Avalara (AVLR) 10-Q 7 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
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		85,969,467
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	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 638,794	$ 673,593
Restricted cash	31,083	19,953
Trade accounts receivable—net of allowance for doubtful accounts of $4,925 and $3,983, respectively	90,126	75,857
Deferred commissions	12,957	12,245
Prepaid expenses and other current assets	29,580	20,098
Total current assets before customer fund assets	802,540	801,746
Funds held from customers	33,633	30,598
Receivable from customers—net of allowance of $749 and $593, respectively	888	563
Total current assets	837,061	832,907
Noncurrent assets:
Restricted cash	37,803	37,700
Deferred commissions	40,273	38,625
Operating lease right-of-use assets—net	50,145	52,320
Property and equipment—net	36,347	34,713
Intangible assets—net	74,679	86,513
Goodwill	520,120	513,234
Other noncurrent assets	5,434	6,321
Total assets	1,601,862	1,602,333
Current liabilities:
Trade payables	18,361	20,280
Accrued expenses	69,151	84,532
Deferred revenue	223,961	208,026
Accrued purchase price related to acquisitions	18,836	22,473
Accrued earnout liabilities	12,503	749
Operating lease liabilities	11,505	11,339
Total current liabilities before customer fund obligations	354,317	347,399
Customer fund obligations	35,147	31,549
Total current liabilities	389,464	378,948
Noncurrent liabilities:
Deferred revenue	1,570	1,664
Accrued purchase price related to acquisitions	48,766	49,057
Accrued earnout liabilities	25,400	34,468
Operating lease liabilities	53,503	56,625
Deferred tax liability	1,171	1,031
Other noncurrent liabilities	542	380
Total liabilities	520,416	522,173
Commitments and contingencies	0	0
Shareholders' equity:
Common stock, $0.0001 par value – 85,760 and 85,058 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively, and 600,000 shares authorized as of March 31, 2021 and December 31, 2020	9	9
Additional paid-in capital	1,672,531	1,640,867
Accumulated other comprehensive loss	(1,729)	(1,339)
Accumulated deficit	(589,365)	(559,377)
Total shareholders’ equity	1,081,446	1,080,160
Total liabilities and shareholders' equity	$ 1,601,862	$ 1,602,333

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowance for doubtful accounts	$ 4,925	$ 3,983
Receivable from customers, allowance	$ 749	$ 593
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares, issued	85,760,000	85,058,000
Common stock, shares, outstanding	85,760,000	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
	Mar. 31, 2021	Mar. 31, 2020
Revenue:
Revenues	$ 153,601	$ 111,443
Cost of revenue:
Cost of revenues	44,671	34,254
Gross profit	108,930	77,189
Operating expenses:
Research and development	39,156	25,847
Sales and marketing	64,304	49,634
General and administrative	30,851	21,388
Total operating expenses	134,311	96,869
Operating loss	(25,381)	(19,680)
Other (income) expense:
Interest income	(24)	(1,442)
Other (income) expense, net	2,274	(3,372)
Total other (income) expense, net	2,250	(4,814)
Loss before income taxes	(27,631)	(14,866)
Provision for income taxes	2,357	417
Net loss	$ (29,988)	$ (15,283)
Net loss per share attributable to common shareholders, basic and diluted	$ (0.35)	$ (0.20)
Weighted average shares of common stock outstanding, basic and diluted	85,436	77,904
Subscription and Returns
Revenue:
Revenues	$ 139,318	$ 105,546
Cost of revenue:
Cost of revenues	38,163	29,517
Professional Services
Revenue:
Revenues	14,283	5,897
Cost of revenue:
Cost of revenues	$ 6,508	$ 4,737

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (29,988)	$ (15,283)
Other comprehensive income (loss) — Foreign currency translation	(390)	625
Total comprehensive loss	$ (30,378)	$ (14,658)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (29,988)	$ (15,283)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	18,777	9,731
Depreciation and amortization	7,071	4,091
Impairment of capitalized cloud computing costs	345	0
Deferred income tax expense	2,028	62
Non-cash operating lease costs	2,175	1,956
Non-cash change in earnout liabilities	1,350	(2,509)
Non-cash bad debt expense	582	631
Other	(389)	(10)
Changes in operating assets and liabilities:
Trade accounts receivable	(14,695)	(2,750)
Prepaid expenses and other current assets	(9,186)	(4,745)
Deferred commissions	(2,360)	(2,250)
Other noncurrent assets	541	(384)
Trade payables	(1,895)	3,659
Accrued expenses	(15,634)	(18,568)
Deferred revenue	15,841	4,128
Operating lease liabilities	(2,810)	(2,230)
Net cash used in operating activities	(28,247)	(24,471)
Cash flows from investing activities:
Purchase of property and equipment	(1,366)	(883)
Capitalized software development costs	(2,311)	(717)
Cash paid for acquisitions of businesses, net of cash and restricted cash equivalents acquired	(2,167)	0
Net cash used in investing activities	(5,844)	(1,600)
Cash flows from financing activities:
Proceeds from exercise of stock options	5,529	7,928
Proceeds from purchases of stock under employee stock purchase plan	7,088	5,716
Acquisition-related post-closing payments	(1,971)	0
Payments related to business combination earnouts	0	(3,760)
Payments related to asset acquisition earnouts	(690)	(65)
Net increase in customer fund obligations	3,598	3,915
Net cash provided by financing activities	13,554	13,734
Foreign currency effect	6	(365)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	(20,531)	(12,702)
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	741,313	478,631
Reconciliation of cash, cash equivalents, restricted cash, and restricted cash equivalents to the Consolidated Balance Sheets, end of period:
Cash and cash equivalents	638,794	450,535
Restricted cash	68,886	0
Restricted cash equivalents—funds held from customers	33,633	28,096
Supplemental cash flow disclosures:
Cash paid for interest expense	0	0
Cash paid for operating lease liabilities	3,493	3,108
Cash paid for income taxes	153	320
Non-cash investing and financing activities:
Stock issued related to business combinations	0	3,750
Accrued value of earnout related to acquisitions of businesses	(1,802)	0
Accrued purchase of intangible assets	178	0
Property and equipment additions in accounts payable and accrued expenses	1,263	743
Fair value of common stock issued to purchase intangible assets	0	87
Operating lease right-of-use assets in exchange for lease obligations	43	6,562
Stock-based compensation costs capitalized to internally developed software	$ 225	$ 36

