3,950,000	$ 7,788,000	$ (1,733,000)	$ 2,093,000	$ 3,953,000	$ 6,064,000	$ 3,030,000	$ 15,380,000	$ 15,140,000	$ 17,651,000
Diluted income per common share | $ / shares			$ 0.29	$ 0.21	$ 0.43	$ (0.10)	$ 0.11	$ 0.22	$ 0.34	$ 0.16	$ 0.84	$ 0.83	$ 0.97
Original maturities											90 days
Number of customers accounted for revenues or accounts receivable greater than 3% or 6% of total | Customer											0
Annual goodwill impairment test, period											November 30th
Goodwill impairment charges											$ 0	$ 0	$ 0
Non-current deferred rent liabilities			$ 6,602,000				$ 7,523,000				6,602,000	7,523,000
Foreign exchange gains (losses)											(603,000)	$ (632,000)	$ 81,000
Contract assets			0								$ 0
Contract with customer, contract duration											1 year
Deferred revenue recognized											$ 134,700,000
Revenue expected to be recognized			262,600,000								262,600,000
Amortization expense related to deferred commissions											$ 32,200,000
Options granted | shares											0
Unamortized fair value stock based compensation			17,100,000								$ 17,100,000
Weighted average remaining recognition period											2 years 6 months
Research Service Revenue [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policy [Line Items]
Customer accounted for percentage											3.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member]
Summary Of Significant Accounting Policy [Line Items]
Customer accounted for percentage											6.00%
ASU No. 2018-02 [Member]
Summary Of Significant Accounting Policy [Line Items]
Reclassification adjustment to retained earnings for tax effects		$ 26,000
ASC 606 [Member] | Initial Application Period Cumulative Effect Transition [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred revenue			7,800,000								$ 7,800,000
Prepaid expenses and other current assets			(5,500,000)								(5,500,000)
Deferred commissions			900,000								900,000
Other assets			600,000								600,000
Retained earnings			3,800,000								3,800,000
ASC 606 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred revenue			(14,000,000)								(14,000,000)
Total assets			(8,800,000)								(8,800,000)
Total revenues											(1,600,000)
Net income											$ (1,400,000)
Diluted income per common share | $ / shares											$ 0.08
SiriusDecisions, Inc [Member] | Subsequent Event [Member]
Summary Of Significant Accounting Policy [Line Items]
Percentage of issued and outstanding shares acquired	100.00%
Cash paid	$ 247,300,000
Minimum [Member]
Summary Of Significant Accounting Policy [Line Items]
Number of consumers and business leaders included in annual surveys | ConsumerandBusinessLeader											675,000
Advisory services period											1 hour
Consulting services period											14 days
Minimum [Member] | ASU No. 2016-02 [Member]
Summary Of Significant Accounting Policy [Line Items]
Right-of-use asset			50,000,000								$ 50,000,000
Liability			58,000,000								$ 58,000,000
Maximum [Member]
Summary Of Significant Accounting Policy [Line Items]
Advisory services period											2 days
Consulting services period											3 months
Contract with customer, expected payment term											one year
Maximum [Member] | ASU No. 2016-02 [Member]
Summary Of Significant Accounting Policy [Line Items]
Right-of-use asset			54,000,000								$ 54,000,000
Liability			$ 62,000,000								$ 62,000,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Effect of Adopting ASC 606 In Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts receivable, net	$ 67,318	$ 70,023
Deferred commissions	15,677	13,731
Prepaid expenses and other current assets	12,802	18,942
Total current assets	236,093	236,819
Other assets	5,310	6,231
Total assets	353,524	345,200
Deferred revenue	135,332	145,207
Total current liabilities	189,985	195,053
Total liabilities	201,924	204,011
Retained earnings	127,717	123,010
Total stockholders’ equity	151,600	141,189	$ 150,036	$ 127,302
Total liabilities and stockholders’ equity	353,524	$ 345,200
ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Accounts receivable, net	71,858
Deferred commissions	14,725
Prepaid expenses and other current assets	18,587
Total current assets	245,467
Other assets	4,748
Total assets	362,336
Deferred revenue	149,344
Total current liabilities	203,997
Total liabilities	215,936
Retained earnings	122,517
Total stockholders’ equity	146,400
Total liabilities and stockholders’ equity	$ 362,336

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Effect of Adopting ASC 606 In Consolidated Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total revenues	$ 98,583	$ 84,890	$ 96,353	$ 77,749	$ 90,377	$ 80,369	$ 89,733	$ 77,194	$ 357,575	$ 337,673	$ 326,095
Operating expenses:
Selling and marketing									131,824	123,917	116,898
Total operating expenses									335,150	310,124	295,321
Income from operations	8,744	4,942	11,027	(2,288)	7,451	6,749	10,213	3,136	22,425	27,549	30,774
Income before income taxes									23,525	27,371	30,709
Income tax provision									8,145	12,231	13,058
Net income	$ 5,375	$ 3,950	$ 7,788	$ (1,733)	$ 2,093	$ 3,953	$ 6,064	$ 3,030	$ 15,380	$ 15,140	$ 17,651
Basic income per common share	$ 0.29	$ 0.22	$ 0.43	$ (0.10)	$ 0.12	$ 0.22	$ 0.34	$ 0.17	$ 0.85	$ 0.84	$ 0.98
Diluted income per common share	$ 0.29	$ 0.21	$ 0.43	$ (0.10)	$ 0.11	$ 0.22	$ 0.34	$ 0.16	$ 0.84	$ 0.83	$ 0.97
ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Revenues:
Total revenues									$ 355,931
Operating expenses:
Selling and marketing									131,907
Total operating expenses									335,397
Income from operations									20,534
Income before income taxes									21,634
Income tax provision									7,652
Net income									$ 13,982
Basic income per common share									$ 0.77
Diluted income per common share									$ 0.76
Research Services [Member]
Revenues:
Total revenues									$ 228,399	$ 216,471	$ 215,216
Research Services [Member] | ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Revenues:
Total revenues									227,059
Advisory Services and Events [Member]
Revenues:
Total revenues									129,176	121,202	110,879
Advisory Services and Events [Member] | ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Revenues:
Total revenues									128,872
Cost of Services and Fulfillment [Member]
Operating expenses:
Cost of services and fulfillment									146,502	$ 136,872	$ 128,175
Cost of Services and Fulfillment [Member] | ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Operating expenses:
Cost of services and fulfillment									$ 146,666

