Avalara (AVLR) 10-Q 5 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	AVLR
Entity Registrant Name	AVALARA, INC.
Entity Central Index Key	0001348036
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		86,915,885
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38525
Entity Tax Identification Number	91-1995935
Entity Address, Address Line One	255 South King Street
Entity Address, Address Line Two	Suite 1800
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98104
City Area Code	206
Local Phone Number	826-4900
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, Par Value $0.0001 Per Share
Security Exchange Name	NYSE
Entity Incorporation, State or Country Code	WA
Document Quarterly Report	true
Document Transition Report	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,536,422	$ 673,593
Restricted cash	37,700	19,953
Trade accounts receivable—net of allowance for doubtful accounts of $5,394 and $3,983, respectively	96,305	75,857
Deferred commissions	15,735	12,245
Prepaid expenses and other current assets	31,102	20,098
Total current assets before customer fund assets	1,717,264	801,746
Funds held from customers	79,884	30,598
Receivable from customers—net of allowance of $912 and $593, respectively	1,280	563
Total current assets	1,798,428	832,907
Noncurrent assets:
Restricted cash	0	37,700
Deferred commissions	47,896	38,625
Operating lease right-of-use assets—net	46,798	52,320
Property and equipment—net	42,645	34,713
Intangible assets—net	88,417	86,513
Goodwill	603,768	513,234
Other noncurrent assets	10,323	6,321
Total assets	2,638,275	1,602,333
Current liabilities:
Trade payables	18,741	20,280
Accrued expenses	91,978	84,532
Deferred revenue	256,182	208,026
Accrued purchase price related to acquisitions	48,869	22,473
Accrued earnout liabilities	29,456	749
Operating lease liabilities	11,839	11,339
Total current liabilities before customer fund obligations	457,065	347,399
Customer fund obligations	81,955	31,549
Total current liabilities	539,020	378,948
Noncurrent liabilities:
Convertible senior notes—net	960,373	0
Deferred revenue	1,701	1,664
Accrued purchase price related to acquisitions	3,889	49,057
Accrued earnout liabilities	46,416	34,468
Operating lease liabilities	48,416	56,625
Deferred tax liability	2,195	1,031
Other noncurrent liabilities	817	380
Total liabilities	1,602,827	522,173
Commitments and contingencies	0	0
Shareholders' equity:
Preferred stock, $0.0001 par value – no shares issued and outstanding at September 30, 2021 and December 31, 2020, and 20,000 shares authorized as of September 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value – 86,843 and 85,058 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively, and 600,000 shares authorized as of September 30, 2021 and December 31, 2020	9	9
Additional paid-in capital	1,687,579	1,640,867
Accumulated other comprehensive loss	(2,579)	(1,339)
Accumulated deficit	(649,561)	(559,377)
Total shareholders’ equity	1,035,448	1,080,160
Total liabilities and shareholders' equity	$ 2,638,275	$ 1,602,333

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowance for doubtful accounts	$ 5,394	$ 3,983
Receivable from customers, allowance	$ 912	$ 593
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, shares authorized	20,000,000	20,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares, issued	86,843,000	85,058,000
Common stock, shares, outstanding	86,843,000	85,058,000
Common stock, shares authorized	600,000,000	600,000,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Revenues	$ 181,167	$ 127,879	$ 503,835	$ 355,809
Cost of revenue:
Cost of revenues	53,040	34,932	146,386	102,516
Gross profit	128,127	92,947	357,449	253,293
Operating expenses:
Research and development	42,574	32,562	121,841	85,253
Sales and marketing	75,867	49,057	212,068	144,731
General and administrative	35,887	23,885	101,982	65,595
Total operating expenses	154,328	105,504	435,891	295,579
Operating loss	(26,201)	(12,557)	(78,442)	(42,286)
Other (income) expense:
Interest income	(28)	(36)	(75)	(1,646)
Interest expense	815		815
Other (income) expense, net	6,168	(185)	9,403	(3,435)
Total other (income) expense, net	6,955	(221)	10,143	(5,081)
Loss before income taxes	(33,156)	(12,336)	(88,585)	(37,205)
(Benefit from) provision for income taxes	(610)	393	1,599	947
Net loss	$ (32,546)	$ (12,729)	$ (90,184)	$ (38,152)
Net loss per share attributable to common shareholders, basic and diluted	$ (0.38)	$ (0.15)	$ (1.05)	$ (0.48)
Weighted average shares of common stock outstanding, basic and diluted	86,530	82,288	86,023	79,715
Subscription and Returns
Revenue:
Revenues	$ 164,237	$ 119,193	$ 455,997	$ 333,258
Cost of revenue:
Cost of revenues	44,824	31,155	123,970	89,451
Professional Services
Revenue:
Revenues	16,930	8,686	47,838	22,551
Cost of revenue:
Cost of revenues	$ 8,216	$ 3,777	$ 22,416	$ 13,065

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (32,546)	$ (12,729)	$ (90,184)	$ (38,152)
Other comprehensive (loss) income — Foreign currency translation	(1,172)	(225)	(1,240)	835
Total comprehensive loss	$ (33,718)	$ (12,954)	$ (91,424)	$ (37,317)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (90,184)	$ (38,152)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation	65,330	34,799
Depreciation and amortization	25,732	11,923
Asset impairments	0	794
Amortization of debt issuance costs	482	0
Impairment of capitalized cloud computing costs	345	0
Deferred income tax (benefit) expense	(2,036)	193
Non-cash operating lease costs	7,102	6,027
Non-cash change in earnout liabilities	8,711	(2,325)
Non-cash bad debt expense	1,326	1,445
Other	(799)	(221)
Changes in operating assets and liabilities:
Trade accounts receivable	(18,713)	(12,205)
Prepaid expenses and other current assets	(13,721)	(4,179)
Deferred commissions	(12,761)	(7,425)
Other noncurrent assets	(3,719)	(2,698)
Trade payables	(2,327)	4,683
Accrued expenses	5,981	6,247
Deferred revenue	46,876	19,397
Operating lease liabilities	(8,900)	(7,243)
Net cash provided by operating activities	8,725	11,060
Cash flows from investing activities:
Purchase of property and equipment	(4,463)	(2,968)
Capitalized software development costs	(9,608)	(2,706)
Cash paid for acquisitions of businesses, net of cash and restricted cash equivalents acquired	(33,555)	0
Cash paid for acquired intangible assets	(1,500)	0
Cash paid for purchases of customer fund available-for-sale securities	(381)	0
Net cash used in investing activities	(49,507)	(5,674)
Cash flows from financing activities:
Proceeds from common stock offering, net of underwriting discounts	0	556,312
Payments of deferred financing costs	0	(300)
Proceeds from convertible senior notes	977,500	0
Payments of debt issuance costs	(17,343)	0
Purchase of capped calls	(75,268)	0
Proceeds from exercise of stock options	18,146	30,717
Proceeds from purchases of stock under employee stock purchase plan	14,446	11,337
Acquisition-related post-closing payments	(20,821)	(2,763)
Payments related to business combination earnouts	(33)	(3,760)
Payments related to asset acquisition earnouts	(1,266)	(65)
Net increase in customer fund obligations	37,942	1,681
Net cash provided by financing activities	933,303	593,159
Foreign currency effect	(732)	(504)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	891,789	598,041
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period	761,844	491,333
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period	1,653,633	1,089,374
Reconciliation of cash, cash equivalents, restricted cash, and restricted cash equivalents to the Consolidated Balance Sheets, end of period:
Cash and cash equivalents	1,536,422	1,064,077
Restricted cash	37,700	0
Restricted cash equivalents—funds held from customers	79,511	25,297
Supplemental cash flow disclosures:
Cash paid for operating lease liabilities	11,149	10,156
Cash paid for income taxes	936	865
Non-cash investing and financing activities:
Stock issued related to business combinations	22,971	7,500
Accrued purchase price related to acquisitions	3,366	0
Accrued value of earnout related to acquisitions of businesses	32,350	0
Customer fund obligations assumed in business combinations	12,464	0
Accrued purchase of intangible assets	870	433
Debt issuance costs in accounts payable and accrued expenses	265	0
Property and equipment additions in accounts payable and accrued expenses	1,453	981
Deferred financing costs in accounts payable and accrued expenses	0	401
Operating lease right-of-use assets in exchange for lease obligations	1,579	7,818
Stock-based compensation costs capitalized to internally developed software	968	152
Capitalized internally developed software costs included in accounts payable and accrued expenses	$ 1,045	$ 0

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Avalara, Inc. (the “Company”) provides software solutions that help businesses of all types and sizes comply with transaction tax requirements worldwide. The Company offers a broad and growing suite of compliance solutions for transaction and other product-related taxes such as sales and use tax, value-added tax (“VAT”), fuel excise tax, beverage alcohol, cross-border taxes (including tariffs and duties), lodging tax, communications tax, and insurance premium The Company has wholly owned subsidiaries outside of the U.S. in Brazil, Canada, Europe, and India, which conduct sales and operations and provide business development, software development, and support services.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Interim Financial Information The accompanying consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes for the year ended December 31, 2020, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (the “2020 Annual Report”) filed with the Securities and Exchange Commission (the “SEC”) on February 25, 2021. The accompanying interim consolidated balance sheet as of September 30, 2021, the consolidated interim statements of operations and consolidated statements of comprehensive loss for the three and nine months ended September 30, 2021 and 2020, and the consolidated statements of cash flows for the nine months ended September 30, 2021 and 2020, are unaudited. The unaudited interim consolidated financial statements have been prepared on a basis consistent with that used to prepare the audited annual consolidated financial statements and include, in the opinion of management, all adjustments, consisting of normal and recurring items, necessary for the fair presentation of the consolidated financial statements. The operating results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results expected for the full year ending December 31, 2021. Prior Period Restatements and Adjustments During the fourth quarter of 2020, management concluded there was an immaterial error in the Company’s presentation and classification of funds held from customers in the consolidated statements of cash flows for the first three quarters of 2020, impacting previously reported quarterly cash flows. The error related to the adoption of ASU 2016-18, which amends previous guidance to address the classification and presentation of changes in restricted cash and restricted cash equivalents in the consolidated statements of cash flows. Historically, the Company presented the change in funds held from customers as a separate caption within Investing Activities in the consolidated statements of cash flows. While not legally or otherwise contractually restricted, the Company has since concluded that funds held from customers are better classified as generally restricted under the accounting guidance and should be presented as restricted cash equivalents in the consolidated statement of cash flows. To correct this classification error, amounts previously reported as investing activities for the changes in funds held from customers for the nine months ended September 30, 2020 are reported as restricted cash equivalents in the consolidated statement of cash flows. The correction resulted in a change of $0.8 million to net cash provided by operating activities and a change of $1.7 million to net cash used in investing activities for the nine months ended September 30, 2020. The correction had no impact on the consolidated balance sheets, consolidated statements of operations, or the consolidated statements of comprehensive loss. The following table presents the consolidated statements of cash flows line items after giving effect to the adoption of ASU 2016-18: For the Nine Months Ended September 30, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash provided by operating activities: Other $ 546 $ (767 ) $ (221 ) Net cash provided by operating activities 11,827 (767 ) 11,060 Cash flows from investing activities: Net (increase) in customer fund assets (1,681 ) 1,681 — Net cash used in investing activities (7,355 ) 1,681 (5,674 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents 597,127 914 598,041 Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period 466,950 24,383 491,333 Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period $ 1,064,077 $ 25,297 $ 1,089,374 Reclassifications Certain prior period amounts have been reclassified to conform to current period presentation. Principles of Consolidation The accompanying consolidated financial statements include those of the Company, its subsidiaries, and a variable interest entity for which the Company is the primary beneficiary, after elimination of all intercompany accounts and transactions. Funds Held from Customers The Company has established a Delaware statutory trust (the “Customer Trust”) and appointed a federally insured bank as trustee, and the Customer Trust holds certain funds provided by its customers pending remittance to tax authorities. The Company is the sole beneficial owner of the Customer Trust. The Customer Trust is intended to be a bankruptcy-remote legal entity and meets the criteria in Accounting Standards Codification (“ASC”) Topic 810, Consolidation In the first quarter of 2021, the Company began having certain customers remit tax payments to the Customer Trust with the intention that all customer funds will eventually be held by the Customer Trust. Funds held from customers represent restricted cash equivalents and available for sale securities that, based upon the Company’s intent, are restricted solely for satisfying the obligations to remit funds relating to the Company’s tax remittance services. Customer fund obligations represent the Company's contractual obligations to remit funds to satisfy customers' tax obligations and are recorded on the consolidated balance sheets at the time that the Company or the Customer Trust collects funds from customers. The following table details funds held from customers and customer fund obligations held by the Company and by the Customer Trust as of September 30, 2021 a September 30, December 31, 2021 2020 Funds held from customers (current assets): Restricted cash equivalents - Company $ 5,537 $ 30,598 Restricted cash equivalents - Customer Trust 73,974 — Available-for-sale securities - Customer Trust 373 — Funds held from customers $ 79,884 $ 30,598 Customer fund obligations (current liabilities): Customer fund obligations - Company $ 81,955 $ 31,549 Customer fund obligations $ 81,955 $ 31,549 Segments The Company operates its business as one operating segment. Operating segments are defined as components of an enterprise about which separate financial information is evaluated regularly by the chief operating decision maker, the Company’s Chief Executive Officer, in deciding how to allocate resources and assess performance. The Company’s chief operating decision maker allocates resources and assesses performance based upon discrete financial information at the consolidated level. Use of Estimates The preparation of financial statements 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 consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and judgments related to revenue are described below in the Revenue Recognition Accounting Policy. Significant estimates impacting expenses include: expected credit losses associated with the allowance for doubtful accounts; the measurement of fair values of stock-based compensation; the expected payout level of performance share unit grants; the expected earnout obligations in connection with acquisitions; the expected term of the customer relationship for capitalized contract cost amortization; the valuation and useful lives of acquired intangible assets; the valuation of the fair value of reporting units for analyzing goodwill; and the capitalization and useful life of capitalized software development costs. Actual results could materially differ from those estimates. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level fair value hierarchy prioritizes the inputs used to measure fair value. The hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 : Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 : Inputs are quoted prices for similar assets and liabilities in active markets or quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. Level 3 : Inputs are unobservable inputs based on the Company’s assumptions and valuation techniques used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation. The Company’s assessment of the significance of an input to the fair value measurement requires judgment, which may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. The carrying amounts reported in the consolidated financial statements approximate the fair value for cash equivalents, restricted cash equivalents, trade accounts receivable, trade payables, and accrued expenses, due to their short-term nature. The Company has measured the fair value of money market funds and available-for-sale securities based on quoted prices in active markets for identical assets and liabilities. Acquisitions and Goodwill The Company’s identifiable assets acquired and liabilities assumed in a business combination are recorded at their acquisition date fair values, which may be considered preliminary and subject to adjustment during the measurement period, which is up to one year from the acquisition date. The valuation requires management to make significant estimates and assumptions, especially with respect to long-lived and intangible assets. Critical estimates in valuing intangible assets include, but are not limited to: • future expected cash flows from customer agreements, customer lists, distribution agreements, non-compete agreements, and proprietary content and technology; • assumptions about the length of time the brand will continue to be used in the Company’s suite of solutions; • royalty rates used to estimate the fees that could be charged to license the proprietary content and technology; and • discount rates used to determine the present value of recognized assets and liabilities. The Company’s estimates of fair value are based upon assumptions it believes to be reasonable, but that are inherently uncertain and unpredictable. Assumptions may be incomplete or inaccurate, and unanticipated events and circumstances may occur. Goodwill is calculated as the excess of the purchase price over the fair value of net assets acquired, including the amount assigned to identifiable intangible assets. Acquisition-related costs, including advisory, legal, accounting, valuation, and other costs, are expensed in the periods in which these costs are incurred. The results of operations of an acquired business are included in the consolidated financial statements beginning at the acquisition date. Goodwill is tested for impairment annually on October 31, or in the event of certain occurrences. There was no goodwill impairment recorded for the three and nine months ended September 30, 2021, respectively, or the year ended December 31, 2020. The Company estimates the fair value of the earnout liabilities related to business combinations using various valuation approaches, as well as significant unobservable inputs, reflecting the Company’s assessment of the assumptions market participants would use to value these liabilities. The fair value of the earnout is remeasured each reporting period, with any change in the value recorded as other income or expense. The Company recorded increases in the fair value of earnout liabilities related to business combinations of $6.2 million and $8.7 million for the three and nine months ended September 30, 2021, respectively. The Company recorded no changes in the fair value of earnout liabilities related to business combinations and decreases in the fair value of $2.3 million for the three and nine months ended September 30, 2020, respectively (see Note 3). Long-Lived Assets The Company evaluates long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. An impairment is recognized in the event the carrying value of such assets is not recoverable. If the carrying value is not recoverable, the fair value is determined, and an impairment is recognized for the amount by which the carrying value exceeds the fair value. No impairment of long-lived assets occurred in the nine months ended September 30, 2021. An impairment of the Company’s operating lease right-of-use assets and property and equipment of $0.8 million was recorded in the nine months ended September 30, 2020. Acquired Intangible Assets Acquired intangible assets consist of developed technology, including in-process research and development (“IPR&D”), customer relationships, backlog, database content, noncompetition agreements, and tradenames and trademarks, resulting from the Company’s acquisitions. Acquired intangible assets are recorded at fair value on the date of acquisition and amortized over their estimated useful lives. IPR&D is initially capitalized at fair value as a developed technology intangible asset with an indefinite life and assessed for impairment thereafter. When an IPR&D project is completed, it is amortized over the asset’s estimated useful life. The Company recognizes an earnout liability for acquisitions of intangible assets that are accounted for as an asset acquisition when the liability is earned and the amount is known. The earnout liability is capitalized as part of the cost of the assets acquired and amortized over the remaining useful life of the asset. Asset acquisition-related costs, primarily legal fees, are capitalized and included in the cost basis of the intangible asset when incurred. Income Taxes The Company’s deferred tax assets and liabilities are determined based on temporary differences between the financial reporting and income tax basis of assets and liabilities and are measured using the tax rates that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company assesses its income tax positions and records tax benefits or expense based upon management’s evaluation of the facts, circumstances, and information available at the reporting date. The objectives of accounting for income taxes are to recognize the amount of taxes payable or refundable for the current period and deferred tax liabilities and assets for the future tax consequences of events that have been recognized in an entity’s financial statements or tax returns. The Company will recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. Judgement is required in assessing the future tax consequences of events that have been recognized in the Company’s consolidated financial statements or tax returns. Variations in the actual outcome of these future tax consequences could materially impact the consolidated financial statements. Stock-Based Compensation The Company accounts for stock-based compensation by calculating the fair value of each option, restricted stock unit (“RSU”) or performance share unit (“PSU”) issued under the 2018 Equity Incentive Plan (the “2018 Plan”) Revenue Recognition The Company primarily generates revenue from fees paid for subscriptions to tax compliance solutions and fees paid for services performed in preparing and filing tax returns on behalf of its customers. Amounts that have been invoiced are recorded in trade accounts receivable and deferred revenue, contract liabilities, or revenue, depending upon whether the revenue recognition criteria have been met. Revenue is recognized once the customer is provisioned and services are provided in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services. The Company’s revenue recognition policy follows guidance from Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers. The Company determines revenue recognition through the following five-step framework: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, the Company satisfies a performance obligation. The Company identifies performance obligations in its contracts with customers, which primarily include subscription services and professional services. The transaction price is determined based on the amount which the Company expects to be entitled to in exchange for providing the promised services to the customer, and is comprised of both fixed and variable consideration. The transaction price in the contract is allocated to each distinct performance obligation on a relative standalone selling price basis. Revenue is recognized when performance obligations are satisfied. Contract payment terms are typically net 30 days. Collectability is assessed based on a number of factors including collection history and creditworthiness of the customer, and the Company may mitigate exposure to credit risk by requiring payments in advance. If collectability of substantially all consideration to which the Company is entitled under the contract is determined to be not probable, revenue is not recorded until collectability becomes probable at a later date. Revenue is recorded based on the transaction price excluding amounts collected on behalf of third parties, such as sales taxes collected and remitted to governmental authorities. Subscription and Returns Revenue Subscription and returns revenue primarily consist of contractually agreed upon fees paid for using the Company’s cloud-based solutions, which include tax calculation and compliance management services, preparing and filing transaction tax returns on behalf of customers, and tax content subscription services. Under most of the Company’s subscription agreements, customers select a price plan that includes an allotted maximum number of transactions over the subscription term. Unused transactions are not carried over to the customer’s next subscription term, and customers are not entitled to refunds of fees paid or relief from fees due in the event they do not use the allotted number of transactions. If customers exceed the maximum transaction level within their price plan, the Company will generally upgrade the customer to a higher transaction price plan or, in some cases, charge overage fees on a per transaction basis. Fees paid for subscription services to tax content vary depending on the volume of tax information accessible to the customer. The Company’s subscription arrangements do not provide the customer with the right to take possession of the software supporting the cloud-based application services. The Company’s standard subscription contracts are non-cancelable except where contract terms provide rights to cancel in the first 60 days of the contract term. Cancellations under the Company’s standard subscription contracts are not material, and do not have a significant impact on revenue recognized. Tax returns processing services include collection of tax data and amounts, preparation of compliance forms, and submission to taxing authorities. Returns processing services are primarily charged on a subscription basis for an allotted number of returns to process within a given time period. Revenue is recognized ratably over the contractual term of the arrangement, beginning on the date that the service is made available to the customer. The Company invoices its subscription customers for the initial term at contract signing and at each subscription renewal. Initial terms generally range from 12 to 18 months, and renewal periods are typically one year. Amounts that are contractually billable and have been invoiced, or which have been collected as cash, are initially recorded as deferred revenue or contract liabilities. While most of the Company’s customers are invoiced once at the beginning of the term, a portion of customers are invoiced semi-annually, quarterly, or monthly. Included in the total subscription fee for cloud-based solutions are non-refundable upfront fees that are typically charged to new customers. These fees are associated with work performed to set up a customer with the Company’s services, and do not represent a distinct good or service. Instead, the fees are included within the transaction price and allocated to the remaining performance obligations in the contract. The Company recognizes revenue for these fees in accordance with the revenue recognition for those performance obligations. Also included in subscription and returns revenue is interest income on funds held from customers. The Company uses trust accounts at FDIC-insured institutions to provide tax remittance services to customers and collect funds from customers in advance of remittance to tax authorities. After collection and prior to remittance, the Company earns interest on these funds. Professional Services Revenue The Company generates professional services revenue from providing tax analysis and services, including tax registrations, voluntary disclosure agreements, nexus studies, and backfiling services. Additionally, the Company provides configurations, data migrations, integration, and training for its subscriptions and returns products. The 2020 acquisitions of Transaction Tax Resources, Inc. (“TTR”) and Business Licenses, LLC (“Business Licenses”) (see Note 5) expanded the scope of professional services to include business licenses and registration services and tax refund claims and recovery assistance. The Company invoices for professional service arrangements on a fixed fee, milestone, or time and materials basis. The transaction price allocated to professional services performance obligations is recognized as revenue as services are performed or upon completion of work. Judgments and Estimates The Company’s contracts with customers often include obligations to provide multiple services to a customer. Determining whether services are considered distinct performance obligations that should be accounted for separately from one another requires judgment. Subscription services and professional services are both distinct performance obligations that are accounted for separately. Judgment is required to determine the standalone selling price (“SSP”) for each distinct performance obligation. The Company allocates revenue to each performance obligation based on the relative SSP. The Company determines SSP for performance obligations based on overall pricing objectives, which take into consideration observable prices, market conditions and entity-specific factors. This includes a review of historical data related to the services being sold and customer demographics. The Company uses a range of amounts to estimate SSP for performance obligations. There is typically more than one SSP for individual services due to the stratification of those services by information, such as size and type of customer. Assets Recognized from the Costs to Obtain a Contract with a Customer The Company recognizes an asset for the incremental costs of obtaining a contract with a customer if it expects the benefit of those costs to be longer than one year. The Company has determined that certain costs related to employee sales incentive programs (sales commissions) and partner commission programs represent incremental costs of obtaining a contract and therefore should be capitalized. Capitalized costs are included in deferred commissions on the consolidated balance sheets. These deferred commissions are amortized over an estimated period of benefit, generally six years. The Company determines the period of benefit by taking into consideration past experience with customers, the expected life of acquired technology that generates revenue, industry peers, and other available information. The period of benefit is generally longer than the term of the initial contract because of anticipated renewals. The Company elected to apply the practical expedient to recognize the incremental costs of obtaining a contract as an expense if the amortization period of the asset would have been one year or less. L eases Leases arise from contracts which convey the right to control the use of identified property or equipment for a period of time in exchange for consideration. The Company’s leasing arrangements are primarily for office space used to conduct operations. The Company determines whether an arrangement is or contains a lease at the inception date, based on whether there is an identified asset and whether the Company controls the use of the identified asset throughout the period of use. Leases commence when the lessor makes the asset available for use. Leases are classified at commencement as either operating or finance leases. All the Company’s leases are classified as operating leases. Rent expense for operating leases is recognized on the straight-line method over the term of the agreement beginning on the lease commencement date. Lease-related costs, which are variable rather than fixed, are expensed in the period incurred. Variable lease costs consist primarily of common area maintenance and utilities costs for the Company’s office spaces that are due based on the actual costs incurred by the landlord. Lease payments that depend on an index or a rate are measured using the index or rate at the commencement date and are included in operating lease costs. Subsequent increases to lease payments due to a change in the index or rate are expensed as a variable lease cost. Recently Adopted Accounting Standards ASU 2019-12 In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which amends the existing guidance relating to the accounting for income taxes. This ASU is intended to simplify the accounting for income taxes by removing certain exceptions to the general principles of accounting for income taxes and to improve the consistent application of U.S. GAAP for other areas of accounting for income taxes by clarifying and amending existing guidance. This ASU is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company adopted the guidance on January 1, 2021 and the adoption of this new guidance does not have a material effect on its consolidated financial statements. ASU-2020-06 In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which amends the accounting standards for convertible debt instruments that may be settled entirely or partially in cash upon conversion. ASU No. 2020-06 eliminates requirements to separately account for liability and equity components of such convertible debt instruments and eliminates the ability to use the treasury stock method for calculating diluted earnings per share for convertible instruments whose principal amount may be settled using shares. Instead, ASU No. 2020-06 requires (i) the entire amount of the security to be presented as a liability on the balance sheet and (ii) application of the “if-converted” method for calculating diluted earnings per share. The required use of the “if-converted” method will not impact the Company’s diluted earnings per share as long as the Company is in a net loss position. The guidance in ASU No. 2020-06 is required for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2021, for public business entities. Early adoption is permitted, but no earlier than annual reporting periods beginning after December 15, 2020, including interim periods within those annual reporting periods. The Company early adopted this guidance for the fiscal year beginning January 1, 2021, and did so on a modified retrospective basis, without requiring any adjustments. The adoption of ASU No. 2020-06 impacted the accounting for the offering of $977.5 million of 0.25% convertible senior notes due 2026 (the “2026 Notes”) issued by the Company in August 2021, see Note 10 for further discussion. New Accounting Standards Not Yet Adopted ASU 2021-08 In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which amends the accounting related to contract assets and liabilities acquired in business combinations. Under current GAAP, an entity generally recognizes assets and liabilities acquired in a business combination, including contract assets and contract liabilities arising from revenue contracts with customers, at fair value on the acquisition date. ASU 2021-08 requires that entities recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with ASC Topic 606, Revenue from Contracts with Customers. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and should be applied prospectively to businesses combinations occurring on or after the effective date of the amendment. Early adoption is permitted, including adoption in an interim period. The Company is currently evaluating the impact of this new guidance on the consolidated financial statements.