Nature of Operations

Nature of Operations	3 Months Ended
	Mar. 31, 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 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, and communications tax. These solutions enable customers to automate the process of determining taxability, identifying applicable tax rates, determining and collecting taxes, preparing and filing returns, remitting taxes, maintaining tax records, and managing compliance documents. The Company, a Washington corporation, was originally incorporated in 1999 and is headquartered in Seattle, Washington. 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	3 Months Ended
	Mar. 31, 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 March 31, 2021, and the consolidated interim statements of operations, consolidated statement of cash flows, and consolidated statements of comprehensive loss for the three months ended March 31, 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 months ended March 31, 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 three months ended March 31, 2020 are reported as restricted cash equivalents in the consolidated statement of cash flows. The correction resulted in a change of $0.2 million to net cash used in operating activities and a change of $3.9 million to net cash used in investing activities for the three months ended March 31, 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 Three Months Ended March 31, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash used in operating activities: Other $ 192 $ (202 ) $ (10 ) Net cash used in operating activities (24,269 ) (202 ) (24,471 ) Cash flows from investing activities: Net (increase) decrease in customer fund assets (3,915 ) 3,915 — Net cash used in investing activities (5,515 ) 3,915 (1,600 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents (16,415 ) 3,713 (12,702 ) 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 $ 450,535 $ 28,096 $ 478,631 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. 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 award grants; 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. 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 months ended March 31, 2021 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 expenses from increases in the fair value of earnout liabilities related to business combinations of $1.4 million and income from decreases in the fair value of $2.5 million for the three months ended March 31, 2021 and 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 three months ended March 31, 2021 or 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”), 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 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 for 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. New Accounting Standards Not Yet Adopted There are no new accounting standards that have not yet been adopted.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements 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 March 31, 2021 Value (Level 1) (Level 2) (Level 3) Money market funds $ 578,158 $ 578,158 $ — $ — Earnouts related to business combinations 37,653 — — 37,653 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 2020 acquisition of TTR is based on the achievement of specific revenue growth thresholds through December 2022. As of March 31, 2021, the earnout liability associated with the acquisition of TTR was valued utilizing a discount rate of 12%. 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 and asset 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 March 31, 2021, the earnout liability associated with the acquisition of Business Licenses was valued utilizing a discount rate of 5% 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. Additional information regarding payments of earnout liabilities that occurred during the three months ended March 31, 2021 is included in Note 5. 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): Three Months Ended March 31, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 34,501 $ 13,808 Measurement period adjustment 1,802 — Payments of earnout liabilities — (7,700 ) Total unrealized loss (gain) included in other (income) expense, net 1,350 (2,509 ) Balance end of period $ 37,653 $ 3,599 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 fair value measurements of these assets during the first quarter of 2021, except as discussed in Note 5.

Balance Sheet Detail

Balance Sheet Detail	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Detail	4 . Balance Sheet Detail Property and equipment, net consisted of the following (in thousands): Useful March 31, December 31, Life (Years) 2021 2020 Computer equipment and software 3 to 5 $ 17,106 $ 15,749 Internally developed software 3 to 6 12,978 10,438 Furniture and fixtures 5 6,686 6,651 Office equipment 3 to 5 1,052 1,006 Leasehold improvements 1 to 10 30,069 29,928 67,891 63,772 Accumulated depreciation (31,544 ) (29,059 ) Property and equipment—net $ 36,347 $ 34,713 Depreciation expense was $2.6 million for the three months ended March 31, 2021 Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, 2021 2020 Prepaid expenses $ 24,528 $ 13,968 Deposits 2,801 2,557 Other 2,251 3,573 Total $ 29,580 $ 20,098 Accrued expenses consisted of the following (in thousands): March 31, December 31, 2021 2020 Accrued payroll and related taxes $ 13,539 $ 7,903 Accrued federal, state, local, and foreign taxes 4,919 4,338 Accrued bonus 9,577 29,518 Self-insurance reserves 1,633 1,563 Employee stock purchase plan contributions 3,617 5,927 Accrued sales commissions 3,189 5,563 Accrued partner commissions 9,010 9,173 Contract liabilities 12,466 10,134 Other 11,201 10,413 Total $ 69,151 $ 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	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Acquisitions of Businesses	5. Acquisitions of Businesses Announced Acquisition of Davo On April 20, 2021, the Company acquired substantially all the assets of Davo Technologies LLC, a Delaware limited liability company (“Davo”) under an asset purchase agreement for aggregate cash consideration of $26.2 million. Approximately $2.6 million of the purchase price will be paid to Davo shareholders over the next 18 months, subject to reduction for certain indemnifications and other potential obligations of Davo shareholders. Additional purchase price will be paid to Davo’s shareholders following the achievement of certain performance metrics during the 2021 and 2022 fiscal years. Davo helps emerging small businesses automate the daily and ongoing requirements for sales tax. In the first quarter of 2021, the Company paid Davo shareholders a $0.3 million deposit, which is recorded in prepaid and other current assets on the consolidated balance sheet as of March 31, 2021. The Company will account for the Davo acquisition as a business combination. Announced Acquisition of Inposia On April 1, 2021, the Company acquired the outstanding equity of Inposia Solutions, GmbH (“Inposia”) under a Share Purchase Agreement for aggregate cash and share consideration of €30 million (or approximately $35.2 million using the exchange rate on April 1, 2021), subject to certain purchase price adjustments. Approximately €4.5 million (or approximately $5.3 million using the exchange rate on April 1, 2021) of the consideration shares will be paid to the shareholders over the next 18 months, subject to reduction for certain indemnification and other potential obligations of the Inposia shareholders. 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. In the fourth quarter of 2020, the Company paid Inposia shareholders a $2.4 million deposit, which is recorded in prepaid and other current assets in the consolidated balance sheets as of March 31, 2021 and December 31, 2020 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 million and is based on the achievement of certain TTR revenue growth performance metrics during the 2021 and 2022 fiscal years. The potential amount of all future payments that could be required under the earnout is between $0 and $ 26.4 million. The earnout was recognized at fair value at the date of the business combination and 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 values for customer relationships, contract backlog, and earnout liability, and a net working capital adjustment. Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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 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 $18.9 million and $19.9 million included in current portion as of March 31, 2021 and December 31, 2020, respectively, and $37.7 million included in noncurrent portion on the consolidated balance sheet as of March 31, 2021 and December 31, 2020. A portion of the acquisition holdback liability in the amount of $1.0 million was settled in the first quarter of 2021, resulting in additional cash of $0.8 million paid 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 eighteen 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 relate to the finalization of the estimated fair value of the earnout liability and a net working capital adjustment. Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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. The acquisition holdback liability of $11.1 million and $11.4 million is recorded in accrued purchase price related to acquisitions, noncurrent portion on the consolidated balance sheet as of March 31, 2021 and December 31, 2020 respectively. 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. Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment Adjusted Assets acquired: Cash and cash equivalents $ 1,347 $ — $ 1,347 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.

Revenue

Revenue	3 Months Ended
	Mar. 31, 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 March 31, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 76,396 $ 58,971 Tax returns and compliance management 52,847 39,433 Interest income on funds held for customers 141 525 Total subscription and returns 129,384 98,929 Professional services 13,288 5,462 Total revenue (U.S.) 142,672 104,391 Total revenue (non-U.S.) 10,929 7,052 Total revenue $ 153,601 $ 111,443 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 months ended March 31, 2021 For the Three Months Ended March 31, 2021 2020 Contract liabilities: Balance beginning of period $ 10,134 $ 5,197 Contract liabilities transferred to deferred revenue (3,866 ) (2,538 ) Addition to contract liabilities 6,198 3,671 Balance end of period $ 12,466 $ 6,330 As of March 31, 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 months ended March 31, 2021 and For the Three Months Ended March 31, 2021 2020 Deferred revenue: Balance beginning of period $ 209,690 $ 161,241 Revenue recognized (153,601 ) (111,443 ) Additional amounts deferred 169,442 115,571 Balance end of period $ 225,531 $ 165,369 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 months ended March 31, 2021 and 2020 is presented below (in thousands): For the Three Months Ended March 31, 2021 2020 Deferred commissions: Balance beginning of period $ 50,870 $ 38,416 Additional commissions deferred 5,695 4,897 Amortization of deferred commissions (3,335 ) (2,647 ) Balance end of period $ 53,230 $ 40,666 As of March 31, 2021, $13.0 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 three months ended March 31, 2021 or 2020. There were no assets recognized related to the costs to fulfill contracts during the three months ended March 31, 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 additional performance obligations that are not yet recorded in the consolidated balance sheets. As of March 31, 2021, amounts allocated to these additional contractual obligations to which enforceable rights exist are $ 49.6 million, of which $ 49.0 million is expected to be recognized as revenue over the next 12 months with the remaining amount thereafter.