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Effect of Adopting ASC 606 In Consolidated Statement of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 5,375	$ 3,950	$ 7,788	$ (1,733)	$ 2,093	$ 3,953	$ 6,064	$ 3,030	$ 15,380	$ 15,140	$ 17,651
Comprehensive income									12,264	$ 20,701	$ 14,904
ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Net income									13,982
Comprehensive income									$ 10,866

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Summary of Effect of Adopting ASC 606 In Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 5,375	$ 3,950	$ 7,788	$ (1,733)	$ 2,093	$ 3,953	$ 6,064	$ 3,030	$ 15,380	$ 15,140	$ 17,651
Accounts receivable									2,588	(10,327)	7,963
Deferred commissions									(1,077)	(1,679)	1,477
Prepaid expenses and other current assets									285	(4,146)	861
Deferred revenue									(604)	$ 8,586	$ (5,140)
ASC 606 [Member] | Amounts as if Previous Guidance in Effect [Member]
Cash flows from operating activities:
Net income									13,982
Accounts receivable									(1,952)
Deferred commissions									(994)
Prepaid expenses and other current assets									(43)
Deferred revenue									$ 5,580

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Schedule of Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 141,189	$ 150,036	$ 127,302
Foreign currency translation before reclassification			(2,764)
Foreign currency translation	(3,257)	5,593	(2,764)
Reclassification of stranded tax effects from tax reform	(26)
Unrealized (gain) loss on investments before reclassification, net of tax	12	(32)	17
Reclassification adjustment for net losses realized in net income, net of tax	129
Ending Balance	151,600	141,189	150,036
Net Unrealized Gain (Loss) on Marketable Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(115)	(83)	(100)
Reclassification of stranded tax effects from tax reform	(26)
Unrealized (gain) loss on investments before reclassification, net of tax	12	(32)	17
Reclassification adjustment for net losses realized in net income, net of tax	129
Ending Balance		(115)	(83)
Cumulative Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,897)	(7,490)	(4,726)
Foreign currency translation before reclassification			(2,764)
Foreign currency translation	(3,257)	5,593
Ending Balance	(5,154)	(1,897)	(7,490)
Total Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,012)	(7,573)	(4,826)
Foreign currency translation	(3,257)	5,593	(2,764)
Ending Balance	$ (5,154)	$ (2,012)	$ (7,573)

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Schedule of Components of Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Comprehensive Income Loss Tax Parenthetical Disclosures [Abstract]
Tax expense (benefit) on unrealized gain (loss) on investments	$ (4)	$ 22	$ (14)
Tax on reclassification adjustment for net losses realized in net income, net of tax	$ (75)

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Additional Information1 (Detail) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01	Dec. 31, 2018
Minimum [Member]
Summary Of Significant Accounting Policy [Line Items]
Performance obligation, revenue expected to be recognized	12 months
Maximum [Member]
Summary Of Significant Accounting Policy [Line Items]
Performance obligation, revenue expected to be recognized	24 months

Summary of Significant Accou_12

Summary of Significant Accounting Policies - Summary of Stock-Based Compensation Expense Recorded in Expense Categories (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 8,300	$ 8,490	$ 7,976
Cost of Services and Fulfillment [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	4,329	4,538	4,431
Selling and Marketing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	1,065	717	1,054
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total allocated share-based compensation expense	$ 2,906	$ 3,235	$ 2,491

Summary of Significant Accou_13

Summary of Significant Accounting Policies - Options Granted Under Equity Incentive Plans and Shares Subject to Employee Stock Purchase Plan Valuation Assumptions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average risk-free interest rate			1.30%
Expected dividend yield			2.20%
Expected life			5 years
Expected volatility			24.00%
Weighted average fair value			$ 6.16
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average risk-free interest rate	1.90%	0.90%	0.32%
Expected dividend yield	1.90%	1.90%	2.10%
Expected life	6 months	6 months	6 months
Expected volatility	23.00%	24.00%	24.00%
Weighted average fair value	$ 9.13	$ 8.36	$ 6.69

Summary of Significant Accou_14

Summary of Significant Accounting Policies - Depreciation and Amortization of Property and Equipment, Useful Life (Detail)	12 Months Ended
	Dec. 31, 2018
Computers and Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	3 years
Computers and Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	10 years
Computer Software [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	3 years
Computer Software [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	5 years
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	7 years
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Life	Shorter of asset life or lease term

