0001660280-21-000027 | 10-K | XBRL Viewer

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Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38600
Entity Registrant Name	TENABLE HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-5580846
Entity Address, Address Line One	6100 Merriweather Drive
Entity Address, City or Town	Columbia
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21044
City Area Code	410
Local Phone Number	872-0555
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	TENB
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 2.1
Entity Common Stock, Shares Outstanding (in shares)		104,036,276
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive Proxy Statement relating to the 2021 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K. The Proxy Statement will be filed with the Securities and Exchange Commission within 120 days after the year ended December 31, 2020.
Entity Central Index Key	0001660280
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 178,223	$ 74,363
Short-term investments	113,623	137,904
Accounts receivable (net of allowance for doubtful accounts of $261 and $764 at December 31, 2020 and 2019, respectively)	115,342	94,827
Deferred commissions	32,143	28,499
Prepaid expenses and other current assets	44,462	27,369
Total current assets	483,793	362,962
Property and equipment, net	38,920	26,847
Deferred commissions (net of current portion)	46,733	43,766
Operating lease right-of-use assets	39,426	42,847
Acquired intangible assets, net	13,193	15,508
Goodwill	54,414	54,138
Other assets	14,110	12,544
Total assets	690,589	558,612
Current liabilities:
Accounts payable and accrued expenses	5,731	10,168
Accrued compensation	35,509	36,634
Deferred revenue	328,819	274,348
Operating lease liabilities	3,815	5,209
Other current liabilities	1,028	1,284
Total current liabilities	374,902	327,643
Deferred revenue (net of current portion)	105,691	88,779
Operating lease liabilities (net of current portion)	54,529	40,663
Other liabilities	4,802	2,622
Total liabilities	539,924	459,707
Stockholders’ equity:
Common stock (par value: $0.01; 500,000 shares authorized, 103,715 and 98,587 shares issued and outstanding at December 31, 2020 and 2019, respectively)	1,037	986
Additional paid-in capital	757,470	662,990
Accumulated other comprehensive income	10	50
Accumulated deficit	(607,852)	(565,121)
Total stockholders’ equity	150,665	98,905
Total liabilities and stockholders’ equity	$ 690,589	$ 558,612

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 261	$ 764
Stockholders’ equity:
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	103,715,000	98,587,000
Common stock, shares outstanding (in shares)	103,715,000	98,587,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 440,221	$ 354,586	$ 267,360
Cost of revenue	77,554	60,818	43,167
Gross profit	362,667	293,768	224,193
Operating expenses:
Sales and marketing	224,277	228,035	173,344
Research and development	101,687	87,064	76,698
General and administrative	73,136	69,468	46,732
Total operating expenses	399,100	384,567	296,774
Loss from operations	(36,433)	(90,799)	(72,581)
Interest income, net	1,244	5,830	2,355
Other expense, net	(1,885)	(680)	(931)
Loss before income taxes	(37,074)	(85,649)	(71,157)
Provision for income taxes	5,657	13,364	2,364
Net loss	(42,731)	(99,013)	(73,521)
Accretion of Series A and B redeemable convertible preferred stock	0	0	(434)
Net loss attributable to common stockholders	$ (42,731)	$ (99,013)	$ (73,955)
Net loss per share attributable to common stockholders, basic and diluted (in usd per share)	$ (0.42)	$ (1.03)	$ (1.38)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	101,009	96,014	53,669

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (42,731)	$ (99,013)	$ (73,521)
Other comprehensive (loss) income, net of tax:
Unrealized (loss) gain on available-for-sale securities	(40)	50	0
Other comprehensive (loss) income	(40)	50	0
Comprehensive loss	$ (42,771)	$ (98,963)	$ (73,521)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock
Beginning balance (in shares) at Dec. 31, 2017						15,848	39,538
Beginning balance at Dec. 31, 2017						$ 49,935	$ 227,800
Redeemable Convertible Preferred Stock [Roll Forward]
Accretion of Series A and B redeemable convertible preferred stock						$ 13	$ 421
Conversion of redeemable convertible preferred stock to common stock upon initial offering period (in shares)						(15,848)	(39,538)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering						$ (49,948)	$ (228,221)
Ending balance (in shares) at Dec. 31, 2018						0	0
Ending balance at Dec. 31, 2018						$ 0	$ 0
Beginning balance (in shares) at Dec. 31, 2017		24,472
Beginning balance at Dec. 31, 2017	$ (371,665)	$ 246	$ 20,676	$ 0	$ (392,587)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Accretion of Series A and B redeemable convertible preferred stock	$ (434)		(434)
Exercise of stock options (in shares)	740	740
Exercise of stock options	$ 1,668	$ 7	1,661
Repurchase of common stock (in shares)		(7)
Repurchase of common stock	(75)	$ (1)	(74)
Issuance of common stock in connection with initial public offering, net of underwriting discounts and commissions and other offering expenses (in shares)		12,535
Issuance of common stock in connection with initial public offering, net of underwriting discounts and commissions and other offering expenses	264,599	$ 125	264,474
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		55,386
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	278,169	$ 554	277,615
Stock-based compensation	23,022		23,022
Other comprehensive loss	0
Net loss	(73,521)				(73,521)
Ending balance (in shares) at Dec. 31, 2018		93,126
Ending balance at Dec. 31, 2018	$ 121,763	$ 931	586,940	0	(466,108)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)	4,205	4,205
Exercise of stock options	$ 19,048	$ 42	19,006
Vesting of restricted stock units (in shares)		479
Vesting of restricted stock units	0	$ 5	(5)
Issuance of common stock under employee stock purchase plan (in shares)		777
Issuance of common stock under employee stock purchase plan	15,129	$ 8	15,121
Stock-based compensation	41,928		41,928
Other comprehensive loss	50			50
Net loss	$ (99,013)				(99,013)
Ending balance (in shares) at Dec. 31, 2019	98,587	98,587
Ending balance at Dec. 31, 2019	$ 98,905	$ 986	662,990	50	(565,121)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)	2,956	2,956
Exercise of stock options	$ 21,709	$ 29	21,680
Vesting of restricted stock units (in shares)		1,504
Vesting of restricted stock units	0	$ 15	(15)
Issuance of common stock under employee stock purchase plan (in shares)		668
Issuance of common stock under employee stock purchase plan	13,040	$ 7	13,033
Stock-based compensation	59,782		59,782
Other comprehensive loss	(40)			(40)
Net loss	$ (42,731)				(42,731)
Ending balance (in shares) at Dec. 31, 2020	103,715	103,715
Ending balance at Dec. 31, 2020	$ 150,665	$ 1,037	$ 757,470	$ 10	$ (607,852)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (42,731)	$ (99,013)	$ (73,521)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Deferred income taxes	161	4,243	0
Depreciation and amortization	10,633	6,880	6,192
Stock-based compensation	59,573	41,610	22,875
Other	1,071	(784)	533
Changes in operating assets and liabilities:
Accounts receivable	(20,012)	(25,941)	(17,408)
Prepaid expenses and other assets	(19,372)	(16,954)	(15,231)
Accounts payable, accrued expenses and accrued compensation	(5,282)	10,513	11,406
Deferred revenue	71,383	72,799	64,085
Other current and noncurrent liabilities	8,808	(4,097)	(1,490)
Net cash provided by (used in) operating activities	64,232	(10,744)	(2,559)
Cash flows from investing activities:
Purchases of property and equipment	(20,277)	(20,674)	(5,733)
Purchases of short-term investments	(184,516)	(242,059)	(117,488)
Sales and maturities of short-term investments	209,148	224,594	0
Business combination, net of cash acquired	(276)	(74,911)	0
Net cash provided by (used in) investing activities	4,079	(113,050)	(123,221)
Cash flows from financing activities:
Proceeds from loan agreement	2,000	0	0
Proceeds from stock issued in connection with the employee stock purchase plan	13,040	15,129	0
Proceeds from the exercise of stock options	21,709	19,048	1,668
Repurchases of common stock	0	0	(75)
Proceeds from initial public offering, net of underwriting discounts and commissions	0	0	268,531
Payments of costs related to initial public offering	0	0	(3,932)
Other financing activities	(346)	(16)	(1,443)
Net cash provided by financing activities	36,403	34,161	264,749
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(916)	(1,080)	(1,063)
Net increase (decrease) in cash and cash equivalents and restricted cash	103,798	(90,713)	137,906
Cash and cash equivalents and restricted cash at beginning of year	74,665	165,378	27,472
Cash and cash equivalents and restricted cash at end of year	178,463	74,665	165,378
Supplemental disclosure of cash flow information:
Cash paid for interest	335	96	111
Cash paid for income taxes	5,729	8,530	1,207
Supplemental cash flow information related to leases:
Cash payments for operating leases	$ 8,807	$ 4,452	$ 4,313