Investments and Fair Value Meas

Investments and Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Investments and Fair Value Measurements	3. Assets and liabilities measured at fair value on a recurring basis The following financial assets and liabilities are measured at fair value on a recurring basis. The fair values recognized in the accompanying consolidated balance sheets and the level within the fair value hierarchy in which the fair value measurements fall is as follows (in thousands): Fair Value Measurements Using Quoted Prices Significant in Active Other Significant Markets for Observable Unobservable Fair Identical Assets Inputs Inputs September 30, 2021 Value (Level 1) (Level 2) (Level 3) Money market funds $ 1,460,482 $ 1,460,482 $ — $ — Available-for-sale securities: U.S. treasury securities 373 373 — — Earnouts related to business combinations 75,528 — — 75,528 Fair Value Measurements Using Quoted Prices Significant in Active Other Significant Markets for Observable Unobservable Fair Identical Assets Inputs Inputs December 31, 2020 Value (Level 1) (Level 2) (Level 3) Money market funds $ 649,603 $ 649,603 $ — $ — Earnouts related to business combinations 34,501 — — 34,501 Earnout Liability Earnout liabilities recorded in connection with an acquisition accounted for as a business combination under ASC 805 are recorded at estimated fair value on a recurring basis. Business combinations are discussed in Note 5. Earnouts recorded in connection with asset acquisitions are recorded as earnout payments become known. As such, earnouts related to asset acquisitions, which are discussed in Note 7, Earnout liabilities are classified as Level 3 liabilities because the Company uses unobservable inputs to value them, reflecting its assessment of the assumptions market participants would use to value these liabilities. Changes in the fair value of earnout liabilities are recorded in other (income) expense, net in the consolidated statements of operations. The Company estimates the fair value of earnout liabilities for business combinations using either probability-weighted discounted cash flows and Monte Carlo simulations or a scenario-based approach. The earnout liability associated with the acquisition of Davo Technologies LLC (“Davo”) is based on the achievement of specific revenue growth thresholds through March 2023. As of September 30, 2021, the earnout liability associated with the acquisition of Davo was valued utilizing a discount rate of 7 %. The Davo discount rate was calculated using the build-up method with a risk-free rate commensurate with the term of the earnout based on the equity, asset and revenue betas, size premium, and the Company’s specific risk premium, as well as the market risk premium using a bottom-up approach . The earnout liability associated with the 2020 acquisition of T TR is based on the achievement of specific revenue growth thresholds through December 2022. As of September 30 , 2021, the earnout liability associated with the acquisition of TTR was valued utilizing a discount rate of %. The TTR discount rate was calculated using the build-up method with a risk-free rate commensurate with the term of the earnout based on the equity , asset and revenue betas, size premium, and the Company’s specific risk premium, as well as the market risk premium using a bottom-up approach. The earnout liability associated with the 2020 acquisition of Business Licenses is based on the achievement of certain performance metrics through November 2024. As of September 30 , 2021, the earnout liability associated with the acquisition of Business Licenses was valued utilizing a discount rate of % based on the Company’s estimated pre-tax cost of debt. The Business Licenses earnout was assumed by management to have a high probability of achievement. The earnout period for the 2019 acquisition of Portway International Inc. (“Portway”) ended as of January 31, 2021 and did not result in any additional earnout payments due to not meeting the revenue targets. A reconciliation of the beginning and ending balances of recurring fair value measurements recognized in the accompanying consolidated balance sheets using significant unobservable (Level 3) inputs, is as follows (in thousands): For the Three Months Ended September 30, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 67,454 $ 33 Measurement period adjustment 1,927 — Payments of earnout liabilities (33 ) — Total unrealized loss included in other (income) expense, net 6,180 — Balance end of period $ 75,528 $ 33 For the Nine Months Ended September 30, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 34,501 $ 13,808 Fair value recorded at acquisition 28,620 — Measurement period adjustment 3,729 — Payments of earnout liabilities (33 ) (11,450 ) Total unrealized net (gain) loss included in other (income) expense, net 8,711 (2,325 ) Balance end of period $ 75,528 $ 33 Assets and liabilities measured at fair value on a non-recurring basis The Company’s non-financial assets and liabilities, which include goodwill, intangible assets, long-lived assets and deferred revenue, and the Company’s liabilities for the accrued purchase price related to acquisitions, The estimation of fair value for these assets and liabilities requires the use of significant unobservable inputs, and as a result, the Company classifies these assets and liabilities as Level 3 within the fair value hierarchy. There were no additional fair value measurements of these assets during the first nine months of 2021, except as discussed in Note 5. Fair Value of Other Financial Instruments The Company has a principal amount of $977.5 million of 2026 Notes that are carried on the balance sheet at amortized cost. The estimated fair value of the 2026 Notes is $1.0 billion as of September 30, 2021. The estimated fair value of the 2026 Notes was determined through inputs that are observable in the market, and are classified as Level 2.

Balance Sheet Detail

Balance Sheet Detail	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Detail	4 . Balance Sheet Detail Property and equipment, net consisted of the following (in thousands): Useful September 30, December 31, Life (Years) 2021 2020 Computer equipment and software 3 to 5 $ 18,840 $ 15,749 Internally developed software 3 to 6 22,043 10,438 Furniture and fixtures 5 6,487 6,651 Office equipment 3 to 5 1,096 1,006 Leasehold improvements 1 to 10 29,823 29,928 78,289 63,772 Accumulated depreciation (35,644 ) (29,059 ) Property and equipment—net $ 42,645 $ 34,713 Depreciation expense was $3.3 million. and $8.7 million for the three and nine months ended September 30, 2021, respectively, Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, 2021 2020 Prepaid expenses $ 29,286 $ 13,968 Deposits 205 2,557 Other 1,611 3,573 Total $ 31,102 $ 20,098 Accrued expenses consisted of the following (in thousands): September 30, December 31, 2021 2020 Accrued payroll and related taxes $ 12,372 $ 7,903 Accrued federal, state, local, and foreign taxes 7,343 4,338 Accrued bonus 31,874 29,518 Self-insurance reserves 1,725 1,563 Employee stock purchase plan contributions 2,944 5,927 Accrued sales commissions 4,924 5,563 Accrued partner commissions 10,224 9,173 Contract liabilities 8,597 10,134 Interest payable on convertible senior notes 333 — Other 11,642 10,413 Total $ 91,978 $ 84,532 Contract liabilities represent amounts that are collected in advance of the satisfaction of performance obligations. See Contract Liabilities

Acquisitions of Businesses

Acquisitions of Businesses	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Acquisitions of Businesses	5 . Acquisitions of Businesses Announced Acquisition of CrowdReason and CorrelationAdvisors On October 18, 2021, the Company acquired substantially all the assets of CrowdReason LLC, a Texas limited liability company (“CrowdReason”), and CorrelationAdvisors LLC, a Texas limited liability company (“CorrelationAdvisors”) under an asset purchase agreement. At close, the Company paid $8.3 million in cash. The agreement includes an acquisition holdback of $2.0 million payable in 18 months or less subject to reductions for certain indemnifications and other potential obligations of CrowdReason and Correlation Advisors. The agreement also contains a three-year software applications, solutions , and services for property tax compliance. CorrelationAdvisors provides consulting services related to property valuation and property tax compliance. The Company will account for the CrowdReason and CorrelationAdvisors acquisition as a business combination and plans to provide a preliminary asset valuation and other required acquisition-related disclosures in its annual report on Form 10-K for the year ending December 31, 2021 . Announced Acquisition of Track1099 On October 1, 2021, the Company acquired substantially all the assets of Track1099 LLC, a Delaware limited liability company (“Track1099”) under an asset purchase agreement. At close, the Company paid $35.0 million in cash . The agreement includes an acquisition holdback two-year September 2021 Acquisition of 3CE Technologies, Inc On September 7, 2021, the Company acquired substantially all the assets of 3CE Technologies, Inc. (“3CE”) under an Asset Purchase Agreement (the “3CE Purchase”). expand and improve Avalara’s HS classification content and provide a new self-service model to sell to the Company’s customers. The Company accounted for the 3CE Purchase as a business combination. The acquisition has been included in the Company’s consolidated results of operations since the acquisition date; however, the effect of the business combination is not material to the consolidated results of operations. The total consideration related to this transaction is $11.2 million, consisting of $9.9 million cash paid at close and an acquisition holdback with a fair value upon acquisition of $1.3 million. Preliminary estimated fair values of the assets acquired and the liabilities assumed in the 3CE Purchase as of the acquisition date include intangible assets of $2.5 million primarily attributable to developed technology and customer relationships and goodwill of $8.3 million. The estimated fair values for acquired accounts receivable, deferred revenue, and intangible assets are preliminary in nature and subject to adjustment when the necessary information is available to complete the valuation April 2021 Acquisition of Inposia On April 1, 2021, the Company acquired the outstanding equity of Inposia Solutions, GmbH (“Inposia”) under a Share Purchase Agreement (the “Inposia Purchase”). Inposia is a German software company that delivers e-invoicing, digital tax reporting, and system and data integration to support digital transformation efforts and address real-time compliance requirements for businesses. Inposia will build upon Avalara’s existing e-invoicing capabilities in Brazil and India to support customers worldwide with real-time compliance. The Company accounted for the Inposia Purchase as a business combination. Acquisition-related costs of $1.4 million were primarily for legal and due-diligence related fees and were recorded in general and administrative expense, of which $1.0 million was incurred in the second half of 2020 and $0.4 million was incurred in the first nine months of 2021. The total consideration transferred related to this transaction was €31.8 million (or approximately $37.4 million using the exchange rate on April 1, 2021), consisting of net cash consideration of $14.5 million and 164,416 shares of the Company’s common stock paid at closing with an acquisition date fair value of $23.0 million. Net cash consideration consists of $12.2 million cash paid at closing, and a million cash deposit paid in the fourth quarter of 2020, offset by $0.2 million cash received by the Company in the third quarter of 2021 as a result of net working capital adjustments. A portion of shares issued are held in escrow as of September 30, 2021, and will be released to the Inposia shareholders during the 18 months following the acquisition, subject to reduction for certain indemnification and other potential obligations of the Inposia shareholders. The shares held in escrow are considered issued and outstanding, and are recorded in shareholders’ equity on the consolidated balance sheet as of September 30, 2021. Measurement period adjustments recognized in the third quarter of 2021 related primarily to updated estimated fair values for acquired intangible assets, deferred tax liabilities, and a net working capital adjustment. Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing (net of amounts returned) $ 14,671 $ (188 ) $ 14,483 Fair value of common stock issued at closing 22,971 — 22,971 Total consideration $ 37,642 $ (188 ) $ 37,454 Preliminary estimated fair values of the assets acquired and the liabilities assumed in the Inposia Purchase as of the acquisition date are provided in the following table (in thousands): Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 1,264 $ — $ 1,264 Trade accounts receivable 1,767 — 1,767 Other current assets 268 — 268 Operating lease right-of-use assets 928 — 928 Property and equipment 98 — 98 Developed technology, customer relationships, and other intangibles 12,684 1,820 14,504 Goodwill 27,702 (1,486 ) 26,216 Other noncurrent assets 35 — 35 Total assets acquired 44,746 334 45,080 Liabilities assumed: Trade payables and accrued expenses 1,340 — 1,340 Deferred revenue 811 (55 ) 756 Other liabilities, noncurrent 106 — 106 Operating lease liabilities 928 — 928 Deferred tax liability 3,919 577 4,496 Total liabilities assumed 7,104 522 7,626 Net assets acquired $ 37,642 $ (188 ) $ 37,454 The estimated fair values for acquired intangible assets, deferred revenue, and deferred tax liabilities are preliminary in nature and subject to adjustment when the necessary information is available to complete the valuation. The carrying amount of trade accounts receivable acquired in the Inposia Purchase approximates the fair value. The fair value of deferred revenue was estimated utilizing a discount rate of 4.0% based on the Company’s estimated pre-tax cost of debt. The Company utilizes different valuation approaches and methodologies to determine the fair value of acquired intangible assets. The weighted-average amortization period for all intangibles acquired in the Inposia Purchase is 6.2 years . A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Inposia Purchase are provided in the below table (in thousands ): Intangible Previously Reported Assigned Value As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 1,585 $ 1,938 $ 3,523 Multi-period excess earnings-income approach 18.5 % 8 years Developed technology 9,572 — 9,572 Relief from royalty-income approach 18.5 % 6 years Noncompetition agreements 1,292 (118 ) 1,174 With-and-without valuation-income approach 21.0 % 3 years Tradename 235 — 235 Relief from royalty-income approach 18.5 % 3 years The excess of the purchase price over the net identified tangible and intangible assets is $26.2 million and has been recorded as goodwill, which includes synergies expected from the combined service offerings and the value of the assembled workforce. The goodwill is not expected to be deductible for tax purposes. For the period from the date of the Inposia Purchase through September 30, 2021, revenue was $4.0 million and pre-tax loss was $1.5 million from the Inposia business. April 2021 Acquisition of Davo On April 20, 2021, the Company acquired substantially all the assets of Davo under an Asset Purchase Agreement (the “Davo Purchase”). Davo helps emerging small businesses automate the daily and ongoing requirements for sales tax. As a result of the acquisition, Davo extends Avalara’s ability to provide integrated sales tax compliance processes to alleviate the burden of compliance on small businesses. The Company accounted for the Davo Purchase as a business combination. Acquisition-related costs of $0.1 million were primarily for legal and due-diligence related fees and were recorded in general and administrative expense. The total consideration transferred related to this transaction was $56.9 million, consisting of $23.5 million cash paid at close, a $0.3 million cash deposit paid in the first quarter of 2021, an acquisition holdback with a fair value upon acquisition of $2.6 million, and an earnout provision with a fair value upon acquisition of $30.5 million. The acquisition holdback represents an additional $2.6 million of cash to be paid Davo shareholders during the 18 months following the acquisition date, subject to reduction for certain indemnifications and other potential obligations of Davo shareholders. The acquisition holdback liability is recorded in accrued purchase price related to acquisitions, noncurrent portion on the consolidated balance sheet as of September 30, 2021. The earnout will be calculated as a multiple of certain performance metrics during the 12-month measurement periods ending March 31, 2022 and 2023, and there is not a stated minimum or maximum payment required under the earnout. Of the earnout liability recognized at the date of the business combination, $15.1 million is recorded in accrued earnout liabilities, current and $15.4 million is recorded in accrued earnout liabilities, noncurrent. The earnout liability is adjusted to fair value quarterly (see Note 3). Measurement period adjustments recognized in the third quarter of 2021 related primarily to updated estimated fair values for acquired intangible assets, earnout liability, and a net working capital adjustment. Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid through closing $ 23,818 $ — $ 23,818 Fair value of earnout provision 28,620 1,927 30,547 Fair value of holdbacks 2,600 (9 ) 2,591 Total consideration $ 55,038 $ 1,918 $ 56,956 Preliminary estimated fair values of the assets acquired and the liabilities assumed in the Davo Purchase as of the acquisition date are provided in the following table (in thousands): Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 198 $ — $ 198 Funds held from customers 12,464 — 12,464 Trade accounts receivable 119 — 119 Other current assets 58 — 58 Operating lease right-of-use assets 46 — 46 Developed technology, customer relationships, and other intangibles 6,427 414 6,841 Goodwill 48,426 1,505 49,931 Other noncurrent assets 2 (1 ) 1 Total assets acquired 67,740 1,918 69,658 Liabilities assumed: Accrued expenses 117 — 117 Deferred revenue 75 — 75 Operating lease liabilities 46 — 46 Customer fund obligations 12,464 — 12,464 Total liabilities assumed 12,702 — 12,702 Net assets acquired $ 55,038 $ 1,918 $ 56,956 The estimated fair values for acquired intangible assets and earnout consideration are preliminary in nature and subject to adjustment, when the necessary information is available to complete the valuation. The carrying amount of trade accounts receivable acquired in the Davo Purchase approximates the fair value. The Company utilizes different valuation approaches and methodologies to determine the fair value of acquired intangible assets. The weighted-average amortization period for all intangibles acquired in the Davo Purchase is 6.8 years. A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Davo Purchase are provided in the below table (in thousands): Intangible Previously Reported Assigned Value As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 4,350 $ (50 ) $ 4,300 Multi-period excess earnings-income approach and replacement cost method-cost approach 14.5 % 8 years Developed technology 1,800 100 1,900 Relief from royalty-income approach 14.5 % 5 years Noncompetition agreements 191 364 555 With-and-without valuation-income approach 16.5 % 5 years Tradename 86 — 86 Relief from royalty-income approach 14.5 % 1 years The excess of the purchase price over the net identified tangible and intangible assets is $49.9 million and has been recorded as goodwill, which includes synergies expected from the combined service offerings and the value of the assembled workforce. The goodwill is expected to be deductible for tax purposes. For the period from the date of the Davo Purchase through September 30, 2021, revenue was $1.3 million and pre-tax loss was $1.2 million from the Davo business. October 2020 Acquisition of Transaction Tax Resources On October 5, 2020, the Company acquired the outstanding equity of TTR under a Merger Agreement (the “TTR Merger”). TTR is a leading provider of tax content, research, consulting, and automation tools in the U.S., with products that include software solutions for companies and governments. As a result of the acquisition, the Company expanded its tax content, added new product offerings, and reached new customer segments. The total consideration related to this transaction was $370.1 million, consisting of $294.0 million in cash paid at closing, acquisition holdbacks with a fair value upon acquisition of $57.3 million, and an earnout provision with a fair value upon acquisition of $18.9 million. The acquisition holdbacks represent the present value of an additional $57.3 million of cash to be paid up to three years following the acquisition, subject to reduction for certain indemnifications and other potential obligations of the TTR shareholders, discounted utilizing a risk-free discount rate of 0.13%. The earnout is payable to TTR’s founder and shareholder no later than February 2023. The maximum earnout payment is $26.4 Measurement period adjustments recognized in the first quarter of 2021 related to the finalization of the estimated fair values for customer relationships, contract backlog, and earnout liability, and a net working capital adjustment. Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 294,017 $ — $ 294,017 Fair value of holdbacks 57,477 (217 ) 57,260 Fair value of earnout provision 15,740 3,131 18,871 Total consideration $ 367,234 $ 2,914 $ 370,148 Estimated fair values of the assets acquired and the liabilities assumed in the TTR Merger as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 2,294 $ — $ 2,294 Trade accounts receivable 5,966 — 5,966 Other current assets 93 — 93 Operating lease right-of-use assets 1,760 — 1,760 Property and equipment 848 — 848 Developed technology, customer relationships, and other intangibles 49,000 (7,500 ) 41,500 Goodwill 327,039 8,526 335,565 Total assets acquired 387,000 1,026 388,026 Liabilities assumed: Trade payables and accrued expenses 731 — 731 Deferred revenue 8,500 — 8,500 Operating lease liabilities 1,760 — 1,760 Deferred tax liability 8,775 (1,888 ) 6,887 Total liabilities assumed 19,766 (1,888 ) 17,878 Net assets acquired $ 367,234 $ 2,914 $ 370,148 The carrying amount of trade accounts receivable acquired in the TTR Mer ger was $7.2 million and was recorded at $6.0 million on the date of acquisition to approximate the fair value. The fair value of deferred revenue was estimated using the income approach, utilizing a bottom-up method that estimated the costs required to support the remaining obligations plus an assumed profit margin, and discounted to present value utilizing a risk-adjusted discount rate of 3.5 %. The Company utilizes different valuation approaches and methodologies to determine the fair value of acquired intangible assets. The weighted-average amortization period for all intangibles acquired in the TTR Merger is 4.7 years. The weighted-average amortization period for developed technology intangibles acquired in the TTR Merger is 4.0 years. A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the TTR Merger are provided in the below table (in thousands): Intangible Previously Reported Assigned Value As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 26,000 $ (5,000 ) $ 21,000 Multi-period excess earnings-income approach 18% 6 years Developed technology 9,600 — 9,600 Relief from royalty-income approach and replacement cost method-cost approach 17% to 18% 3 to 6 years Tradename 5,800 — 5,800 Relief from royalty-income approach 17% 2 years Contract backlog 5,800 (2,500 ) 3,300 Multi-period excess earnings-income approach 17% 3 years Noncompetition agreements 1,800 — 1,800 With-and-without valuation-income approach 19% 5 years The excess of the purchase price over the net identified tangible and intangible assets is $335.6 million and has been recorded as goodwill, which includes synergies expected from the combined service offerings and the value of the assembled workforce. The goodwill is not expected to be deductible for tax purposes. The acquisition holdback liability is recorded in accrued purchase price related to acquisitions, with $37.8 million included in the current portion on the consolidated balance sheet as of September 30, 2021, and $19.9 million and $37.7 million included in the current and noncurrent portions, respectively, on the consolidated balance sheet as of December 31, 2020. A portion of the acquisition holdback liability in the amount of $19.9 million was settled in the first nine months of 2021, comprised of cash paid of $0.8 million in the first quarter, $18.8 million paid in the second quarter and no additional payments in the third quarter to sellers. November 2020 Acquisition of Business Licenses On November 5, 2020, the Company acquired substantially all of the assets of Business Licenses under an Asset Purchase Agreement (the “Business Licenses Purchase”). Business Licenses is a leading provider of license content, software, management, and services that automate and streamline business license compliance for companies of all sizes. As a result of the acquisition, the Company expanded its product offerings to include complementary compliance solutions beyond tax, such as business licenses and registrations. The Company accounted for the Business Licenses Purchase as a business combination. The total consideration transferred related to this transaction was $93.3 million, consisting of $64.8 million paid in cash at closing, an acquisition holdback with a fair value upon acquisition of $11.1 million, and an earnout provision with a fair value upon acquisition of $17.4 million. The acquisition holdback represents the present value of an additional $11.1 million of cash to be paid after 18 months to Business Licenses’ shareholders, subject to reduction for certain indemnification obligations, discounted utilizing a risk-free discount rate of 0.13%. The maximum earnout payment of up to $20.7 million will be paid, in shares of the Company’s common stock, to Business Licenses’ shareholders following the achievement of certain Business Licenses operating performance metrics during the four years following the acquisition. The potential amount of all future payments that could be required under the earnout is between $0 and $20.7 million. The earnout was originally recognized at fair value at the date of the business combination is adjusted to fair value quarterly (see Note 3). Measurement period adjustments recognized in the first quarter of 2021 related to the finalization of the estimated fair value of the earnout liability and a net working capital adjustment. Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 64,812 $ — $ 64,812 Fair value of holdbacks 11,415 (306 ) 11,109 Fair value of earnout provision 18,728 (1,328 ) 17,400 Total consideration $ 94,955 $ (1,634 ) $ 93,321 Estimated fair values of the assets acquired and the liabilities assumed in the Business Licenses Purchase as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 120 $ — $ 120 Trade accounts receivable 1,326 — 1,326 Customer fund assets 1,074 — 1,074 Other current assets 101 — 101 Operating lease right-of-use assets 1,644 — 1,644 Property and equipment 87 — 87 Developed technology, customer relationships, and other intangibles 19,525 — 19,525 Goodwill 73,775 (1,634 ) 72,141 Other noncurrent assets 31 — 31 Total assets acquired 97,683 (1,634 ) 96,049 Liabilities assumed: Accrued expenses 56 — 56 Customer fund obligations 1,028 — 1,028 Operating lease liabilities 1,644 — 1,644 Total liabilities assumed 2,728 — 2,728 Net assets acquired $ 94,955 $ (1,634 ) $ 93,321 The carrying amount of trade accounts receivable acquired in the Business Licenses Purchase approximate the fair value. The Company utilizes different valuation approaches and methodologies to determine the fair value of acquired intangible assets. The weighted-average amortization period for all intangibles acquired in the Business Licenses Purchase is 5.3 years. The weighted-average amortization period for developed technology intangibles acquired in the Business Licenses Purchase is 3.1 years. A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Business Licenses Purchase are provided in the below table (in thousands): Intangible Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 15,000 Multi-period excess earnings-income approach 19.5% 6 years Developed technology 3,625 Relief from royalty-income approach and replacement cost method-cost approach 19.5% 1 to 5 years Noncompetition agreements 500 With-and-without valuation-income approach 19.5% 5 years Tradename 400 Relief from royalty-income approach 19.5% 1 year The excess of the purchase price over the net identified tangible and intangible assets is $72.1 million and has been recorded as goodwill, which includes synergies expected from the combined service offerings and the value of the assembled workforce. The goodwill is expected to be deductible for tax purposes. As of September 30, 2021, the acquisition holdback liability of $11.1 million is recorded in accrued purchase price related to acquisitions, current portion on the consolidated balance sheet. As of December 31, 2020 the acquisition holdback liability of $11.4 million is recorded in accrued purchase price related to acquisitions, noncurrent portion on the consolidated balance sheet. December 2020 Acquisition of Impendulo On December 1, 2020, the Company acquired the shares of Impendulo (the “Impendulo Purchase”). Impendulo is a London-based provider of insurance tax compliance solutions and offers insurance tax compliance management technology and services, specializing in support for multi-national insurance companies. With the acquisition of Impendulo, the Company expands its product offerings to include insurance premium tax compliance. The Company accounted for the Impendulo Purchase as a business combination. The total consideration transferred related to this transaction was $14.0 million, consisting of $11.7 million paid in cash at closing, $1.2 million paid in the Company’s common stock, and an additional $1.1 million that was paid in the first quarter of 2021 based on final revenue metrics achieved up to the date of acquisition. Measurement period adjustments recognized in the first quarter of 2021 relate to the finalization of the net working capital adjustment. Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 11,713 $ — $ 11,713 Common stock paid at close 1,190 — 1,190 Cash payable accrual 694 425 1,119 Total consideration $ 13,597 $ 425 $ 14,022 Estimated fair values of the assets acquired and the liabilities assumed in the Impendulo Purchase as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 1,347 $ — $ 1,347 Trade accounts receivable 371 — 371 Other assets 147 — 147 Developed technology, customer relationships, and other intangibles 3,617 — 3,617 Goodwill 10,217 425 10,642 Total assets acquired 15,699 425 16,124 Liabilities assumed: Trade payables and accrued expenses 663 — 663 Deferred revenue and contract liabilities 694 — 694 Deferred tax liability 745 — 745 Total liabilities assumed 2,102 — 2,102 Net assets acquired $ 13,597 $ 425 $ 14,022 The carrying amount of trade accounts receivable acquired in the Impendulo Purchase approximate the fair value. The Company utilizes different valuation approaches and methodologies to determine the fair value of acquired intangible assets. The weighted-average amortization period for all intangibles acquired in the Impendulo Purchase is 5.9 years. A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Impendulo Purchase are provided in the below table (in thousands): Intangible Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationship $ 2,964 Multi-period excess earnings-income approach 20% 6 years Developed technology 616 Relief from royalty-income approach 20% 6 years Tradename 37 Relief from royalty-income approach 20% 1 year The excess of the purchase price over the net identified tangible and intangible assets is $10.6 million and has been recorded as goodwill, which includes synergies expected from the combined service offerings and the value of the assembled workforce. The goodwill is not expected to be deductible for tax purposes. Pro Forma Financial Information for the 2021 Acquisitions (Unaudited) T he unaudited pro forma financial information in the table below summarizes the combined results of operations for Avalara, Inposia, and Davo (which are considered relevant for the purposes of unaudited pro forma financial information disclosure) as though the companies were combined as of January 1, 2020. The unaudited pro forma financial information presented also includes certain business combination accounting effects resulting from the acquisitions, including amortization charges from acquired intangible assets, but does not include the fair value adjustment for deferred revenue and contract liabilities. The unaudited pro forma financial information as presented below is for informational purposes only and is not necessarily indicative of the results of operations that would have been achieved if the acquisitions had taken place as of January 1, 2020. For the Nine Months Ended September 30, 2021 2020 Total revenue $ 511,837 $ 362,729 Net loss (92,837 ) (41,664 )