Summary of Significant Accou_15

Summary of Significant Accounting Policies - Amortization of Intangible Assets, Useful Life (Detail)	12 Months Ended
	Dec. 31, 2018
Customer Relationships [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	5 years
Customer Relationships [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	11 years
Research Content [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	1 year
Research Content [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	2 years
Technology [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	5 years
Technology [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	7 years
Trademarks [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	8 years
Trademarks [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets, estimated useful life	9 years

Summary of Significant Accou_16

Summary of Significant Accounting Policies - Summary of Basic and Diluted Weighted Average Common Shares (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding	18,091	17,919	17,984
Weighted average common equivalent shares	289	321	285
Diluted weighted average common shares outstanding	18,380	18,240	18,269
Options excluded from diluted weighted average share calculation as effect would have been anti-dilutive	8	133	706

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($)	Jul. 06, 2018	Jun. 22, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 85,165,000	$ 85,165,000	$ 76,169,000	$ 73,193,000
Increase to goodwill			$ 400,000
Increase (decrease) in goodwill				9,000,000
Decrease in goodwill due to foreign currency fluctuations				$ 1,182,000	$ (2,976,000)
SocialGlimpz Inc. [Member]
Business Acquisition [Line Items]
Acquisition date		Jun. 22, 2018
Name of the business entity acquired				SocialGlimpz Inc.
Description of acquired entity				On June 22, 2018, Forrester acquired substantially all of the assets of SocialGlimpz Inc. (“GlimpzIt”), an artificial intelligence and machine-learning provider based in San Francisco. The acquisition is part of Forrester's plan to build a real-time customer experience or CX cloud solution, integrating a range of inputs to help companies monitor and improve customer experience. Forrester intends to deploy the GlimpzIt technology to extend the analytics engine in Forrester’s planned real-time CX cloud.
Purchase price paid		$ 1,300,000
Goodwill		700,000
Cash contingent to be paid on achievement of certain employment conditions		$ 300,000
Compensation expense to be recognized over related service period of employees		2 years
SocialGlimpz Inc. [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets		$ 600,000
Estimated useful life		5 years
FeedbackNow [Member]
Business Acquisition [Line Items]
Acquisition date	Jul. 6, 2018
Purchase price paid	$ 8,425,000
Goodwill	$ 9,513,000
Percentage of shares acquired	100.00%
Acquisition price due and subject to indemnity provisions from seller	$ 1,485,000
Additional purchase price payable based on acquired working capital	$ 798,000
Balance acquisition price payable period	2 years
Maximum consideration payable based on the financial performance of acquired company	$ 4,200,000
Revenue				$ 1,200,000
Direct expenses				1,900,000
Acquisition costs recognized				1,800,000
SocialGlimpz Inc and FeedbackNow [Member]
Business Acquisition [Line Items]
Increase (decrease) in goodwill				$ 10,200,000

Acquisitions - Summary of Fair

Acquisitions - Summary of Fair Value of Aggregate Consideration Paid or Payable (Detail) - FeedbackNow [Member] - USD ($) $ in Thousands	Jul. 06, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Cash paid at close	$ 8,425
Working capital adjustment	798
Indemnity holdback	1,485
Contingent purchase price	3,388	$ 3,400
Total	$ 14,096

Acquisitions - Summary of Fai_2

Acquisitions - Summary of Fair Value of Aggregate Consideration Paid or Payable (Parenthetical) (Detail)	Jul. 06, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Net cash paid					$ 9,250,000
FeedbackNow [Member]
Business Acquisition [Line Items]
Cash acquired	$ 500,000
Net cash paid	8,000,000
Holdback amount expected to be paid	1,485,000
Business acquisition undiscounted amounts could be payable, minimum	0
Business acquisition undiscounted amounts could be payable, maximum	4,200,000
Contingent purchase price	3,388,000	$ 3,400,000			$ 3,400,000
Increase to contingent consideration		$ 400,000
FeedbackNow [Member] | Provisional Fair Value [Member]
Business Acquisition [Line Items]
Contingent purchase price	$ 3,000,000
FeedbackNow [Member] | Level 3 [Member] | Contingent Consideration [Member] | Discount Rate [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration dicount rate	23.7	23.8			23.8
FeedbackNow [Member] | Level 3 [Member] | Contingent Consideration [Member] | Revenue Volatility [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration dicount rate	20.8	21.9			21.9
FeedbackNow [Member] | Scenario Forecast [Member]
Business Acquisition [Line Items]
Holdback amount expected to be paid			$ 1,000,000	$ 500,000
FeedbackNow [Member] | Maximum [Member] | Scenario Forecast [Member]
Business Acquisition [Line Items]
Additional consideration payable to sellers based on financial performance			$ 2,500,000	$ 1,700,000

Acquisitions - Summary of Preli

Acquisitions - Summary of Preliminary Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 06, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Goodwill	$ 85,165		$ 76,169	$ 73,193
FeedbackNow [Member]
Assets:
Cash		$ 463
Accounts receivable		738
Prepaids and other current assets		487
Goodwill		9,513
Acquired intangible assets		4,780
Other assets		75
Total assets		16,056
Liabilities:
Accounts payable and accrued liabilities		837
Contract liabilities		298
Deferred tax liability		825
Total liabilities		1,960
Net assets acquired		$ 14,096