Business and Summary of Significant Accounting Policies	12 Months Ended
Business and Summary of Significant Accounting Policies	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Summary of Significant Accounting Policies	Business and Summary of Significant Accounting Policies Business Description Tenable Holdings, Inc. (the “Company,” “we,” "us," or “our”) is a provider of Cyber Exposure solutions, which is a discipline for managing, measuring and comparing cybersecurity risk in the digital era. Our platform offerings provide broad visibility into security issues such as vulnerabilities, misconfigurations, internal and regulatory compliance violations and other indicators of the state of an organization’s security across IT infrastructure and applications, cloud environments and industrial internet of things and operational technology environments. Basis of Presentation The accompanying consolidated financial statements include the accounts of Tenable Holdings, Inc. and our wholly owned subsidiaries and have been prepared in conformity with United States generally accepted accounting principles (“GAAP”). All intercompany accounts and transactions have been eliminated in consolidation. Initial Public Offering On July 30, 2018, we completed our initial public offering ("IPO"), in which we issued and sold 12,535,000 shares of common stock at a price to the public of $23.00 per share, including 1,635,000 shares of common stock purchased by our underwriters from the full exercise of their over-allotment option. All of the shares sold in the IPO were sold by the Company. We received net proceeds of $264.6 million after deducting underwriting discounts and commissions and other offering expenses. Upon the completion of our IPO, all 15,847,500 shares of our Series A Redeemable Convertible Preferred Stock ("Series A") and 39,538,354 shares of our Series B Redeemable Convertible Preferred Stock ("Series B") automatically converted into an aggregate of 55,385,854 shares of our common stock. Our Amended and Restated Certificate of Incorporation adopted in connection with the IPO authorizes a total of 500,000,000 shares of common stock and 10,000,000 shares of preferred stock. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates include, but are not limited to, the determination of the estimated economic life of perpetual licenses for revenue recognition, the estimated period of benefit for deferred commissions, the useful lives of long-lived assets, the fair value of acquired intangible assets, the valuation of stock-based compensation, including the estimated underlying fair value of our common stock prior to our IPO, the incremental borrowing rate for operating leases, and the valuation of deferred tax assets. We base these estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ significantly from these estimates. Foreign Currency The functional currency for all of our foreign subsidiaries is the U.S. dollar. Assets and liabilities denominated in other currencies are remeasured into U.S. dollars at current exchange rates for monetary assets and liabilities and at historical exchange rates for non-monetary assets and liabilities. We bill our customers in U.S. dollars. Expenses incurred in non U.S. dollar currencies are remeasured into U.S. dollars when incurred. Remeasurement losses in currencies other than the functional currency were $1.7 million, $1.1 million and $1.0 million in 2020, 2019 and 2018, respectively, and are included as a component of other expense, net in the consolidated statements of operations. Revenue Recognition We recognize revenue in order to depict the transfer of promised goods or services to customers in an amount that reflects the consideration we expect to be entitled in exchange for those goods or services. To achieve this, we apply the following steps: •Identify the contract with a customer •Identify the performance obligations in the contract •Determine the transaction price •Allocate the transaction price to the performance obligations in the contract •Recognize revenue when or as performance obligations are satisfied In situations where we enter into a contractual arrangement that includes non-standard terms and conditions, such as acceptance provisions or options to purchase additional products and services, as well as contract modifications, we apply judgment in identifying and assessing the impact on revenue recognition. We generate revenue from subscription arrangements for software and cloud-based solutions, perpetual licenses, maintenance associated with perpetual licenses, and professional services and other revenue. We begin to recognize revenue when control of our software or services is transferred to the customer, which for sales made through distributors is concurrent with the transfer to the end user. Subscription Revenue Subscription arrangements generally have annual or multi-year contractual terms and allow customers to use our software or cloud solutions, including ongoing software updates and the ability to identify the latest cybersecurity vulnerabilities. Revenue is recognized ratably over the subscription term given the critical utility provided by the ongoing updates that are released throughout the contract period. Perpetual License and Maintenance Revenue Our perpetual licenses are generally sold with one or more years of maintenance, which include ongoing software updates and the ongoing ability to identify the latest cybersecurity vulnerabilities. Given the critical utility provided by the ongoing software updates and updated ability to identify network vulnerabilities included in maintenance, we combine the perpetual license and the maintenance into a single performance obligation. Perpetual license arrangements generally contain a material right related to the customer’s ability to renew maintenance at a price that is less than the initial license fee. We apply a practical alternative to allocating a portion of the transaction price to the material right performance obligation and estimate a hypothetical transaction price which includes fees for expected maintenance renewals based on the estimated economic life of the perpetual license contracts. We allocate the transaction price between the cybersecurity subscription provided in the initial contract and the material right related to expected contract renewals based on the hypothetical transaction price. We recognize the amount allocated to the combined license and maintenance performance obligation over the initial contractual period, which is generally one year. We recognize the amount allocated to the material right over the expected maintenance renewal period, which begins at the end of the initial contractual term and is generally four years. We have estimated the five-year economic life of perpetual license contracts based on historical contract attrition, expected renewal periods, the lifecycle of the our technology and other factors. While we believe that the estimates we have made are reasonable and appropriate, different assumptions and estimates could materially impact our reported financial results. Professional Services and Other Revenue Professional services and other revenue is primarily comprised of advisory services and training related to the deployment and optimization of our products. These services do not result in significant customization of our products. Professional services and other revenue is recognized as the services are performed. Contracts with Multiple Performance Obligations In cases where our contracts with customers contain multiple performance obligations, the contract transaction price is allocated on a relative standalone selling price basis. We typically determine standalone selling price based on observable selling prices of our products and services. Variable Consideration We record revenue from sales at the net sales price, which is the transaction price, including estimates of variable consideration when applicable. Certain of our customers may be entitled to receive credits and in certain circumstances, refunds, if service level commitments are not met. We have not historically experienced significant incidents affecting the ability to meet these service level commitments and any estimated refunds related to these agreements have not been material. Sales through our channel network of distributors and resellers are generally discounted as compared to the price that we would sell to an end user. Revenue for sales through our channel network is recorded net of any distributor or reseller margin. Cash and Cash Equivalents We consider all highly liquid financial instruments with an original maturity of three months or less when purchased to be cash equivalents. At December 31, 2020 and 2019, cash and cash equivalents included $0.4 million of restricted cash, which is related to collateral for a lease and credit card deposits. At December 31, 2020 and 2019, cash and cash equivalents excluded $0.2 million and $0.3 million, respectively, of restricted cash, which is related to an account established as collateral for a lease arrangement and is included in other assets on the consolidated balance sheets. Fair Value of Financial Instruments Fair value is defined as the price that would be received from selling an asset, or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. We apply fair value accounting for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. We measure cash and cash equivalents and short-term investments at fair value using a fair value hierarchy of inputs. We approximate fair value by using the carrying amounts for accounts receivable, accounts payable and accrued expenses due to their short-term nature. Investments We currently invest in commercial paper, corporate bonds, and U.S. treasury and agency obligations. Our investments are classified as available-for-sale and recorded at fair value, with unrealized gains and losses reported in accumulated other comprehensive income within stockholders’ equity (deficit). We evaluate potential impairments of available-for-sale debt securities due to credit-related and non-credit-related factors, including market risk, and if it is more-likely-than-not that we would have to sell the security before the recovery of the amortized cost basis. Identified credit-related impairments would be recognized as a charge in the statement of operations. Accounts Receivable Accounts receivable are recorded at the invoiced amount, less an allowance for doubtful accounts, and do not bear interest. We maintain an allowance for doubtful accounts at an amount estimated to be sufficient to cover the risk of collecting less than full payment of the receivables. At each balance sheet date, we evaluate our receivables and assess the allowance for doubtful accounts based on specific customer collection issues and historical write-off trends. Our allowance for doubtful accounts reflects our best estimate of expected future credit losses. We consider various factors that may impact our ability to collect on accounts receivable, including our historical collection experience, age of accounts receivable balances, current conditions, reasonable and supportable forecasts of future economic conditions, as well as other factors. However, given the uncertainty caused by the COVID-19 pandemic and other factors, these estimates may change and future credit losses may differ from our estimates. Expected credit losses from accounts receivable are recognized as expense in our statement of operations. Deferred Commissions Sales commissions, including related fringe benefit costs, are considered to be incremental costs of obtaining a contract. Sales commissions on initial sales are not commensurate with sales commissions on contract renewals and therefore are recognized over an estimated period of benefit, which ranges between three and four years for subscription arrangements and five years for perpetual license arrangements. We estimated the period of benefit based on the expected contract term including renewal periods, the lifecycle of our technology, and other factors. Sales commissions on contract renewals are capitalized and amortized ratably over the contract term as part of sales and marketing expense, with the exception of contracts with renewal periods that are one year or less, in which case the incremental costs are expensed as incurred. Property and Equipment, net Property and equipment, net is stated at historical cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets: three years for computer software and equipment and five years for furniture and fixtures. Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful lives of the assets or the terms of the respective leases. Property and equipment, net includes right-of-use assets acquired under finance leases. Amortization of assets acquired under finance leases is included in depreciation expense. Repairs and maintenance costs are expensed as incurred. Leases We determine if an arrangement contains a lease and the classification of that lease, if applicable, at inception. We have elected to not recognize a lease liability or right-of-use ("ROU") asset for short-term leases (leases with a term of twelve months or less). For contracts with lease and non-lease components, we have elected to not allocate the contract consideration, and account for the lease and non-lease components as a single lease component. Additionally, we enter into arrangements to use shared office spaces and other facilities, and have determined that these arrangements do not contain leases as we do not have the right to use an identified asset. Operating leases are included in operating lease ROU assets, operating lease liabilities and operating lease liabilities (net of current portion) in our consolidated balance sheets. Finance leases are included in property and equipment, other current liabilities and other liabilities in our consolidated balance sheets. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments under the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The implicit rate within our operating leases are generally not determinable and we use our incremental borrowing rate at the lease commencement date to determine the present value of lease payments. The determination of our incremental borrowing rate requires judgment. We determine our incremental borrowing rate for each lease using our current borrowing rate, adjusted for various factors including level of collateralization, term and currency to align with the terms of the lease. The operating lease ROU asset also includes any lease prepayments, offset by lease incentives. Certain of our leases include options to extend or terminate the lease. An option to extend the lease is considered in connection with determining the ROU asset and lease liability when it is reasonably certain we will exercise that option. An option to terminate is considered unless it is reasonably certain we will not exercise the option. Lease expense for lease payments is recognized on a straight-line basis over the term of the lease. Impairment of Long-Lived Assets We evaluate our long-lived assets for impairment whenever events or changes in circumstance indicate that the carrying amount may not be fully recoverable. Recoverability of the long-lived assets is measured by a comparison of the carrying amount of the assets to future undiscounted net cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured as the excess of the carrying amount over the fair value. There was no impairment of long-lived assets in 2020, 2019 or 2018. Business Combinations We account for business combinations by recognizing the fair value of acquired assets and liabilities. The excess purchase consideration over the fair value of acquired assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, we make estimates and assumptions, especially with respect to intangible assets. Estimates in valuing certain identifiable intangible assets include, but are not limited to, projected revenue growth rates, future expected operating expenses, obsolescence projections and an appropriate discount rate. Our estimate of fair value is based upon assumptions we believe to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, we may make adjustments to the fair value of assets acquired and liabilities assumed, with offsetting adjustments to goodwill. Any adjustments made after the measurement period will be reflected in the consolidated statements of operations. Acquisition-related transaction costs are expensed as incurred. Goodwill The excess of the purchase consideration over the fair value of acquired assets and liabilities is recorded as goodwill. We perform our annual impairment assessment on October 1, or more frequently, when events or circumstances indicate impairment may have occurred. We operate as one reporting unit and have elected to first assess qualitative factors to determine whether it is more likely than not that the fair value of the Company as a whole is less than its carrying amount, including goodwill. The qualitative assessment includes an evaluation of relevant events and circumstances, including macroeconomic, industry and market conditions, our overall financial performance, and trends in the value of our common stock. During the periods presented, there were no indications of impairment and it was not more likely than not that goodwill was impaired. Advertising Advertising costs are expensed as they are incurred. We incurred advertising costs of $8.2 million, $5.3 million and $3.3 million in 2020, 2019 and 2018, respectively, which are included in sales and marketing expense in the consolidated statements of operations. Software Development Costs Research and development costs to develop software to be sold, leased or marketed are expensed as incurred up to the point of technological feasibility for the related software product. We have not capitalized development costs for software to be sold, leased or marketed to date, as the software development process is essentially completed concurrent with the establishment of technological feasibility. As such, these costs are expensed as incurred and recognized in research and development costs in the consolidated statements of operations. Software developed for internal use, with no substantive plans to market such software at the time of development, are capitalized and included in property and equipment, net in the consolidated balance sheets. Costs incurred during the preliminary planning and evaluation and post implementation stages of the project are expensed as incurred. Costs incurred during the application development stage of the project are capitalized. In 2020, 2019 and 2018, we capitalized $1.6 million, $4.2 million and $2.4 million, respectively, of development costs related to internal use software. Stock-Based Compensation Stock-based compensation expense related to our restricted stock units ("RSUs"), purchase rights issued under our 2018 Employee Stock Purchase Plan ("2018 ESPP"), stock options and restricted stock is calculated based on the fair value of the awards granted and is recognized on a straight-line basis over the requisite service period, which is generally two to four years. RSUs that include performance-based vesting conditions and are expensed using the accelerated attribution method. We account for forfeitures as they occur. The fair value of RSUs is based on the estimated fair value of our common stock on the date of grant. The fair value of stock options and 2018 ESPP purchase rights is estimated on the grant date using the Black-Scholes option pricing model, which requires us to make assumptions and judgments, including the expected term, expected volatility, and risk-free interest rates. Prior to our IPO, we estimated the fair value of our common stock at the date of grant. Following our IPO, we use the market price of our common stock at the date of grant. Net Loss per Share We calculate basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. Under the two-class method, the net loss attributable to common stockholders is not allocated to the redeemable convertible preferred stock as the holders of our redeemable convertible preferred stock do not have a contractual obligation to share in losses. Under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Net loss attributable to common stockholders is calculated by adjusting net loss by the current period accretion of redeemable convertible preferred stock. Upon the completion of our IPO, all of our Series A and Series B redeemable convertible preferred stock automatically converted into shares of our common stock. Diluted earnings per share attributable to common stockholders is computed by giving effect to all potentially dilutive common stock equivalents in the period, including unvested RSUs, stock options, unvested restricted shares, redeemable convertible preferred stock and shares to be issued under our 2018 ESPP. As we have reported losses for all periods presented, all potentially dilutive securities have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect would be antidilutive. Segment Information We operate as one operating segment as our chief executive officer, who is our chief operating decision maker, reviews financial information on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. Income Taxes Income taxes are accounted for under the asset and liability method. This method requires recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities, net operating loss carryforwards, and tax credit carryforwards. A valuation allowance is provided if it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize tax benefits from an uncertain tax position if it is more likely than not to be sustained upon audit by the relevant taxing authority. Interest and penalties associated with such uncertain tax positions are classified as a component of income tax expense. Recently Adopted Accounting Pronouncements We adopted Accounting Standards Update ("ASU") No. 2016-13 — Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, effective January 1, 2020 using the modified retrospective approach. The new standard replaces the previous incurred loss impairment methodology with a methodology that reflects current expected credit losses for financial assets, including trade receivables, which are not measured at fair value, through net income. The adoption of this guidance did not have a material impact on our condensed consolidated financial statements. Recently Issued Accounting Pronouncements In December 2019, the Financial Accounting Standards Board ("FASB") issued ASU No. 2019-12 - Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This ASU eliminates previously allowed exceptions and clarifies existing guidance in the accounting for income taxes, including in the areas of franchise taxes, the tax basis of goodwill and interim period effects of changes in tax laws. This guidance was effective for us beginning January 1, 2021. We do not expect the impact of adopting this standard to be material for our consolidated financial statements.