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	7 . Intangible Assets Intangible assets consisted of the following (in thousands): March 31, 2021 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 3,300 $ (454 ) $ 2,846 Customer relationships 3 to 10 59,254 (16,707 ) 42,547 Developed technology (1) 3 to 8 52,091 (29,582 ) 22,509 Noncompetition agreements 3 to 5 3,053 (884 ) 2,169 Tradename and trademarks 1 to 4 6,672 (2,064 ) 4,608 $ 124,370 $ (49,691 ) $ 74,679 (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 $4.4 million for the three months ended March 31, 2021, and $1.8 million for the three months ended March 31, 2020. 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 March 31, 2021, the sellers have earned approximately $1.3 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 March 31, 2021 for the earnout period ending June 30, 2021 and is expected to be paid in cash to the sellers in the third quarter of 2021. Goodwill Changes in the carrying amount of goodwill for the three months ended March 31, 2021 Balance—December 31, 2020 $ 513,234 Measurement period adjustment - acquisition of Transaction Tax Resources 8,526 Measurement period adjustment - acquisition of Business Licenses (1,634 ) Measurement period adjustment - acquisition of Impendulo 425 Cumulative translation adjustments (431 ) Balance—March 31, 2021 $ 520,120 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 March 31, 2021, the Brazilian reporting unit had no associated goodwill.

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	8. Leases Total lease cost, net of sublease income, was $3.9 million and $3.8 million for the three months ended March 31, 2021 and 2020, respectively. Sublease income was $0.4 million for the three months ended March 31, 2021 and 2020. No leases commenced in the three months ended March 31, 2021.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 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.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2021
Stockholders Equity Note [Abstract]
Shareholders' Equity	1 0 . 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 three months ended March 31, 2021 Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Income (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 The changes to the Company’s shareholders’ equity for the three months ended March 31, 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

Equity Incentive Plans

Equity Incentive Plans	3 Months Ended
	Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	1 1 . 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 March 31, 2021, the Company had stock options outstanding under the 2018 Equity Incentive Plan (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 March 31, 2021, 4,094,254 shares were subject to outstanding awards and 12,251,898 shares were available for issuance under the 2018 Plan. As of March 31, 2021, 2,057,873 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 March 31, 2021 2020 Stock-based compensation cost: Stock options $ 3,223 $ 3,849 Restricted stock units 11,689 4,933 Performance share units 2,832 — Employee stock purchase plan 1,303 967 Total stock-based compensation cost $ 19,047 $ 9,749 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 three months ended March 31, 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 (296,226 ) $ 18.67 Options cancelled or expired (6,079 ) $ 15.19 Options outstanding as of March 31, 2021 3,234,709 $ 29.07 6.72 $ 337,587 Options exercisable as of March 31, 2021 2,021,107 $ 20.97 6.11 $ 227,301 A summary of options outstanding and vested as of March 31, 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) $1.50 to $1.90 3,075 0.7 3,075 0.7 $2.86 to $6.40 29,900 1.8 29,900 1.8 $8.04 to $11.72 177,781 3.0 177,781 3.0 $12.20 to $15.06 804,003 5.5 790,741 5.5 $16.06 to $24.00 1,043,114 6.8 594,080 6.8 $31.99 to $42.21 679,071 7.7 305,387 7.7 $55.10 to $99.65 455,610 8.6 120,143 8.4 $124.35 to $151.76 42,155 9.5 — — 3,234,709 2,021,107 The total intrinsic value of options exercised during the three months ended March 31, 2021 and 2020 There were no options granted during the three months ended March 31, 2021. The weighted average grant date fair value of options granted during the three months ended March 31, 2020 As of March 31, 2021, $20.4 million of total unrecognized compensation cost related to stock options was expected to be recognized over a weighted average period of approximately 2.1 years. All options given 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 of options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended March 31, 2021 2020 Fair market value of common stock — $67.27 - $86.61 Volatility — 43% Expected term — 6 years Expected dividend yield — n/a Risk-free interest rate — 0.82% - 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 three months ended March 31, 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 826,051 130.22 RSUs vested (346,008 ) 56.75 RSUs cancelled (42,320 ) 68.11 RSUs outstanding as of March 31, 2021 2,796,786 $ 89.60 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 March 31, 2021, $234.1 million of total unrecognized compensation cost related to RSUs was expected to be recognized over a weighted average period of approximately 3.3 years. Performance Share Units The following table summarizes PSU activity for the Company’s stock-based compensation plans for the three months ended March 31, 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 March 31, 2021 120,632 $ 147.39 During the first quarter of 2020, 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 March 31, 2021, $35.0 million of total unrecognized compensation cost related to PSUs was expected to be recognized over a weighted average period of approximately 2.3 years. Employee Stock Purchase Plan During the three months ended March 31, 2021, 60,064 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 March 31, 2021 2020 Fair market value of common stock $ 152.35 $ 85.14 Volatility 34% 32% Expected term 0.5 years 0.5 years Expected dividend yield n/a n/a Risk-free interest rate 0.08% 1.54%

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Shareholders	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Shareholders	1 2 . 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. 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 March 31, 2021 2020 Numerator: Net loss attributable to common shareholders $ (29,988 ) $ (15,283 ) Denominator: Weighted-average common shares outstanding-basic 85,436 77,904 Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, and ESPP shares — — Weighted-average common shares outstanding-diluted 85,436 77,904 Net loss per common share, basic and diluted $ (0.35 ) $ (0.20 ) 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 March 31, 2021 2020 Options to purchase common shares 3,396 5,664 Unvested restricted stock units 2,258 1,554 Unvested performance share units 75 — ESPP shares 7 9 Total 5,736 7,227

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	1 3 . Subsequent Events On April 20, 2021, the Company acquired substantially all the assets of Davo. On April 1, 2021, the Company acquired the outstanding equity of Inposia. See discussion in Note 5.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 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 March 31, 2021, and the consolidated interim statements of operations, consolidated statement of cash flows, and consolidated statements of comprehensive loss for the three months ended March 31, 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 months ended March 31, 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 three months ended March 31, 2020 are reported as restricted cash equivalents in the consolidated statement of cash flows. The correction resulted in a change of $0.2 million to net cash used in operating activities and a change of $3.9 million to net cash used in investing activities for the three months ended March 31, 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 Three Months Ended March 31, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash used in operating activities: Other $ 192 $ (202 ) $ (10 ) Net cash used in operating activities (24,269 ) (202 ) (24,471 ) Cash flows from investing activities: Net (increase) decrease in customer fund assets (3,915 ) 3,915 — Net cash used in investing activities (5,515 ) 3,915 (1,600 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents (16,415 ) 3,713 (12,702 ) 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 $ 450,535 $ 28,096 $ 478,631
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.
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 award grants; 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.
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 months ended March 31, 2021 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 expenses from increases in the fair value of earnout liabilities related to business combinations of $1.4 million and income from decreases in the fair value of $2.5 million for the three months ended March 31, 2021 and 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 three months ended March 31, 2021 or 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”), 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 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 for 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.
New Accounting Standards Not Yet Adopted	New Accounting Standards Not Yet Adopted There are no new accounting standards that have not yet been adopted.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 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 Three Months Ended March 31, 2020 As Previously Reported ASU 2016-18 Adjustments As Corrected Cash flows from operating activities: Adjustments to reconcile net loss to net cash used in operating activities: Other $ 192 $ (202 ) $ (10 ) Net cash used in operating activities (24,269 ) (202 ) (24,471 ) Cash flows from investing activities: Net (increase) decrease in customer fund assets (3,915 ) 3,915 — Net cash used in investing activities (5,515 ) 3,915 (1,600 ) Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents (16,415 ) 3,713 (12,702 ) 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 $ 450,535 $ 28,096 $ 478,631