Acquisitions - Summary of Pre_2

Acquisitions - Summary of Preliminary Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed (Parenthetical) (Detail) - USD ($) $ in Thousands	Jul. 06, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Amortization of intangible assets		$ 1,162	$ 781	$ 831
FeedbackNow [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 4,780
Acquired intangible assets, Useful life	4 years 9 months 18 days
Amortization of intangible assets		$ 400
FeedbackNow [Member] | Technology Asset Class [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 3,000
Acquired intangible assets, Useful life	6 years 6 months
FeedbackNow [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 1,300
Acquired intangible assets, Useful life	6 years 1 month 6 days
FeedbackNow [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Acquired intangible assets, Useful life	4 years 6 months
FeedbackNow [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Acquired intangible assets, Useful life	7 years 6 months
FeedbackNow [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 500
Acquired intangible assets, Useful life	8 years 6 months

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Summary of Goodwill by Segment and Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 76,169	$ 73,193
Acquisitions	10,178
Translation adjustments	(1,182)	2,976
Goodwill, Ending Balance	85,165	76,169
Product Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	2,438	2,343
Acquisitions	10,178
Translation adjustments	(98)	95
Goodwill, Ending Balance	12,518	2,438
Research Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	73,731	70,850
Translation adjustments	(1,084)	2,881
Goodwill, Ending Balance	$ 72,647	$ 73,731

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Accumulated goodwill impairment losses	$ 0
Amortization of intangible assets	1,162,000	$ 781,000	$ 831,000
FeedbackNow [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	4,800,000
Amortization of intangible assets	400,000
SocialGlimpz Inc. [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 600,000

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 36,876	$ 32,818
Accumulated Amortization	31,925	32,086
Total	4,951	732
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	32,823	31,735
Accumulated Amortization	31,604	31,003
Total	1,219	732
Research Content [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		1,083
Accumulated Amortization		$ 1,083
Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,610
Accumulated Amortization	295
Total	3,315
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	443
Accumulated Amortization	26
Total	$ 417

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Summary of Estimated Intangible Assets Amortization Expense (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
Year ending December 31, 2019	$ 865
Year ending December 31, 2020	865
Year ending December 31, 2021	865
Year ending December 31, 2022	865
Year ending December 31, 2023	693
Thereafter	798
Total	$ 4,951	$ 732

Marketable Investments - Summar

Marketable Investments - Summary of Company's Marketable Investments (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 54,521
Gross Unrealized Losses	(188)
Market Value	54,333
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52,721
Gross Unrealized Losses	(181)
Market Value	52,540
Federal Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,800
Gross Unrealized Losses	(7)
Market Value	$ 1,793

Marketable Investments - Summ_2

Marketable Investments - Summary of Gross Unrealized Losses and Market Value of Available-for-Sale Securities with Unrealized Losses (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less Than 12 Months, Market Value	$ 31,723
Available for sale securities, Less Than 12 Months, Unrealized Losses	149
Available for sale securities, 12 Months or Greater, Market Value	22,610
Available for sale securities, 12 Months or Greater, Unrealized Losses	39
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less Than 12 Months, Market Value	31,723
Available for sale securities, Less Than 12 Months, Unrealized Losses	149
Available for sale securities, 12 Months or Greater, Market Value	20,817
Available for sale securities, 12 Months or Greater, Unrealized Losses	32
Federal Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, 12 Months or Greater, Market Value	1,793
Available for sale securities, 12 Months or Greater, Unrealized Losses	$ 7

Marketable Investments - Additi

Marketable Investments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Other Income, Net [Member]
Schedule of Available-for-sale Securities [Line Items]
Realized losses on sales of available-for-sale securities	$ 0.2

Non-Marketable Investments - Ad

Non-Marketable Investments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Carrying value of the Company's non-marketable investments	$ 2,500,000	$ 1,900,000
Book value of investment			$ 400,000
Gain (losses) from non-marketable investments	600,000	(500,000)	(800,000)
Distributions received from funds	$ 0	$ 400,000	$ 0
Limited Partnerships Investments [Member] | Minimum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Ownership interest of Company	5.00%

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Company's Fair Value Hierarchy for its Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Fair value of investments	$ 255	$ 54,825
Liabilities:
Fair value of liabilities	(4,196)
Corporate Obligations [Member]
Assets:
Fair value of investments		52,540
Contingent Purchase Price [Member]
Liabilities:
Fair value of liabilities	(4,196)
Federal Agency Obligations [Member]
Assets:
Fair value of investments		1,793
Money Market Funds [Member]
Assets:
Fair value of cash equivalents	255	492
Level 1 [Member]
Assets:
Fair value of investments	255	492
Level 1 [Member] | Money Market Funds [Member]
Assets:
Fair value of cash equivalents	255	492
Level 2 [Member]
Assets:
Fair value of investments		54,333
Level 2 [Member] | Corporate Obligations [Member]
Assets:
Fair value of investments		52,540
Level 2 [Member] | Federal Agency Obligations [Member]
Assets:
Fair value of investments		$ 1,793
Level 3 [Member]
Liabilities:
Fair value of liabilities	(4,196)
Level 3 [Member] | Contingent Purchase Price [Member]
Liabilities:
Fair value of liabilities	$ (4,196)

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Company's Fair Value Hierarchy for its Financial Assets and Liabilities (Parenthetical) (Detail) - Fair Value, Measurements, Recurring [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities	$ 4,196
Accrued Expenses and Other Current Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities	1,800
Non-current Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities	2,400
Corporate Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized, loss	$ 200