Revenue

Revenue	9 Months Ended
	Sep. 30, 2021
Revenue From Contract With Customer [Abstract]
Revenue	6 . Revenue See Note 2 for a description of the Company’s revenue recognition accounting policy. Disaggregation of Revenue The following table disaggregates revenue generated within the United States (U.S.) from revenue generated from customers outside of the U.S. Revenue for transaction tax compliance in the U.S. is further disaggregated based on the solutions or services purchased by customers. Total revenues consisted of the following (in thousands): For the Three Months Ended September 30, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 91,539 $ 65,312 Tax returns and compliance management 58,846 46,087 Interest income on funds held from customers 215 118 Total subscription and returns 150,600 111,517 Professional services 15,440 8,186 Total revenue (U.S.) 166,040 119,703 Total revenue (non-U.S.) 15,127 8,176 Total revenue $ 181,167 $ 127,879 For the Nine Months Ended September 30, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 251,301 $ 185,986 Tax returns and compliance management 168,445 126,384 Interest income on funds held from customers 557 701 Total subscription and returns 420,303 313,071 Professional services 43,299 20,978 Total revenue (U.S.) 463,602 334,049 Total revenue (non-U.S.) 40,233 21,760 Total revenue $ 503,835 $ 355,809 Disclosures Related to Contracts with Customers Timing may differ between the satisfaction of performance obligations and the invoicing and collection of amounts related to contracts with customers. Liabilities are recorded for amounts that are collected in advance of the satisfaction of performance obligations. To the extent a contract exists, as defined by ASC 606, these liabilities are classified as current and non-current deferred revenue. To the extent that a contract does not exist, as defined by ASC 606 (e.g., customer agreements with non-standard termination rights), these liabilities are classified as contract liabilities. Contract liabilities are transferred to deferred revenue at the point in time when the criteria that establish the existence of a contract are met. Contract Liabilities A summary of the activity impacting the contract liabilities during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Contract liabilities: Balance beginning of period $ 11,406 $ 6,195 Contract liabilities transferred to deferred revenue (6,420 ) (2,737 ) Addition to contract liabilities 3,611 4,215 Balance end of period $ 8,597 $ 7,673 For the Nine Months Ended September 30, 2021 2020 Contract liabilities: Balance beginning of period $ 10,134 $ 5,197 Contract liabilities transferred to deferred revenue (15,550 ) (7,992 ) Addition to contract liabilities 14,013 10,468 Balance end of period $ 8,597 $ 7,673 As of September 30, 2021, contract liabilities are expected to be transferred to deferred revenue within the next 12 months and therefore are included in accrued expenses on the consolidated balance sheets. Deferred Revenue A summary of the activity impacting deferred revenue balances during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Deferred revenue: Balance beginning of period $ 239,395 $ 167,719 Revenue recognized (181,167 ) (127,879 ) Additional amounts deferred 199,655 140,800 Balance end of period $ 257,883 $ 180,640 For the Nine Months Ended September 30, 2021 2020 Deferred revenue: Balance beginning of period $ 209,690 $ 161,241 Revenue recognized (503,835 ) (355,809 ) Additional amounts deferred 552,028 375,208 Balance end of period $ 257,883 $ 180,640 As of September 30, 2021, $256.2 million of deferred revenue is expected to be recognized within the next 12 months and is included in current liabilities on the consolidated balance sheets. The remaining amount of deferred revenue is included in noncurrent liabilities and is expected to be recognized within the next 18 months. Assets Recognized from the Costs to Obtain Contracts with Customers Assets are recognized for the incremental costs of obtaining a contract with a customer if the benefit of those costs is expected to be longer than one year. These deferred commissions are amortized over an expected period of benefit of generally six years. A summary of the activity impacting the deferred commissions during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Deferred commissions: Balance beginning of period $ 60,643 $ 43,356 Additional commissions deferred 6,997 5,406 Amortization of deferred commissions (4,009 ) (2,921 ) Balance end of period $ 63,631 $ 45,841 For the Nine Months Ended September 30, 2021 2020 Deferred commissions: Balance beginning of period $ 50,870 $ 38,416 Additional commissions deferred 23,599 15,818 Amortization of deferred commissions (10,838 ) (8,393 ) Balance end of period $ 63,631 $ 45,841 As of September 30, 2021, $15.7 million of deferred commissions are expected to be amortized within the next 12 months and are included in current assets on the consolidated balance sheets. The remaining amount of deferred commissions is included in noncurrent assets. There were no impairments of assets related to deferred commissions during the nine months ended September 30, 2021 or 2020. There were no assets recognized related to the costs to fulfill contracts during the nine months ended September 30, 2021 or 2020 as these costs were not material. Remaining Performance Obligations Contracts with customers include amounts allocated to performance obligations that will be satisfied at a later date. These amounts include deferred revenue that has been invoiced and non-cancellable amounts that will be invoiced and recognized as revenue in future periods. As of September 30, 2021, the remaining performance obligations to which enforceable rights exist are $

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	7 . Intangible Assets Intangible assets consisted of the following (in thousands): September 30, 2021 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 3,300 $ (1,288 ) $ 2,012 Customer relationships 3 to 10 68,506 (21,279 ) 47,227 Developed technology (1) 3 to 8 66,882 (34,568 ) 32,314 Noncompetition agreements 3 to 5 5,073 (1,404 ) 3,669 Tradename and trademarks 1 to 4 7,023 (3,828 ) 3,195 $ 150,784 $ (62,367 ) $ 88,417 (1) December 31, 2020 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 5,800 $ (937 ) $ 4,863 Customer relationships 3 to 10 64,302 (14,890 ) 49,412 Developed technology (1) 3 to 8 52,144 (27,646 ) 24,498 Noncompetition agreements 3 to 5 3,062 (766 ) 2,296 Tradename and trademarks 1 to 4 6,679 (1,235 ) 5,444 $ 131,987 $ (45,474 ) $ 86,513 (1) Finite-lived intangible assets are amortized over their estimated useful life. Finite-lived intangible assets amortization expense was $6.3 million and $17.0 million for the three and nine months ended September 30, 2021, respectively, and $1.5 million and $4.9 million for the three and nine months ended September 30, 2020, respectively. Acquisitions of finite-lived intangible assets In May 2018, the Company acquired developed technology to facilitate cross-border transactions (e.g., tariffs and duties), from Tradestream Technologies Inc. and Wise 24 Inc. (the “Sellers”) for cash and common stock. Total consideration for the purchase includes an earnout computed on future billings recognized by the Company over the next six years, up to a maximum of $30.0 million. The earnout is payable in cash or common stock at the end of each six-month measurement period ending on June 30 or December 31 through 2023. Through September 30, 2021, the sellers have earned approximately $1.9 million under the earnout provision since the acquisition date. An earnout liability of $0.3 million was recorded within the current portion of accrued earnout liabilities as of September 30, 2021 for the earnout period ending December 31, 2021 and is expected to be paid in cash to the sellers in the first quarter of 2022. Goodwill Changes in the carrying amount of goodwill for the nine months ended September 30, 2021 Balance—December 31, 2020 $ 513,234 Measurement period adjustment - 2020 acquisitions (1) 7,317 Acquisition of Davo 49,931 Acquisition of Inposia 26,216 Acquisition of 3CE 8,290 Cumulative translation adjustments (1,220 ) Balance—September 30, 2021 $ 603,768 (1) Goodwill is tested for impairment annually on October 31 at the reporting unit level or whenever circumstances occur indicating goodwill might be impaired. The impairment test involves comparing the fair value of each reporting unit to its carrying value, including goodwill. Fair value reflects the price a market participant would be willing to pay in a potential sale of the reporting unit. If the fair value exceeds carrying value, the Company will conclude that no goodwill impairment has occurred. If the carrying value of the reporting unit exceeds its fair value, the Company will recognize an impairment loss in an amount equal to the excess, not to exceed the carrying value. The Company has three reporting units for goodwill impairment testing consisting of its U.S., European, and Brazilian operations. As of September 30, 2021, the Brazilian reporting unit had no associated goodwill.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	8. Leases Total lease cost, net of sublease income, was $4.1 million and $12.4 million for the three and nine months ended September 30, 2021, respectively, and $4.1 million and $11.8 million for the three and nine months ended September 30, 2020, respectively Sublease income was $0.4 million and $1.2 million for the three and nine months ended September 30, 2021, respectively and $0.4 million and $1.1 million for the three and nine months ended September 30, 2020, respectively. Leases that commenced in the first nine months of 2021 increased operating lease right-of-use assets by $1.8 million.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9 . Commitments and Contingencies Contingencies Loss contingencies may arise in connection with the ordinary conduct of the Company’s business activities. The Company considers all loss contingencies on a quarterly basis and based on known facts assesses whether potential losses are considered reasonably possible, probable, and estimable. The Company establishes an accrual for loss contingencies when the loss is both probable and reasonably estimable. If the estimated loss is a range of potential outcomes and there is no better estimate within the range, management accrues the amount at the low end of the range. These accruals represent management’s estimate of probable losses and, in such cases, there may be an exposure to loss in excess of the amounts accrued. Significant judgment is required to determine both likelihood of there being a probable loss and the estimated amount of a loss. If a loss contingency is not both probable and reasonably estimable, the Company does not establish an accrual, but will evaluate other disclosure requirements and continue to monitor the matter for developments that would make the loss contingency both probable and reasonably estimable. The ultimate outcome of any litigation relating to a loss contingency is uncertain and, regardless of outcome, litigation can have an adverse impact on the Company because of defense costs, negative publicity, diversion of management resources and other factors. In its standard subscription agreements, the Company has agreed to indemnification provisions with respect to certain matters. Further, from time to time, the Company has also assumed indemnification obligations through its acquisition activity. These indemnification provisions can create a liability to the Company if its services do not appropriately calculate taxes due to tax jurisdictions, or if the Company is delinquent in the filing of returns on behalf of its customers. Although the Company’s agreements have disclaimers of warranties that limit its liability (beyond the amounts the Company agrees to pay pursuant to its indemnification obligations and guarantees, as applicable), a court could determine that such disclaimers and limitations are unenforceable as a matter of law and hold the Company liable for certain errors. Further, in some instances the Company has negotiated agreements with specific customers or assumed agreements in connection with the Company’s acquisitions that do not limit this liability or disclaim these warranties. It is not possible to reasonably estimate the potential loss under these indemnification arrangements.