Revenue

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Revenue

Disaggregation of Revenue

The following table presents a summary of revenue:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Subscription revenue	$	377,354	$	290,549	$	205,827
Perpetual license and maintenance revenue	50,594		54,173		54,622
Professional services and other revenue	12,273		9,864		6,911
Revenue	$	440,221	$	354,586	$	267,360

Concentrations

We sell and market our products and services through our field sales force that works closely with our channel partners, which includes a network of distributors and resellers, in developing sales opportunities. We use a two-tiered channel model whereby we sell our products and services to our distributors, which in turn sell to resellers, which then sell to end users. We derived 91%, 90% and 88% of revenue through our channel network in 2020, 2019 and 2018, respectively. One of our distributors accounted for 43%, 43% and 46% of revenue in 2020, 2019 and 2018, respectively. That same distributor accounted for 41% and 40% of accounts receivable at December 31, 2020 and 2019, respectively.

Contract Balances

We generally bill our customers in advance and accounts receivable are recorded when we have the right to invoice the customer. Contract liabilities consist of deferred revenue and include customer billings and payments received in advance of performance under the contract. In 2020, 2019 and 2018, we recognized revenue of $274.3 million, $214.0 million and $154.9 million, respectively, that was included in the deferred revenue balance at the beginning of each of the respective periods.

Remaining Performance Obligations

At December 31, 2020, the future estimated revenue related to unsatisfied performance obligations was $443.2 million, of which approximately 76% is expected to be recognized as revenue over the succeeding twelve months, and the remainder expected to be recognized over the four years thereafter.

Deferred Commissions

The following summarizes the activity of deferred incremental costs of obtaining a contract:


	Year Ended December 31,
(in thousands)	2020		2019
Beginning balance	$	72,265	$	59,434
Capitalization of contract acquisition costs	38,756		40,172
Amortization of deferred contract acquisition costs	(32,145)		(27,341)
Ending balance	$	78,876	$	72,265

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Cash and Cash Equivalents and Short-Term Investments

12 Months Ended

Dec. 31, 2020

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents, and Marketable Securities

Cash and Cash Equivalents and Short-Term Investments

The following tables summarize the amortized cost, unrealized gain and loss and estimated fair value of cash equivalents and short-term investments:


	December 31, 2020
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Cash equivalents:
Money market funds	$	44,153	$	—	$	—	$	44,153
Commercial paper	4,500		—		—		4,500
Total cash equivalents	$	48,653	$	—	$	—	$	48,653

Short-term investments:
Commercial paper	$	71,425	$	—	$	—	$	71,425
Corporate bonds	4,502		3		—		4,505
U.S. Treasury and agency obligations	37,686		7		—		37,693
Total short-term investments	$	113,613	$	10	$	—	$	113,623


	December 31, 2019
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Cash equivalents:
Money market funds	$	13,588	$	—	$	—	$	13,588
Commercial paper	8,987		—		—		8,987
Total cash equivalents	$	22,575	$	—	$	—	$	22,575

Short-term investments:
Commercial paper	$	61,371	$	—	$	—	$	61,371
Corporate bonds	23,856		14		(1)		23,869
U.S. Treasury and agency obligations	52,627		38		(1)		52,664
Total short-term investments	$	137,854	$	52	$	(2)	$	137,904

At December 31, 2020, all of our short-term investments had maturities within the next twelve months.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

We measure certain financial instruments at fair value using a fair value hierarchy. In the hierarchy, assets are classified based on the lowest level inputs used in valuation into the following categories:

•Level 1 — Quoted prices in active markets for identical assets and liabilities;

•Level 2 — Observable inputs including quoted market prices for similar assets and liabilities in active markets, quoted prices for identical assets and liabilities in inactive markets, or inputs that are corroborated by observable market data; and

•Level 3 — Unobservable inputs.

The following tables summarize assets that are measured at fair value on a recurring basis:


	December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	44,153	$	—	$	—	$	44,153
Commercial paper	—		4,500		—		4,500
	$	44,153	$	4,500	$	—	$	48,653

Short-term investments
Commercial paper	$	—	$	71,425	$	—	$	71,425
Corporate bonds	—		4,505		—		4,505
U.S. Treasury and agency obligations	—		37,693		—		37,693
	$	—	$	113,623	$	—	$	113,623


	December 31, 2019
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	13,588	$	—	$	—	$	13,588
Commercial paper	—		8,987		—		8,987
	$	13,588	$	8,987	$	—	$	22,575

Short-term investments
Commercial paper	$	—	$	61,371	$	—	$	61,371
Corporate bonds	—		23,869		—		23,869
U.S. Treasury and agency obligations	—		52,664		—		52,664
	$	—	$	137,904	$	—	$	137,904

We did not have any liabilities measured and recorded at fair value at December 31, 2020 and 2019

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property and Equipment, Net

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following:


	December 31,
(in thousands)	2020		2019
Computer software and equipment	$	22,930	$	21,234
Furniture and fixtures	6,011		4,504
Leasehold improvements	26,210		16,953
Right-of-use assets under finance leases	1,571		1,866
Total	56,722		44,557
Less: accumulated depreciation and amortization	(17,802)		(17,710)
Property and equipment, net	$	38,920	$	26,847

Depreciation and amortization related to property and equipment was $8.1 million, $6.3 million and $5.6 million in 2020, 2019 and 2018, respectively.

Acquisition, Goodwill and Intangible Assets (Notes)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Acquisition, Goodwill and Intangible Assets

Business Combination

On December 2, 2019, we acquired Indegy Ltd. (“Indegy”) to expand our OT-specific capabilities. Through a share purchase agreement, we acquired 100% of Indegy's equity in exchange for total cash consideration of $80.3 million, including cash acquired of $5.5 million and a working capital adjustment of $0.3 million paid in November 2020. As part of the acquisition, all unvested options to acquire ordinary shares of Indegy vested immediately, and all options to acquire ordinary shares of Indegy were canceled in exchange for a right to receive a portion of the cash consideration. We paid $1.8 million for unvested options, which is included in post-acquisition stock-based compensation expense in our consolidated statements of operations.

The cash consideration was allocated as follows:


(in thousands)
Cash acquired	$	5,500
Other net tangible assets acquired	735
Deferred tax assets, net	4,243
Intangible assets	15,700
Goodwill	54,149
Total purchase price allocation	$	80,327

Acquired intangible assets and their estimated useful lives at the date of acquisition are as follows:


	Intangible Assets
(dollars in thousands)	Cost		Weighted Average Useful Life
Acquired technology	$	15,500	7 years
Trade name	200		2 years
Acquired intangible assets	$	15,700

The Indegy results of operations and pro forma results were not material to the consolidated statement of operations in 2019.

In general and administrative expense, we recognized $0.3 million of acquisition-related transaction costs in 2020. In 2019, we recognized $4.0 million of acquisition-related transaction costs, including $2.1 million of expense related to the intercompany transfer of intellectual property.

Goodwill and Acquired Intangible Assets

The changes in the carrying amount of goodwill are as follows:


(in thousands)
Balance at December 31, 2019	$	54,138
Working capital adjustment	276
Balance at December 31, 2020	$	54,414

The excess purchase consideration over the fair value of acquired assets and liabilities is recorded as goodwill. The acquired goodwill reflects the synergies we expect from integrating Indegy's capabilities into our enterprise platform

offerings and from marketing and selling these new capabilities to our customers. None of the acquired goodwill is tax deductible.

Acquired intangible assets subject to amortization are as follows:


	December 31, 2020						December 31, 2019
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Acquired technology	$	17,325	$	(4,224)	$	13,101	$	17,325	$	(2,009)	$	15,316
Trade name	200		(108)		92		200		(8)		192
	$	17,525	$	(4,332)	$	13,193	$	17,525	$	(2,017)	$	15,508

Amortization of acquired intangible assets was $2.3 million, $0.6 million, and $0.6 million in 2020, 2019 and 2018, respectively.

At December 31, 2020, estimated future amortization of intangible assets is as follows:


(in thousands)
Year ending December 31,
2021	$	2,306
2022	2,214
2023	2,214
2024	2,214
2025	2,214
Thereafter	2,031
Total	$	13,193

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

We have operating leases for office facilities and finance leases for computer and office equipment. Our leases have remaining terms of less than one year to just over eleven years, some of which include one or more options to renew, with renewal terms up to five years and some of which include options to terminate the leases within the next one to four years. The ROU assets and liabilities at December 31, 2020 assume we exercise the option to early terminate one of our leases in 2025.