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Changes in the Fair Value of Level 3 Contingent Consideration (Detail) - Level 3 [Member] - Contingent Consideration [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Foreign exchange effect	$ (28)
Ending balance	(4,196)
FeedbackNow [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Acquisition of FeedbackNow	(3,388)
Fair value adjustment of FeedbackNow	$ (780)

Fair Value Measurements - Sum_4

Fair Value Measurements - Summary of Changes in the Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail) - Level 3 [Member] - Contingent Consideration [Member] - FeedbackNow [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Jul. 06, 2018
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Increase in fair value of contingent consideration	$ 780
Discount Rate [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value of contingent consideration dicount rate	23.8	23.7
Revenue Volatility [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value of contingent consideration dicount rate	21.9	20.8

Income Taxes - Income Before In

Income Taxes - Income Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ 17,718	$ 20,061	$ 22,303
Foreign	5,807	7,310	8,406
Income before income taxes	$ 23,525	$ 27,371	$ 30,709

Income Taxes - Components of th

Income Taxes - Components of the Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 2,278	$ 2,587	$ 6,094
State	1,173	1,060	2,330
Foreign	1,763	2,159	2,032
Total current	5,214	5,806	10,456
Deferred:
Federal	2,111	5,550	2,719
State	667	700	59
Foreign	153	175	(176)
Total deferred	2,931	6,425	2,602
Income tax provision	$ 8,145	$ 12,231	$ 13,058

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax provision at federal statutory rate	21.00%	35.00%	35.00%
Increase (decrease) in tax resulting from:
State tax provision, net of federal benefit	6.20%	4.00%	5.00%
Foreign tax rate differential	(0.20%)	(3.40%)	(4.40%)
Stock option compensation deduction	(1.10%)	0.10%	0.60%
Withholding taxes	2.10%	1.70%	0.50%
Non-deductible expenses	5.30%	1.80%	1.50%
Change in valuation allowance		3.90%	3.20%
Change in tax legislation	1.90%	5.80%
Audit settlements		(4.00%)
Other, net	(0.60%)	(0.20%)	1.10%
Effective tax rate	34.60%	44.70%	42.50%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Corporate tax rate		21.00%	35.00%	35.00%
Amounts related to the remeasurement of federal deferred tax assets and liabilities		$ 1,200,000
Amounts related to one-time transition tax on mandatory deemed repatriation of foreign earnings		400,000
Cumulative foreign earnings from tax cuts and jobs act of 2017		$ 22,600,000
Tax Cuts and Jobs Act of 2017, accounting complete		true
Additional income tax expense due to tax cuts and jobs act of 2017		$ 400,000
Long-term net deferred tax assets		1,100,000	$ 3,500,000
Long-term net deferred tax liabilities		1,000,000	100,000
Valuation allowance		2,574,000	2,686,000	$ 2,193,000	$ 1,534,000
Operating loss carryforwards related to a prior acquisition		3,200,000
U.S. federal and state capital loss carryforwards		6,200,000
Deferred tax assets, Capital loss carryforwards expires in 2020		1,600,000
Deferred tax assets, Capital loss carryforwards expires in 2021		1,400,000
Deferred tax assets, Capital loss carryforwards expires in 2022		3,200,000
Unremitted earnings of U.S. deferred tax liability of foreign subsidiaries		0
Unremitted earnings		13,800,000
Unrecognized tax benefits		799,000	$ 806,000	1,774,000	$ 1,910,000
Unrecognized tax benefits, reversal				31,000
Accrued interest and penalties related to uncertain tax positions				$ 100,000
Scenario Forecast [Member]
Income Taxes [Line Items]
Unrecognized tax benefits, reversal	$ 400,000
Additional Tax expense	$ 500,000
Foreign Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards		$ 20,800,000

Income Taxes - Components of De

Income Taxes - Components of Deferred Income Taxes (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Non-deductible reserves and accruals	$ 3,835	$ 4,936
Net operating loss and other carryforwards	7,954	8,528
Stock compensation	2,125	2,644
Depreciation and amortization	727	402
Other assets		46
Gross deferred tax asset	14,641	16,556
Less - valuation allowance	(2,574)	(2,686)	$ (2,193)	$ (1,534)
Sub-total	12,067	13,870
Other liabilities	(1,249)	(911)
Goodwill and intangible assets	(6,201)	(5,677)
Deferred commissions	(4,479)	(3,873)
Net deferred tax asset	$ 138	$ 3,409

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Deferred Tax Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred tax valuation allowance, Beginning Balance	$ 2,686	$ 2,193	$ 1,534
Additions	74	1,439	1,256
Deductions	(139)	(70)	(455)
Change in tax legislation		(954)
Translation adjustments	(47)	78	(142)
Deferred tax valuation allowance, Ending Balance	$ 2,574	$ 2,686	$ 2,193

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, Beginning Balance	$ 806	$ 1,774	$ 1,910
Reductions for tax positions of prior years			(31)
Additions for tax positions of current year			75
Settlements		(986)	(163)
Translation adjustments	(7)	18	(17)
Unrecognized tax benefits, Ending Balance	$ 799	$ 806	$ 1,774

Commitments - Future Contractua

Commitments - Future Contractual Obligations for Operating Leases (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,019	$ 12,498
2,020	11,762
2,021	10,145
2,022	8,552
2,023	7,856
Thereafter	22,222
Total minimum lease payments	$ 73,035

Commitments - Additional Inform

Commitments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Aggregate rent expense	$ 17.5	$ 17.4	$ 16.1