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2021 Value (Level 1) (Level 2) (Level 3) Money market funds $ 578,158 $ 578,158 $ — $ — Earnouts related to business combinations 37,653 — — 37,653 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): Three Months Ended March 31, 2021 2020 Earnout liabilities related to business combinations: Balance beginning of period $ 34,501 $ 13,808 Measurement period adjustment 1,802 — Payments of earnout liabilities — (7,700 ) Total unrealized loss (gain) included in other (income) expense, net 1,350 (2,509 ) Balance end of period $ 37,653 $ 3,599

Balance Sheet Detail (Tables)

Balance Sheet Detail (Tables)	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): Useful March 31, December 31, Life (Years) 2021 2020 Computer equipment and software 3 to 5 $ 17,106 $ 15,749 Internally developed software 3 to 6 12,978 10,438 Furniture and fixtures 5 6,686 6,651 Office equipment 3 to 5 1,052 1,006 Leasehold improvements 1 to 10 30,069 29,928 67,891 63,772 Accumulated depreciation (31,544 ) (29,059 ) Property and equipment—net $ 36,347 $ 34,713
Schedule of Prepaid Expense And Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, 2021 2020 Prepaid expenses $ 24,528 $ 13,968 Deposits 2,801 2,557 Other 2,251 3,573 Total $ 29,580 $ 20,098
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): March 31, December 31, 2021 2020 Accrued payroll and related taxes $ 13,539 $ 7,903 Accrued federal, state, local, and foreign taxes 4,919 4,338 Accrued bonus 9,577 29,518 Self-insurance reserves 1,633 1,563 Employee stock purchase plan contributions 3,617 5,927 Accrued sales commissions 3,189 5,563 Accrued partner commissions 9,010 9,173 Contract liabilities 12,466 10,134 Other 11,201 10,413 Total $ 69,151 $ 84,532

Acquisitions of Businesses (Tab

Acquisitions of Businesses (Tables)	3 Months Ended
	Mar. 31, 2021
Business Licenses
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 estimated fair value of the earnout liability and a net working capital adjustment. Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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	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
Fair Value | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Summary of Reconciliation of Preliminary Total Consideration	A reconciliation of preliminary total consideration as December 31, 2020 and total consideration as of March 31, 2021 is presented below (in thousands): Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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	Intangible Previously Reported Assigned Value 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
Fair Value | Impendulo
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. Purchase Price Allocation Previously Measurement Period As Reported Adjustment 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): Purchase Price Allocation Previously Measurement Period As Reported Adjustment Adjusted Assets acquired: Cash and cash equivalents $ 1,347 $ — $ 1,347 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)	3 Months Ended
	Mar. 31, 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 March 31, 2021 2020 Revenue (U.S.): Subscription and returns Tax calculations $ 76,396 $ 58,971 Tax returns and compliance management 52,847 39,433 Interest income on funds held for customers 141 525 Total subscription and returns 129,384 98,929 Professional services 13,288 5,462 Total revenue (U.S.) 142,672 104,391 Total revenue (non-U.S.) 10,929 7,052 Total revenue $ 153,601 $ 111,443
Summary of Activity Impacting Contract Liabilities	A summary of the activity impacting the contract liabilities during the three months ended March 31, 2021 For the Three Months Ended March 31, 2021 2020 Contract liabilities: Balance beginning of period $ 10,134 $ 5,197 Contract liabilities transferred to deferred revenue (3,866 ) (2,538 ) Addition to contract liabilities 6,198 3,671 Balance end of period $ 12,466 $ 6,330
Summary of Activity Impacting Deferred Revenue	A summary of the activity impacting deferred revenue balances during the three months ended March 31, 2021 and For the Three Months Ended March 31, 2021 2020 Deferred revenue: Balance beginning of period $ 209,690 $ 161,241 Revenue recognized (153,601 ) (111,443 ) Additional amounts deferred 169,442 115,571 Balance end of period $ 225,531 $ 165,369
Summary of Activity Impacting Deferred Commissions	A summary of the activity impacting the deferred commissions during the three months ended March 31, 2021 and 2020 is presented below (in thousands): For the Three Months Ended March 31, 2021 2020 Deferred commissions: Balance beginning of period $ 50,870 $ 38,416 Additional commissions deferred 5,695 4,897 Amortization of deferred commissions (3,335 ) (2,647 ) Balance end of period $ 53,230 $ 40,666

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Finite-lived Intangible Assets	Intangible assets consisted of the following (in thousands): March 31, 2021 Average Useful Life (Years) Gross Accumulated Amortization Net Backlog 3 $ 3,300 $ (454 ) $ 2,846 Customer relationships 3 to 10 59,254 (16,707 ) 42,547 Developed technology (1) 3 to 8 52,091 (29,582 ) 22,509 Noncompetition agreements 3 to 5 3,053 (884 ) 2,169 Tradename and trademarks 1 to 4 6,672 (2,064 ) 4,608 $ 124,370 $ (49,691 ) $ 74,679 (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 three months ended March 31, 2021 Balance—December 31, 2020 $ 513,234 Measurement period adjustment - acquisition of Transaction Tax Resources 8,526 Measurement period adjustment - acquisition of Business Licenses (1,634 ) Measurement period adjustment - acquisition of Impendulo 425 Cumulative translation adjustments (431 ) Balance—March 31, 2021 $ 520,120

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Stockholders Equity Note [Abstract]
Summary of Changes of Shareholders' Equity	The changes to the Company’s shareholders’ equity during the three months ended March 31, 2021 Accumulated Additional Other Total Common Stock Paid-In Comprehensive Accumulated Shareholders’ Shares Amount Capital Income (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 The changes to the Company’s shareholders’ equity for the three months ended March 31, 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

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2021 2020 Stock-based compensation cost: Stock options $ 3,223 $ 3,849 Restricted stock units 11,689 4,933 Performance share units 2,832 — Employee stock purchase plan 1,303 967 Total stock-based compensation cost $ 19,047 $ 9,749
Summary of Stock Option Activity	Stock Options The following table summarizes stock option activity for the Company’s stock-based compensation plans for the three months ended March 31, 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 (296,226 ) $ 18.67 Options cancelled or expired (6,079 ) $ 15.19 Options outstanding as of March 31, 2021 3,234,709 $ 29.07 6.72 $ 337,587 Options exercisable as of March 31, 2021 2,021,107 $ 20.97 6.11 $ 227,301
Summary of Options Outstanding and Vested by Range of Exercise Prices	A summary of options outstanding and vested as of March 31, 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) $1.50 to $1.90 3,075 0.7 3,075 0.7 $2.86 to $6.40 29,900 1.8 29,900 1.8 $8.04 to $11.72 177,781 3.0 177,781 3.0 $12.20 to $15.06 804,003 5.5 790,741 5.5 $16.06 to $24.00 1,043,114 6.8 594,080 6.8 $31.99 to $42.21 679,071 7.7 305,387 7.7 $55.10 to $99.65 455,610 8.6 120,143 8.4 $124.35 to $151.76 42,155 9.5 — — 3,234,709 2,021,107
Summary of Fair Value Estimated Using Black-Scholes Option Pricing Model Assumptions	For the options granted during the periods presented, the fair value of options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended March 31, 2021 2020 Fair market value of common stock — $67.27 - $86.61 Volatility — 43% Expected term — 6 years Expected dividend yield — n/a Risk-free interest rate — 0.82% - 1.25%
Summary of RSU Activity	The following table summarizes RSU activity for the Company’s stock-based compensation plans for the three months ended March 31, 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 826,051 130.22 RSUs vested (346,008 ) 56.75 RSUs cancelled (42,320 ) 68.11 RSUs outstanding as of March 31, 2021 2,796,786 $ 89.60
Summary of PSU Activity	The following table summarizes PSU activity for the Company’s stock-based compensation plans for the three months ended March 31, 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 March 31, 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 March 31, 2021 2020 Fair market value of common stock $ 152.35 $ 85.14 Volatility 34% 32% Expected term 0.5 years 0.5 years Expected dividend yield n/a n/a Risk-free interest rate 0.08% 1.54%