Debt

Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt	10. Debt Convertible Senior Notes In August 2021, the Company completed a private offering of $977.5 million principal amount of 0.25% convertible senior notes due 2026 (the “2026 Notes”). The 2026 Notes are unsecured obligations and bear interest at a fixed rate of 0.25% per annum, payable semi-annually in arrears on February 1 and August 1 of each year, commencing on February 1, 2022. The 2026 Notes will mature on August 1, 2026, unless earlier converted, redeemed or repurchased. The Company incurred $17.6 million of debt issuance costs in connection with the 2026 Notes offering consisting of the initial purchasers’ commissions and legal, accounting, and other direct costs of the offering. The total proceeds from the offering, net of the debt issuance costs, were $959.9 million. The Company used $75.3 million of the net proceeds from the sale of the 2026 Notes to pay the premiums of the capped call options described further below. The Company may not redeem the 2026 Notes prior to August 6, 2024. The Company may redeem all or any portion of the 2026 Notes, at the Company’s option, on or after August 6, 2024, through the 41st scheduled trading day immediately prior to the maturity date, if the common stock price is at least 130% of the conversion price then in effect for at least 20 of any 30 consecutive trading day period. The Company may redeem all or part of the 2026 Notes at a redemption price equal to the principal amount plus accrued and unpaid interest to, but excluding, the redemption date, with not less than 50 nor more than 60 scheduled trading days’ notice to holders. The 2026 Notes are convertible at an initial conversion rate of 4.1940 shares of common stock per $1,000 principal amount of 2026 Notes, which is equivalent to an initial conversion price of approximately $238.44 per share of common stock. The conversion rate is subject to customary adjustments for certain events as described in the indenture governing the 2026 Notes. The Company may settle the conversion option obligation with cash, shares of the Company’s common stock, or any combination of cash and shares of the Company’s common stock. On or after February 1, 2026, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the 2026 Notes may convert their notes at their option. Prior to the close of business on the business day immediately preceding February 1, 2026, the 2026 Notes are convertible at the option of the holders of such notes only under the following circumstances: • during any calendar quarter commencing after the quarter ending on December 31, 2021 (and only during such calendar quarter), if the Company’s common stock price exceeds 130% of the conversion price for at least 20 trading days during the 30 consecutive trading days at the end of the prior calendar quarter; • during the five business days after any five consecutive trading days in which the trading price per $1,000 Notes was less than 98% of the product of the closing sale price of the Company’s common stock and the then current conversion rate; • upon the occurrence of specified corporate events; or • if the Company calls any or all 2026 Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date, but only with respect to the notes called for redemption. Upon the occurrence of a make‑whole fundamental change or the exercise of the Company’s redemption option, the Company will, under certain circumstances, increase the applicable conversion rate for a holder that elects to convert its 2026 Notes. As of September 30, 2021, none of the conditions of the 2026 Notes to early convert have been met. As discussed in Note 2, the Company early adopted ASU No. 2020‑06 as of January 1, 2021 and concluded that the 2026 Notes will be accounted for as debt, with no bifurcation of the embedded conversion feature. Debt issuance costs were recorded as a direct deduction from the related liability in the consolidated balance sheet and are amortized to interest expense over the term of the 2026 Notes. The effective interest rate for the 2026 Notes is 0.6%. The net carrying amount of the 2026 Notes was as follows: September 30, 2021 (in thousands) Principal $ 977,500 Unamortized debt issuance costs (17,127 ) Net carrying amount $ 960,373 The following table sets forth the interest expense recognized related to the 2026 Notes: For the Three Months Ended September 30, 2021 (in thousands) Contractual interest expense $ 333 Amortization of debt issuance costs 482 Total interest expense related to 2026 Notes $ 815 For the Nine Months Ended September 30, 2021 (in thousands) Contractual interest expense $ 333 Amortization of debt issuance costs 482 Total interest expense related to 2026 Notes $ 815 Capped Call Transactions In connection with the offering of the 2026 Notes, the Company purchased capped calls from certain financial institutions with respect to its common stock. The capped calls each have an initial strike price of $238.44 per share of the Company’s common stock, which corresponds to the initial conversion price of the 2026 Notes. The capped calls each have an initial cap price of $323.30 per share and expire in incremental components on each trading date beginning on June 4, 2026 and ending on July 30, 2026. The capped calls are intended to offset potential dilution to the Company’s common stock or offset any cash payments the Company is required to make in excess of the principal amount, as the case may be, with such reduction or offset subject to the cap price. The capped calls are subject to adjustments for certain corporate events and standard anti-dilution provisions. The Company paid an aggregate amount of $75.3 million for the capped calls, covering approximately 4.1 million shares of the Company’s common stock. As the capped calls are both legally detachable and separately exercisable from the 2026 Notes, the Company accounts for the capped calls separately from the 2026 Notes. The capped calls are indexed to the Company’s own common stock and classified in stockholders’ equity. As such, the premiums paid for the capped calls have been included as a net reduction to additional paid-in capital in the consolidated balance sheet.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2021
Stockholders Equity Note [Abstract]
Shareholders' Equity	1 1 . Shareholders’ Equity Authorized Capital—Common Stock and Preferred Stock Under the Amended and Restated Articles of Incorporation, which became effective in June 2018, the Company is authorized to issue two classes of stock designated as common stock and preferred stock. The Company’s total authorized capital stock is 620,000,000 shares, consisting of 600,000,000 shares of common stock, $0.0001 par value per share, and 20,000,000 shares of undesignated preferred stock, $0.0001 par value per share. The changes to the Company’s shareholders’ equity during the nine months ended September 30, 2021 Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Loss Deficit Equity Balance at January 1, 2021 85,057,727 $ 9 $ 1,640,867 $ (1,339 ) $ (559,377 ) $ 1,080,160 Exercise of stock options 296,226 5,529 5,529 Vesting of restricted stock units 346,008 Stock-based compensation cost 19,047 19,047 Shares issued under employee stock purchase plan 60,064 7,088 7,088 Loss on translation adjustment (390 ) (390 ) Net loss (29,988 ) (29,988 ) Balance at March 31, 2021 85,760,025 $ 9 $ 1,672,531 $ (1,729 ) $ (589,365 ) $ 1,081,446 Exercise of stock options 253,395 4,668 4,668 Vesting of restricted stock units 75,571 — Stock-based compensation cost 23,592 23,592 Shares issued for acquisitions of businesses 164,416 22,971 22,971 Gain on translation adjustment 322 322 Net loss (27,650 ) (27,650 ) Balance at June 30, 2021 86,253,407 $ 9 $ 1,723,762 $ (1,407 ) $ (617,015 ) $ 1,105,349 Exercise of stock options 488,992 7,950 7,950 Vesting of restricted stock units 43,374 — Stock-based compensation cost 23,777 23,777 Shares issued under employee stock purchase plan 56,817 7,358 7,358 Purchase of capped calls (75,268 ) (75,268 ) Loss on translation adjustment (1,172 ) (1,172 ) Net loss (32,546 ) (32,546 ) Balance at September 30, 2021 86,842,590 $ 9 $ 1,687,579 $ (2,579 ) $ (649,561 ) $ 1,035,448 The changes to the Company’s shareholders’ equity for the nine months ended September 30, 2020 is as follows (in thousands, except share data): Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Income (Loss) Deficit Equity Balance at January 1, 2020 77,447,620 $ 8 $ 976,627 $ (2,719 ) $ (510,194 ) $ 463,722 Exercise of stock options 532,848 7,928 7,928 Vesting of restricted stock units 186,475 Stock-based compensation cost 9,749 9,749 Shares issued under employee stock purchase plan 81,894 5,716 5,716 Shares issued related to business combination earnouts 44,659 3,750 3,750 Shares issued to purchase intangible assets 1,191 87 87 Gain on translation adjustment 625 625 Net loss (15,283 ) (15,283 ) Balance at March 31, 2020 78,294,687 $ 8 $ 1,003,857 $ (2,094 ) $ (525,477 ) $ 476,294 Exercise of stock options 1,117,805 17,495 17,495 Vesting of restricted stock units 57,832 — Stock-based compensation cost 12,368 12,368 Shares issued related to business combination earnouts 44,659 3,750 3,750 Gain on translation adjustment 435 435 Net loss (10,140 ) (10,140 ) Balance at June 30, 2020 79,514,983 $ 8 $ 1,037,470 $ (1,659 ) $ (535,617 ) $ 500,202 Proceeds from common stock offering, net of underwriting discounts 4,527,558 556,312 556,312 Public offering costs (701 ) (701 ) Exercise of stock options 333,977 5,294 5,294 Vesting of restricted stock units 19,178 — Stock-based compensation cost 12,916 12,916 Shares issued under employee stock purchase plan 75,811 5,621 5,621 Loss on translation adjustment (225 ) (225 ) Net loss (12,729 ) (12,729 ) Balance at September 30, 2020 84,471,507 $ 8 $ 1,616,912 $ (1,884 ) $ (548,346 ) $ 1,066,690

Equity Incentive Plans

Equity Incentive Plans	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	1 2 . Equity Incentive Plans The Company has stock-based compensation plans that provide for the award of equity incentives, including stock options, stock awards, RSUs, PSUs, and purchase rights. As of September 30, 2021, the Company had stock options outstanding under the 2018 Plan and the 2006 Equity Incentive Plan (the “2006 Plan”), RSUs and PSUs outstanding under the 2018 Plan, and purchase rights issued under the ESPP. The 2018 Plan became effective in connection with the Company’s IPO at which time the 2006 Plan was terminated. Outstanding awards under the 2006 Plan continue to be subject to the terms and conditions of the 2006 Plan. As of September 30, 2021, 4,035,218 shares were subject to outstanding awards and 12,158,970 shares were available for issuance under the 2018 Plan. As of September 30, 2021, 1,348,505 shares were subject to outstanding stock options under the 2006 Plan. Stock-Based Compensation The Company recognized total stock-based compensation cost related to equity incentive awards as follows (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Stock-based compensation cost: Stock options $ 2,913 $ 3,749 $ 9,210 $ 11,757 Restricted stock units 14,993 8,052 41,618 20,472 Performance share units 4,683 — 12,148 — Employee stock purchase plan 1,188 1,115 3,440 2,804 Total stock-based compensation cost $ 23,777 $ 12,916 $ 66,416 $ 35,033 A small portion of stock-based compensation cost above is capitalized in accordance with the accounting guidance for internal-use software. The Company uses the straight-line attribution method for recognizing stock-based compensation expense. Stock Options The following table summarizes stock option activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Weighted Average Aggregate Average Remaining Intrinsic Exercise Contractual Value Shares Price Life (in Years) (in thousands) Options outstanding as of January 1, 2021 3,537,014 $ 28.17 6.89 $ 483,577 Options granted — $ — Options exercised (1,038,613 ) $ 17.47 Options cancelled or expired (24,525 ) $ 16.65 Options outstanding as of September 30, 2021 2,473,876 $ 32.78 6.45 $ 351,272 Options exercisable as of September 30, 2021 1,741,687 $ 26.18 6.07 $ 258,789 A summary of options outstanding and vested as of September 30, 2021 is as follows: Options Outstanding Options Vested and Exercisable Exercise Number Weighted Average Number Vested Weighted Average Prices Outstanding Life (in Years) and Exercisable Life (in Years) $1.90 to $6.40 23,065 1.3 23,065 1.3 $8.04 to $11.72 79,506 2.5 79,506 2.5 $12.20 to $15.06 491,764 5.0 491,764 5.0 $16.06 to $24.00 754,170 6.3 578,159 6.3 $31.99 to $42.21 658,855 7.2 392,185 7.2 $55.10 to $99.65 424,361 8.0 167,684 7.8 $124.35 to $151.76 42,155 6.6 9,324 5.9 2,473,876 1,741,687 The total intrinsic value of options exercised during the nine months ended September 30, 2021 and 2020 There were no options granted during the nine months ended September 30, 2021. The weighted average grant date fair value of options granted during the nine months ended September 30, 2020 As of September 30, 2021, $14.3 million of total unrecognized compensation cost related to stock options was expected to be recognized over a weighted average period of approximately 1.8 years. All options granted to participants, including employees and non-employee directors, are measured based on the grant date fair value of the awards and recognized in the consolidated statements of operations over the period during which the participant is required to perform services in exchange for the award. The vesting period is generally four years for employees and one year for non-employee directors. For the options granted during the periods presented, the fair value was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Fair market value of common stock — $124.35 - 130.82 — $66.26 - 130.82 Volatility — 43% — 43% Expected term — 6 years — 5-6 years Expected dividend yield — n/a — n/a Risk-free interest rate — 0.44% - 0.51% — 0.33% - 1.25% Options are granted with an exercise price per share not less than the per share fair market value of the Company’s common stock on the grant date. The fair market value per share of the Company’s common stock for purposes of determining stock-based compensation is the closing price of the Company’s common stock as reported on the applicable grant date. Expected volatility for stock options is based on a combination of annualized daily historical volatility of the Company’s stock price and the historical and implied volatility of comparable publicly traded companies over a similar expected term. The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. Given the Company’s relative inexperience of significant exercise activity, the expected term assumptions were determined based on application of the simplified method of expected term calculation by averaging the contractual life of option grants and the vesting period of such grants. This application, when coupled with the contractual life of ten years four years six years The Company has not paid and does not expect to pay dividends. The risk-free interest rate was based on the rate for a U.S. Treasury zero-coupon issue with a term that closely approximates the expected life of the option grant at the date nearest the option grant date. Restricted Stock Units The following table summarizes RSU activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Average Grant Date Fair Restricted Stock Units Value Per Share RSUs outstanding as of January 1, 2021 2,359,063 $ 70.17 RSUs granted 1,068,582 136.76 RSUs vested (464,953 ) 65.29 RSUs cancelled (173,477 ) 81.12 RSUs outstanding as of September 30, 2021 2,789,215 $ 95.81 Stock-based compensation cost for RSUs is recognized on a straight-line basis in the consolidated statements of operations over the period during which the participant is required to perform services in exchange for the award, based on the fair value of the Company’s underlying common stock on the grant date. The vesting period of each RSU grant is generally four years for employees and one year for non-employee directors. As of September 30, 2021, $231.6 million of total unrecognized compensation cost related to RSUs was expected to be recognized over a weighted average period of approximately 2.9 years. Performance Share Units The following table summarizes PSU activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Average Grant Date Fair Performance Share Units Value Per Share PSUs outstanding as of January 1, 2021 — $ — PSUs granted 120,632 147.39 PSUs vested — — PSUs cancelled — — PSUs outstanding as of September 30, 2021 120,632 $ 147.39 During the first quarter of 2021, PSUs were granted for the first time and are intended to replace stock option grants for executives. Stock-based compensation cost for PSUs is recognized on a graded vesting basis in the consolidated statements of operations over the period during which the participant is required to perform services in exchange for the award, based on the fair value of the Company’s underlying common stock on the grant date and the number of PSUs expected to be earned over the service period. Each PSU grant will vest in annual tranches over a three-year three-year As of September 30, 2021, $25.6 million of total unrecognized compensation cost related to PSUs was expected to be recognized over a weighted average period of approximately 2.0 years. Employee Stock Purchase Plan During the nine months ended September 30, 2021, 116,881 shares of common stock were purchased under the ESPP. As of For the periods presented, the fair value of ESPP purchase rights was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Fair market value of common stock $ 166.84 $ 138.83 $152.35 to $166.84 $87.23 to $138.83 Volatility 31% 49% 31% to 34% 32% to 49% Expected term 0.5 years 0.5 years 0.5 years 0.5 years Expected dividend yield n/a n/a n/a n/a Risk-free interest rate 0.06% 0.11% 0.06% to 0.08% 0.11% to 1.54%

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Shareholders	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Shareholders	1 3 . Net Loss Per Share Attributable to Common Shareholders The Company calculates basic and diluted net loss per share attributable to common shareholders in conformity with the two-class method required for companies with participating securities. The diluted net loss per share attributable to common shareholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. The Company uses the if-converted method for calculating any potential dilutive effect of the convertible senior notes on diluted net loss per share. For purposes of this calculation, all common stock equivalents have been excluded from the calculation of diluted net loss per share attributable to common shareholders as their effect is antidilutive. As a result, basic and diluted net loss per common share was the same for each period presented. The following table sets forth the computation of basic and diluted net loss per common share (in thousands, except per share data): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss attributable to common shareholders $ (32,546 ) $ (12,729 ) $ (90,184 ) $ (38,152 ) Denominator: Weighted-average common shares outstanding-basic 86,530 82,288 86,023 79,715 Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, ESPP shares, and convertible senior notes (if converted) — — — — Weighted-average common shares outstanding-diluted 86,530 82,288 86,023 79,715 Net loss per common share, basic and diluted $ (0.38 ) $ (0.15 ) $ (1.05 ) $ (0.48 ) The following weighted-average outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common shareholders for the periods presented because the impact of including them would have been antidilutive (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common shares 2,750 4,229 3,085 4,938 Unvested restricted stock units 2,748 2,267 2,586 2,009 Unvested performance share units 121 — 106 — ESPP shares 4 5 4 2 Convertible senior notes (if converted) 2,184 — 736 — Total 7,807 6,501 6,517 6,949