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended												12 Months Ended
	May 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2012	Feb. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized		500,000				500,000								500,000	500,000
Preferred stock, par value		$ 0.01				$ 0.01								$ 0.01	$ 0.01
Authorized to purchase of common stock under the stock repurchase program		$ 535,000,000												$ 535,000,000				$ 50,000,000
Cumulative repurchase of common stock		16,300,000												16,300,000
Aggregate cost of repurchase of common stock														$ 474,900,000
Dividend declared and paid per share		$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.18	$ 0.18	$ 0.18	$ 0.18
Dividend declared per share														$ 0.80	$ 0.76	$ 0.72
Aggregate dividend declared for the year														$ 14,500,000	$ 13,600,000	$ 13,000,000
Option Outstanding and vested		583,000				937,000								583,000	937,000
Common stock, par value		$ 0.01				$ 0.01								$ 0.01	$ 0.01
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	500,000
Increase in number of shares issuable under plan	400,000
Shares authorized	1,100,000
Common stock, par value	$ 0.01
Hours of work per week	20 hours
Duration of purchase periods under employee stock purchase plan	6 months
Holding period of stocks acquired under employee stock purchase plan	1 year
Value used to derive maximum number of shares per participant for employee stock purchase	$ 12,500
Employee maximum elected percentage reduction of compensation to purchase shares	10.00%
Exercise price rate of fair value	85.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value for RSUs granted														$ 43.71	$ 39.73	$ 37.87
Number of shares received per restricted stock unit on lapse of restrictions and vesting condition met														1
Value of RSUs vested and converted to common stock														$ 9,100,000	$ 8,700,000	$ 6,600,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised														$ 3,300,000	$ 4,500,000	$ 3,700,000
Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan extended term														10 years
Equity incentive plan expiration														2026-05
Increase in number of shares issuable under plan														2,000,000
Equity Incentive Plan [Member] | Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans		2,500,000												2,500,000
Shares authorized																	6,350,000
Shares returned																	713,275
Option expiration period														10 years
Equity Incentive Plan [Member] | Equity Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested period														4 years
Equity Incentive Plan [Member] | Equity Plan [Member] | Non-Employee Directors [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested period														1 year
1996 Equity Plan [Member] | Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans		0												0
2006 Director Plan [Member] | Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans		0												0
Shares authorized		450,000												450,000
Shares returned																	80,000,000
Option Outstanding and vested		36,000												36,000
1996 Director [Member] | Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans		0												0

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Units (RSUs) [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested at December 31, 2017	509
Number of Shares, Granted	261
Number of Shares, Vested	(198)
Number of Shares, Forfeited	(75)
Number of Shares, Unvested at December 31, 2018	497	509
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance	$ 37.59
Weighted-Average Grant Date Fair Value, Granted	43.71	$ 39.73	$ 37.87
Weighted-Average Grant Date Fair Value, Vested	37.12
Weighted-Average Grant Date Fair Value, Forfeited	38.31
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance	$ 40.89	$ 37.59

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding at December 31, 2017	937,000
Number of Shares, Granted	0
Number of Shares, Exercised	(319,000)
Number of Shares, Forfeited	(35,000)
Number of Shares, Outstanding at December 31, 2018	583,000
Number of Shares, Exercisable at December 31, 2018	488,000
Number of Shares, Vested and expected to vest at December 31, 2018	583,000
Weighted - Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 35.10
Weighted - Average Exercise Price Per Share, Exercised | $ / shares	34.83
Weighted - Average Exercise Price Per Share, Forfeited | $ / shares	34.78
Weighted - Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	35.27
Weighted - Average Exercise Price Per Share, Exercisable at December 31, 2018 | $ / shares	35.40
Weighted - Average Exercise Price Per Share, Vested and expected to vest at December 31, 2018 | $ / shares	$ 35.27
Weighted - Average Remaining Contractual Term, Outstanding at December 31, 2018	4 years 9 months 25 days
Weighted - Average Remaining Contractual Term, Exercisable at December 31, 2018	4 years 5 months 8 days
Weighted - Average Remaining Contractual Term, Vested and expected to vest at December 31, 2018	4 years 9 months 25 days
Aggregate Intrinsic Value, Outstanding at December 31, 2018 | $	$ 5,496
Aggregate Intrinsic Value, Exercisable at December 31, 2018 | $	4,545
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2018 | $	$ 5,496

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shares Purchased by Employees Under the Stock Purchase Plan (Detail) - $ / shares shares in Thousands	6 Months Ended
	Aug. 31, 2018	Feb. 28, 2018	Aug. 31, 2017	Feb. 28, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Purchased	28	27	26	24
Purchase Price	$ 34.21	$ 34.43	$ 31.71	$ 31.03

Employee Pension Plans - Additi

Employee Pension Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Contribution to defined contribution plans	$ 5	$ 5.2	$ 4.3

Reorganization - Additional Inf

Reorganization - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Restructuring And Related Activities [Abstract]
Percentage of workforce reduction	2.00%
Severance costs	$ 1