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Shareholders (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2021 2020 Numerator: Net loss attributable to common shareholders $ (29,988 ) $ (15,283 ) Denominator: Weighted-average common shares outstanding-basic 85,436 77,904 Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, and ESPP shares — — Weighted-average common shares outstanding-diluted 85,436 77,904 Net loss per common share, basic and diluted $ (0.35 ) $ (0.20 )
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 March 31, 2021 2020 Options to purchase common shares 3,396 5,664 Unvested restricted stock units 2,258 1,554 Unvested performance share units 75 — ESPP shares 7 9 Total 5,736 7,227

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details)	Oct. 31, 2018USD ($)	Mar. 31, 2021USD ($)Segment	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Accounting Policies [Line Items]
Number of operating segment | Segment		1
Goodwill impairment	$ 0	$ 0		$ 0
(Expenses) income from increases decreases in fair value of earnout liabilities related to business combinations		1,400,000	$ (2,500,000)
Impairment of long-lived assets		$ 0	0
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%
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
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
Restatement Adjustment | Accounting Standards Update 2016-18
Accounting Policies [Line Items]
Change in net cash used in operating activities due to correction			200,000
Change in net cash used in investing activities due to correction			$ 3,900,000

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	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Adjustments to reconcile net loss to net cash used in operating activities:
Other	$ 389	$ 10
Net cash used in operating activities	(28,247)	(24,471)
Cash flows from investing activities:
Net cash used in investing activities	(5,844)	(1,600)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	(20,531)	(12,702)
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	$ 741,313	478,631
As Previously Reported
Adjustments to reconcile net loss to net cash used in operating activities:
Other		192
Net cash used in operating activities		(24,269)
Cash flows from investing activities:
Net (increase) decrease in customer fund assets		(3,915)
Net cash used in investing activities		(5,515)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		(16,415)
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		450,535
Accounting Standards Update 2016-18
Adjustments to reconcile net loss to net cash used in operating activities:
Other		(10)
Net cash used in operating activities		(24,471)
Cash flows from investing activities:
Net cash used in investing activities		(1,600)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		(12,702)
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		478,631
Accounting Standards Update 2016-18 | ASU 2016-18 Adjustments
Adjustments to reconcile net loss to net cash used in operating activities:
Other		(202)
Net cash used in operating activities		(202)
Cash flows from investing activities:
Net (increase) decrease in customer fund assets		3,915
Net cash used in investing activities		3,915
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents		3,713
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		$ 28,096

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Recurring Basis - USD ($) $ in Thousands	Mar. 31, 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	$ 37,653	$ 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	37,653	34,501
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Assets	578,158	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	$ 578,158	$ 649,603

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - Discount Rate - Discounted Cash Flows and Monte Carlo Simulations	Mar. 31, 2021
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	12.00%
Business Licenses
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate utilized for valuation of earnout liability	5.00%

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnout liabilities related to business combinations:
Total unrealized loss (gain) included in other (income) expense, net	$ (1,400)	$ 2,500
Recurring Basis | Significant Unobservable Inputs (Level 3) | Earnout Related to Acquisitions
Earnout liabilities related to business combinations:
Balance beginning of period	34,501	13,808
Measurement period adjustment	1,802	0
Payments of earnout liabilities	0	(7,700)
Total unrealized loss (gain) included in other (income) expense, net	1,350	(2,509)
Balance end of period	$ 37,653	$ 3,599

Balance Sheet Detail - Property

Balance Sheet Detail - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 67,891	$ 63,772
Accumulated depreciation	(31,544)	(29,059)
Property and equipment—net	36,347	34,713
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 17,106	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	$ 12,978	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	$ 6,686	6,651
Property and equipment, Useful Life	5 years
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,052	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	$ 30,069	$ 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
	Mar. 31, 2021	Mar. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 2.6	$ 2.3

Balance Sheet Detail - Prepaid

Balance Sheet Detail - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 24,528	$ 13,968
Deposits	2,801	2,557
Other	2,251	3,573
Total	$ 29,580	$ 20,098

Balance Sheet Detail - Accrued

Balance Sheet Detail - Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Accrued payroll and related taxes	$ 13,539	$ 7,903
Accrued federal, state, local, and foreign taxes	4,919	4,338
Accrued bonus	9,577	29,518
Self-insurance reserves	1,633	1,563
Employee stock purchase plan contributions	3,617	5,927
Accrued sales commissions	3,189	5,563
Accrued partner commissions	9,010	9,173
Contract liabilities	12,466	10,134	$ 6,330	$ 5,197
Other	11,201	10,413
Total	$ 69,151	$ 84,532

Acquisitions of Businesses - Ad

Acquisitions of Businesses - Additional Information (Details) $ in Thousands, € in Millions

Apr. 20, 2021USD ($)

Mar. 29, 2021USD ($)

Dec. 01, 2020USD ($)

Nov. 05, 2020USD ($)

Oct. 05, 2020USD ($)

Mar. 31, 2021USD ($)

Mar. 31, 2021EUR (€)

Dec. 31, 2020USD ($)

Mar. 31, 2020USD ($)

Dec. 31, 2022USD ($)

Dec. 31, 2021USD ($)

Apr. 01, 2021USD ($)

Apr. 01, 2021EUR (€)

Business Acquisition [Line Items]

Accrued value of earnout related to acquisition

$ 1,802

$ 0

Goodwill

520,120

$ 513,234

Earnout liability

12,503

749

Accrued earnout liabilities

25,400

34,468

Common stock consideration

$ 3,750

Davo Technologies LLC | Subsequent Event

Business Acquisition [Line Items]

Consideration in cash

$ 26,200

Additional cash to be paid, as consideration, after eighteen months

$ 2,600

Davo Technologies LLC | Prepaid and Other Current Assets

Business Acquisition [Line Items]

Consideration in cash

300

Inposia

Business Acquisition [Line Items]

Total consideration transferred

$ 12,200

€ 10.4

Inposia | Subsequent Event

Business Acquisition [Line Items]

Additional cash to be paid, as consideration, after eighteen months

$ 5,300

€ 4.5

Acquisition of outstanding equity under share purchase agreement for aggregate cash and share consideration

$ 35,200

€ 30

Inposia | Prepaid and Other Current Assets

Business Acquisition [Line Items]

Consideration in cash

2,400

Transaction Tax Resources, Inc.