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	1 4 . Subsequent Events On October 1, 2021, the Company acquired substantially all of the assets of Track1099 and on October 18, 2021, the Company acquired substantially all of the assets of CrowdReason and CorrelationAdvisors. See discussion in Note 5.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Interim Financial Information	Interim Financial Information The accompanying consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes for the year ended December 31, 2020, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (the “2020 Annual Report”) filed with the Securities and Exchange Commission (the “SEC”) on February 25, 2021. The accompanying interim consolidated balance sheet as of September 30, 2021, the consolidated interim statements of operations and consolidated statements of comprehensive loss for the three and nine months ended September 30, 2021 and 2020, and the consolidated statements of cash flows for the nine months ended September 30, 2021 and 2020, are unaudited. The unaudited interim consolidated financial statements have been prepared on a basis consistent with that used to prepare the audited annual consolidated financial statements and include, in the opinion of management, all adjustments, consisting of normal and recurring items, necessary for the fair presentation of the consolidated financial statements. The operating results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results expected for the full year ending December 31, 2021.
Prior Period Restatements and Adjustments	Prior Period Restatements and Adjustments During the fourth quarter of 2020, management concluded there was an immaterial error in the Company’s presentation and classification of funds held from customers in the consolidated statements of cash flows for the first three quarters of 2020, impacting previously reported quarterly cash flows. The error related to the adoption of ASU 2016-18, which amends previous guidance to address the classification and presentation of changes in restricted cash and restricted cash equivalents in the consolidated statements of cash flows. Historically, the Company presented the change in funds held from customers as a separate caption within Investing Activities in the consolidated statements of cash flows. While not legally or otherwise contractually restricted, the Company has since concluded that funds held from customers are better classified as generally restricted under the accounting guidance and should be presented as restricted cash equivalents in the consolidated statement of cash flows. To correct this classification error, amounts previously reported as investing activities for the changes in funds held from customers for the nine months ended September 30, 2020 are reported as restricted cash equivalents in the consolidated statement of cash flows. The correction resulted in a change of $0.8 million to net cash provided by operating activities and a change of $1.7 million to net cash used in investing activities for the nine months ended September 30, 2020. The correction had no impact on the consolidated balance sheets, consolidated statements of operations, or the consolidated statements of comprehensive loss. The following table presents the consolidated statements of cash flows line items after giving effect to the adoption of ASU 2016-18: For the Nine Months Ended September 30, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash provided by operating activities: Other $ 546 $ (767 ) $ (221 ) Net cash provided by operating activities 11,827 (767 ) 11,060 Cash flows from investing activities: Net (increase) in customer fund assets (1,681 ) 1,681 — Net cash used in investing activities (7,355 ) 1,681 (5,674 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents 597,127 914 598,041 Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period 466,950 24,383 491,333 Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period $ 1,064,077 $ 25,297 $ 1,089,374
Reclassifications	Reclassifications Certain prior period amounts have been reclassified to conform to current period presentation.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include those of the Company, its subsidiaries, and a variable interest entity for which the Company is the primary beneficiary, after elimination of all intercompany accounts and transactions.
Funds Held from Customers	Funds Held from Customers The Company has established a Delaware statutory trust (the “Customer Trust”) and appointed a federally insured bank as trustee, and the Customer Trust holds certain funds provided by its customers pending remittance to tax authorities. The Company is the sole beneficial owner of the Customer Trust. The Customer Trust is intended to be a bankruptcy-remote legal entity and meets the criteria in Accounting Standards Codification (“ASC”) Topic 810, Consolidation In the first quarter of 2021, the Company began having certain customers remit tax payments to the Customer Trust with the intention that all customer funds will eventually be held by the Customer Trust. Funds held from customers represent restricted cash equivalents and available for sale securities that, based upon the Company’s intent, are restricted solely for satisfying the obligations to remit funds relating to the Company’s tax remittance services. Customer fund obligations represent the Company's contractual obligations to remit funds to satisfy customers' tax obligations and are recorded on the consolidated balance sheets at the time that the Company or the Customer Trust collects funds from customers. The following table details funds held from customers and customer fund obligations held by the Company and by the Customer Trust as of September 30, 2021 a September 30, December 31, 2021 2020 Funds held from customers (current assets): Restricted cash equivalents - Company $ 5,537 $ 30,598 Restricted cash equivalents - Customer Trust 73,974 — Available-for-sale securities - Customer Trust 373 — Funds held from customers $ 79,884 $ 30,598 Customer fund obligations (current liabilities): Customer fund obligations - Company $ 81,955 $ 31,549 Customer fund obligations $ 81,955 $ 31,549
Segments	Segments The Company operates its business as one operating segment. Operating segments are defined as components of an enterprise about which separate financial information is evaluated regularly by the chief operating decision maker, the Company’s Chief Executive Officer, in deciding how to allocate resources and assess performance. The Company’s chief operating decision maker allocates resources and assesses performance based upon discrete financial information at the consolidated level.
Use of Estimates	Use of Estimates The preparation of financial statements 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 consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and judgments related to revenue are described below in the Revenue Recognition Accounting Policy. Significant estimates impacting expenses include: expected credit losses associated with the allowance for doubtful accounts; the measurement of fair values of stock-based compensation; the expected payout level of performance share unit grants; the expected earnout obligations in connection with acquisitions; the expected term of the customer relationship for capitalized contract cost amortization; the valuation and useful lives of acquired intangible assets; the valuation of the fair value of reporting units for analyzing goodwill; and the capitalization and useful life of capitalized software development costs. Actual results could materially differ from those estimates.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level fair value hierarchy prioritizes the inputs used to measure fair value. The hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 : Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 : Inputs are quoted prices for similar assets and liabilities in active markets or quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. Level 3 : Inputs are unobservable inputs based on the Company’s assumptions and valuation techniques used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation. The Company’s assessment of the significance of an input to the fair value measurement requires judgment, which may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. The carrying amounts reported in the consolidated financial statements approximate the fair value for cash equivalents, restricted cash equivalents, trade accounts receivable, trade payables, and accrued expenses, due to their short-term nature. The Company has measured the fair value of money market funds and available-for-sale securities based on quoted prices in active markets for identical assets and liabilities.
Acquisitions and Goodwill	Acquisitions and Goodwill The Company’s identifiable assets acquired and liabilities assumed in a business combination are recorded at their acquisition date fair values, which may be considered preliminary and subject to adjustment during the measurement period, which is up to one year from the acquisition date. The valuation requires management to make significant estimates and assumptions, especially with respect to long-lived and intangible assets. Critical estimates in valuing intangible assets include, but are not limited to: • future expected cash flows from customer agreements, customer lists, distribution agreements, non-compete agreements, and proprietary content and technology; • assumptions about the length of time the brand will continue to be used in the Company’s suite of solutions; • royalty rates used to estimate the fees that could be charged to license the proprietary content and technology; and • discount rates used to determine the present value of recognized assets and liabilities. The Company’s estimates of fair value are based upon assumptions it believes to be reasonable, but that are inherently uncertain and unpredictable. Assumptions may be incomplete or inaccurate, and unanticipated events and circumstances may occur. Goodwill is calculated as the excess of the purchase price over the fair value of net assets acquired, including the amount assigned to identifiable intangible assets. Acquisition-related costs, including advisory, legal, accounting, valuation, and other costs, are expensed in the periods in which these costs are incurred. The results of operations of an acquired business are included in the consolidated financial statements beginning at the acquisition date. Goodwill is tested for impairment annually on October 31, or in the event of certain occurrences. There was no goodwill impairment recorded for the three and nine months ended September 30, 2021, respectively, or the year ended December 31, 2020. The Company estimates the fair value of the earnout liabilities related to business combinations using various valuation approaches, as well as significant unobservable inputs, reflecting the Company’s assessment of the assumptions market participants would use to value these liabilities. The fair value of the earnout is remeasured each reporting period, with any change in the value recorded as other income or expense. The Company recorded increases in the fair value of earnout liabilities related to business combinations of $6.2 million and $8.7 million for the three and nine months ended September 30, 2021, respectively. The Company recorded no changes in the fair value of earnout liabilities related to business combinations and decreases in the fair value of $2.3 million for the three and nine months ended September 30, 2020, respectively (see Note 3).
Long-Lived Assets	Long-Lived Assets The Company evaluates long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. An impairment is recognized in the event the carrying value of such assets is not recoverable. If the carrying value is not recoverable, the fair value is determined, and an impairment is recognized for the amount by which the carrying value exceeds the fair value. No impairment of long-lived assets occurred in the nine months ended September 30, 2021. An impairment of the Company’s operating lease right-of-use assets and property and equipment of $0.8 million was recorded in the nine months ended September 30, 2020.
Acquired Intangible Assets	Acquired Intangible Assets Acquired intangible assets consist of developed technology, including in-process research and development (“IPR&D”), customer relationships, backlog, database content, noncompetition agreements, and tradenames and trademarks, resulting from the Company’s acquisitions. Acquired intangible assets are recorded at fair value on the date of acquisition and amortized over their estimated useful lives. IPR&D is initially capitalized at fair value as a developed technology intangible asset with an indefinite life and assessed for impairment thereafter. When an IPR&D project is completed, it is amortized over the asset’s estimated useful life. The Company recognizes an earnout liability for acquisitions of intangible assets that are accounted for as an asset acquisition when the liability is earned and the amount is known. The earnout liability is capitalized as part of the cost of the assets acquired and amortized over the remaining useful life of the asset. Asset acquisition-related costs, primarily legal fees, are capitalized and included in the cost basis of the intangible asset when incurred.
Income Taxes	Income Taxes The Company’s deferred tax assets and liabilities are determined based on temporary differences between the financial reporting and income tax basis of assets and liabilities and are measured using the tax rates that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company assesses its income tax positions and records tax benefits or expense based upon management’s evaluation of the facts, circumstances, and information available at the reporting date. The objectives of accounting for income taxes are to recognize the amount of taxes payable or refundable for the current period and deferred tax liabilities and assets for the future tax consequences of events that have been recognized in an entity’s financial statements or tax returns. The Company will recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. Judgement is required in assessing the future tax consequences of events that have been recognized in the Company’s consolidated financial statements or tax returns. Variations in the actual outcome of these future tax consequences could materially impact the consolidated financial statements.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation by calculating the fair value of each option, restricted stock unit (“RSU”) or performance share unit (“PSU”) issued under the 2018 Equity Incentive Plan (the “2018 Plan”)
Revenue Recognition	Revenue Recognition The Company primarily generates revenue from fees paid for subscriptions to tax compliance solutions and fees paid for services performed in preparing and filing tax returns on behalf of its customers. Amounts that have been invoiced are recorded in trade accounts receivable and deferred revenue, contract liabilities, or revenue, depending upon whether the revenue recognition criteria have been met. Revenue is recognized once the customer is provisioned and services are provided in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services. The Company’s revenue recognition policy follows guidance from Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers. The Company determines revenue recognition through the following five-step framework: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, the Company satisfies a performance obligation. The Company identifies performance obligations in its contracts with customers, which primarily include subscription services and professional services. The transaction price is determined based on the amount which the Company expects to be entitled to in exchange for providing the promised services to the customer, and is comprised of both fixed and variable consideration. The transaction price in the contract is allocated to each distinct performance obligation on a relative standalone selling price basis. Revenue is recognized when performance obligations are satisfied. Contract payment terms are typically net 30 days. Collectability is assessed based on a number of factors including collection history and creditworthiness of the customer, and the Company may mitigate exposure to credit risk by requiring payments in advance. If collectability of substantially all consideration to which the Company is entitled under the contract is determined to be not probable, revenue is not recorded until collectability becomes probable at a later date. Revenue is recorded based on the transaction price excluding amounts collected on behalf of third parties, such as sales taxes collected and remitted to governmental authorities. Subscription and Returns Revenue Subscription and returns revenue primarily consist of contractually agreed upon fees paid for using the Company’s cloud-based solutions, which include tax calculation and compliance management services, preparing and filing transaction tax returns on behalf of customers, and tax content subscription services. Under most of the Company’s subscription agreements, customers select a price plan that includes an allotted maximum number of transactions over the subscription term. Unused transactions are not carried over to the customer’s next subscription term, and customers are not entitled to refunds of fees paid or relief from fees due in the event they do not use the allotted number of transactions. If customers exceed the maximum transaction level within their price plan, the Company will generally upgrade the customer to a higher transaction price plan or, in some cases, charge overage fees on a per transaction basis. Fees paid for subscription services to tax content vary depending on the volume of tax information accessible to the customer. The Company’s subscription arrangements do not provide the customer with the right to take possession of the software supporting the cloud-based application services. The Company’s standard subscription contracts are non-cancelable except where contract terms provide rights to cancel in the first 60 days of the contract term. Cancellations under the Company’s standard subscription contracts are not material, and do not have a significant impact on revenue recognized. Tax returns processing services include collection of tax data and amounts, preparation of compliance forms, and submission to taxing authorities. Returns processing services are primarily charged on a subscription basis for an allotted number of returns to process within a given time period. Revenue is recognized ratably over the contractual term of the arrangement, beginning on the date that the service is made available to the customer. The Company invoices its subscription customers for the initial term at contract signing and at each subscription renewal. Initial terms generally range from 12 to 18 months, and renewal periods are typically one year. Amounts that are contractually billable and have been invoiced, or which have been collected as cash, are initially recorded as deferred revenue or contract liabilities. While most of the Company’s customers are invoiced once at the beginning of the term, a portion of customers are invoiced semi-annually, quarterly, or monthly. Included in the total subscription fee for cloud-based solutions are non-refundable upfront fees that are typically charged to new customers. These fees are associated with work performed to set up a customer with the Company’s services, and do not represent a distinct good or service. Instead, the fees are included within the transaction price and allocated to the remaining performance obligations in the contract. The Company recognizes revenue for these fees in accordance with the revenue recognition for those performance obligations. Also included in subscription and returns revenue is interest income on funds held from customers. The Company uses trust accounts at FDIC-insured institutions to provide tax remittance services to customers and collect funds from customers in advance of remittance to tax authorities. After collection and prior to remittance, the Company earns interest on these funds. Professional Services Revenue The Company generates professional services revenue from providing tax analysis and services, including tax registrations, voluntary disclosure agreements, nexus studies, and backfiling services. Additionally, the Company provides configurations, data migrations, integration, and training for its subscriptions and returns products. The 2020 acquisitions of Transaction Tax Resources, Inc. (“TTR”) and Business Licenses, LLC (“Business Licenses”) (see Note 5) expanded the scope of professional services to include business licenses and registration services and tax refund claims and recovery assistance. The Company invoices for professional service arrangements on a fixed fee, milestone, or time and materials basis. The transaction price allocated to professional services performance obligations is recognized as revenue as services are performed or upon completion of work. Judgments and Estimates The Company’s contracts with customers often include obligations to provide multiple services to a customer. Determining whether services are considered distinct performance obligations that should be accounted for separately from one another requires judgment. Subscription services and professional services are both distinct performance obligations that are accounted for separately. Judgment is required to determine the standalone selling price (“SSP”) for each distinct performance obligation. The Company allocates revenue to each performance obligation based on the relative SSP. The Company determines SSP for performance obligations based on overall pricing objectives, which take into consideration observable prices, market conditions and entity-specific factors. This includes a review of historical data related to the services being sold and customer demographics. The Company uses a range of amounts to estimate SSP for performance obligations. There is typically more than one SSP for individual services due to the stratification of those services by information, such as size and type of customer. Assets Recognized from the Costs to Obtain a Contract with a Customer The Company recognizes an asset for the incremental costs of obtaining a contract with a customer if it expects the benefit of those costs to be longer than one year. The Company has determined that certain costs related to employee sales incentive programs (sales commissions) and partner commission programs represent incremental costs of obtaining a contract and therefore should be capitalized. Capitalized costs are included in deferred commissions on the consolidated balance sheets. These deferred commissions are amortized over an estimated period of benefit, generally six years. The Company determines the period of benefit by taking into consideration past experience with customers, the expected life of acquired technology that generates revenue, industry peers, and other available information. The period of benefit is generally longer than the term of the initial contract because of anticipated renewals. The Company elected to apply the practical expedient to recognize the incremental costs of obtaining a contract as an expense if the amortization period of the asset would have been one year or less.
Leases	L eases Leases arise from contracts which convey the right to control the use of identified property or equipment for a period of time in exchange for consideration. The Company’s leasing arrangements are primarily for office space used to conduct operations. The Company determines whether an arrangement is or contains a lease at the inception date, based on whether there is an identified asset and whether the Company controls the use of the identified asset throughout the period of use. Leases commence when the lessor makes the asset available for use. Leases are classified at commencement as either operating or finance leases. All the Company’s leases are classified as operating leases. Rent expense for operating leases is recognized on the straight-line method over the term of the agreement beginning on the lease commencement date. Lease-related costs, which are variable rather than fixed, are expensed in the period incurred. Variable lease costs consist primarily of common area maintenance and utilities costs for the Company’s office spaces that are due based on the actual costs incurred by the landlord. Lease payments that depend on an index or a rate are measured using the index or rate at the commencement date and are included in operating lease costs. Subsequent increases to lease payments due to a change in the index or rate are expensed as a variable lease cost.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards ASU 2019-12 In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which amends the existing guidance relating to the accounting for income taxes. This ASU is intended to simplify the accounting for income taxes by removing certain exceptions to the general principles of accounting for income taxes and to improve the consistent application of U.S. GAAP for other areas of accounting for income taxes by clarifying and amending existing guidance. This ASU is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company adopted the guidance on January 1, 2021 and the adoption of this new guidance does not have a material effect on its consolidated financial statements. ASU-2020-06 In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which amends the accounting standards for convertible debt instruments that may be settled entirely or partially in cash upon conversion. ASU No. 2020-06 eliminates requirements to separately account for liability and equity components of such convertible debt instruments and eliminates the ability to use the treasury stock method for calculating diluted earnings per share for convertible instruments whose principal amount may be settled using shares. Instead, ASU No. 2020-06 requires (i) the entire amount of the security to be presented as a liability on the balance sheet and (ii) application of the “if-converted” method for calculating diluted earnings per share. The required use of the “if-converted” method will not impact the Company’s diluted earnings per share as long as the Company is in a net loss position. The guidance in ASU No. 2020-06 is required for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2021, for public business entities. Early adoption is permitted, but no earlier than annual reporting periods beginning after December 15, 2020, including interim periods within those annual reporting periods. The Company early adopted this guidance for the fiscal year beginning January 1, 2021, and did so on a modified retrospective basis, without requiring any adjustments. The adoption of ASU No. 2020-06 impacted the accounting for the offering of $977.5 million of 0.25% convertible senior notes due 2026 (the “2026 Notes”) issued by the Company in August 2021, see Note 10 for further discussion.
New Accounting Standards Not Yet Adopted	New Accounting Standards Not Yet Adopted ASU 2021-08 In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which amends the accounting related to contract assets and liabilities acquired in business combinations. Under current GAAP, an entity generally recognizes assets and liabilities acquired in a business combination, including contract assets and contract liabilities arising from revenue contracts with customers, at fair value on the acquisition date. ASU 2021-08 requires that entities recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with ASC Topic 606, Revenue from Contracts with Customers. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and should be applied prospectively to businesses combinations occurring on or after the effective date of the amendment. Early adoption is permitted, including adoption in an interim period. The Company is currently evaluating the impact of this new guidance on the consolidated financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Consolidated Statements of Cash Flows Line Items after Giving Effect to the Adoption of ASU 2016-18	The following table presents the consolidated statements of cash flows line items after giving effect to the adoption of ASU 2016-18: For the Nine Months Ended September 30, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash provided by operating activities: Other $ 546 $ (767 ) $ (221 ) Net cash provided by operating activities 11,827 (767 ) 11,060 Cash flows from investing activities: Net (increase) in customer fund assets (1,681 ) 1,681 — Net cash used in investing activities (7,355 ) 1,681 (5,674 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents 597,127 914 598,041 Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period 466,950 24,383 491,333 Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period $ 1,064,077 $ 25,297 $ 1,089,374
Summary of Funds Held from Customers and Customer Fund Obligations Held by Company and by Customer Trust	The following table details funds held from customers and customer fund obligations held by the Company and by the Customer Trust as of September 30, 2021 a September 30, December 31, 2021 2020 Funds held from customers (current assets): Restricted cash equivalents - Company $ 5,537 $ 30,598 Restricted cash equivalents - Customer Trust 73,974 — Available-for-sale securities - Customer Trust 373 — Funds held from customers $ 79,884 $ 30,598 Customer fund obligations (current liabilities): Customer fund obligations - Company $ 81,955 $ 31,549 Customer fund obligations $ 81,955 $ 31,549

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following financial assets and liabilities are measured at fair value on a recurring basis. The fair values recognized in the accompanying consolidated balance sheets and the level within the fair value hierarchy in which the fair value measurements fall is as follows (in thousands): Fair Value Measurements Using Quoted Prices Significant in Active Other Significant Markets for Observable Unobservable Fair Identical Assets Inputs Inputs September 30, 2021 Value (Level 1) (Level 2) (Level 3) Money market funds $ 1,460,482 $ 1,460,482 $ — $ — Available-for-sale securities: U.S. treasury securities 373 373 — — Earnouts related to business combinations 75,528 — — 75,528 Fair Value Measurements Using Quoted Prices Significant in Active Other Significant Markets for Observable Unobservable Fair Identical Assets Inputs Inputs December 31, 2020 Value (Level 1) (Level 2) (Level 3) Money market funds $ 649,603 $ 649,603 $ — $ — Earnouts related to business combinations 34,501 — — 34,501
Summary of Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements	A reconciliation of the beginning and ending balances of recurring fair value measurements recognized in the accompanying consolidated balance sheets using significant unobservable (Level 3) inputs, is as follows (in thousands): For the Three Months Ended September 30, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 67,454 $ 33 Measurement period adjustment 1,927 — Payments of earnout liabilities (33 ) — Total unrealized loss included in other (income) expense, net 6,180 — Balance end of period $ 75,528 $ 33 For the Nine Months Ended September 30, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 34,501 $ 13,808 Fair value recorded at acquisition 28,620 — Measurement period adjustment 3,729 — Payments of earnout liabilities (33 ) (11,450 ) Total unrealized net (gain) loss included in other (income) expense, net 8,711 (2,325 ) Balance end of period $ 75,528 $ 33

Balance Sheet Detail (Tables)

Balance Sheet Detail (Tables)	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): Useful September 30, December 31, Life (Years) 2021 2020 Computer equipment and software 3 to 5 $ 18,840 $ 15,749 Internally developed software 3 to 6 22,043 10,438 Furniture and fixtures 5 6,487 6,651 Office equipment 3 to 5 1,096 1,006 Leasehold improvements 1 to 10 29,823 29,928 78,289 63,772 Accumulated depreciation (35,644 ) (29,059 ) Property and equipment—net $ 42,645 $ 34,713
Schedule of Prepaid Expense And Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, 2021 2020 Prepaid expenses $ 29,286 $ 13,968 Deposits 205 2,557 Other 1,611 3,573 Total $ 31,102 $ 20,098
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): September 30, December 31, 2021 2020 Accrued payroll and related taxes $ 12,372 $ 7,903 Accrued federal, state, local, and foreign taxes 7,343 4,338 Accrued bonus 31,874 29,518 Self-insurance reserves 1,725 1,563 Employee stock purchase plan contributions 2,944 5,927 Accrued sales commissions 4,924 5,563 Accrued partner commissions 10,224 9,173 Contract liabilities 8,597 10,134 Interest payable on convertible senior notes 333 — Other 11,642 10,413 Total $ 91,978 $ 84,532

Acquisitions of Businesses (Tab

Acquisitions of Businesses (Tables)	9 Months Ended
	Sep. 30, 2021
Business Acquisition [Line Items]
Schedule of Pro Forma Financial Information (Unaudited)	The unaudited pro forma financial information as presented below is for informational purposes only and is not necessarily indicative of the results of operations that would have been achieved if the acquisitions had taken place as of January 1, 2020. For the Nine Months Ended September 30, 2021 2020 Total revenue $ 511,837 $ 362,729 Net loss (92,837 ) (41,664 )
Inposia | Fair Value
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	Measurement period adjustments recognized in the third quarter of 2021 related primarily to updated estimated fair values for acquired intangible assets, deferred tax liabilities, and a net working capital adjustment. Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing (net of amounts returned) $ 14,671 $ (188 ) $ 14,483 Fair value of common stock issued at closing 22,971 — 22,971 Total consideration $ 37,642 $ (188 ) $ 37,454
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed	Preliminary estimated fair values of the assets acquired and the liabilities assumed in the Inposia Purchase as of the acquisition date are provided in the following table (in thousands): Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 1,264 $ — $ 1,264 Trade accounts receivable 1,767 — 1,767 Other current assets 268 — 268 Operating lease right-of-use assets 928 — 928 Property and equipment 98 — 98 Developed technology, customer relationships, and other intangibles 12,684 1,820 14,504 Goodwill 27,702 (1,486 ) 26,216 Other noncurrent assets 35 — 35 Total assets acquired 44,746 334 45,080 Liabilities assumed: Trade payables and accrued expenses 1,340 — 1,340 Deferred revenue 811 (55 ) 756 Other liabilities, noncurrent 106 — 106 Operating lease liabilities 928 — 928 Deferred tax liability 3,919 577 4,496 Total liabilities assumed 7,104 522 7,626 Net assets acquired $ 37,642 $ (188 ) $ 37,454
Summary of Valuation Methodologies, Significant Assumptions and Estimated Useful Lives	A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Inposia Purchase are provided in the below table (in thousands ): Intangible Previously Reported Assigned Value As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 1,585 $ 1,938 $ 3,523 Multi-period excess earnings-income approach 18.5 % 8 years Developed technology 9,572 — 9,572 Relief from royalty-income approach 18.5 % 6 years Noncompetition agreements 1,292 (118 ) 1,174 With-and-without valuation-income approach 21.0 % 3 years Tradename 235 — 235 Relief from royalty-income approach 18.5 % 3 years
Davo | Fair Value
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	Measurement period adjustments recognized in the third quarter of 2021 related primarily to updated estimated fair values for acquired intangible assets, earnout liability, and a net working capital adjustment. Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid through closing $ 23,818 $ — $ 23,818 Fair value of earnout provision 28,620 1,927 30,547 Fair value of holdbacks 2,600 (9 ) 2,591 Total consideration $ 55,038 $ 1,918 $ 56,956
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed	Preliminary estimated fair values of the assets acquired and the liabilities assumed in the Davo Purchase as of the acquisition date are provided in the following table (in thousands): Previously Reported As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 198 $ — $ 198 Funds held from customers 12,464 — 12,464 Trade accounts receivable 119 — 119 Other current assets 58 — 58 Operating lease right-of-use assets 46 — 46 Developed technology, customer relationships, and other intangibles 6,427 414 6,841 Goodwill 48,426 1,505 49,931 Other noncurrent assets 2 (1 ) 1 Total assets acquired 67,740 1,918 69,658 Liabilities assumed: Accrued expenses 117 — 117 Deferred revenue 75 — 75 Operating lease liabilities 46 — 46 Customer fund obligations 12,464 — 12,464 Total liabilities assumed 12,702 — 12,702 Net assets acquired $ 55,038 $ 1,918 $ 56,956
Summary of Valuation Methodologies, Significant Assumptions and Estimated Useful Lives	A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Davo Purchase are provided in the below table (in thousands): Intangible Previously Reported Assigned Value As of June 30, 2021 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 4,350 $ (50 ) $ 4,300 Multi-period excess earnings-income approach and replacement cost method-cost approach 14.5 % 8 years Developed technology 1,800 100 1,900 Relief from royalty-income approach 14.5 % 5 years Noncompetition agreements 191 364 555 With-and-without valuation-income approach 16.5 % 5 years Tradename 86 — 86 Relief from royalty-income approach 14.5 % 1 years
Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	A reconciliation of preliminary total consideration as of December 31, 2020 and total consideration as of September 30, 2021 is presented below (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 294,017 $ — $ 294,017 Fair value of holdbacks 57,477 (217 ) 57,260 Fair value of earnout provision 15,740 3,131 18,871 Total consideration $ 367,234 $ 2,914 $ 370,148
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed	Estimated fair values of the assets acquired and the liabilities assumed in the TTR Merger as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 2,294 $ — $ 2,294 Trade accounts receivable 5,966 — 5,966 Other current assets 93 — 93 Operating lease right-of-use assets 1,760 — 1,760 Property and equipment 848 — 848 Developed technology, customer relationships, and other intangibles 49,000 (7,500 ) 41,500 Goodwill 327,039 8,526 335,565 Total assets acquired 387,000 1,026 388,026 Liabilities assumed: Trade payables and accrued expenses 731 — 731 Deferred revenue 8,500 — 8,500 Operating lease liabilities 1,760 — 1,760 Deferred tax liability 8,775 (1,888 ) 6,887 Total liabilities assumed 19,766 (1,888 ) 17,878 Net assets acquired $ 367,234 $ 2,914 $ 370,148
Summary of Valuation Methodologies, Significant Assumptions and Estimated Useful Lives	A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the TTR Merger are provided in the below table (in thousands): Intangible Previously Reported Assigned Value As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Reported Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 26,000 $ (5,000 ) $ 21,000 Multi-period excess earnings-income approach 18% 6 years Developed technology 9,600 — 9,600 Relief from royalty-income approach and replacement cost method-cost approach 17% to 18% 3 to 6 years Tradename 5,800 — 5,800 Relief from royalty-income approach 17% 2 years Contract backlog 5,800 (2,500 ) 3,300 Multi-period excess earnings-income approach 17% 3 years Noncompetition agreements 1,800 — 1,800 With-and-without valuation-income approach 19% 5 years
Business Licenses
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	Measurement period adjustments recognized in the first quarter of 2021 related to the finalization of the estimated fair value of the earnout liability and a net working capital adjustment. Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 64,812 $ — $ 64,812 Fair value of holdbacks 11,415 (306 ) 11,109 Fair value of earnout provision 18,728 (1,328 ) 17,400 Total consideration $ 94,955 $ (1,634 ) $ 93,321
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed	Estimated fair values of the assets acquired and the liabilities assumed in the Business Licenses Purchase as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 120 $ — $ 120 Trade accounts receivable 1,326 — 1,326 Customer fund assets 1,074 — 1,074 Other current assets 101 — 101 Operating lease right-of-use assets 1,644 — 1,644 Property and equipment 87 — 87 Developed technology, customer relationships, and other intangibles 19,525 — 19,525 Goodwill 73,775 (1,634 ) 72,141 Other noncurrent assets 31 — 31 Total assets acquired 97,683 (1,634 ) 96,049 Liabilities assumed: Accrued expenses 56 — 56 Customer fund obligations 1,028 — 1,028 Operating lease liabilities 1,644 — 1,644 Total liabilities assumed 2,728 — 2,728 Net assets acquired $ 94,955 $ (1,634 ) $ 93,321
Summary of Valuation Methodologies, Significant Assumptions and Estimated Useful Lives	A summary of the valuation methodologies, significant assumptions, and estimated useful lives of acquired intangible assets in the Business Licenses Purchase are provided in the below table (in thousands): Intangible Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationships $ 15,000 Multi-period excess earnings-income approach 19.5% 6 years Developed technology 3,625 Relief from royalty-income approach and replacement cost method-cost approach 19.5% 1 to 5 years Noncompetition agreements 500 With-and-without valuation-income approach 19.5% 5 years Tradename 400 Relief from royalty-income approach 19.5% 1 year
Impendulo | Fair Value
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	Measurement period adjustments recognized in the first quarter of 2021 relate to the finalization of the net working capital adjustment. Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Cash paid at closing $ 11,713 $ — $ 11,713 Common stock paid at close 1,190 — 1,190 Cash payable accrual 694 425 1,119 Total consideration $ 13,597 $ 425 $ 14,022
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed	Estimated fair values of the assets acquired and the liabilities assumed in the Impendulo Purchase as of the acquisition date and including measurement period adjustments are provided in the following table (in thousands): Previously Reported As of December 31, 2020 Purchase Price Allocation Measurement Period Adjustment As Adjusted Assets acquired: Cash and cash equivalents $ 1,347 $ — $ 1,347 Trade accounts receivable 371 — 371 Other assets 147 — 147 Developed technology, customer relationships, and other intangibles 3,617 — 3,617 Goodwill 10,217 425 10,642 Total assets acquired 15,699 425 16,124 Liabilities assumed: Trade payables and accrued expenses 663 — 663 Deferred revenue and contract liabilities 694 — 694 Deferred tax liability 745 — 745 Total liabilities assumed 2,102 — 2,102 Net assets acquired $ 13,597 $ 425 $ 14,022
Summary of Valuation Methodologies, Significant Assumptions and Estimated Useful Lives	Intangible Assigned Value Valuation Methodology Discount Rate Estimated Useful Life Customer relationship $ 2,964 Multi-period excess earnings-income approach 20% 6 years Developed technology 616 Relief from royalty-income approach 20% 6 years Tradename 37 Relief from royalty-income approach 20% 1 year