The components of lease expense were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Operating lease cost	$	9,870	$	6,045	$	3,694

Finance lease cost
Amortization of ROU assets	$	242	$	607	$	614
Interest on lease liabilities	6		7		35
Total finance lease cost	$	248	$	614	$	649

Rent expense for short-term leases in 2020, 2019 and 2018 was not material.

Supplemental information related to leases was as follows:


	December 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	10.0 years	10.0 years
Weighted average discount rate	5.6%	5.8%


	Year Ended December 31,
(in thousands)	2020		2019		2018
ROU assets obtained in exchange for lease obligations
Operating leases	$	3,188	$	39,170	$	1,525
Finance leases	—		11		15

In 2020, we received proceeds from lease incentives of $14.2 million. The proceeds from lease incentives received are included with the change in the lease liabilities under the other current and noncurrent liabilities caption in the operating activities section of the statement of cash flows.

Maturities of operating lease liabilities at December 31, 2020 were as follows:


(in thousands)
Year ending December 31,
2021	$	3,891
2022	8,050
2023	7,711
2024	7,866
2025	7,435
Thereafter	44,525
Total lease payments	79,478
Less: Imputed interest	(21,134)
Total	$	58,344

Leases

The components of lease expense were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Operating lease cost	$	9,870	$	6,045	$	3,694

Finance lease cost
Amortization of ROU assets	$	242	$	607	$	614
Interest on lease liabilities	6		7		35
Total finance lease cost	$	248	$	614	$	649

Rent expense for short-term leases in 2020, 2019 and 2018 was not material.

Supplemental information related to leases was as follows:


	December 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	10.0 years	10.0 years
Weighted average discount rate	5.6%	5.8%


	Year Ended December 31,
(in thousands)	2020		2019		2018
ROU assets obtained in exchange for lease obligations
Operating leases	$	3,188	$	39,170	$	1,525
Finance leases	—		11		15

Maturities of operating lease liabilities at December 31, 2020 were as follows:


(in thousands)
Year ending December 31,
2021	$	3,891
2022	8,050
2023	7,711
2024	7,866
2025	7,435
Thereafter	44,525
Total lease payments	79,478
Less: Imputed interest	(21,134)
Total	$	58,344

Debt	12 Months Ended
Debt	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	Debt In July 2020, we entered into a new $45.0 million senior secured credit facility ("2020 Credit Facility") with Silicon Valley Bank in connection with the expiration of our $25.0 million revolving credit facility ("2017 Credit Facility"). The 2020 Credit Facility bears interest at either LIBOR plus 2%, with a 1% LIBOR floor, or the base rate plus 1%, and terminates on July 24, 2022. A commitment fee of 0.35% per annum is payable quarterly in arrears based on the unused portion. The obligations under 2020 Credit Facility are secured by a lien on our tangible and intangible property except intellectual property and certain subsidiaries and by a pledge of all of the equity interests of the Company's material direct and indirect domestic subsidiaries and 65% of each class of capital stock of any material first-tier foreign subsidiaries, subject to limited exceptions. The 2020 Credit Facility includes a $45.0 million uncommitted expansion, as well as a $10.0 million sublimit for the issuance of letters of credit and a swingline sub-facility of up to $10.0 million, and has a financial covenant requiring a minimum consolidated quick ratio of at least 1.5:1.0 on the last day of each quarter. In 2020 and 2019, there were no amounts outstanding under our 2020 Credit Facility or, prior to its expiration, the 2017 Credit Facility. At December 31, 2020, we were in compliance with the financial covenant and our borrowing capacity was reduced by $5.5 million related to standby letters of credit.

Redeemable Convertible Preferred Stock and Common Stock	12 Months Ended
Redeemable Convertible Preferred Stock and Common Stock	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Redeemable Convertible Preferred Stock and Common Stock	Redeemable Convertible Preferred Stock and Common Stock Redeemable Convertible Preferred Stock In October 2012, Tenable, Inc. (now a wholly owned subsidiary of Tenable Holdings, Inc.) issued 15,847,500 shares of Series A redeemable convertible preferred stock. In December 2015, we issued 15,847,500 shares, par value of $0.01, of Series A redeemable convertible preferred stock ("Series A") in exchange for Series A redeemable convertible preferred stock of Tenable, Inc. in connection with a recapitalization. This exchange was made on a one for one basis. In addition, we authorized 42,000,000 shares and issued 39,538,354 shares, par value of $0.01, of Series B redeemable convertible preferred stock ("Series B"). Upon completion of our IPO, Series A and Series B (together, the “Redeemable Convertible Preferred Stock”) automatically converted into an aggregate of 55,385,854 shares of our common stock. We accreted the Redeemable Convertible Preferred Stock to the redemption price at the redemption date using the effective interest method. Upon completion of our IPO, the accretion rights of the Redeemable Convertible Preferred Stock were terminated. Upon the completion of our IPO, we filed an Amended and Restated Certificate of Incorporation, authorizing a total of 500,000,000 shares of common stock and 10,000,000 shares of preferred stock. There were no shares of preferred stock issued or outstanding at December 31, 2020 or 2019. Common Stock The voting, dividend, and liquidation rights of common stockholders are subject to, and qualified by, the rights of preferred stockholders. The common stockholders are entitled to receive dividends when, as and if, declared by the Board of Directors, subject to preferential dividend rights of preferred stockholders. Upon dissolution or liquidation, our common stockholders will be entitled to receive all assets available for distribution to stockholders, subject to any preferential rights of preferred stockholders.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

In 2018, our Board of Directors adopted, and our stockholders approved, our 2018 Equity Incentive Plan ("2018 Plan"). Under the evergreen provision in the 2018 Plan, in January 2020 we reserved an additional 4,929,361 shares of our common stock. At December 31, 2020, there were 17,766,262 shares available for grant.

Stock-based compensation expense included in the consolidated statements of operations was as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Cost of revenue	$	3,158	$	2,817	$	1,707
Sales and marketing	19,842		16,032		6,911
Research and development	14,794		8,911		5,804
General and administrative	21,779		15,683		8,453
Total stock-based compensation expense	$	59,573	$	43,443	$	22,875

At December 31, 2020, the unrecognized stock-based compensation expense related to unvested RSUs was $107.5 million, which is expected to be recognized over an estimated weighted average remaining period of 2.8 years.

At December 31, 2020, the unrecognized stock-based compensation expense related to outstanding stock options was $10.4 million, which is expected to be recognized over an estimated remaining weighted average period of 1.3 years.

At December 31, 2020, the unrecognized stock-based compensation expense related to unvested awards of restricted stock was immaterial.

Restricted Stock and RSUs

A summary of our restricted stock and RSU activity is presented below:


	Restricted Stock			RSUs
(in thousands, except for per share data)	Number of Shares	Weighted Average Grant Date Fair Value		Number of Shares	Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2017	1,583	$	4.25	—	$	—
Granted	—	—		1,200	18.75
Vested	(693)	4.25		—	—
Forfeited	—	—		(71)	16.27
Unvested balance at December 31, 2018	890	4.25		1,129	18.90
Granted	—	—		2,715	27.81
Vested	(395)	4.25		(479)	18.28
Forfeited	—	—		(471)	25.21
Unvested balance at December 31, 2019	495	4.25		2,894	26.34
Granted	—	—		3,570	28.23
Vested	(396)	4.25		(1,504)	25.37
Forfeited	—	—		(470)	26.68
Unvested balance at December 31, 2020	99	4.25		4,490	28.13

RSUs granted under our stock incentive plans generally vest over a period of two to four years. RSUs granted before July 30, 2018 vest upon the satisfaction of both service-based and performance-based vesting conditions. The performance-based condition was satisfied upon the completion of our IPO. RSUs granted after July 30, 2018 vest upon the satisfaction of a service-based vesting condition.

Stock Options

A summary of our stock option activity is below:


(in thousands, except for per share data and years)	Number of Shares	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2017	14,573	$	4.38	8.2	$	77,020
Granted	6,108	15.17
Exercised	(740)	2.26			9,902
Forfeited/canceled	(722)	7.23
Outstanding at December 31, 2018	19,219	7.78		8.0	277,114
Granted	—	—
Exercised	(4,205)	4.53			98,378
Forfeited/canceled	(2,075)	10.63
Outstanding at December 31, 2019	12,939	8.38		7.1	201,608
Granted	—	—
Exercised	(2,956)	7.34			73,277
Forfeited/canceled	(542)	10.80
Outstanding at December 31, 2020	9,441	8.56		6.4	412,547
Exercisable at December 31, 2020	6,189	6.53		6.1	283,024

At December 31, 2020, there were 9.4 million stock options outstanding that were vested and expected to vest.

Stock options granted under our stock incentive plans have a maximum term of ten years, generally vest over a period of three to four years, and the exercise price cannot be less than the fair market value on the date of grant. In 2018, we granted stock options to employees that had a per share weighted average grant date fair value of $6.84. Estimating the fair value of stock options using the Black-Scholes option-pricing model requires assumptions as to the estimated term of the option, the risk-free interest rate, the expected volatility of the price of our common stock, the expected dividend yield, and the fair value of our underlying common stock prior to our IPO.

Fair Value of Common Stock. Following our IPO, we use the market price of our common stock at the date of grant. Prior to our IPO, the lack of an active public market for our common stock required an estimate of the fair value of the common stock for granting stock options and restricted shares, and for determining stock-based compensation expense. Contemporaneous third-party valuations were obtained to assist in determining the fair value of our common stock. The contemporaneous valuations were performed in accordance with applicable methodologies, approaches and assumptions of the technical practice-aid issued by the American Institute of Certified Public Accountants Practice Aid entitled Valuation of Privately-Held Company Equity Securities Issued as Compensation.

Expected Term. This is the period of time that the options granted are expected to remain unexercised. We employ the simplified method to calculate the average expected term.

Expected Volatility. Volatility is a measure of the amount by which a financial variable, such as a share price, has fluctuated (historical volatility) or is expected to fluctuate (expected volatility) during a period. We have identified several public entities of similar size, complexity, and stage of development and estimate our volatility based on the volatility of the common stock of these companies.

Risk-Free Interest Rate. This is the U.S. Treasury rate, having a term that most closely resembles the expected life of the stock option.

Expected Dividend Yield. We have never declared or paid dividends and have no plans to do so in the foreseeable future.

The fair value of each stock option was estimated on the grant date based on the following assumptions:


			Year Ended December 31, 2018
Expected term (in years)			6.3
Expected volatility			41.3% — 43.3%
Risk-free interest rate			2.7% — 2.9%
Expected dividend yield			—
Expected forfeiture rate			—

2018 Employee Stock Purchase Plan

In 2018, our board of directors adopted, and our stockholders approved, our 2018 ESPP. Under the evergreen provision, in January 2020 we reserved an additional 1,478,808 shares of our common stock for issuance. At December 31, 2020, there were 5,431,176 shares reserved for issuance under the 2018 ESPP.