Business Acquisition [Line Items]

Consideration in cash

$ 294,000

294,017

Total consideration transferred

370,100

370,148

Acquisition holdbacks with a fair value upon acquisition

57,300

57,260

Accrued value of earnout related to acquisition

$ 18,900

18,871

Risk-free discount rate

0.13%

Earnout payable period

2023-02

Maximum payout earned

$ 26,400

Minimum payout earned

0

Carrying amount of trade accounts receivable

7,200

Recorded fair value of acquisition

$ 6,000

Risk adjusted discount rate

3.50%

Weighted average amortization period for intangibles

4 years 8 months 12 days

Goodwill

$ 335,600

Earnout liability

18,900

19,900

Accrued earnout liabilities

37,700

37,700

Acquisition holdback liability

1,000

Additional accrued cash payable to sellers

800

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

$ 26,400

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

Business Licenses

Business Acquisition [Line Items]

Consideration in cash

$ 64,800

64,812

Total consideration transferred

93,300

93,321

Acquisition holdbacks with a fair value upon acquisition

11,100

11,109

Accrued value of earnout related to acquisition

$ 17,400

17,400

Risk-free discount rate

0.13%

Maximum payout earned

$ 20,700

Minimum payout earned

$ 0

Weighted average amortization period for intangibles

5 years 3 months 18 days

Goodwill

$ 72,141

Accrued earnout liabilities

11,100

$ 11,400

Business Licenses | Developed Technology

Business Acquisition [Line Items]

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

Business Licenses | After Eighteen Months from Closing of Acquisition

Business Acquisition [Line Items]

Acquisition holdbacks with a fair value upon acquisition

$ 11,100

Impendulo

Business Acquisition [Line Items]

Consideration in cash

$ 11,700

11,713

Total consideration transferred

$ 14,000

14,022

Weighted average amortization period for intangibles

5 years 10 months 24 days

Goodwill

$ 10,642

Impendulo | Common Stock

Business Acquisition [Line Items]

Common stock consideration

$ 1,200

Impendulo | Final Revenue Metrics

Business Acquisition [Line Items]

Additional accrued cash payable to sellers

$ 1,100

Acquisitions of Businesses - Su

Acquisitions of Businesses - Summary of Reconciliation of Preliminary Total Consideration (Details) - USD ($) $ in Thousands	Dec. 01, 2020	Nov. 05, 2020	Oct. 05, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Business Acquisition [Line Items]
Accrued value of earnout related to acquisition				$ 1,802		$ 0
Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Consideration in cash			$ 294,000	294,017
Acquisition holdbacks with a fair value upon acquisition			57,300	57,260
Accrued value of earnout related to acquisition			18,900	18,871
Total consideration			$ 370,100	370,148
Business Licenses
Business Acquisition [Line Items]
Consideration in cash		$ 64,800		64,812
Acquisition holdbacks with a fair value upon acquisition		11,100		11,109
Accrued value of earnout related to acquisition		17,400		17,400
Total consideration		$ 93,300		93,321
Impendulo
Business Acquisition [Line Items]
Consideration in cash	$ 11,700			11,713
Common stock paid at close				1,190
Cash payable accrual				1,119
Total consideration	$ 14,000			14,022
Previously Reported | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Consideration in cash					$ 294,017
Acquisition holdbacks with a fair value upon acquisition					57,477
Accrued value of earnout related to acquisition					15,740
Total consideration					367,234
Previously Reported | Business Licenses
Business Acquisition [Line Items]
Consideration in cash					64,812
Acquisition holdbacks with a fair value upon acquisition					11,415
Accrued value of earnout related to acquisition					18,728
Total consideration					94,955
Previously Reported | Impendulo
Business Acquisition [Line Items]
Consideration in cash					11,713
Common stock paid at close					1,190
Cash payable accrual					694
Total consideration					$ 13,597
Restatement Adjustment | Transaction Tax Resources, Inc.
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition				(217)
Accrued value of earnout related to acquisition				3,131
Total consideration				2,914
Restatement Adjustment | Business Licenses
Business Acquisition [Line Items]
Acquisition holdbacks with a fair value upon acquisition				(306)
Accrued value of earnout related to acquisition				(1,328)
Total consideration				(1,634)
Restatement Adjustment | Impendulo
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	Mar. 31, 2021	Dec. 31, 2020	Dec. 01, 2020	Nov. 05, 2020	Oct. 05, 2020
Assets acquired:
Goodwill	$ 520,120	$ 513,234
Transaction Tax Resources, Inc.
Assets acquired:
Goodwill					$ 335,600
Transaction Tax Resources, Inc. | Fair Value
Assets acquired:
Cash and cash equivalents					2,294
Trade accounts receivable					5,966
Other current assets					93
Operating lease right-of-use assets					1,760
Property and equipment					848
Developed technology, customer relationships, and other intangibles					41,500
Goodwill					335,565
Total assets acquired					388,026
Liabilities assumed:
Trade payables and accrued expenses					731
Deferred revenue					8,500
Operating lease liabilities					1,760
Deferred tax liability					6,887
Total liabilities assumed					17,878
Net assets acquired					370,148
Transaction Tax Resources, Inc. | Fair Value | Previously Reported
Assets acquired:
Cash and cash equivalents					2,294
Trade accounts receivable					5,966
Other current assets					93
Operating lease right-of-use assets					1,760
Property and equipment					848
Developed technology, customer relationships, and other intangibles					49,000
Goodwill					327,039
Total assets acquired					387,000
Liabilities assumed:
Trade payables and accrued expenses					731
Deferred revenue					8,500
Operating lease liabilities					1,760
Deferred tax liability					8,775
Total liabilities assumed					19,766
Net assets acquired					367,234
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
Trade accounts receivable				1,326
Other current assets				101
Operating lease right-of-use assets				1,644
Property and equipment				87
Developed technology, customer relationships, and other intangibles				19,525
Goodwill				72,141
Total assets acquired				96,049
Customer fund assets				1,074
Other noncurrent assets				31
Liabilities assumed:
Operating lease liabilities				1,644
Total liabilities assumed				2,728
Accrued expenses				56
Customer fund obligations				1,028
Net assets acquired				93,321
Business Licenses | Previously Reported
Assets acquired:
Cash and cash equivalents				120
Trade accounts receivable				1,326
Other current assets				101
Operating lease right-of-use assets				1,644
Property and equipment				87
Developed technology, customer relationships, and other intangibles				19,525
Goodwill				73,775
Total assets acquired				97,683
Customer fund assets				1,074
Other noncurrent assets				31
Liabilities assumed:
Operating lease liabilities				1,644
Total liabilities assumed				2,728
Accrued expenses				56
Customer fund obligations				1,028
Net assets acquired				94,955
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
Trade accounts receivable			371
Developed technology, customer relationships, and other intangibles			3,617
Goodwill			10,642
Total assets acquired			16,124
Other assets			147
Liabilities assumed:
Trade payables and accrued expenses			663
Deferred tax liability			745
Total liabilities assumed			2,102
Deferred revenue and contract liabilities			694
Net assets acquired			14,022
Impendulo | Previously Reported
Assets acquired:
Cash and cash equivalents			1,347
Trade accounts receivable			371
Developed technology, customer relationships, and other intangibles			3,617
Goodwill			10,217
Total assets acquired			15,699
Other assets			147
Liabilities assumed:
Trade payables and accrued expenses			663
Deferred tax liability			745
Total liabilities assumed			2,102
Deferred revenue and contract liabilities			694
Net assets acquired			13,597
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	Dec. 01, 2020	Nov. 05, 2020	Oct. 05, 2020	Mar. 31, 2021	Dec. 31, 2020
Transaction Tax Resources, Inc. | Fair Value
Business Acquisition [Line Items]
Intangible assets Assigned value			$ 41,500
Transaction Tax Resources, Inc. | Fair Value | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value			49,000
Transaction Tax Resources, Inc. | Fair Value | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value			$ (7,500)
Business Licenses
Business Acquisition [Line Items]
Intangible assets Assigned value		$ 19,525
Business Licenses | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value		19,525
Impendulo
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 3,617
Impendulo | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value	$ 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 | 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. | Fair Value | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value			26,000
Customer Relationships | Transaction Tax Resources, Inc. | Fair Value | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value			$ (5,000)
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 | 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. | Fair Value | Previously Reported
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 | 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 | 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. | Fair Value | Previously Reported
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
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. | Fair Value | Previously Reported
Business Acquisition [Line Items]
Intangible assets Assigned value			5,800
ContractBacklogMember | Transaction Tax Resources, Inc. | Fair Value | Restatement Adjustment
Business Acquisition [Line Items]
Intangible assets Assigned value			$ (2,500)
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 | 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. | Fair Value | Previously Reported
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