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue From Contract With Customer [Abstract]
Summary of Total Revenues	The following table disaggregates revenue generated within the United States (U.S.) from revenue generated from customers outside of the U.S. Revenue for transaction tax compliance in the U.S. is further disaggregated based on the solutions or services purchased by customers. Total revenues consisted of the following (in thousands): For the Three Months Ended September 30, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 91,539 $ 65,312 Tax returns and compliance management 58,846 46,087 Interest income on funds held from customers 215 118 Total subscription and returns 150,600 111,517 Professional services 15,440 8,186 Total revenue (U.S.) 166,040 119,703 Total revenue (non-U.S.) 15,127 8,176 Total revenue $ 181,167 $ 127,879 For the Nine Months Ended September 30, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 251,301 $ 185,986 Tax returns and compliance management 168,445 126,384 Interest income on funds held from customers 557 701 Total subscription and returns 420,303 313,071 Professional services 43,299 20,978 Total revenue (U.S.) 463,602 334,049 Total revenue (non-U.S.) 40,233 21,760 Total revenue $ 503,835 $ 355,809
Summary of Activity Impacting Contract Liabilities	A summary of the activity impacting the contract liabilities during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Contract liabilities: Balance beginning of period $ 11,406 $ 6,195 Contract liabilities transferred to deferred revenue (6,420 ) (2,737 ) Addition to contract liabilities 3,611 4,215 Balance end of period $ 8,597 $ 7,673 For the Nine Months Ended September 30, 2021 2020 Contract liabilities: Balance beginning of period $ 10,134 $ 5,197 Contract liabilities transferred to deferred revenue (15,550 ) (7,992 ) Addition to contract liabilities 14,013 10,468 Balance end of period $ 8,597 $ 7,673
Summary of Activity Impacting Deferred Revenue	A summary of the activity impacting deferred revenue balances during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Deferred revenue: Balance beginning of period $ 239,395 $ 167,719 Revenue recognized (181,167 ) (127,879 ) Additional amounts deferred 199,655 140,800 Balance end of period $ 257,883 $ 180,640 For the Nine Months Ended September 30, 2021 2020 Deferred revenue: Balance beginning of period $ 209,690 $ 161,241 Revenue recognized (503,835 ) (355,809 ) Additional amounts deferred 552,028 375,208 Balance end of period $ 257,883 $ 180,640
Summary of Activity Impacting Deferred Commissions	A summary of the activity impacting the deferred commissions during the three and nine months ended September 30, 2021 and 2020 is presented below (in thousands): For the Three Months Ended September 30, 2021 2020 Deferred commissions: Balance beginning of period $ 60,643 $ 43,356 Additional commissions deferred 6,997 5,406 Amortization of deferred commissions (4,009 ) (2,921 ) Balance end of period $ 63,631 $ 45,841 For the Nine Months Ended September 30, 2021 2020 Deferred commissions: Balance beginning of period $ 50,870 $ 38,416 Additional commissions deferred 23,599 15,818 Amortization of deferred commissions (10,838 ) (8,393 ) Balance end of period $ 63,631 $ 45,841

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Finite-lived Intangible Assets	Intangible assets consisted of the following (in thousands): September 30, 2021 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 3,300 $ (1,288 ) $ 2,012 Customer relationships 3 to 10 68,506 (21,279 ) 47,227 Developed technology (1) 3 to 8 66,882 (34,568 ) 32,314 Noncompetition agreements 3 to 5 5,073 (1,404 ) 3,669 Tradename and trademarks 1 to 4 7,023 (3,828 ) 3,195 $ 150,784 $ (62,367 ) $ 88,417 (1) December 31, 2020 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 5,800 $ (937 ) $ 4,863 Customer relationships 3 to 10 64,302 (14,890 ) 49,412 Developed technology (1) 3 to 8 52,144 (27,646 ) 24,498 Noncompetition agreements 3 to 5 3,062 (766 ) 2,296 Tradename and trademarks 1 to 4 6,679 (1,235 ) 5,444 $ 131,987 $ (45,474 ) $ 86,513 (1)
Schedule of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill for the nine months ended September 30, 2021 Balance—December 31, 2020 $ 513,234 Measurement period adjustment - 2020 acquisitions (1) 7,317 Acquisition of Davo 49,931 Acquisition of Inposia 26,216 Acquisition of 3CE 8,290 Cumulative translation adjustments (1,220 ) Balance—September 30, 2021 $ 603,768 (1)

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Summary of Net Carrying Amount of Notes	The net carrying amount of the 2026 Notes was as follows: September 30, 2021 (in thousands) Principal $ 977,500 Unamortized debt issuance costs (17,127 ) Net carrying amount $ 960,373
Summary of Interest Expense Recognized	The following table sets forth the interest expense recognized related to the 2026 Notes: For the Three Months Ended September 30, 2021 (in thousands) Contractual interest expense $ 333 Amortization of debt issuance costs 482 Total interest expense related to 2026 Notes $ 815 For the Nine Months Ended September 30, 2021 (in thousands) Contractual interest expense $ 333 Amortization of debt issuance costs 482 Total interest expense related to 2026 Notes $ 815

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders Equity Note [Abstract]
Summary of Changes of Shareholders' Equity	The changes to the Company’s shareholders’ equity during the nine months ended September 30, 2021 Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Loss Deficit Equity Balance at January 1, 2021 85,057,727 $ 9 $ 1,640,867 $ (1,339 ) $ (559,377 ) $ 1,080,160 Exercise of stock options 296,226 5,529 5,529 Vesting of restricted stock units 346,008 Stock-based compensation cost 19,047 19,047 Shares issued under employee stock purchase plan 60,064 7,088 7,088 Loss on translation adjustment (390 ) (390 ) Net loss (29,988 ) (29,988 ) Balance at March 31, 2021 85,760,025 $ 9 $ 1,672,531 $ (1,729 ) $ (589,365 ) $ 1,081,446 Exercise of stock options 253,395 4,668 4,668 Vesting of restricted stock units 75,571 — Stock-based compensation cost 23,592 23,592 Shares issued for acquisitions of businesses 164,416 22,971 22,971 Gain on translation adjustment 322 322 Net loss (27,650 ) (27,650 ) Balance at June 30, 2021 86,253,407 $ 9 $ 1,723,762 $ (1,407 ) $ (617,015 ) $ 1,105,349 Exercise of stock options 488,992 7,950 7,950 Vesting of restricted stock units 43,374 — Stock-based compensation cost 23,777 23,777 Shares issued under employee stock purchase plan 56,817 7,358 7,358 Purchase of capped calls (75,268 ) (75,268 ) Loss on translation adjustment (1,172 ) (1,172 ) Net loss (32,546 ) (32,546 ) Balance at September 30, 2021 86,842,590 $ 9 $ 1,687,579 $ (2,579 ) $ (649,561 ) $ 1,035,448 The changes to the Company’s shareholders’ equity for the nine months ended September 30, 2020 is as follows (in thousands, except share data): Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Income (Loss) Deficit Equity Balance at January 1, 2020 77,447,620 $ 8 $ 976,627 $ (2,719 ) $ (510,194 ) $ 463,722 Exercise of stock options 532,848 7,928 7,928 Vesting of restricted stock units 186,475 Stock-based compensation cost 9,749 9,749 Shares issued under employee stock purchase plan 81,894 5,716 5,716 Shares issued related to business combination earnouts 44,659 3,750 3,750 Shares issued to purchase intangible assets 1,191 87 87 Gain on translation adjustment 625 625 Net loss (15,283 ) (15,283 ) Balance at March 31, 2020 78,294,687 $ 8 $ 1,003,857 $ (2,094 ) $ (525,477 ) $ 476,294 Exercise of stock options 1,117,805 17,495 17,495 Vesting of restricted stock units 57,832 — Stock-based compensation cost 12,368 12,368 Shares issued related to business combination earnouts 44,659 3,750 3,750 Gain on translation adjustment 435 435 Net loss (10,140 ) (10,140 ) Balance at June 30, 2020 79,514,983 $ 8 $ 1,037,470 $ (1,659 ) $ (535,617 ) $ 500,202 Proceeds from common stock offering, net of underwriting discounts 4,527,558 556,312 556,312 Public offering costs (701 ) (701 ) Exercise of stock options 333,977 5,294 5,294 Vesting of restricted stock units 19,178 — Stock-based compensation cost 12,916 12,916 Shares issued under employee stock purchase plan 75,811 5,621 5,621 Loss on translation adjustment (225 ) (225 ) Net loss (12,729 ) (12,729 ) Balance at September 30, 2020 84,471,507 $ 8 $ 1,616,912 $ (1,884 ) $ (548,346 ) $ 1,066,690

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2021
Summary of Stock-Based Compensation Expense Related to Equity Incentive Rewards	The Company recognized total stock-based compensation cost related to equity incentive awards as follows (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Stock-based compensation cost: Stock options $ 2,913 $ 3,749 $ 9,210 $ 11,757 Restricted stock units 14,993 8,052 41,618 20,472 Performance share units 4,683 — 12,148 — Employee stock purchase plan 1,188 1,115 3,440 2,804 Total stock-based compensation cost $ 23,777 $ 12,916 $ 66,416 $ 35,033
Summary of Stock Option Activity	Stock Options The following table summarizes stock option activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Weighted Average Aggregate Average Remaining Intrinsic Exercise Contractual Value Shares Price Life (in Years) (in thousands) Options outstanding as of January 1, 2021 3,537,014 $ 28.17 6.89 $ 483,577 Options granted — $ — Options exercised (1,038,613 ) $ 17.47 Options cancelled or expired (24,525 ) $ 16.65 Options outstanding as of September 30, 2021 2,473,876 $ 32.78 6.45 $ 351,272 Options exercisable as of September 30, 2021 1,741,687 $ 26.18 6.07 $ 258,789
Summary of Options Outstanding and Vested by Range of Exercise Prices	A summary of options outstanding and vested as of September 30, 2021 is as follows: Options Outstanding Options Vested and Exercisable Exercise Number Weighted Average Number Vested Weighted Average Prices Outstanding Life (in Years) and Exercisable Life (in Years) $1.90 to $6.40 23,065 1.3 23,065 1.3 $8.04 to $11.72 79,506 2.5 79,506 2.5 $12.20 to $15.06 491,764 5.0 491,764 5.0 $16.06 to $24.00 754,170 6.3 578,159 6.3 $31.99 to $42.21 658,855 7.2 392,185 7.2 $55.10 to $99.65 424,361 8.0 167,684 7.8 $124.35 to $151.76 42,155 6.6 9,324 5.9 2,473,876 1,741,687
Summary of Fair Value Estimated Using Black-Scholes Option Pricing Model Assumptions	For the options granted during the periods presented, the fair value was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Fair market value of common stock — $124.35 - 130.82 — $66.26 - 130.82 Volatility — 43% — 43% Expected term — 6 years — 5-6 years Expected dividend yield — n/a — n/a Risk-free interest rate — 0.44% - 0.51% — 0.33% - 1.25%
Summary of RSU Activity	The following table summarizes RSU activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Average Grant Date Fair Restricted Stock Units Value Per Share RSUs outstanding as of January 1, 2021 2,359,063 $ 70.17 RSUs granted 1,068,582 136.76 RSUs vested (464,953 ) 65.29 RSUs cancelled (173,477 ) 81.12 RSUs outstanding as of September 30, 2021 2,789,215 $ 95.81
Summary of PSU Activity	The following table summarizes PSU activity for the Company’s stock-based compensation plans for the nine months ended September 30, 2021: Weighted Average Grant Date Fair Performance Share Units Value Per Share PSUs outstanding as of January 1, 2021 — $ — PSUs granted 120,632 147.39 PSUs vested — — PSUs cancelled — — PSUs outstanding as of September 30, 2021 120,632 $ 147.39
2018 Employee Stock Purchase Plan
Summary of Fair Value Estimated Using Black-Scholes Option Pricing Model Assumptions	For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Fair market value of common stock $ 166.84 $ 138.83 $152.35 to $166.84 $87.23 to $138.83 Volatility 31% 49% 31% to 34% 32% to 49% Expected term 0.5 years 0.5 years 0.5 years 0.5 years Expected dividend yield n/a n/a n/a n/a Risk-free interest rate 0.06% 0.11% 0.06% to 0.08% 0.11% to 1.54%

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Shareholders (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Common Share	The following table sets forth the computation of basic and diluted net loss per common share (in thousands, except per share data): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss attributable to common shareholders $ (32,546 ) $ (12,729 ) $ (90,184 ) $ (38,152 ) Denominator: Weighted-average common shares outstanding-basic 86,530 82,288 86,023 79,715 Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, ESPP shares, and convertible senior notes (if converted) — — — — Weighted-average common shares outstanding-diluted 86,530 82,288 86,023 79,715 Net loss per common share, basic and diluted $ (0.38 ) $ (0.15 ) $ (1.05 ) $ (0.48 )
Schedule of Potential Shares Not Included in the Computation of Diluted Earnings Per Share	The following weighted-average outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common shareholders for the periods presented because the impact of including them would have been antidilutive (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common shares 2,750 4,229 3,085 4,938 Unvested restricted stock units 2,748 2,267 2,586 2,009 Unvested performance share units 121 — 106 — ESPP shares 4 5 4 2 Convertible senior notes (if converted) 2,184 — 736 — Total 7,807 6,501 6,517 6,949

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	Oct. 31, 2018USD ($)	Aug. 31, 2021USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)Segment	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Accounting Policies [Line Items]
Number of operating segment | Segment					1
Goodwill impairment	$ 0		$ 0		$ 0		$ 0
Increases decreases in fair value of earnout liabilities related to business combinations			$ 6,200,000	$ 0	8,700,000	$ (2,300,000)
Impairment of long-lived assets					0
Impairment of operating lease right-of-use assets and property and equipment					$ 0	794,000
Tax position likely of being realized upon ultimate settlement					greater than 50%
Percentage of likelihood of realization of tax position upon ultimate settlement, minimum			50.00%		50.00%
Contract payment net terms					30 days
Concessions and cancellations period allowed for standard subscription contract prior to adoption					60 days
Revenue recognition, contractual renewal period					1 year
Deferred commission amortized period			6 years		6 years
2026 Notes
Accounting Policies [Line Items]
Principal amount		$ 977,500,000	$ 977,500,000		$ 977,500,000
Fixed interest rate		0.25%
Minimum
Accounting Policies [Line Items]
Revenue recognition initial contractual term					12 months
Maximum
Accounting Policies [Line Items]
Revenue recognition initial contractual term					18 months
Amortization period of asset					1 year
ASU No. 2020-06 | 2026 Notes
Accounting Policies [Line Items]
Principal amount		$ 977,500,000
Fixed interest rate		0.25%
Convertible senior notes due year		2026
Restatement Adjustment | Accounting Standards Update 2016-18
Accounting Policies [Line Items]
Change in net cash used in operating activities due to correction						800,000
Change in net cash used in investing activities due to correction						$ 1,700,000

Significant Accounting Polici_5

Significant Accounting Policies - Consolidated Statements of Cash Flows Line Items after Giving Effect to the Adoption of ASU 2016-18 (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Adjustments to reconcile net loss to net cash provided by operating activities:
Other	$ 799	$ 221
Net cash provided by operating activities	8,725	11,060
Cash flows from investing activities:
Net cash used in investing activities	(49,507)	(5,674)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	891,789	598,041
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period	761,844	491,333
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period	$ 1,653,633	1,089,374
As Previously Reported
Adjustments to reconcile net loss to net cash provided by operating activities:
Other		546
Net cash provided by operating activities		11,827
Cash flows from investing activities:
Net (increase) in customer fund assets		(1,681)
Net cash used in investing activities		(7,355)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		597,127
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period		466,950
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period		1,064,077
Accounting Standards Update 2016-18
Adjustments to reconcile net loss to net cash provided by operating activities:
Other		(221)
Net cash provided by operating activities		11,060
Cash flows from investing activities:
Net cash used in investing activities		(5,674)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		598,041
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period		491,333
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period		1,089,374
Accounting Standards Update 2016-18 | ASU 2016-18 Adjustments
Adjustments to reconcile net loss to net cash provided by operating activities:
Other		(767)
Net cash provided by operating activities		(767)
Cash flows from investing activities:
Net (increase) in customer fund assets		1,681
Net cash used in investing activities		1,681
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		914
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period		24,383
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period		$ 25,297

Significant Accounting Polici_6

Significant Accounting Policies - Summary of Funds Held from Customers and Customer Fund Obligations Held by Company and by Customer Trust (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Funds held from customers (current assets):
Funds held from customers	$ 79,884	$ 30,598
Customer fund obligations (current liabilities):
Customer fund obligations	81,955	31,549
Company
Customer fund obligations (current liabilities):
Customer fund obligations	81,955	31,549
Restricted Cash Equivalents | Company
Funds held from customers (current assets):
Funds held from customers	5,537	$ 30,598
Restricted Cash Equivalents | Customer Trust
Funds held from customers (current assets):
Funds held from customers	73,974
Available-for-sale Securities | Customer Trust
Funds held from customers (current assets):
Funds held from customers	$ 373

Investments and Fair Value Me_3

Investments and Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Earnouts Related to Business Combinations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Liabilities	$ 75,528	$ 34,501
Significant Unobservable Inputs (Level 3) | Earnouts Related to Business Combinations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Liabilities	75,528	34,501
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Assets	1,460,482	649,603
Money Market Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Assets	1,460,482	$ 649,603
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Available-for-sale securities	373
U.S. Treasury Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Available-for-sale securities	$ 373

Investments and Fair Value Me_4

Investments and Fair Value Measurements - Additional Information (Details) $ in Millions	Sep. 30, 2021USD ($)
2026 Notes | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Principal amount	$ 977.5
Estimated fair value	$ 1,000
Discount Rate | Discounted Cash Flows and Monte Carlo Simulations | Transaction Tax Resources, Inc.
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate utilized for valuation of earnout liability	13.00%
Discount Rate | Discounted Cash Flows and Monte Carlo Simulations | Business Licenses
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate utilized for valuation of earnout liability	4.50%
Discount Rate | Discounted Cash Flows and Monte Carlo Simulations | Davo Technologies LLC
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate utilized for valuation of earnout liability	7.00%

Investments and Fair Value Me_5

Investments and Fair Value Measurements - Summary of Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnout liabilities related to business combinations:
Total unrealized net (gain) loss included in other (income) expense, net	$ (6,200)	$ 0	$ (8,700)	$ 2,300
Recurring Basis | Significant Unobservable Inputs (Level 3) | Earnout Related to Acquisitions
Earnout liabilities related to business combinations:
Balance beginning of period	67,454	33	34,501	13,808
Fair value recorded at acquisition	0	0	28,620	0
Measurement period adjustment	1,927	0	3,729	0
Payments of earnout liabilities	(33)	0	(33)	(11,450)
Total unrealized net (gain) loss included in other (income) expense, net	6,180	0	8,711	(2,325)
Balance end of period	$ 75,528	$ 33	$ 75,528	$ 33

Balance Sheet Detail - Property

Balance Sheet Detail - Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 78,289	$ 63,772
Accumulated depreciation	(35,644)	(29,059)
Property and equipment—net	42,645	34,713
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 18,840	15,749
Computer Equipment and Software | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	3 years
Computer Equipment and Software | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	5 years
Internally Developed Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 22,043	10,438
Internally Developed Software | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	3 years
Internally Developed Software | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	6 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 6,487	6,651
Property and equipment, Useful Life	5 years
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,096	1,006
Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	3 years
Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 29,823	$ 29,928
Leasehold Improvements | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	1 year
Leasehold Improvements | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	10 years

Balance Sheet Detail - Addition

Balance Sheet Detail - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 3.3	$ 2.5	$ 8.7	$ 7

Balance Sheet Detail - Prepaid

Balance Sheet Detail - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 29,286	$ 13,968
Deposits	205	2,557
Other	1,611	3,573
Total	$ 31,102	$ 20,098

Balance Sheet Detail - Accrued

Balance Sheet Detail - Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Accrued payroll and related taxes	$ 12,372		$ 7,903
Accrued federal, state, local, and foreign taxes	7,343		4,338
Accrued bonus	31,874		29,518
Self-insurance reserves	1,725		1,563
Employee stock purchase plan contributions	2,944		5,927
Accrued sales commissions	4,924		5,563
Accrued partner commissions	10,224		9,173
Contract liabilities	8,597	$ 11,406	10,134	$ 7,673	$ 6,195	$ 5,197
Interest payable on convertible senior notes	333		0
Other	11,642		10,413
Total	$ 91,978		$ 84,532