Under our 2018 ESPP, employees may set aside up to 15% of their gross earnings, on an after-tax basis, to purchase our common stock at a discounted price, which is calculated at 85% of the lower of the fair market value of our common stock on the first day of an offering or on the date of purchase. The 2018 ESPP permits offerings up to 27 months in duration, with one or more purchase periods in each offering. Additionally, in cases where the fair market value of a share of our common stock on the first day of a new purchase period within an offering is less than or equal to the fair market value of a share of our common stock at the beginning of the offering, that offering will be terminated and participants will be automatically enrolled in a new offering with a new 24-month duration with purchase periods every six months.

In 2020, employees purchased 667,719 shares of our common stock at a weighted average price of $19.53 per share, resulting in $13.0 million of cash proceeds.

In 2019, employees purchased 776,809 shares of our common stock at a weighted average price of $19.48 resulting in $15.1 million of cash proceeds.

At December 31, 2020 and 2019 there was $6.5 million and $5.4 million, respectively, of employee contributions to the 2018 ESPP included in accrued compensation. At December 31, 2020, the unrecognized stock-based compensation expense related to our 2018 ESPP was $4.1 million, which is expected to be recognized over the remaining weighted average period of 0.6 years.

The fair value of the 2018 ESPP purchase rights was estimated on the offering or modification dates using a Black-Scholes option-pricing model and the following assumptions:


	Year Ended December 31,
	2020	2019	2018
Expected term (in years)	0.5 — 2.0	0.5 — 2.0	0.6 — 2.1
Expected volatility	41.6% — 60.1%	34.4% — 44.6%	31.9% — 33.5%
Risk-free interest rate	0.1% — 0.9%	1.5% — 2.5%	2.3% — 2.7%
Expected dividend yield	—	—	—

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders:


	Year Ended December 31,
(in thousands, except per share data)	2020		2019		2018
Net loss attributable to common stockholders	$	(42,731)	$	(99,013)	$	(73,955)

Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	101,009		96,014		53,669
Net loss per share attributable to common stockholders, basic and diluted	$	(0.42)	$	(1.03)	$	(1.38)

The following potentially dilutive securities have been excluded from the diluted per share calculations because they would have been antidilutive:


	Year Ended December 31,
(in thousands)	2020	2019	2018
Stock options	9,441	12,939	19,219
RSUs	4,490	2,894	1,129
Restricted stock	99	495	890
Shares to be issued under the 2018 ESPP	321	278	320
Total	14,351	16,606	21,558

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

U.S. and international components of the loss before income taxes were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
U.S. (loss) income	$	(6,719)	$	(21,644)	$	1,429
Foreign loss	(30,355)		(64,005)		(72,586)
Total loss before income taxes	$	(37,074)	$	(85,649)	$	(71,157)

The components of the provision for income taxes were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Current
Federal	$	3	$	(224)	$	—
State	17		100		58
Foreign	5,476		9,245		2,306
Total current tax expense	5,496		9,121		2,364
Deferred
Federal	102		—		—
State	59		—		—
Foreign	—		4,243		—
Total deferred tax expense	161		4,243		—
Total provision for income taxes	$	5,657	$	13,364	$	2,364

The items accounting for the difference between income taxes computed at the federal statutory rate and our effective tax rate were as follows:


	Year Ended December 31,
	2020		2019		2018
U.S. federal statutory tax rate	21.0	%	21.0	%	21.0	%
State and local taxes	10.8		4.8		(1.5)
Research and development tax credit	11.1		3.1		1.9
Stock-based compensation	34.4		19.0		0.5
Uncertain tax positions	0.1		(0.5)		(1.0)
Foreign tax rate differential	(10.6)		(7.9)		(9.4)
Change in valuation allowance	(81.2)		(40.8)		(12.6)
Gain on sale of intellectual property	—		(12.3)		—


Foreign withholding tax	(3.3)		(1.4)		(1.1)
Other	2.4		(0.6)		(1.1)
Effective tax rate	(15.3)	%	(15.6)	%	(3.3)	%

We maintain a valuation allowance on U.S. federal, state and foreign net deferred tax assets as the realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain.

The components of the deferred tax assets and liabilities were as follows:


	December 31,
(in thousands)	2020		2019
Deferred tax assets:
Net operating losses	$	89,053	$	65,494
Deferred revenue	13,454		13,891
Stock-based compensation	11,846		10,032
Tax credits	11,565		7,585
Leases	15,238		10,451
Accrued compensation	1,271		918
Other	379		263
Total deferred tax assets	142,806		108,634
Valuation allowance	(112,363)		(82,237)
Net deferred tax assets	30,443		26,397
Deferred tax liabilities:
Deferred commissions	(15,987)		(15,003)
Property and equipment	(13,257)		(10,086)
Intangible assets	(962)		(919)
Other	(398)		(389)
Total deferred tax liabilities	(30,604)		(26,397)
Net deferred tax liabilities	$	(161)	$	—

At December 31, 2020, we had net operating loss (“NOL”) carryforwards for federal, state and foreign tax purposes of $254.7 million, $188.5 million, and $209.8 million, respectively, which will begin to expire in 2030, as well as $13.9 million of federal, state and foreign research and development tax credits, foreign tax credits, minimum tax credits and certain states’ job creation tax credits. The federal research and development and foreign tax credits will begin to expire in 2032 and the state job creation tax credits will begin to expire in 2021.

In December 2019, we sold acquired intellectual property through an intercompany transaction, which resulted in $6.3 million of current tax expense and $4.2 million of deferred tax expense in Israel.

We are currently subject to the annual limitation under Sections 382 and 383 of the Internal Revenue Code. We will not be precluded from realizing the NOL carryforward and tax credits but may be limited in the amount we could utilize in any given tax year in the event that the federal and state taxable income will exceed the limitation imposed by Section 382. The amount of the annual limitation is determined based on our value immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years.

At December 31, 2020 and 2019, the total amount of gross unrecognized tax benefits was $7.1 million and $7.2 million, respectively, which, if recognized, would impact our effective tax rate by less than $0.1 million in each year. Interest and penalties associated with uncertain tax positions recognized as a component of income tax expense were immaterial in 2020, 2019 and 2018.

The change in gross unrecognized tax benefits, excluding accrued interest, were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Unrecognized tax benefits at the beginning of the period	$	7,163	$	4,814	$	1,199
Additions for tax positions in the current year	232		2,306		3,571
Increase in prior year positions	62		90		102
Decrease in prior year positions	(334)		(89)		(58)
Acquisitions	—		42		—
Unrecognized tax benefits at the end of the period	$	7,123	$	7,163	$	4,814

We file income tax returns in the United States, including various state jurisdictions. Our subsidiaries file income tax returns in various foreign jurisdictions. Tax years after 2014 remain open to examination by the major taxing jurisdictions in which we are subject to tax. At December 31, 2020, we were not under examination for income tax audits by the Internal Revenue Service or any state or foreign tax jurisdiction.

Depending on the jurisdiction, distributions of earnings could be subject to withholding taxes at rates applicable to the distributing jurisdiction. As we intend to continue to reinvest the earnings of foreign subsidiaries indefinitely, we have not provided for a U.S. income tax liability and foreign withholding taxes on undistributed foreign earnings of foreign subsidiaries. It is not practicable for us to determine the amount of unrecognized tax expense on these reinvested international earnings.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Geographic Information

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Geographic Information

We operate as one operating segment. Our Chief Executive Officer, who is our chief operating decision maker, reviews financial information on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance.

Revenue by region, based on the address of the end user as specified in our subscription, license or service agreements, was as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
The Americas	$	293,734	$	243,616	$	191,204
Europe, Middle East and Africa	102,155		77,676		53,839
Asia Pacific	44,332		33,294		22,317
Revenue	$	440,221	$	354,586	$	267,360

Customers located in the United States accounted for 61%, 63% and 67% of revenue in 2020, 2019 and 2018, respectively. No other country accounted for 10% or more of revenue in the periods presented.

Our property and equipment, net by geographic area is summarized as follows:


	December 31,
(in thousands)	2020		2019
United States	$	35,406	$	21,464
International	3,514		5,383
Property and equipment, net	$	38,920	$	26,847

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Benefit Plans	12 Months Ended
Benefit Plans	Dec. 31, 2020
Retirement Benefits [Abstract]
Benefit Plans	Benefit PlansWe maintain a contributory defined contribution 401(k) plan for our U.S. employees, where company-matched contributions are fully vested. Additional contributory plans are in effect internationally, including in the U.K. and Ireland. Our contribution expense for such plans was $6.5 million, $6.2 million and $4.8 million in 2020, 2019 and 2018, respectively.

- Definition

The entire disclosure for retirement benefits.

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+ Details

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsOn February 10, 2021, we entered into a share purchase agreement to acquire Alsid SAS for a total purchase price of $98 million in cash, subject to customary purchase price adjustments. The acquisition is expected to close early in the second quarter of 2021, subject to regulatory approvals and the satisfaction of customary closing conditions.

Quarterly Results (unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (unaudited)

The following tables summarize our unaudited quarterly consolidated statements of operations data for each of the eight quarters through the period ended December 31, 2020. The information for each of these quarters has been prepared on the same basis as our audited annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal, recurring nature that are necessary for the fair presentation of the results of operations for these periods. This data should be read in conjunction with our consolidated financial statements included elsewhere in this Annual Report on Form 10-K. Historical results are not necessarily indicative of the results that may be expected in the future, and the quarterly results are not necessarily indicative of the results that may be expected for the full year or any other period.


	Three Months Ended
(in thousands, except per share amounts)	March 31, 2020		June 30, 2020		September 30, 2020		December 31, 2020
Revenue	$	102,648	$	107,209	$	112,282	$	118,082
Cost of revenue	18,701		19,142		19,394		20,317
Gross profit	83,947		88,067		92,888		97,765
Operating expenses:
Sales and marketing	59,855		55,443		53,045		55,934
Research and development	26,831		25,310		25,128		24,418
General and administrative	18,933		17,879		18,180		18,144
Total operating expenses	105,619		98,632		96,353		98,496
Loss from operations	(21,672)		(10,565)		(3,465)		(731)
Interest income (expense), net	734		455		(12)		67
Other expense, net	(960)		(298)		(561)		(66)
Loss before income taxes	(21,898)		(10,408)		(4,038)		(730)
Provision for income taxes	1,079		1,552		1,820		1,206
Net loss	(22,977)		(11,960)		(5,858)		(1,936)
Net loss per share, basic and diluted	$	(0.23)	$	(0.12)	$	(0.06)	$	(0.02)


	Three Months Ended
(in thousands, except per share amounts)	March 31, 2019		June 30, 2019		September 30, 2019		December 31, 2019
Revenue	$	80,301	$	85,384	$	91,852	$	97,049
Cost of revenue	13,226		13,918		15,245		18,429
Gross profit	67,075		71,466		76,607		78,620
Operating expenses:
Sales and marketing	52,689		56,015		56,699		62,632
Research and development	21,935		21,698		20,763		22,668
General and administrative	15,136		15,987		17,472		20,873
Total operating expenses	89,760		93,700		94,934		106,173
Loss from operations	(22,685)		(22,234)		(18,327)		(27,553)
Interest income, net	1,556		1,594		1,527		1,153
Other expense, net	(214)		(122)		(240)		(104)
Loss before income taxes	(21,343)		(20,762)		(17,040)		(26,504)
Provision for income taxes	97		866		600		11,801
Net loss	(21,440)		(21,628)		(17,640)		(38,305)
Net loss per share, basic and diluted	$	(0.23)	$	(0.23)	$	(0.18)	$	(0.39)

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

SCHEDULE II

SUPPLEMENTARY CONSOLIDATED FINANCIAL STATEMENT SCHEDULE

VALUATION AND QUALIFYING ACCOUNTS


(in thousands)	Balance at Beginning of Year		Additions Charged to Costs and Expenses		Deductions(1)		Balance at End of Year
Allowance for Doubtful Accounts
Year Ended December 31, 2020	$	764	$	336	$	(839)	$	261
Year Ended December 31, 2019	188		967		(391)		764
Year Ended December 31, 2018	160		149		(121)		188

_______________

(1) Consists of write-offs of uncollectible accounts, net of recoveries.

Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Tenable Holdings, Inc. and our wholly owned subsidiaries and have been prepared in conformity with United States generally accepted accounting principles (“GAAP”). All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates include, but are not limited to, the determination of the estimated economic life of perpetual licenses for revenue recognition, the estimated period of benefit for deferred commissions, the useful lives of long-lived assets, the fair value of acquired intangible assets, the valuation of stock-based compensation, including the estimated underlying fair value of our common stock prior to our IPO, the incremental borrowing rate for operating leases, and the valuation of deferred tax assets. We base these estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ significantly from these estimates.
Foreign Currency	Foreign Currency The functional currency for all of our foreign subsidiaries is the U.S. dollar. Assets and liabilities denominated in other currencies are remeasured into U.S. dollars at current exchange rates for monetary assets and liabilities and at historical exchange rates for non-monetary assets and liabilities. We bill our customers in U.S. dollars. Expenses incurred in non U.S. dollar currencies are remeasured into U.S. dollars when incurred. Remeasurement losses in currencies other than the functional currency were $1.7 million, $1.1 million and $1.0 million in 2020, 2019 and 2018, respectively, and are included as a component of other expense, net in the consolidated statements of operations.
Revenue Recognition	Revenue Recognition We recognize revenue in order to depict the transfer of promised goods or services to customers in an amount that reflects the consideration we expect to be entitled in exchange for those goods or services. To achieve this, we apply the following steps: •Identify the contract with a customer •Identify the performance obligations in the contract •Determine the transaction price •Allocate the transaction price to the performance obligations in the contract •Recognize revenue when or as performance obligations are satisfied In situations where we enter into a contractual arrangement that includes non-standard terms and conditions, such as acceptance provisions or options to purchase additional products and services, as well as contract modifications, we apply judgment in identifying and assessing the impact on revenue recognition. We generate revenue from subscription arrangements for software and cloud-based solutions, perpetual licenses, maintenance associated with perpetual licenses, and professional services and other revenue. We begin to recognize revenue when control of our software or services is transferred to the customer, which for sales made through distributors is concurrent with the transfer to the end user. Subscription Revenue Subscription arrangements generally have annual or multi-year contractual terms and allow customers to use our software or cloud solutions, including ongoing software updates and the ability to identify the latest cybersecurity vulnerabilities. Revenue is recognized ratably over the subscription term given the critical utility provided by the ongoing updates that are released throughout the contract period. Perpetual License and Maintenance Revenue Our perpetual licenses are generally sold with one or more years of maintenance, which include ongoing software updates and the ongoing ability to identify the latest cybersecurity vulnerabilities. Given the critical utility provided by the ongoing software updates and updated ability to identify network vulnerabilities included in maintenance, we combine the perpetual license and the maintenance into a single performance obligation. Perpetual license arrangements generally contain a material right related to the customer’s ability to renew maintenance at a price that is less than the initial license fee. We apply a practical alternative to allocating a portion of the transaction price to the material right performance obligation and estimate a hypothetical transaction price which includes fees for expected maintenance renewals based on the estimated economic life of the perpetual license contracts. We allocate the transaction price between the cybersecurity subscription provided in the initial contract and the material right related to expected contract renewals based on the hypothetical transaction price. We recognize the amount allocated to the combined license and maintenance performance obligation over the initial contractual period, which is generally one year. We recognize the amount allocated to the material right over the expected maintenance renewal period, which begins at the end of the initial contractual term and is generally four years. We have estimated the five-year economic life of perpetual license contracts based on historical contract attrition, expected renewal periods, the lifecycle of the our technology and other factors. While we believe that the estimates we have made are reasonable and appropriate, different assumptions and estimates could materially impact our reported financial results. Professional Services and Other Revenue Professional services and other revenue is primarily comprised of advisory services and training related to the deployment and optimization of our products. These services do not result in significant customization of our products. Professional services and other revenue is recognized as the services are performed. Contracts with Multiple Performance Obligations In cases where our contracts with customers contain multiple performance obligations, the contract transaction price is allocated on a relative standalone selling price basis. We typically determine standalone selling price based on observable selling prices of our products and services. Variable Consideration We record revenue from sales at the net sales price, which is the transaction price, including estimates of variable consideration when applicable. Certain of our customers may be entitled to receive credits and in certain circumstances, refunds, if service level commitments are not met. We have not historically experienced significant incidents affecting the ability to meet these service level commitments and any estimated refunds related to these agreements have not been material. Sales through our channel network of distributors and resellers are generally discounted as compared to the price that we would sell to an end user. Revenue for sales through our channel network is recorded net of any distributor or reseller margin. Deferred Commissions Sales commissions, including related fringe benefit costs, are considered to be incremental costs of obtaining a contract. Sales commissions on initial sales are not commensurate with sales commissions on contract renewals and therefore are recognized over an estimated period of benefit, which ranges between three and four years for subscription arrangements and five years for perpetual license arrangements. We estimated the period of benefit based on the expected contract term including renewal periods, the lifecycle of our technology, and other factors. Sales commissions on contract renewals are capitalized and amortized ratably over the contract term as part of sales and marketing expense, with the exception of contracts with renewal periods that are one year or less, in which case the incremental costs are expensed as incurred.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid financial instruments with an original maturity of three months or less when purchased to be cash equivalents. At December 31, 2020 and 2019, cash and cash equivalents included $0.4 million of restricted cash, which is related to collateral for a lease and credit card deposits. At December 31, 2020 and 2019, cash and cash equivalents excluded $0.2 million and $0.3 million, respectively, of restricted cash, which is related to an account established as collateral for a lease arrangement and is included in other assets on the consolidated balance sheets.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received from selling an asset, or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. We apply fair value accounting for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. We measure cash and cash equivalents and short-term investments at fair value using a fair value hierarchy of inputs. We approximate fair value by using the carrying amounts for accounts receivable, accounts payable and accrued expenses due to their short-term nature.
Investments	Investments We currently invest in commercial paper, corporate bonds, and U.S. treasury and agency obligations. Our investments are classified as available-for-sale and recorded at fair value, with unrealized gains and losses reported in accumulated other comprehensive income within stockholders’ equity (deficit). We evaluate potential impairments of available-for-sale debt securities due to credit-related and non-credit-related factors, including market risk, and if it is more-likely-than-not that we would have to sell the security before the recovery of the amortized cost basis. Identified credit-related impairments would be recognized as a charge in the statement of operations.
Accounts Receivable	Accounts Receivable Accounts receivable are recorded at the invoiced amount, less an allowance for doubtful accounts, and do not bear interest. We maintain an allowance for doubtful accounts at an amount estimated to be sufficient to cover the risk of collecting less than full payment of the receivables. At each balance sheet date, we evaluate our receivables and assess the allowance for doubtful accounts based on specific customer collection issues and historical write-off trends. Our allowance for doubtful accounts reflects our best estimate of expected future credit losses. We consider various factors that may impact our ability to collect on accounts receivable, including our historical collection experience, age of accounts receivable balances, current conditions, reasonable and supportable forecasts of future economic conditions, as well as other factors. However, given the uncertainty caused by the COVID-19 pandemic and other factors, these estimates may change and future credit losses may differ from our estimates. Expected credit losses from accounts receivable are recognized as expense in our statement of operations.
Property and Equipment, net	Property and Equipment, net Property and equipment, net is stated at historical cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets: three years for computer software and equipment and five years for furniture and fixtures. Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful lives of the assets or the terms of the respective leases. Property and equipment, net includes right-of-use assets acquired under finance leases. Amortization of assets acquired under finance leases is included in depreciation expense. Repairs and maintenance costs are expensed as incurred.
Leases	Leases We determine if an arrangement contains a lease and the classification of that lease, if applicable, at inception. We have elected to not recognize a lease liability or right-of-use ("ROU") asset for short-term leases (leases with a term of twelve months or less). For contracts with lease and non-lease components, we have elected to not allocate the contract consideration, and account for the lease and non-lease components as a single lease component. Additionally, we enter into arrangements to use shared office spaces and other facilities, and have determined that these arrangements do not contain leases as we do not have the right to use an identified asset. Operating leases are included in operating lease ROU assets, operating lease liabilities and operating lease liabilities (net of current portion) in our consolidated balance sheets. Finance leases are included in property and equipment, other current liabilities and other liabilities in our consolidated balance sheets. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments under the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The implicit rate within our operating leases are generally not determinable and we use our incremental borrowing rate at the lease commencement date to determine the present value of lease payments. The determination of our incremental borrowing rate requires judgment. We determine our incremental borrowing rate for each lease using our current borrowing rate, adjusted for various factors including level of collateralization, term and currency to align with the terms of the lease. The operating lease ROU asset also includes any lease prepayments, offset by lease incentives. Certain of our leases include options to extend or terminate the lease. An option to extend the lease is considered in connection with determining the ROU asset and lease liability when it is reasonably certain we will exercise that option. An option to terminate is considered unless it is reasonably certain we will not exercise the option. Lease expense for lease payments is recognized on a straight-line basis over the term of the lease.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We evaluate our long-lived assets for impairment whenever events or changes in circumstance indicate that the carrying amount may not be fully recoverable. Recoverability of the long-lived assets is measured by a comparison of the carrying amount of the assets to future undiscounted net cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured as the excess of the carrying amount over the fair value. There was no impairment of long-lived assets in 2020, 2019 or 2018.
Business Combinations	Business Combinations We account for business combinations by recognizing the fair value of acquired assets and liabilities. The excess purchase consideration over the fair value of acquired assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, we make estimates and assumptions, especially with respect to intangible assets. Estimates in valuing certain identifiable intangible assets include, but are not limited to, projected revenue growth rates, future expected operating expenses, obsolescence projections and an appropriate discount rate. Our estimate of fair value is based upon assumptions we believe to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, we may make adjustments to the fair value of assets acquired and liabilities assumed, with offsetting adjustments to goodwill. Any adjustments made after the measurement period will be reflected in the consolidated statements of operations. Acquisition-related transaction costs are expensed as incurred.
Goodwill	Goodwill The excess of the purchase consideration over the fair value of acquired assets and liabilities is recorded as goodwill. We perform our annual impairment assessment on October 1, or more frequently, when events or circumstances indicate impairment may have occurred. We operate as one reporting unit and have elected to first assess qualitative factors to determine whether it is more likely than not that the fair value of the Company as a whole is less than its carrying amount, including goodwill. The qualitative assessment includes an evaluation of relevant events and circumstances, including macroeconomic, industry and market conditions, our overall financial performance, and trends in the value of our common stock. During the periods presented, there were no indications of impairment and it was not more likely than not that goodwill was impaired.
Advertising	Advertising Advertising costs are expensed as they are incurred. We incurred advertising costs of $8.2 million, $5.3 million and $3.3 million in 2020, 2019 and 2018, respectively, which are included in sales and marketing expense in the consolidated statements of operations.
Software Development Costs	Software Development Costs Research and development costs to develop software to be sold, leased or marketed are expensed as incurred up to the point of technological feasibility for the related software product. We have not capitalized development costs for software to be sold, leased or marketed to date, as the software development process is essentially completed concurrent with the establishment of technological feasibility. As such, these costs are expensed as incurred and recognized in research and development costs in the consolidated statements of operations. Software developed for internal use, with no substantive plans to market such software at the time of development, are capitalized and included in property and equipment, net in the consolidated balance sheets. Costs incurred during the preliminary planning and evaluation and post implementation stages of the project are expensed as incurred. Costs incurred during the application development stage of the project are capitalized. In 2020, 2019 and 2018, we capitalized $1.6 million, $4.2 million and $2.4 million, respectively, of development costs related to internal use software.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense related to our restricted stock units ("RSUs"), purchase rights issued under our 2018 Employee Stock Purchase Plan ("2018 ESPP"), stock options and restricted stock is calculated based on the fair value of the awards granted and is recognized on a straight-line basis over the requisite service period, which is generally two to four years. RSUs that include performance-based vesting conditions and are expensed using the accelerated attribution method. We account for forfeitures as they occur.The fair value of RSUs is based on the estimated fair value of our common stock on the date of grant. The fair value of stock options and 2018 ESPP purchase rights is estimated on the grant date using the Black-Scholes option pricing model, which requires us to make assumptions and judgments, including the expected term, expected volatility, and risk-free interest rates. Prior to our IPO, we estimated the fair value of our common stock at the date of grant. Following our IPO, we use the market price of our common stock at the date of grant.
Net Loss per Share	Net Loss per Share We calculate basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. Under the two-class method, the net loss attributable to common stockholders is not allocated to the redeemable convertible preferred stock as the holders of our redeemable convertible preferred stock do not have a contractual obligation to share in losses. Under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Net loss attributable to common stockholders is calculated by adjusting net loss by the current period accretion of redeemable convertible preferred stock. Upon the completion of our IPO, all of our Series A and Series B redeemable convertible preferred stock automatically converted into shares of our common stock. Diluted earnings per share attributable to common stockholders is computed by giving effect to all potentially dilutive common stock equivalents in the period, including unvested RSUs, stock options, unvested restricted shares, redeemable convertible preferred stock and shares to be issued under our 2018 ESPP. As we have reported losses for all periods presented, all potentially dilutive securities have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect would be antidilutive.
Segment Information	Segment Information We operate as one operating segment as our chief executive officer, who is our chief operating decision maker, reviews financial information on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. This method requires recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities, net operating loss carryforwards, and tax credit carryforwards. A valuation allowance is provided if it is more likely than not that some or all of the deferred tax assets will not be realized. We recognize tax benefits from an uncertain tax position if it is more likely than not to be sustained upon audit by the relevant taxing authority. Interest and penalties associated with such uncertain tax positions are classified as a component of income tax expense.
Recently Adopted/Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements We adopted Accounting Standards Update ("ASU") No. 2016-13 — Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, effective January 1, 2020 using the modified retrospective approach. The new standard replaces the previous incurred loss impairment methodology with a methodology that reflects current expected credit losses for financial assets, including trade receivables, which are not measured at fair value, through net income. The adoption of this guidance did not have a material impact on our condensed consolidated financial statements. Recently Issued Accounting Pronouncements In December 2019, the Financial Accounting Standards Board ("FASB") issued ASU No. 2019-12 - Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This ASU eliminates previously allowed exceptions and clarifies existing guidance in the accounting for income taxes, including in the areas of franchise taxes, the tax basis of goodwill and interim period effects of changes in tax laws. This guidance was effective for us beginning January 1, 2021. We do not expect the impact of adopting this standard to be material for our consolidated financial statements.