Operating Segment and Enterpr_3

Operating Segment and Enterprise Wide Reporting - Schedule of Information about Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 98,583	$ 84,890	$ 96,353	$ 77,749	$ 90,377	$ 80,369	$ 89,733	$ 77,194	$ 357,575	$ 337,673	$ 326,095
Segment expenses									129,661	119,494	112,165
Contribution margin (loss)									227,914	218,179	213,930
Selling, marketing, administrative and other expenses									(200,540)	(189,849)	(181,299)
Amortization of intangible assets									(1,162)	(781)	(831)
Acquisition and integration costs									(3,787)
Reorganization costs											(1,026)
Other income and gains (losses) on investments									1,100	(178)	(65)
Income before income taxes									23,525	27,371	30,709
Research [Member]
Segment Reporting Information [Line Items]
Total revenues									157,669	148,935	147,576
Connect [Member]
Segment Reporting Information [Line Items]
Total revenues									50,820	48,798	47,291
Analytics [Member]
Segment Reporting Information [Line Items]
Total revenues									19,910	18,738	20,349
Research Services [Member]
Segment Reporting Information [Line Items]
Total revenues									228,399	216,471	215,216
Advisory Services [Member]
Segment Reporting Information [Line Items]
Total revenues									41,564	36,394	34,982
Consulting Services [Member]
Segment Reporting Information [Line Items]
Total revenues									74,141	73,053	65,070
Events [Member]
Segment Reporting Information [Line Items]
Total revenues									13,471	11,755	10,827
Advisory Services and Events [Member]
Segment Reporting Information [Line Items]
Total revenues									129,176	121,202	110,879
Product Organization [Member]
Segment Reporting Information [Line Items]
Total revenues									250,519	238,358	235,590
Segment expenses									50,551	45,205	41,528
Contribution margin (loss)									199,968	193,153	194,062
Product Organization [Member] | Research [Member]
Segment Reporting Information [Line Items]
Total revenues									157,669	148,935	147,576
Product Organization [Member] | Connect [Member]
Segment Reporting Information [Line Items]
Total revenues									50,820	48,798	47,291
Product Organization [Member] | Analytics [Member]
Segment Reporting Information [Line Items]
Total revenues									19,910	18,738	20,349
Product Organization [Member] | Research Services [Member]
Segment Reporting Information [Line Items]
Total revenues									228,399	216,471	215,216
Product Organization [Member] | Consulting Services [Member]
Segment Reporting Information [Line Items]
Total revenues									8,649	10,132	9,547
Product Organization [Member] | Events [Member]
Segment Reporting Information [Line Items]
Total revenues									13,471	11,755	10,827
Product Organization [Member] | Advisory Services and Events [Member]
Segment Reporting Information [Line Items]
Total revenues									22,120	21,887	20,374
Research Organization [Member]
Segment Reporting Information [Line Items]
Total revenues									51,113	45,054	44,631
Segment expenses									51,129	48,812	47,496
Contribution margin (loss)									(16)	(3,758)	(2,865)
Research Organization [Member] | Advisory Services [Member]
Segment Reporting Information [Line Items]
Total revenues									41,086	36,074	34,392
Research Organization [Member] | Consulting Services [Member]
Segment Reporting Information [Line Items]
Total revenues									10,027	8,980	10,239
Research Organization [Member] | Advisory Services and Events [Member]
Segment Reporting Information [Line Items]
Total revenues									51,113	45,054	44,631
Project Consulting [Member]
Segment Reporting Information [Line Items]
Total revenues									55,943	54,261	45,874
Segment expenses									27,981	25,477	23,141
Contribution margin (loss)									27,962	28,784	22,733
Project Consulting [Member] | Advisory Services [Member]
Segment Reporting Information [Line Items]
Total revenues									478	320	590
Project Consulting [Member] | Consulting Services [Member]
Segment Reporting Information [Line Items]
Total revenues									55,465	53,941	45,284
Project Consulting [Member] | Advisory Services and Events [Member]
Segment Reporting Information [Line Items]
Total revenues									$ 55,943	$ 54,261	$ 45,874

Operating Segment and Enterpr_4

Operating Segment and Enterprise Wide Reporting - Schedule of Net Long-lived Tangible Assets by Location (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	$ 22,005	$ 25,249
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	20,880	23,943
United Kingdom [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	522	727
Europe (Excluding United Kingdom) [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	83	163
Asia Pacific [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	517	413
Other [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net long-lived tangible assets	$ 3	$ 3

Operating Segment and Enterpr_5

Operating Segment and Enterprise Wide Reporting - Schedule of Revenues by Geographic Destination, Based on Location Products and Services and as a Percentage of Total Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									100.00%	100.00%	100.00%
Revenue	$ 98,583	$ 84,890	$ 96,353	$ 77,749	$ 90,377	$ 80,369	$ 89,733	$ 77,194	$ 357,575	$ 337,673	$ 326,095
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									77.00%	77.00%	77.00%
Revenue									$ 274,151	$ 260,077	$ 252,222
Europe (Excluding United Kingdom) [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									8.00%	9.00%	8.00%
Revenue									$ 29,741	$ 28,525	$ 27,061
United Kingdom [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									4.00%	4.00%	5.00%
Revenue									$ 15,273	$ 13,651	$ 14,808
Canada [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									4.00%	4.00%	4.00%
Revenue									$ 15,569	$ 14,523	$ 13,806
Asia Pacific [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									5.00%	4.00%	4.00%
Revenue									$ 17,839	$ 15,952	$ 13,686
Other [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues by geographical area percentage									2.00%	2.00%	2.00%
Revenue									$ 5,002	$ 4,945	$ 4,512

Certain Balance Sheet Account_2

Certain Balance Sheet Accounts - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Total property and equipment	$ 84,956	$ 84,205
Less accumulated depreciation	(62,951)	(58,956)
Total property and equipment, net	22,005	25,249
Computers and Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	18,621	18,570
Computer Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	31,276	29,891
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	8,449	9,094
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	$ 26,610	$ 26,650