Acquisitions of Businesses - Ad

Acquisitions of Businesses - Additional Information (Details) € in Millions	Oct. 18, 2021USD ($)	Oct. 01, 2021USD ($)	Sep. 07, 2021USD ($)	Jun. 30, 2021USD ($)	Apr. 20, 2021USD ($)	Apr. 01, 2021USD ($)shares	Apr. 01, 2021EUR (€)shares	Dec. 31, 2020USD ($)	Dec. 01, 2020USD ($)	Nov. 05, 2020USD ($)	Oct. 05, 2020USD ($)	Sep. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2022USD ($)	Dec. 31, 2021USD ($)
Business Acquisition [Line Items]
Goodwill								$ 513,234,000				$ 603,768,000			$ 513,234,000		$ 603,768,000		$ 513,234,000	$ 603,768,000		$ 513,234,000
Revenues												181,167,000				$ 127,879,000				503,835,000	$ 355,809,000
Loss before income taxes												33,156,000				12,336,000				88,585,000	37,205,000
Accrued value of earnout related to acquisition												32,350,000				$ 0	32,350,000			32,350,000	$ 0
Earnout liability								749,000				29,456,000			749,000		29,456,000		749,000	29,456,000		749,000
Accrued earnout liabilities								34,468,000				46,416,000			34,468,000		46,416,000		34,468,000	$ 46,416,000		34,468,000
CrowdReason LLC and CorrelationAdvisors
Business Acquisition [Line Items]
Business acquisition, effective date of acquisition																				Oct. 18, 2021
CrowdReason LLC and CorrelationAdvisors | Subsequent Event
Business Acquisition [Line Items]
Consideration in cash	$ 8,300,000
Additional cash to be paid, as consideration, in eighteen months or less	2,000,000
Maximum payout earned	$ 40,000,000
Earnout arrangement term	3 years
Track1099 LLC
Business Acquisition [Line Items]
Business acquisition, effective date of acquisition																				Oct. 1, 2021
Track1099 LLC | Subsequent Event
Business Acquisition [Line Items]
Consideration in cash		$ 35,000,000
Maximum payout earned		$ 12,500,000
Earnout arrangement term		2 years
Additional cash to be paid, as consideration, in twenty seven months		$ 5,000,000
3CE Technologies, Inc.
Business Acquisition [Line Items]
Consideration in cash			$ 9,900,000
Business acquisition, effective date of acquisition																				Sep. 7, 2021
Total consideration transferred			11,200,000
Acquisition holdbacks with a fair value upon acquisition			1,300,000
Goodwill			8,300,000
Developed technology, customer relationships, and other intangibles			$ 2,500,000
Inposia
Business Acquisition [Line Items]
Consideration in cash						$ 12,200,000						14,483,000			2,400,000			$ 14,671,000
Total consideration transferred						37,400,000	€ 31.8					37,454,000						37,642,000
Goodwill						26,200,000
Acquisition-related costs						$ 1,400,000													1,000,000	$ 400,000
Cash received on net working capital adjustments												200,000
Common stock paid at acquisition closing | shares						164,416	164,416
Common stock consideration						$ 23,000
Term of releasing shares issued are held in escrow																				18 months
Fair value discount rate based on estimated pre-tax cost of debt						4.00%	4.00%
Weighted average amortization period for intangibles						6 years 2 months 12 days	6 years 2 months 12 days
Revenues																				$ 4,000,000
Loss before income taxes																				1,500,000
Inposia | Developed Technology
Business Acquisition [Line Items]
Developed technology, customer relationships, and other intangibles						$ 9,572,000
Davo Technologies LLC
Business Acquisition [Line Items]
Consideration in cash				$ 23,818,000	$ 23,500,000							23,818,000		$ 300,000
Total consideration transferred				55,038,000	56,900,000							56,956,000
Acquisition holdbacks with a fair value upon acquisition				2,600,000	2,600,000							2,591,000	$ 2,600,000				2,591,000	2,600,000		2,591,000
Goodwill					49,900,000
Acquisition-related costs					$ 100,000
Weighted average amortization period for intangibles					6 years 9 months 18 days
Revenues																	1,300,000
Loss before income taxes																	1,200,000
Accrued value of earnout related to acquisition				28,620,000	$ 30,500,000							30,547,000	28,620,000				30,547,000	28,620,000		30,547,000
Business combination, additional cash to be paid, as consideration, during eighteen months following acquisition date					2,600,000
Earnout liability					15,100,000
Accrued earnout liabilities					15,400,000
Davo Technologies LLC | Developed Technology
Business Acquisition [Line Items]
Developed technology, customer relationships, and other intangibles				$ 1,800,000	$ 1,900,000								1,800,000					$ 1,800,000
Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Consideration in cash								294,017,000			$ 294,000,000									294,017,000
Maximum payout earned											26,400,000
Total consideration transferred								367,234,000			370,100,000									370,148,000
Acquisition holdbacks with a fair value upon acquisition								57,477,000			57,300,000	57,260,000			57,477,000		57,260,000		57,477,000	57,260,000		57,477,000
Goodwill											$ 335,600,000
Weighted average amortization period for intangibles											4 years 8 months 12 days
Accrued value of earnout related to acquisition								15,740,000			$ 18,900,000	18,871,000			15,740,000		18,871,000		15,740,000	18,871,000		15,740,000
Earnout liability								19,900,000				37,800,000			19,900,000		37,800,000		19,900,000	37,800,000		19,900,000
Accrued earnout liabilities								37,700,000							37,700,000				37,700,000			37,700,000
Risk-free discount rate											0.13%
Earnout payable period											2023-02
Minimum payout earned											$ 0
Carrying amount of trade accounts receivable											7,200,000
Recorded fair value of acquisition											$ 6,000,000
Risk adjusted discount rate											3.50%
Acquisition holdback liability												19,900,000					19,900,000			19,900,000
Additional accrued cash payable to sellers												0	$ 18,800,000	800,000
Transaction Tax Resources, Inc. | Developed Technology
Business Acquisition [Line Items]
Weighted average amortization period for intangibles											4 years
Transaction Tax Resources, Inc. | Forecast | Revenue Growth Performance Metrics
Business Acquisition [Line Items]
Maximum payout earned																							$ 26,400,000	$ 26,400,000
Transaction Tax Resources, Inc. | Cash to be Paid Up to Three Years Following Acquisition
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition											$ 57,300,000
Business Licenses
Business Acquisition [Line Items]
Consideration in cash										$ 64,800,000										64,812,000		64,812,000
Maximum payout earned										20,700,000
Total consideration transferred										93,300,000										93,321,000		94,955,000
Acquisition holdbacks with a fair value upon acquisition								11,415,000		11,100,000		11,109,000			11,415,000		11,109,000		11,415,000	11,109,000		11,415,000
Goodwill								73,775,000		72,141,000					73,775,000				73,775,000			73,775,000
Developed technology, customer relationships, and other intangibles								19,525,000		$ 19,525,000					19,525,000				19,525,000			19,525,000
Weighted average amortization period for intangibles										5 years 3 months 18 days
Accrued value of earnout related to acquisition								18,728,000		$ 17,400,000		17,400,000			18,728,000		17,400,000		18,728,000	17,400,000		18,728,000
Earnout liability												$ 11,100,000					$ 11,100,000			11,100,000
Accrued earnout liabilities								11,400,000							11,400,000				11,400,000			11,400,000
Risk-free discount rate										0.13%
Minimum payout earned										$ 0
Business Licenses | Developed Technology
Business Acquisition [Line Items]
Developed technology, customer relationships, and other intangibles										$ 3,625,000
Weighted average amortization period for intangibles										3 years 1 month 6 days
Business Licenses | Operating Performance Metrics | Common Stock
Business Acquisition [Line Items]
Maximum payout earned										$ 20,700,000
Business Licenses | After Eighteen Months from Closing of Acquisition
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition										$ 11,100,000
Impendulo
Business Acquisition [Line Items]
Consideration in cash								11,713,000	$ 11,700,000											11,713,000
Total consideration transferred								13,597,000	14,000,000											$ 14,022,000
Goodwill								10,217,000	10,642,000						10,217,000				10,217,000			10,217,000
Developed technology, customer relationships, and other intangibles								$ 3,617,000	$ 3,617,000						$ 3,617,000				$ 3,617,000			$ 3,617,000
Weighted average amortization period for intangibles									5 years 10 months 24 days
Impendulo | Common Stock
Business Acquisition [Line Items]
Common stock consideration									$ 1,200,000
Impendulo | Final Revenue Metrics
Business Acquisition [Line Items]
Additional accrued cash payable to sellers														$ 1,100,000

Acquisitions of Businesses - Su

Acquisitions of Businesses - Summary of Reconciliation of Preliminary Total Consideration (Details) $ in Thousands, € in Millions	Jun. 30, 2021USD ($)	Apr. 20, 2021USD ($)	Apr. 01, 2021USD ($)	Apr. 01, 2021EUR (€)	Dec. 31, 2020USD ($)	Dec. 01, 2020USD ($)	Nov. 05, 2020USD ($)	Oct. 05, 2020USD ($)	Sep. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2021USD ($)	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)
Business Acquisition [Line Items]
Accrued value of earnout related to acquisition									$ 32,350				$ 32,350		$ 0
Inposia
Business Acquisition [Line Items]
Consideration in cash			$ 12,200						14,483		$ 2,400	$ 14,671
Fair value of common stock issued at closing									22,971			22,971
Total consideration			$ 37,400	€ 31.8					37,454			37,642
Inposia | Restatement Adjustment
Business Acquisition [Line Items]
Consideration in cash									(188)
Total consideration									(188)
Davo Technologies LLC
Business Acquisition [Line Items]
Consideration in cash	$ 23,818	$ 23,500							23,818	$ 300
Acquisition holdbacks with a fair value upon acquisition	2,600	2,600							2,591			2,600	2,591
Accrued value of earnout related to acquisition	28,620	30,500							30,547			$ 28,620	30,547
Total consideration	$ 55,038	$ 56,900							56,956
Davo Technologies LLC | Restatement Adjustment
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition									(9)				(9)
Accrued value of earnout related to acquisition									1,927				1,927
Total consideration									1,918
Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Consideration in cash					$ 294,017			$ 294,000					294,017
Acquisition holdbacks with a fair value upon acquisition					57,477			57,300	57,260		57,477		57,260	$ 57,477
Accrued value of earnout related to acquisition					15,740			18,900	18,871		15,740		18,871	15,740
Total consideration					367,234			$ 370,100					370,148
Transaction Tax Resources, Inc. | Restatement Adjustment
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition									(217)				(217)
Accrued value of earnout related to acquisition									3,131				3,131
Total consideration													2,914
Business Licenses
Business Acquisition [Line Items]
Consideration in cash							$ 64,800						64,812	64,812
Acquisition holdbacks with a fair value upon acquisition					11,415		11,100		11,109		11,415		11,109	11,415
Accrued value of earnout related to acquisition					18,728		17,400		17,400		$ 18,728		17,400	18,728
Total consideration							$ 93,300						93,321	$ 94,955
Business Licenses | Restatement Adjustment
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition									(306)				(306)
Accrued value of earnout related to acquisition									$ (1,328)				(1,328)
Total consideration													(1,634)
Impendulo
Business Acquisition [Line Items]
Consideration in cash					11,713	$ 11,700							11,713
Common stock paid at close					1,190								1,190
Cash payable accrual					694								1,119
Total consideration					$ 13,597	$ 14,000							14,022
Impendulo | Restatement Adjustment
Business Acquisition [Line Items]
Cash payable accrual													425
Total consideration													$ 425

Acquisitions of Businesses - Sc

Acquisitions of Businesses - Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Apr. 20, 2021	Apr. 01, 2021	Dec. 31, 2020	Dec. 01, 2020	Nov. 05, 2020	Oct. 05, 2020
Assets acquired:
Goodwill	$ 603,768				$ 513,234
Inposia
Assets acquired:
Goodwill				$ 26,200
Inposia | Fair Value
Assets acquired:
Cash and cash equivalents		$ 1,264		1,264
Trade accounts receivable		1,767		1,767
Other current assets		268		268
Operating lease right-of-use assets		928		928
Property and equipment		98		98
Developed technology, customer relationships, and other intangibles		12,684		14,504
Goodwill		27,702		26,216
Other noncurrent assets		35		35
Total assets acquired		44,746		45,080
Liabilities assumed:
Trade payables and accrued expenses		1,340		1,340
Deferred revenue		811		756
Other liabilities, noncurrent		106		106
Operating lease liabilities		928		928
Deferred tax liability		3,919		4,496
Total liabilities assumed		7,104		7,626
Net assets acquired		37,642		37,454
Inposia | Fair Value | Restatement Adjustment
Assets acquired:
Developed technology, customer relationships, and other intangibles				1,820
Goodwill				(1,486)
Total assets acquired				334
Liabilities assumed:
Deferred revenue				(55)
Deferred tax liability				577
Total liabilities assumed				522
Net assets acquired				$ (188)
Davo Technologies LLC
Assets acquired:
Goodwill			$ 49,900
Davo Technologies LLC | Fair Value
Assets acquired:
Cash and cash equivalents		198	198
Funds held from customers		12,464	12,464
Trade accounts receivable		119	119
Other current assets		58	58
Operating lease right-of-use assets		46	46
Developed technology, customer relationships, and other intangibles		6,427	6,841
Goodwill		48,426	49,931
Other noncurrent assets		2	1
Total assets acquired		67,740	69,658
Liabilities assumed:
Accrued expenses		117	117
Deferred revenue		75	75
Operating lease liabilities		46	46
Customer fund obligations		12,464	12,464
Total liabilities assumed		12,702	12,702
Net assets acquired		$ 55,038	56,956
Davo Technologies LLC | Fair Value | Restatement Adjustment
Assets acquired:
Developed technology, customer relationships, and other intangibles			414
Goodwill			1,505
Other noncurrent assets			(1)
Total assets acquired			1,918
Liabilities assumed:
Net assets acquired			$ 1,918
Transaction Tax Resources, Inc.
Assets acquired:
Goodwill								$ 335,600
Transaction Tax Resources, Inc. | Fair Value
Assets acquired:
Cash and cash equivalents					2,294			2,294
Trade accounts receivable					5,966			5,966
Other current assets					93			93
Operating lease right-of-use assets					1,760			1,760
Property and equipment					848			848
Developed technology, customer relationships, and other intangibles					49,000			41,500
Goodwill					327,039			335,565
Total assets acquired					387,000			388,026
Liabilities assumed:
Trade payables and accrued expenses					731			731
Deferred revenue					8,500			8,500
Operating lease liabilities					1,760			1,760
Deferred tax liability					8,775			6,887
Total liabilities assumed					19,766			17,878
Net assets acquired					367,234			370,148
Transaction Tax Resources, Inc. | Fair Value | Restatement Adjustment
Assets acquired:
Developed technology, customer relationships, and other intangibles								(7,500)
Goodwill								8,526
Total assets acquired								1,026
Liabilities assumed:
Deferred tax liability								(1,888)
Total liabilities assumed								(1,888)
Net assets acquired								$ 2,914
Business Licenses
Assets acquired:
Cash and cash equivalents					120		$ 120
Trade accounts receivable					1,326		1,326
Customer fund assets					1,074		1,074
Other current assets					101		101
Operating lease right-of-use assets					1,644		1,644
Property and equipment					87		87
Developed technology, customer relationships, and other intangibles					19,525		19,525
Goodwill					73,775		72,141
Other noncurrent assets					31		31
Total assets acquired					97,683		96,049
Liabilities assumed:
Accrued expenses					56		56
Operating lease liabilities					1,644		1,644
Customer fund obligations					1,028		1,028
Total liabilities assumed					2,728		2,728
Net assets acquired					94,955		93,321
Business Licenses | Restatement Adjustment
Assets acquired:
Goodwill							(1,634)
Total assets acquired							(1,634)
Liabilities assumed:
Net assets acquired							$ (1,634)
Impendulo
Assets acquired:
Cash and cash equivalents					1,347	$ 1,347
Trade accounts receivable					371	371
Other assets					147	147
Developed technology, customer relationships, and other intangibles					3,617	3,617
Goodwill					10,217	10,642
Total assets acquired					15,699	16,124
Liabilities assumed:
Trade payables and accrued expenses					663	663
Deferred revenue and contract liabilities					694	694
Deferred tax liability					745	745
Total liabilities assumed					2,102	2,102
Net assets acquired					$ 13,597	14,022
Impendulo | Restatement Adjustment
Assets acquired:
Goodwill						425
Total assets acquired						425
Liabilities assumed:
Net assets acquired						$ 425

Acquisitions of Businesses - _2

Acquisitions of Businesses - Summary of the Valuation Methodologies Significant Assumptions, and Estimated Useful Lives of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Apr. 20, 2021	Apr. 01, 2021	Dec. 01, 2020	Nov. 05, 2020	Oct. 05, 2020	Sep. 30, 2021	Dec. 31, 2020	Jun. 30, 2021
Inposia | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 14,504						$ 12,684
Inposia | Restatement Adjustment | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value		1,820
Davo Technologies LLC | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 6,841							6,427
Davo Technologies LLC | Restatement Adjustment | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value	414
Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 41,500		$ 49,000
Transaction Tax Resources, Inc. | Restatement Adjustment | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ (7,500)
Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value				$ 19,525			19,525
Impendulo
Business Acquisition [Line Items]
Intangible assets Assigned value			$ 3,617				$ 3,617
Customer Relationships | Minimum
Business Acquisition [Line Items]
Estimated Useful Life						3 years	3 years
Customer Relationships | Maximum
Business Acquisition [Line Items]
Estimated Useful Life						10 years	10 years
Customer Relationships | Inposia
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 3,523
Valuation Methodology		Multi-period excess earnings-income approach
Discount Rate		18.50%
Estimated Useful Life		8 years
Customer Relationships | Inposia | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 1,938
Customer Relationships | Inposia | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value								1,585
Customer Relationships | Davo Technologies LLC
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 4,300							4,350
Valuation Methodology	Multi-period excess earnings-income approach and replacement cost method-cost approach
Discount Rate	14.50%
Estimated Useful Life	8 years
Customer Relationships | Davo Technologies LLC | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value	$ (50)
Customer Relationships | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Valuation Methodology					Multi-period excess earnings-income approach
Discount Rate					18.00%
Estimated Useful Life					6 years
Customer Relationships | Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 21,000
Customer Relationships | Transaction Tax Resources, Inc. | Restatement Adjustment | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ (5,000)
Customer Relationships | Transaction Tax Resources, Inc. | Previously Reported | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value							$ 26,000
Customer Relationships | Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value				$ 15,000
Valuation Methodology				Multi-period excess earnings-income approach
Discount Rate				19.50%
Estimated Useful Life				6 years
Customer Relationships | Impendulo
Business Acquisition [Line Items]
Valuation Methodology			Multi-period excess earnings-income approach
Discount Rate			20.00%
Estimated Useful Life			6 years
Customer Relationships | Impendulo | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value			$ 2,964
Developed Technology | Minimum
Business Acquisition [Line Items]
Estimated Useful Life						3 years	3 years
Developed Technology | Maximum
Business Acquisition [Line Items]
Estimated Useful Life						8 years	8 years
Developed Technology | Inposia
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 9,572
Valuation Methodology		Relief from royalty-income approach
Discount Rate		18.50%
Estimated Useful Life		6 years
Developed Technology | Inposia | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value								9,572
Developed Technology | Davo Technologies LLC
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 1,900							1,800
Valuation Methodology	Relief from royalty-income approach
Discount Rate	14.50%
Estimated Useful Life	5 years
Developed Technology | Davo Technologies LLC | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 100
Developed Technology | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Valuation Methodology					Relief from royalty-income approach and replacement cost method-cost approach
Developed Technology | Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 9,600
Developed Technology | Transaction Tax Resources, Inc. | Minimum
Business Acquisition [Line Items]
Discount Rate					17.00%
Estimated Useful Life					3 years
Developed Technology | Transaction Tax Resources, Inc. | Maximum
Business Acquisition [Line Items]
Discount Rate					18.00%
Estimated Useful Life					6 years
Developed Technology | Transaction Tax Resources, Inc. | Previously Reported | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value							$ 9,600
Developed Technology | Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value				$ 3,625
Valuation Methodology				Relief from royalty-income approach and replacement cost method-cost approach
Discount Rate				19.50%
Developed Technology | Business Licenses | Minimum
Business Acquisition [Line Items]
Estimated Useful Life				1 year
Developed Technology | Business Licenses | Maximum
Business Acquisition [Line Items]
Estimated Useful Life				5 years
Developed Technology | Impendulo
Business Acquisition [Line Items]
Valuation Methodology			Relief from royalty-income approach
Discount Rate			20.00%
Estimated Useful Life			6 years
Developed Technology | Impendulo | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value			$ 616
Tradename and Trademarks | Minimum
Business Acquisition [Line Items]
Estimated Useful Life						1 year	1 year
Tradename and Trademarks | Maximum
Business Acquisition [Line Items]
Estimated Useful Life						4 years	4 years
Tradename and Trademarks | Inposia
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 235
Valuation Methodology		Relief from royalty-income approach
Discount Rate		18.50%
Estimated Useful Life		3 years
Tradename and Trademarks | Inposia | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value								235
Tradename and Trademarks | Davo Technologies LLC
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 86							86
Valuation Methodology	Relief from royalty-income approach
Discount Rate	14.50%
Estimated Useful Life	1 year
Tradename and Trademarks | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Valuation Methodology					Relief from royalty-income approach
Discount Rate					17.00%
Estimated Useful Life					2 years
Tradename and Trademarks | Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 5,800
Tradename and Trademarks | Transaction Tax Resources, Inc. | Previously Reported | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value							$ 5,800
Tradename and Trademarks | Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value				$ 400
Valuation Methodology				Relief from royalty-income approach
Discount Rate				19.50%
Estimated Useful Life				1 year
Tradename and Trademarks | Impendulo
Business Acquisition [Line Items]
Valuation Methodology			Relief from royalty-income approach
Discount Rate			20.00%
Estimated Useful Life			1 year
Tradename and Trademarks | Impendulo | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value			$ 37
Noncompete Agreements | Minimum
Business Acquisition [Line Items]
Estimated Useful Life						3 years	3 years
Noncompete Agreements | Maximum
Business Acquisition [Line Items]
Estimated Useful Life						5 years	5 years
Noncompete Agreements | Inposia
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 1,174
Valuation Methodology		With-and-without valuation-income approach
Discount Rate		21.00%
Estimated Useful Life		3 years
Noncompete Agreements | Inposia | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value		$ (118)
Noncompete Agreements | Inposia | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value								1,292
Noncompete Agreements | Davo Technologies LLC
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 555							$ 191
Valuation Methodology	With-and-without valuation-income approach
Discount Rate	16.50%
Estimated Useful Life	5 years
Noncompete Agreements | Davo Technologies LLC | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 364
Noncompete Agreements | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Valuation Methodology					With-and-without valuation-income approach
Discount Rate					19.00%
Estimated Useful Life					5 years
Noncompete Agreements | Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 1,800
Noncompete Agreements | Transaction Tax Resources, Inc. | Previously Reported | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value							$ 1,800
Noncompete Agreements | Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value				$ 500
Valuation Methodology				With-and-without valuation-income approach
Discount Rate				19.50%
Estimated Useful Life				5 years
ContractBacklogMember | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Valuation Methodology					Multi-period excess earnings-income approach
Discount Rate					17.00%
Estimated Useful Life					3 years
ContractBacklogMember | Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ 3,300
ContractBacklogMember | Transaction Tax Resources, Inc. | Restatement Adjustment | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value					$ (2,500)
ContractBacklogMember | Transaction Tax Resources, Inc. | Previously Reported | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value							$ 5,800

Acquisitions of Businesses - _3

Acquisitions of Businesses - Schedule of Pro Forma Financial Information (Unaudited) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition Pro Forma Information [Abstract]
Total revenue	$ 511,837	$ 362,729
Net loss	$ (92,837)	$ (41,664)

Revenue - Summary of Total Reve

Revenue - Summary of Total Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Revenues	$ 181,167	$ 127,879	$ 503,835	$ 355,809
U.S.
Disaggregation Of Revenue [Line Items]
Revenues	166,040	119,703	463,602	334,049
Non-U.S.
Disaggregation Of Revenue [Line Items]
Revenues	15,127	8,176	40,233	21,760
Subscription and Returns, Tax Calculations | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	91,539	65,312	251,301	185,986
Subscription and Returns, Tax Returns and Compliance Management | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	58,846	46,087	168,445	126,384
Interest Income on Funds Held from Customers | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	215	118	557	701
Subscription and Returns
Disaggregation Of Revenue [Line Items]
Revenues	164,237	119,193	455,997	333,258
Subscription and Returns | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	150,600	111,517	420,303	313,071
Professional Services
Disaggregation Of Revenue [Line Items]
Revenues	16,930	8,686	47,838	22,551
Professional Services | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	$ 15,440	$ 8,186	$ 43,299	$ 20,978