Revenue (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Summary of revenue

The following table presents a summary of revenue:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Subscription revenue	$	377,354	$	290,549	$	205,827
Perpetual license and maintenance revenue	50,594		54,173		54,622
Professional services and other revenue	12,273		9,864		6,911
Revenue	$	440,221	$	354,586	$	267,360

Activity of deferred contract costs

The following summarizes the activity of deferred incremental costs of obtaining a contract:


	Year Ended December 31,
(in thousands)	2020		2019
Beginning balance	$	72,265	$	59,434
Capitalization of contract acquisition costs	38,756		40,172
Amortization of deferred contract acquisition costs	(32,145)		(27,341)
Ending balance	$	78,876	$	72,265

Cash and Cash Equivalents and Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2020

Cash and Cash Equivalents [Abstract]

Debt Securities, Available-for-sale

The following tables summarize the amortized cost, unrealized gain and loss and estimated fair value of cash equivalents and short-term investments:


	December 31, 2020
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Cash equivalents:
Money market funds	$	44,153	$	—	$	—	$	44,153
Commercial paper	4,500		—		—		4,500
Total cash equivalents	$	48,653	$	—	$	—	$	48,653

Short-term investments:
Commercial paper	$	71,425	$	—	$	—	$	71,425
Corporate bonds	4,502		3		—		4,505
U.S. Treasury and agency obligations	37,686		7		—		37,693
Total short-term investments	$	113,613	$	10	$	—	$	113,623


	December 31, 2019
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Cash equivalents:
Money market funds	$	13,588	$	—	$	—	$	13,588
Commercial paper	8,987		—		—		8,987
Total cash equivalents	$	22,575	$	—	$	—	$	22,575

Short-term investments:
Commercial paper	$	61,371	$	—	$	—	$	61,371
Corporate bonds	23,856		14		(1)		23,869
U.S. Treasury and agency obligations	52,627		38		(1)		52,664
Total short-term investments	$	137,854	$	52	$	(2)	$	137,904

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of assets measured at fair value on recurring basis

The following tables summarize assets that are measured at fair value on a recurring basis:


	December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	44,153	$	—	$	—	$	44,153
Commercial paper	—		4,500		—		4,500
	$	44,153	$	4,500	$	—	$	48,653

Short-term investments
Commercial paper	$	—	$	71,425	$	—	$	71,425
Corporate bonds	—		4,505		—		4,505
U.S. Treasury and agency obligations	—		37,693		—		37,693
	$	—	$	113,623	$	—	$	113,623


	December 31, 2019
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	13,588	$	—	$	—	$	13,588
Commercial paper	—		8,987		—		8,987
	$	13,588	$	8,987	$	—	$	22,575

Short-term investments
Commercial paper	$	—	$	61,371	$	—	$	61,371
Corporate bonds	—		23,869		—		23,869
U.S. Treasury and agency obligations	—		52,664		—		52,664
	$	—	$	137,904	$	—	$	137,904

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and equipment, net

Property and equipment, net consisted of the following:


	December 31,
(in thousands)	2020		2019
Computer software and equipment	$	22,930	$	21,234
Furniture and fixtures	6,011		4,504
Leasehold improvements	26,210		16,953
Right-of-use assets under finance leases	1,571		1,866
Total	56,722		44,557
Less: accumulated depreciation and amortization	(17,802)		(17,710)
Property and equipment, net	$	38,920	$	26,847

Acquisition, Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Assets Acquired and Liabilities Assumed as Part of Business Combination

The cash consideration was allocated as follows:


(in thousands)
Cash acquired	$	5,500
Other net tangible assets acquired	735
Deferred tax assets, net	4,243
Intangible assets	15,700
Goodwill	54,149
Total purchase price allocation	$	80,327

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination

Acquired intangible assets and their estimated useful lives at the date of acquisition are as follows:


	Intangible Assets
(dollars in thousands)	Cost		Weighted Average Useful Life
Acquired technology	$	15,500	7 years
Trade name	200		2 years
Acquired intangible assets	$	15,700

Schedule of Goodwill

The changes in the carrying amount of goodwill are as follows:


(in thousands)
Balance at December 31, 2019	$	54,138
Working capital adjustment	276
Balance at December 31, 2020	$	54,414

Schedule of Finite-Lived Intangible Assets

Acquired intangible assets subject to amortization are as follows:


	December 31, 2020						December 31, 2019
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Acquired technology	$	17,325	$	(4,224)	$	13,101	$	17,325	$	(2,009)	$	15,316
Trade name	200		(108)		92		200		(8)		192
	$	17,525	$	(4,332)	$	13,193	$	17,525	$	(2,017)	$	15,508

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

At December 31, 2020, estimated future amortization of intangible assets is as follows:


(in thousands)
Year ending December 31,
2021	$	2,306
2022	2,214
2023	2,214
2024	2,214
2025	2,214
Thereafter	2,031
Total	$	13,193

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Components of Leases

The components of lease expense were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Operating lease cost	$	9,870	$	6,045	$	3,694

Finance lease cost
Amortization of ROU assets	$	242	$	607	$	614
Interest on lease liabilities	6		7		35
Total finance lease cost	$	248	$	614	$	649

Supplemental information related to leases was as follows:


	December 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	10.0 years	10.0 years
Weighted average discount rate	5.6%	5.8%


	Year Ended December 31,
(in thousands)	2020		2019		2018
ROU assets obtained in exchange for lease obligations
Operating leases	$	3,188	$	39,170	$	1,525
Finance leases	—		11		15

Schedule of Maturities of Operating Lease Liabilities

Maturities of operating lease liabilities at December 31, 2020 were as follows:


(in thousands)
Year ending December 31,
2021	$	3,891
2022	8,050
2023	7,711
2024	7,866
2025	7,435
Thereafter	44,525
Total lease payments	79,478
Less: Imputed interest	(21,134)
Total	$	58,344

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-based Compensation Expense

Stock-based compensation expense included in the consolidated statements of operations was as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Cost of revenue	$	3,158	$	2,817	$	1,707
Sales and marketing	19,842		16,032		6,911
Research and development	14,794		8,911		5,804
General and administrative	21,779		15,683		8,453
Total stock-based compensation expense	$	59,573	$	43,443	$	22,875

Summary of Restricted Stock and Restricted Stock Units

A summary of our restricted stock and RSU activity is presented below:


	Restricted Stock			RSUs
(in thousands, except for per share data)	Number of Shares	Weighted Average Grant Date Fair Value		Number of Shares	Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2017	1,583	$	4.25	—	$	—
Granted	—	—		1,200	18.75
Vested	(693)	4.25		—	—
Forfeited	—	—		(71)	16.27
Unvested balance at December 31, 2018	890	4.25		1,129	18.90
Granted	—	—		2,715	27.81
Vested	(395)	4.25		(479)	18.28
Forfeited	—	—		(471)	25.21
Unvested balance at December 31, 2019	495	4.25		2,894	26.34
Granted	—	—		3,570	28.23
Vested	(396)	4.25		(1,504)	25.37
Forfeited	—	—		(470)	26.68
Unvested balance at December 31, 2020	99	4.25		4,490	28.13