Revenue - Summary of Total Reve

Revenue - Summary of Total Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Revenues	$ 153,601	$ 111,443
U.S.
Disaggregation Of Revenue [Line Items]
Revenues	142,672	104,391
Non-U.S.
Disaggregation Of Revenue [Line Items]
Revenues	10,929	7,052
Subscription and Returns, Tax Calculations | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	76,396	58,971
Subscription and Returns, Tax Returns and Compliance Management | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	52,847	39,433
Subscription and Returns,Interest Income on Funds Held for Customers | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	141	525
Subscription and Returns
Disaggregation Of Revenue [Line Items]
Revenues	139,318	105,546
Subscription and Returns | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	129,384	98,929
Professional Services
Disaggregation Of Revenue [Line Items]
Revenues	14,283	5,897
Professional Services | U.S.
Disaggregation Of Revenue [Line Items]
Revenues	$ 13,288	$ 5,462

Revenue - Summary of Activity I

Revenue - Summary of Activity Impacting Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Contract Liabilities [Rollforward]
Balance beginning of period	$ 10,134	$ 5,197
Contract liabilities transferred to deferred revenue	(3,866)	(2,538)
Addition to contract liabilities	6,198	3,671
Balance end of period	$ 12,466	$ 6,330

Revenue - Summary of Activity_2

Revenue - Summary of Activity Impacting Deferred Revenue (Details) - Deferred Revenue - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Deferred Revenue Rollforward
Balance beginning of period	$ 209,690	$ 161,241
Revenue recognized	(153,601)	(111,443)
Additional amounts deferred	169,442	115,571
Balance end of period	$ 225,531	$ 165,369

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 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	$ 12,957,000		$ 12,245,000
Impairments of deferred contract costs	0	$ 0
Assets recognized related to costs to fulfill contracts	0	$ 0
Additional contractual obligations	49,600,000
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	$ 13,000,000

Revenue - Summary of Activity_3

Revenue - Summary of Activity Impacting Deferred Commissions (Details) - Deferred Commissions - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Capitalized Contract Cost [Line Items]
Balance beginning of period	$ 50,870	$ 38,416
Additional commissions deferred	5,695	4,897
Amortization of deferred commissions	(3,335)	(2,647)
Balance end of period	$ 53,230	$ 40,666

Revenue - Additional Informat_2

Revenue - Additional Information (Details 1) $ in Millions	Mar. 31, 2021USD ($)
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Additional contractual obligations	$ 49.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-04-01
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Additional contractual obligations	$ 49
Revenue expected to be recognized with remaining amount	12 months

Intangible Assets - Schedule of

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross	$ 124,370	$ 131,987
Accumulated Amortization	(49,691)	(45,474)
Net	$ 74,679	$ 86,513
Backlog
Finite Lived Intangible Assets [Line Items]
Average Useful Life (Years)	3 years	3 years
Gross	$ 3,300	$ 5,800
Accumulated Amortization	(454)	(937)
Net	2,846	4,863
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross	59,254	64,302
Accumulated Amortization	(16,707)	(14,890)
Net	$ 42,547	$ 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	$ 52,091	$ 52,144
Accumulated Amortization	(29,582)	(27,646)
Net	$ 22,509	$ 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	$ 3,053	$ 3,062
Accumulated Amortization	(884)	(766)
Net	$ 2,169	$ 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	$ 6,672	$ 6,679
Accumulated Amortization	(2,064)	(1,235)
Net	$ 4,608	$ 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	Mar. 31, 2021	Dec. 31, 2020
IPR&D
Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-lived intangible assets, net	$ 0.6	$ 0.6

Intangible Assets - Additional

Intangible Assets - Additional Information (Details)	Oct. 31, 2018USD ($)	May 31, 2018USD ($)	Mar. 31, 2021USD ($)Unit	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization expense			$ 4,400,000	$ 1,800,000
Earnout liability			$ 12,503,000		$ 749,000
Number of goodwill impairment reporting units | Unit			3
Goodwill impairment charge	$ 0		$ 0		0
Goodwill			520,120,000		$ 513,234,000
Brazilian Reporting Unit
Finite Lived Intangible Assets [Line Items]
Goodwill			0
Accrued Expenses
Finite Lived Intangible Assets [Line Items]
Earnout liability			300,000
Tradestream Technologies Inc. and Wise 24 Inc
Finite Lived Intangible Assets [Line Items]
Future revenue recognized period		6 years
Earnout provision			$ 1,300,000
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	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill [Line Items]
Balance—December 31, 2020	$ 513,234
Cumulative translation adjustments	(431)
Balance—March 31, 2021	520,120
Transaction Tax Resources
Goodwill [Line Items]
Measurement period adjustment, goodwill acquired during period	8,526
Business Licenses
Goodwill [Line Items]
Measurement period adjustment, goodwill acquired during period	(1,634)
Impendulo
Goodwill [Line Items]
Measurement period adjustment, goodwill acquired during period	$ 425

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Total lease cost, net of sublease income	$ 3.9	$ 3.8
Sublease income	$ 0.4	$ 0.4
Lease not yet commenced, description	No leases commenced in the three months ended March 31, 2021

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details)	3 Months Ended
	Mar. 31, 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
Preferred stock, par value | $ / shares	$ 0.0001

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Changes of Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Class Of Stock [Line Items]
Beginning balance	$ 1,080,160	$ 463,722
Exercise of stock options	$ 5,529	7,928
Exercise of stock options, Shares	296,226
Stock-based compensation cost	$ 19,047	9,749
Shares issued under employee stock purchase plan	7,088	5,716
Shares issued related to business combination earnouts		3,750
Shares issued to purchase intangible assets	0	87
Gain (Loss) on translation adjustment	(390)	625
Net loss	(29,988)	(15,283)
Ending balance	1,081,446	476,294
Common Stock
Class Of Stock [Line Items]
Beginning balance	$ 9	$ 8
Beginning balance, Shares	85,057,727	77,447,620
Exercise of stock options, Shares	296,226	532,848
Vesting of restricted stock units	346,008	186,475
Shares issued under employee stock purchase plan, Shares	60,064	81,894
Shares issued related to business combination earnouts, Shares		44,659
Shares issued to purchase intangible assets, Shares		1,191
Ending balance	$ 9	$ 8
Ending balance, Shares	85,760,025	78,294,687
Additional Paid-In Capital
Class Of Stock [Line Items]
Beginning balance	$ 1,640,867	$ 976,627
Exercise of stock options	5,529	7,928
Stock-based compensation cost	19,047	9,749
Shares issued under employee stock purchase plan	7,088	5,716
Shares issued related to business combination earnouts		3,750
Shares issued to purchase intangible assets		87
Ending balance	1,672,531	1,003,857
Accumulated Other Comprehensive Income (Loss)
Class Of Stock [Line Items]
Beginning balance	(1,339)	(2,719)
Gain (Loss) on translation adjustment	(390)	625
Ending balance	(1,729)	(2,094)
Accumulated Deficit
Class Of Stock [Line Items]
Beginning balance	(559,377)	(510,194)
Net loss	(29,988)	(15,283)
Ending balance	$ (589,365)	$ (525,477)