Revenue - Summary of Activity I

Revenue - Summary of Activity Impacting Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Contract Liabilities [Rollforward]
Balance beginning of period	$ 11,406	$ 6,195	$ 10,134	$ 5,197
Contract liabilities transferred to deferred revenue	(6,420)	(2,737)	(15,550)	(7,992)
Addition to contract liabilities	3,611	4,215	14,013	10,468
Balance end of period	$ 8,597	$ 7,673	$ 8,597	$ 7,673

Revenue - Summary of Activity_2

Revenue - Summary of Activity Impacting Deferred Revenue (Details) - Deferred Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Deferred Revenue Rollforward
Balance beginning of period	$ 239,395	$ 167,719	$ 209,690	$ 161,241
Revenue recognized	(181,167)	(127,879)	(503,835)	(355,809)
Additional amounts deferred	199,655	140,800	552,028	375,208
Balance end of period	$ 257,883	$ 180,640	$ 257,883	$ 180,640

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred commissions amortization expected period	6 years
Deferred contract costs, expected to be amortized within next 12 Months	$ 15,735,000		$ 12,245,000
Impairments of deferred contract costs	0	$ 0
Assets recognized related to costs to fulfill contracts	0	$ 0
Remaining performance obligations	344,800,000
Non-cancellable Amount Not Yet Invoiced
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligations	87,000,000
Current Liabilities
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue expected to be recognized within next 12 months	256,200,000
Prepaid and Other Current Assets
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred contract costs, expected to be amortized within next 12 Months	$ 15,700,000

Revenue - Summary of Activity_3

Revenue - Summary of Activity Impacting Deferred Commissions (Details) - Deferred Commissions - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Capitalized Contract Cost [Line Items]
Balance beginning of period	$ 60,643	$ 43,356	$ 50,870	$ 38,416
Additional commissions deferred	6,997	5,406	23,599	15,818
Amortization of deferred commissions	(4,009)	(2,921)	(10,838)	(8,393)
Balance end of period	$ 63,631	$ 45,841	$ 63,631	$ 45,841

Revenue - Additional Informat_2

Revenue - Additional Information (Details 1) $ in Millions	Sep. 30, 2021USD ($)
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligations	$ 344.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-10-01
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligations	$ 322.1
Revenue expected to be recognized with remaining amount	12 months
Non-cancellable Amount Not Yet Invoiced
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligations	$ 87
Non-cancellable Amount Not Yet Invoiced | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-10-01
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligations	$ 66
Revenue expected to be recognized with remaining amount	12 months

Intangible Assets - Schedule of

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross	$ 150,784	$ 131,987
Accumulated Amortization	(62,367)	(45,474)
Net	$ 88,417	$ 86,513
Backlog
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	3 years	3 years
Gross	$ 3,300	$ 5,800
Accumulated Amortization	(1,288)	(937)
Net	2,012	4,863
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross	68,506	64,302
Accumulated Amortization	(21,279)	(14,890)
Net	$ 47,227	$ 49,412
Customer Relationships | Minimum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	3 years	3 years
Customer Relationships | Maximum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	10 years	10 years
Developed Technology
Finite Lived Intangible Assets [Line Items]
Gross	$ 66,882	$ 52,144
Accumulated Amortization	(34,568)	(27,646)
Net	$ 32,314	$ 24,498
Developed Technology | Minimum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	3 years	3 years
Developed Technology | Maximum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	8 years	8 years
Noncompete Agreements
Finite Lived Intangible Assets [Line Items]
Gross	$ 5,073	$ 3,062
Accumulated Amortization	(1,404)	(766)
Net	$ 3,669	$ 2,296
Noncompete Agreements | Minimum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	3 years	3 years
Noncompete Agreements | Maximum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	5 years	5 years
Tradename and Trademarks
Finite Lived Intangible Assets [Line Items]
Gross	$ 7,023	$ 6,679
Accumulated Amortization	(3,828)	(1,235)
Net	$ 3,195	$ 5,444
Tradename and Trademarks | Minimum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	1 year	1 year
Tradename and Trademarks | Maximum
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	4 years	4 years

Intangible Assets - Schedule _2

Intangible Assets - Schedule of Intangible Assets (Parenthetical) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
IPR&D
Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, net	$ 0.4	$ 0.6

Intangible Assets - Additional

Intangible Assets - Additional Information (Details)	Oct. 31, 2018USD ($)	May 31, 2018USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)Unit	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization expense			$ 6,300,000	$ 1,500,000	$ 17,000,000	$ 4,900,000
Earnout liability			29,456,000		$ 29,456,000		$ 749,000
Number of goodwill impairment reporting units | Unit					3
Goodwill impairment charge	$ 0		0		$ 0		0
Goodwill			603,768,000		603,768,000		$ 513,234,000
Brazilian Reporting Unit
Finite Lived Intangible Assets [Line Items]
Goodwill			0		0
Accrued Expenses
Finite Lived Intangible Assets [Line Items]
Earnout liability			$ 300,000		300,000
Tradestream Technologies Inc. and Wise 24 Inc
Finite Lived Intangible Assets [Line Items]
Future revenue recognized period		6 years
Earnout provision					$ 1,900,000
Tradestream Technologies Inc. and Wise 24 Inc | Maximum
Finite Lived Intangible Assets [Line Items]
Total consideration		$ 30,000,000

Intangible Assets - Schedule _3

Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Goodwill [Line Items]
Balance—December 31, 2020	$ 513,234
Cumulative translation adjustments	(1,220)
Balance—September 30, 2021	603,768
2020 Acquisition
Goodwill [Line Items]
Measurement period adjustment, goodwill acquired during period	7,317
Davo
Goodwill [Line Items]
Acquisition	49,931
3CE Technologies, Inc.
Goodwill [Line Items]
Acquisition	8,290
Inposia
Goodwill [Line Items]
Acquisition	$ 26,216

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Total lease cost, net of sublease income	$ 4.1	$ 4.1	$ 12.4	$ 11.8
Sublease income	$ 0.4	$ 0.4	1.2	$ 1.1
Increase in operating lease right-of-use assets			$ 1.8

Debt - Additional Information (

Debt - Additional Information (Details) - 2026 Notes - USD ($)	1 Months Ended	9 Months Ended
	Aug. 31, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Principal amount	$ 977,500,000	$ 977,500,000
Description of interest rate		The 2026 Notes are unsecured obligations and bear interest at a fixed rate of 0.25% per annum, payable semi-annually in arrears on February 1 and August 1 of each year, commencing on February 1, 2022.
Fixed interest rate	0.25%
Debt instrument, description of maturity date		The 2026 Notes will mature on August 1, 2026, unless earlier converted, redeemed or repurchased.
Debt instrument, maturity date	Aug. 1, 2026
Debt issuance costs	$ 17,600,000
Proceeds from offering, net of debt issuance costs	959,900,000
Net proceeds from sale	$ 75,300,000
Redemption description		The Company may not redeem the 2026 Notes prior to August 6, 2024. The Company may redeem all or any portion of the 2026 Notes, at the Company’s option, on or after August 6, 2024, through the 41st scheduled trading day immediately prior to the maturity date, if the common stock price is at least 130% of the conversion price then in effect for at least 20 of any 30 consecutive trading day period. The Company may redeem all or part of the 2026 Notes at a redemption price equal to the principal amount plus accrued and unpaid interest to, but excluding, the redemption date, with not less than 50 nor more than 60 scheduled trading days’ notice to holders.
Percentage of common stock price to conversion price		130.00%
Debt conversion, description		The 2026 Notes are convertible at an initial conversion rate of 4.1940 shares of common stock per $1,000 principal amount of 2026 Notes, which is equivalent to an initial conversion price of approximately $238.44 per share of common stock. The conversion rate is subject to customary adjustments for certain events as described in the indenture governing the 2026 Notes.
Debt conversion, shares of common stock		4.1940
Principal amount		$ 1,000
Initial conversion price		$ 238.44
Percentage of trading price per $1000 notes to product of closing sale price of common stock and current conversion rate		98.00%
Effective interest rate		0.60%
Capped Call Transactions
Debt Instrument [Line Items]
Initial strike price		$ 238.44
Initial cap price		$ 323.30
Aggregate amount for capped calls		$ 75,300,000
Shares of common stock covered		4,100,000
Minimum
Debt Instrument [Line Items]
Consecutive trading day period		20 days
Scheduled trading days		50 days
Maximum
Debt Instrument [Line Items]
Consecutive trading day period		30 days
Scheduled trading days		60 days

Debt - Summary of Net Carrying

Debt - Summary of Net Carrying Amount of Notes (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Aug. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Net carrying amount	$ 960,373		$ 0
2026 Notes
Debt Instrument [Line Items]
Principal	977,500	$ 977,500
Unamortized debt issuance costs	(17,127)
Net carrying amount	$ 960,373

Debt - Summary of Interest Expe

Debt - Summary of Interest Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Amortization of debt issuance costs		$ 482	$ 0
2026 Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 333	333
Amortization of debt issuance costs	482	482
Total interest expense related to 2026 Notes	$ 815	$ 815

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021Class$ / sharesshares	Dec. 31, 2020$ / sharesshares
Equity [Abstract]
Number of classes of stock | Class	2
Capital stock, authorized shares	620,000,000
Common stock, shares authorized	600,000,000	600,000,000
Common stock, par value | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, par value | $ / shares	$ 0.0001	$ 0.0001

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Changes of Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Class Of Stock [Line Items]
Beginning balance	$ 1,105,349	$ 1,081,446	$ 1,080,160	$ 500,202	$ 476,294	$ 463,722	$ 1,080,160	$ 463,722
Proceeds from common stock offering, net of underwriting discounts				556,312
Public offering costs				(701)
Exercise of stock options	7,950	4,668	5,529	5,294	17,495	7,928
Exercise of stock options, Shares							1,038,613
Stock-based compensation cost	23,777	23,592	19,047	12,916	12,368	9,749
Shares issued under employee stock purchase plan	7,358		7,088	5,621		5,716
Purchase of capped calls	(75,268)
Shares issued related to business combination earnouts		22,971			3,750	3,750
Shares issued to purchase intangible assets						87
Gain (Loss) on translation adjustment	(1,172)	322	(390)	(225)	435	625	$ (1,240)	835
Net loss	(32,546)	(27,650)	(29,988)	(12,729)	(10,140)	(15,283)	(90,184)	(38,152)
Ending balance	1,035,448	1,105,349	1,081,446	1,066,690	500,202	476,294	1,035,448	1,066,690
Common Stock
Class Of Stock [Line Items]
Beginning balance	$ 9	$ 9	$ 9	$ 8	$ 8	$ 8	$ 9	$ 8
Beginning balance, Shares	86,253,407	85,760,025	85,057,727	79,514,983	78,294,687	77,447,620	85,057,727	77,447,620
Proceeds from common stock offering, net of underwriting discounts, shares				4,527,558
Exercise of stock options, Shares	488,992	253,395	296,226	333,977	1,117,805	532,848
Vesting of restricted stock units	43,374	75,571	346,008	19,178	57,832	186,475
Shares issued under employee stock purchase plan, Shares	56,817		60,064	75,811		81,894
Shares issued related to business combination earnouts, Shares		164,416			44,659	44,659
Shares issued to purchase intangible assets, Shares						1,191
Shares issued for acquisitions of businesses, Shares		164,416			44,659	44,659
Ending balance	$ 9	$ 9	$ 9	$ 8	$ 8	$ 8	$ 9	$ 8
Ending balance, Shares	86,842,590	86,253,407	85,760,025	84,471,507	79,514,983	78,294,687	86,842,590	84,471,507
Additional Paid-In Capital
Class Of Stock [Line Items]
Beginning balance	$ 1,723,762	$ 1,672,531	$ 1,640,867	$ 1,037,470	$ 1,003,857	$ 976,627	$ 1,640,867	$ 976,627
Proceeds from common stock offering, net of underwriting discounts				556,312
Public offering costs				(701)
Exercise of stock options	7,950	4,668	5,529	5,294	17,495	7,928
Stock-based compensation cost	23,777	23,592	19,047	12,916	12,368	9,749
Shares issued under employee stock purchase plan	7,358		7,088	5,621		5,716
Purchase of capped calls	(75,268)
Shares issued related to business combination earnouts		22,971			3,750	3,750
Shares issued to purchase intangible assets						87
Ending balance	1,687,579	1,723,762	1,672,531	1,616,912	1,037,470	1,003,857	1,687,579	1,616,912
Accumulated Other Comprehensive Income (Loss)
Class Of Stock [Line Items]
Beginning balance	(1,407)	(1,729)	(1,339)	(1,659)	(2,094)	(2,719)	(1,339)	(2,719)
Gain (Loss) on translation adjustment	(1,172)	322	(390)	(225)	435	625
Ending balance	(2,579)	(1,407)	(1,729)	(1,884)	(1,659)	(2,094)	(2,579)	(1,884)
Accumulated Deficit
Class Of Stock [Line Items]
Beginning balance	(617,015)	(589,365)	(559,377)	(535,617)	(525,477)	(510,194)	(559,377)	(510,194)
Net loss	(32,546)	(27,650)	(29,988)	(12,729)	(10,140)	(15,283)
Ending balance	$ (649,561)	$ (617,015)	$ (589,365)	$ (548,346)	$ (535,617)	$ (525,477)	$ (649,561)	$ (548,346)

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	2,473,876		2,473,876		3,537,014
Total intrinsic value of options exercised			$ 148.4	$ 168.3
Options granted			0
Weighted average grant date fair value of options granted				$ 32.87
Number of shares, vested			1,080,356
Number of options unvested	732,189		732,189
Contractual life			10 years
Expected term		6 years
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term				5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term				6 years
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, average vesting term			4 years
Expected term			6 years
Non Employee Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, average vesting term			1 year
Expected term			5 years
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation expense related to stock options	$ 14.3		$ 14.3
Unrecognized compensation expense expected to be recognized over weighted average period			1 year 9 months 18 days
Stock Options | Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period			4 years
Stock Options | Non Employee Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period			1 year
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense expected to be recognized over weighted average period			2 years 10 months 24 days
Total unrecognized compensation expense expected to be recognized	231.6		$ 231.6
Restricted Stock Units (RSUs) | Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period			4 years
Restricted Stock Units (RSUs) | Non Employee Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period			1 year
Performance Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense expected to be recognized over weighted average period			2 years
Stock options vesting period			3 years
Total unrecognized compensation expense expected to be recognized	$ 25.6		$ 25.6
Vesting term, description			Each PSU grant will vest in annual tranches over a three-year service period. Total units earned for grants made in 2021 may vary between 0% and 250% of the units granted based on the attainment of company-specific performance targets during the related three-year period and continued service.
Service period			3 years
Performance Share Units (PSUs) | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage			0.00%
Performance Share Units (PSUs) | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage			250.00%
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	4,035,218		4,035,218
Shares available for future issuance	12,158,970		12,158,970
2006 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	1,348,505		1,348,505
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares purchased			116,881
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation expense related to stock options	$ 1.6		$ 1.6
Expected term	6 months	6 months	6 months	6 months

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Stock-Based Compensation Expense Related to Equity Incentive Rewards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	$ 23,777	$ 12,916	$ 66,416	$ 35,033
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	2,913	3,749	9,210	11,757
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	14,993	8,052	41,618	20,472
Performance Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	4,683	0	12,148	0
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	$ 1,188	$ 1,115	$ 3,440	$ 2,804

Equity Incentive Plans - Summ_2

Equity Incentive Plans - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Shares
Options outstanding beginning balance	3,537,014
Options granted	0
Options exercised	(1,038,613)
Options cancelled or expired	(24,525)
Options outstanding ending balance	2,473,876	3,537,014
Options exercisable	1,741,687
Weighted Average Exercise Price
Options outstanding beginning balance | $ / shares	$ 28.17
Options exercised | $ / shares	17.47
Options cancelled or expired | $ / shares	16.65
Options outstanding ending balance | $ / shares	32.78	$ 28.17
Options exercisable | $ / shares	$ 26.18
Weighted Average Remaining Contractual Life (in Years)
Options outstanding	6 years 5 months 12 days	6 years 10 months 20 days
Options exercisable	6 years 25 days
Aggregate Intrinsic Value
Options outstanding | $	$ 351,272	$ 483,577
Options exercisable | $	$ 258,789

Equity Incentive Plans - Summ_3

Equity Incentive Plans - Summary of Options Outstanding and Vested (Details)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Option Outstanding, Number Outstanding	2,473,876
Options Vested and Exercisable, Number Vested and Exercisable	1,741,687
Options Vested and Exercisable, Weighted Average Life (in Years)	6 years 25 days
$1.90 to $6.40
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 1.90
Exercise Prices, High | $ / shares	$ 6.40
Option Outstanding, Number Outstanding	23,065
Options Outstanding, Weighted Average Life (in Years)	1 year 3 months 18 days
Options Vested and Exercisable, Number Vested and Exercisable	23,065
Options Vested and Exercisable, Weighted Average Life (in Years)	1 year 3 months 18 days
$8.04 to $11.72
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 8.04
Exercise Prices, High | $ / shares	$ 11.72
Option Outstanding, Number Outstanding	79,506
Options Outstanding, Weighted Average Life (in Years)	2 years 6 months
Options Vested and Exercisable, Number Vested and Exercisable	79,506
Options Vested and Exercisable, Weighted Average Life (in Years)	2 years 6 months
$12.20 to $15.06
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 12.20
Exercise Prices, High | $ / shares	$ 15.06
Option Outstanding, Number Outstanding	491,764
Options Outstanding, Weighted Average Life (in Years)	5 years
Options Vested and Exercisable, Number Vested and Exercisable	491,764
Options Vested and Exercisable, Weighted Average Life (in Years)	5 years
$16.06 to $24.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 16.06
Exercise Prices, High | $ / shares	$ 24
Option Outstanding, Number Outstanding	754,170
Options Outstanding, Weighted Average Life (in Years)	6 years 3 months 18 days
Options Vested and Exercisable, Number Vested and Exercisable	578,159
Options Vested and Exercisable, Weighted Average Life (in Years)	6 years 3 months 18 days
$31.99 to $42.21
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 31.99
Exercise Prices, High | $ / shares	$ 42.21
Option Outstanding, Number Outstanding	658,855
Options Outstanding, Weighted Average Life (in Years)	7 years 2 months 12 days
Options Vested and Exercisable, Number Vested and Exercisable	392,185
Options Vested and Exercisable, Weighted Average Life (in Years)	7 years 2 months 12 days
$55.10 to $99.65
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 55.10
Exercise Prices, High | $ / shares	$ 99.65
Option Outstanding, Number Outstanding	424,361
Options Outstanding, Weighted Average Life (in Years)	8 years
Options Vested and Exercisable, Number Vested and Exercisable	167,684
Options Vested and Exercisable, Weighted Average Life (in Years)	7 years 9 months 18 days
$124.35 to $151.76
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 124.35
Exercise Prices, High | $ / shares	$ 151.76
Option Outstanding, Number Outstanding	42,155
Options Outstanding, Weighted Average Life (in Years)	6 years 7 months 6 days
Options Vested and Exercisable, Number Vested and Exercisable	9,324
Options Vested and Exercisable, Weighted Average Life (in Years)	5 years 10 months 24 days

Equity Incentive Plans - Summ_4

Equity Incentive Plans - Summary of Fair Value Estimated Using Black-Scholes Option Pricing Model Assumptions (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility		43.00%		43.00%
Expected term		6 years
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate, minimum		0.44%		0.33%
Risk-free interest rate, maximum		0.51%		1.25%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		$ 124.35		$ 66.26
Expected term				5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		$ 130.82		$ 130.82
Expected term				6 years

Equity Incentive Plans - Summ_5

Equity Incentive Plans - Summary of RSU Activity (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs/PSUs outstanding as of January 1, 2021, Shares | shares	2,359,063
RSUs/PSUs granted, Shares | shares	1,068,582
RSUs/PSUs vested, Shares | shares	(464,953)
RSUs/PSUs cancelled, Shares | shares	(173,477)
RSUs/PSUs outstanding as of September 30, 2021, Shares | shares	2,789,215
RSUs/PSUs outstanding as of January 1, 2021, Weighted average grant date fair value per share | $ / shares	$ 70.17
RSUs/PSUs granted, Weighted average grant date fair value per share | $ / shares	136.76
RSUs/PSUs vested, Weighted average grant date fair value per share | $ / shares	65.29
RSUs/PSUs cancelled, Weighted average grant date fair value per share | $ / shares	81.12
RSUs/PSUs outstanding as of September 30, 2021, Weighted average grant date fair value per share | $ / shares	$ 95.81

Equity Incentive Plans - Summ_6

Equity Incentive Plans - Summary of PSU Activity (Details) - Performance Share Units (PSUs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs/PSUs granted, Shares | shares	120,632
RSUs/PSUs outstanding as of September 30, 2021, Shares | shares	120,632
RSUs/PSUs granted, Weighted average grant date fair value per share | $ / shares	$ 147.39
RSUs/PSUs outstanding as of September 30, 2021, Weighted average grant date fair value per share | $ / shares	$ 147.39

Equity Incentive Plans - Summ_7

Equity Incentive Plans - Summary of Fair Value of ESPP Purchase Rights Was Estimated Using Black-Scholes Option-pricing Model Assumptions (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility		43.00%		43.00%
Expected term		6 years
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate, minimum		0.44%		0.33%
Risk-free interest rate, maximum		0.51%		1.25%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		$ 124.35		$ 66.26
Expected term				5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		130.82		$ 130.82
Expected term				6 years
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock	$ 166.84	$ 138.83
Volatility	31.00%	49.00%
Expected term	6 months	6 months	6 months	6 months
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.06%	0.11%
Risk-free interest rate, minimum			0.06%	0.11%
Risk-free interest rate, maximum			0.08%	1.54%
2018 Employee Stock Purchase Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock			$ 152.35	$ 87.23
Volatility			31.00%	32.00%
2018 Employee Stock Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock			$ 166.84	$ 138.83
Volatility			34.00%	49.00%

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Shareholders - Schedule of Computation of Basic and Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss attributable to common shareholders	$ (32,546)	$ (27,650)	$ (29,988)	$ (12,729)	$ (10,140)	$ (15,283)	$ (90,184)	$ (38,152)
Denominator:
Weighted-average common shares outstanding-basic	86,530			82,288			86,023	79,715
Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, ESPP shares, and convertible senior notes (if converted)	0			0			0	0
Weighted-average common shares outstanding-diluted	86,530			82,288			86,023	79,715
Net loss per common share, basic and diluted	$ (0.38)			$ (0.15)			$ (1.05)	$ (0.48)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Shareholders - Schedule of Potential Shares Not Included in the Computation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	7,807	6,501	6,517	6,949
Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	2,750	4,229	3,085	4,938
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	2,748	2,267	2,586	2,009
Unvested Performance Share Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	121	0	106	0
ESPP Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	4	5	4	2
Convertible Senior Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	2,184	0	736	0

Subsequent Events - Additional

Subsequent Events - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021
Track1099 LLC
Subsequent Event [Line Items]
Date of acquisition	Oct. 1, 2021
CrowdReason LLC and CorrelationAdvisors
Subsequent Event [Line Items]
Date of acquisition	Oct. 18, 2021