Certain Balance Sheet Account_3

Certain Balance Sheet Accounts - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Amortization of capitalized internal use software costs	$ 4.2	$ 2.7	$ 3.1

Certain Balance Sheet Account_4

Certain Balance Sheet Accounts - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Payroll and related benefits	$ 35,467	$ 34,809
Taxes	2,991	3,912
Other	15,607	10,908
Total	$ 54,065	$ 49,629

Certain Balance Sheet Account_5

Certain Balance Sheet Accounts - Summary of Non-Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Liabilities Noncurrent [Abstract]
Deferred tax liability	$ 969	$ 408
Deferred rent	6,602	7,523
Contingent consideration and indemnity holdback	3,433
Other	935	1,027
Total	$ 11,939	$ 8,958

Certain Balance Sheet Account_6

Certain Balance Sheet Accounts - Summary of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Balance, beginning of year	$ 155	$ 140	$ 153
Provision for doubtful accounts	567	331	150
Write-offs	(363)	(316)	(163)
Balance, end of year	$ 359	$ 155	$ 140

Summary Selected Quarterly Fi_3

Summary Selected Quarterly Financial Data - Summary of Selected Consolidated Quarterly Financial Data (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 98,583	$ 84,890	$ 96,353	$ 77,749	$ 90,377	$ 80,369	$ 89,733	$ 77,194	$ 357,575	$ 337,673	$ 326,095
Income (loss) from operations	8,744	4,942	11,027	(2,288)	7,451	6,749	10,213	3,136	22,425	27,549	30,774
Net income (loss)	$ 5,375	$ 3,950	$ 7,788	$ (1,733)	$ 2,093	$ 3,953	$ 6,064	$ 3,030	$ 15,380	$ 15,140	$ 17,651
Basic income (loss) per common share	$ 0.29	$ 0.22	$ 0.43	$ (0.10)	$ 0.12	$ 0.22	$ 0.34	$ 0.17	$ 0.85	$ 0.84	$ 0.98
Diluted income (loss) per common share	$ 0.29	$ 0.21	$ 0.43	$ (0.10)	$ 0.11	$ 0.22	$ 0.34	$ 0.16	$ 0.84	$ 0.83	$ 0.97

Summary Selected Quarterly Fi_4

Summary Selected Quarterly Financial Data - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Research Services [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Out-of-period correction revenue	$ 1
Out-of-period correction revenue, after tax	$ 0.7
Understatement of Revenue from Reprint Product Line [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Out-of-period correction revenue		$ 0.8	$ 0.2
Out-of-period correction revenue, after tax		$ 0.5	$ 0.1

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	Jan. 03, 2019USD ($)Employee	Dec. 31, 2018USD ($)
Subsequent Event [Line Items]
Net cash paid		$ 9,250,000
Subsequent Event [Member] | Term Loans [Member]
Subsequent Event [Line Items]
Senior secured term loans	$ 125,000,000
Subsequent Event [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Line of credit facility current borrowing capacity	$ 50,000,000
SiriusDecisions, Inc [Member]
Subsequent Event [Line Items]
Business combination acquisition and integration cost		$ 1,800,000
SiriusDecisions, Inc [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Percentage of issued and outstanding shares acquired	100.00%
Number of employees | Employee	350
Consideration paid at closing	$ 247,300,000
Purchase price consideration	245,000,000
Cash acquired	7,200,000
Net cash paid	240,100,000
Credit facility, maximum borrowing capacity amount	$ 200,000,000
Percentage of voting equity of subsidiaries	65.00%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Term Loans [Member]
Subsequent Event [Line Items]
Senior secured term loans	$ 125,000,000
Debt instrument maturity date	Jan. 3, 2024
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	$ 75,000,000
Credit facility maturity date	Jan. 3, 2024
Percentage of commitment fee on the unused portion of the facility	0.35%
Line of credit facility unused capacity commitment fee percentage	0.30%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Letters of Credit [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Available for issuance of letter of credit	$ 5,000,000
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Minimum [Member] | LIBOR [Member]
Subsequent Event [Line Items]
Interest rate	1.75%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Minimum [Member] | Base Rate [Member]
Subsequent Event [Line Items]
Interest rate	0.75%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Minimum [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Line of credit facility unused capacity commitment fee percentage	0.25%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Maximum [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Increase (decrease) in line of credit facility	$ 50,000,000
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Maximum [Member] | LIBOR [Member]
Subsequent Event [Line Items]
Interest rate	2.50%
SiriusDecisions, Inc [Member] | Subsequent Event [Member] | Maximum [Member] | Base Rate [Member]
Subsequent Event [Line Items]
Interest rate	1.50%

Subsequent Events - Schedule of

Subsequent Events - Schedule of Maturities of Long-term Debt (Detail) - Subsequent Event [Member] - SiriusDecisions, Inc [Member]	Jan. 03, 2019USD ($)
Business Acquisition [Line Items]
Long-term maturities, repayment of principal in year one	$ 6,250,000
Long-term maturities, repayment of principal in year two	9,375,000
Long-term maturities, repayment of principal in year three	12,500,000
Long-term maturities, repayment of principal in year four	12,500,000
Long-term maturities, repayment of principal in year five	15,625,000
Long-term maturities, repayment of principal in thereafter	$ 68,750,000