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	3,234,709		3,537,014
Total intrinsic value of options exercised	$ 41.9	$ 36.8
Options granted	0
Weighted average grant date fair value of options granted		$ 28.99
Number of shares, vested	306,533
Number of options unvested	1,213,602
Contractual life	10 years
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	$ 20.4
Unrecognized compensation expense expected to be recognized over weighted average period	2 years 1 month 6 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	3 years 3 months 18 days
Total unrecognized compensation expense expected to be recognized	$ 234.1
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 3 months 18 days
Stock options vesting period	3 years
Total unrecognized compensation expense expected to be recognized	$ 35
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	4,094,254
Shares available for future issuance	12,251,898
2006 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	2,057,873
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares purchased	60,064
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation expense related to stock options	$ 1.7
Expected term	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
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	$ 19,047	$ 9,749
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	3,223	3,849
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	11,689	4,933
Performance Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	2,832	0
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost	$ 1,303	$ 967

Equity Incentive Plans - Summ_2

Equity Incentive Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Shares
Options outstanding beginning balance	3,537,014
Options granted	0
Options exercised	(296,226)
Options cancelled or expired	(6,079)
Options outstanding ending balance	3,234,709	3,537,014
Options exercisable	2,021,107
Weighted Average Exercise Price
Options outstanding beginning balance	$ 28.17
Options exercised	18.67
Options cancelled or expired	15.19
Options outstanding ending balance	29.07	$ 28.17
Options exercisable	$ 20.97
Weighted Average Remaining Contractual Life (in Years)
Options outstanding	6 years 8 months 19 days	6 years 10 months 20 days
Options exercisable	6 years 1 month 9 days
Aggregate Intrinsic Value
Options outstanding	$ 337,587	$ 483,577
Options exercisable	$ 227,301

Equity Incentive Plans - Summ_3

Equity Incentive Plans - Summary of Options Outstanding and Vested (Details)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Option Outstanding, Number Outstanding	3,234,709
Options Vested and Exercisable, Number Vested and Exercisable	2,021,107
Options Vested and Exercisable, Weighted Average Life (in Years)	6 years 1 month 9 days
$1.50 to $1.90
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 1.50
Exercise Prices, High | $ / shares	$ 1.90
Option Outstanding, Number Outstanding	3,075
Options Outstanding, Weighted Average Life (in Years)	8 months 12 days
Options Vested and Exercisable, Number Vested and Exercisable	3,075
Options Vested and Exercisable, Weighted Average Life (in Years)	8 months 12 days
2.86 to 6.40
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 2.86
Exercise Prices, High | $ / shares	$ 6.40
Option Outstanding, Number Outstanding	29,900
Options Outstanding, Weighted Average Life (in Years)	1 year 9 months 18 days
Options Vested and Exercisable, Number Vested and Exercisable	29,900
Options Vested and Exercisable, Weighted Average Life (in Years)	1 year 9 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	177,781
Options Outstanding, Weighted Average Life (in Years)	3 years
Options Vested and Exercisable, Number Vested and Exercisable	177,781
Options Vested and Exercisable, Weighted Average Life (in Years)	3 years
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	804,003
Options Outstanding, Weighted Average Life (in Years)	5 years 6 months
Options Vested and Exercisable, Number Vested and Exercisable	790,741
Options Vested and Exercisable, Weighted Average Life (in Years)	5 years 6 months
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	1,043,114
Options Outstanding, Weighted Average Life (in Years)	6 years 9 months 18 days
Options Vested and Exercisable, Number Vested and Exercisable	594,080
Options Vested and Exercisable, Weighted Average Life (in Years)	6 years 9 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	679,071
Options Outstanding, Weighted Average Life (in Years)	7 years 8 months 12 days
Options Vested and Exercisable, Number Vested and Exercisable	305,387
Options Vested and Exercisable, Weighted Average Life (in Years)	7 years 8 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	455,610
Options Outstanding, Weighted Average Life (in Years)	8 years 7 months 6 days
Options Vested and Exercisable, Number Vested and Exercisable	120,143
Options Vested and Exercisable, Weighted Average Life (in Years)	8 years 4 months 24 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)	9 years 6 months
Options Vested and Exercisable, Number Vested and Exercisable	0
Options Vested and Exercisable, Weighted Average Life (in Years)	0 years

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
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility		43.00%
Expected term		6 years
Expected dividend yield	0.00%	0.00%
Risk-free interest rate, minimum		0.82%
Risk-free interest rate, maximum		1.25%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		$ 67.27
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock		$ 86.61

Equity Incentive Plans - Summ_5

Equity Incentive Plans - Summary of RSU Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 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	826,051
RSUs/PSUs vested, Shares | shares	(346,008)
RSUs/PSUs cancelled, Shares | shares	(42,320)
RSUs/PSUs outstanding as of March 31, 2021, Shares | shares	2,796,786
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	130.22
RSUs/PSUs vested, Weighted average grant date fair value per share | $ / shares	56.75
RSUs/PSUs cancelled, Weighted average grant date fair value per share | $ / shares	68.11
RSUs/PSUs outstanding as of March 31, 2021, Weighted average grant date fair value per share | $ / shares	$ 89.60

Equity Incentive Plans - Summ_6

Equity Incentive Plans - Summary of PSU Activity (Details) - Performance Share Units (PSUs)	3 Months Ended
	Mar. 31, 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 March 31, 2021, Shares | shares	120,632
RSUs/PSUs granted, Weighted average grant date fair value per share | $ / shares	$ 147.39
RSUs/PSUs outstanding as of March 31, 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
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility		43.00%
Expected term		6 years
Expected dividend yield	0.00%	0.00%
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of common stock	$ 152.35	$ 85.14
Volatility	34.00%	32.00%
Expected term	6 months	6 months
Expected dividend yield	0.00%	0.00%
Risk-free interest rate	0.08%	1.54%

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
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss attributable to common shareholders	$ (29,988)	$ (15,283)
Denominator:
Weighted-average common shares outstanding-basic	85,436	77,904
Dilutive effect of share equivalents resulting from stock options, restricted stock units, performance share units, and ESPP shares	0	0
Weighted-average common shares outstanding-diluted	85,436	77,904
Net loss per common share, basic and diluted	$ (0.35)	$ (0.20)

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
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	5,736	7,227
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	3,396	5,664
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	2,258	1,554
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	75	0
ESPP Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	7	9

Subsequent Events - Additional

Subsequent Events - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021
Davo Technologies LLC
Subsequent Event [Line Items]
Date of acquisition	Apr. 20, 2021
Inposia
Subsequent Event [Line Items]
Date of acquisition	Apr. 1, 2021