Stock Option Activity

A summary of our stock option activity is below:


(in thousands, except for per share data and years)	Number of Shares	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2017	14,573	$	4.38	8.2	$	77,020
Granted	6,108	15.17
Exercised	(740)	2.26			9,902
Forfeited/canceled	(722)	7.23
Outstanding at December 31, 2018	19,219	7.78		8.0	277,114
Granted	—	—
Exercised	(4,205)	4.53			98,378
Forfeited/canceled	(2,075)	10.63
Outstanding at December 31, 2019	12,939	8.38		7.1	201,608
Granted	—	—
Exercised	(2,956)	7.34			73,277
Forfeited/canceled	(542)	10.80
Outstanding at December 31, 2020	9,441	8.56		6.4	412,547
Exercisable at December 31, 2020	6,189	6.53		6.1	283,024

Valuation Assumptions

The fair value of each stock option was estimated on the grant date based on the following assumptions:


			Year Ended December 31, 2018
Expected term (in years)			6.3
Expected volatility			41.3% — 43.3%
Risk-free interest rate			2.7% — 2.9%
Expected dividend yield			—
Expected forfeiture rate			—

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The fair value of the 2018 ESPP purchase rights was estimated on the offering or modification dates using a Black-Scholes option-pricing model and the following assumptions:


	Year Ended December 31,
	2020	2019	2018
Expected term (in years)	0.5 — 2.0	0.5 — 2.0	0.6 — 2.1
Expected volatility	41.6% — 60.1%	34.4% — 44.6%	31.9% — 33.5%
Risk-free interest rate	0.1% — 0.9%	1.5% — 2.5%	2.3% — 2.7%
Expected dividend yield	—	—	—

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders:


	Year Ended December 31,
(in thousands, except per share data)	2020		2019		2018
Net loss attributable to common stockholders	$	(42,731)	$	(99,013)	$	(73,955)

Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	101,009		96,014		53,669
Net loss per share attributable to common stockholders, basic and diluted	$	(0.42)	$	(1.03)	$	(1.38)

Potentially Dilutive Securities

The following potentially dilutive securities have been excluded from the diluted per share calculations because they would have been antidilutive:


	Year Ended December 31,
(in thousands)	2020	2019	2018
Stock options	9,441	12,939	19,219
RSUs	4,490	2,894	1,129
Restricted stock	99	495	890
Shares to be issued under the 2018 ESPP	321	278	320
Total	14,351	16,606	21,558

Income Taxes Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Loss Before Income Taxes

U.S. and international components of the loss before income taxes were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
U.S. (loss) income	$	(6,719)	$	(21,644)	$	1,429
Foreign loss	(30,355)		(64,005)		(72,586)
Total loss before income taxes	$	(37,074)	$	(85,649)	$	(71,157)

Schedule of Components of the Provision for Income Taxes

The components of the provision for income taxes were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Current
Federal	$	3	$	(224)	$	—
State	17		100		58
Foreign	5,476		9,245		2,306
Total current tax expense	5,496		9,121		2,364
Deferred
Federal	102		—		—
State	59		—		—
Foreign	—		4,243		—
Total deferred tax expense	161		4,243		—
Total provision for income taxes	$	5,657	$	13,364	$	2,364

Schedule of Effective Income Tax Rate Reconciliation

The items accounting for the difference between income taxes computed at the federal statutory rate and our effective tax rate were as follows:


	Year Ended December 31,
	2020		2019		2018
U.S. federal statutory tax rate	21.0	%	21.0	%	21.0	%
State and local taxes	10.8		4.8		(1.5)
Research and development tax credit	11.1		3.1		1.9
Stock-based compensation	34.4		19.0		0.5
Uncertain tax positions	0.1		(0.5)		(1.0)
Foreign tax rate differential	(10.6)		(7.9)		(9.4)
Change in valuation allowance	(81.2)		(40.8)		(12.6)
Gain on sale of intellectual property	—		(12.3)		—


Foreign withholding tax	(3.3)		(1.4)		(1.1)
Other	2.4		(0.6)		(1.1)
Effective tax rate	(15.3)	%	(15.6)	%	(3.3)	%

Components of Deferred Tax Assets and Liabilities

The components of the deferred tax assets and liabilities were as follows:


	December 31,
(in thousands)	2020		2019
Deferred tax assets:
Net operating losses	$	89,053	$	65,494
Deferred revenue	13,454		13,891
Stock-based compensation	11,846		10,032
Tax credits	11,565		7,585
Leases	15,238		10,451
Accrued compensation	1,271		918
Other	379		263
Total deferred tax assets	142,806		108,634
Valuation allowance	(112,363)		(82,237)
Net deferred tax assets	30,443		26,397
Deferred tax liabilities:
Deferred commissions	(15,987)		(15,003)
Property and equipment	(13,257)		(10,086)
Intangible assets	(962)		(919)
Other	(398)		(389)
Total deferred tax liabilities	(30,604)		(26,397)
Net deferred tax liabilities	$	(161)	$	—

Schedule Change of Gross Unrealized Tax Benefits

The change in gross unrecognized tax benefits, excluding accrued interest, were as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
Unrecognized tax benefits at the beginning of the period	$	7,163	$	4,814	$	1,199
Additions for tax positions in the current year	232		2,306		3,571
Increase in prior year positions	62		90		102
Decrease in prior year positions	(334)		(89)		(58)
Acquisitions	—		42		—
Unrecognized tax benefits at the end of the period	$	7,123	$	7,163	$	4,814

Geographic Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Revenue by Region

Revenue by region, based on the address of the end user as specified in our subscription, license or service agreements, was as follows:


	Year Ended December 31,
(in thousands)	2020		2019		2018
The Americas	$	293,734	$	243,616	$	191,204
Europe, Middle East and Africa	102,155		77,676		53,839
Asia Pacific	44,332		33,294		22,317
Revenue	$	440,221	$	354,586	$	267,360

Property and Equipment, Net by Geographic Area

Our property and equipment, net by geographic area is summarized as follows:


	December 31,
(in thousands)	2020		2019
United States	$	35,406	$	21,464
International	3,514		5,383
Property and equipment, net	$	38,920	$	26,847

Quarterly Results (unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (unaudited)


	Three Months Ended
(in thousands, except per share amounts)	March 31, 2020		June 30, 2020		September 30, 2020		December 31, 2020
Revenue	$	102,648	$	107,209	$	112,282	$	118,082
Cost of revenue	18,701		19,142		19,394		20,317
Gross profit	83,947		88,067		92,888		97,765
Operating expenses:
Sales and marketing	59,855		55,443		53,045		55,934
Research and development	26,831		25,310		25,128		24,418
General and administrative	18,933		17,879		18,180		18,144
Total operating expenses	105,619		98,632		96,353		98,496
Loss from operations	(21,672)		(10,565)		(3,465)		(731)
Interest income (expense), net	734		455		(12)		67
Other expense, net	(960)		(298)		(561)		(66)
Loss before income taxes	(21,898)		(10,408)		(4,038)		(730)
Provision for income taxes	1,079		1,552		1,820		1,206
Net loss	(22,977)		(11,960)		(5,858)		(1,936)
Net loss per share, basic and diluted	$	(0.23)	$	(0.12)	$	(0.06)	$	(0.02)


	Three Months Ended
(in thousands, except per share amounts)	March 31, 2019		June 30, 2019		September 30, 2019		December 31, 2019
Revenue	$	80,301	$	85,384	$	91,852	$	97,049
Cost of revenue	13,226		13,918		15,245		18,429
Gross profit	67,075		71,466		76,607		78,620
Operating expenses:
Sales and marketing	52,689		56,015		56,699		62,632
Research and development	21,935		21,698		20,763		22,668
General and administrative	15,136		15,987		17,472		20,873
Total operating expenses	89,760		93,700		94,934		106,173
Loss from operations	(22,685)		(22,234)		(18,327)		(27,553)
Interest income, net	1,556		1,594		1,527		1,153
Other expense, net	(214)		(122)		(240)		(104)
Loss before income taxes	(21,343)		(20,762)		(17,040)		(26,504)
Provision for income taxes	97		866		600		11,801
Net loss	(21,440)		(21,628)		(17,640)		(38,305)
Net loss per share, basic and diluted	$	(0.23)	$	(0.23)	$	(0.18)	$	(0.39)

Business and Summary of Significant Accounting Policies - Initial Public Offering (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jul. 30, 2018	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)	55,385,854
Common stock, authorized (in shares)	500,000,000		500,000,000	500,000,000
Preferred stock, authorized (in shares)	10,000,000
IPO
Subsidiary, Sale of Stock [Line Items]
Stock sold, price per share (in usd per share)	$ 23.00
Net proceeds from sale of stock	$ 264.6
Common Stock
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)		55,386,000
Common Stock \| IPO
Subsidiary, Sale of Stock [Line Items]
Stock sold (in shares)	12,535,000
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)	55,385,854
Common Stock \| Over-allotment option
Subsidiary, Sale of Stock [Line Items]
Stock sold (in shares)	1,635,000
Redeemable convertible Series A preferred stock \| IPO
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)	15,847,500
Redeemable convertible Series B preferred stock \| IPO
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)	39,538,354

Business and Summary of Significant Accounting Policies - Foreign Currency (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Foreign currency transaction loss	$ (1.7)	$ (1.1)	$ (1.0)

Business and Summary of Significant Accounting Policies - Perpetual License and Maintenance Revenue (Details) - License and Maintenance	12 Months Ended
	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
License and maintenance period	1 year
Estimated maintenance renewal period	4 years
Economic life of perpetual license contracts	5 years

Business and Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 0.4	$ 0.4
Other Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 0.2	$ 0.3

Business and Summary of Significant Accounting Policies - Deferred Commissions (Details)	Dec. 31, 2020
License and Maintenance
Capitalized Contract Cost [Line Items]
Estimated period of benefit	5 years
Minimum \| License
Capitalized Contract Cost [Line Items]
Estimated period of benefit	3 years
Maximum \| License
Capitalized Contract Cost [Line Items]
Estimated period of benefit	4 years

Business and Summary of Significant Accounting Policies - Property and Equipment, net (Details)	12 Months Ended
	Dec. 31, 2020
Computer software and equipment
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years

Business and Summary of Significant Accounting Policies - Goodwill (Details)	12 Months Ended
	Dec. 31, 2020 segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reporting units	1

Business and Summary of Significant Accounting Policies - Advertising (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Advertising costs incurred	$ 8.2	$ 5.3	$ 3.3

Business and Summary of Significant Accounting Policies - Software Development Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Capitalized development costs of internal use software	$ 1.6	$ 4.2	$ 2.4

Business and Summary of Significant Accounting Policies - Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2020
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite period	2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite period	4 years

Business and Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2020 segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1

Revenue - Summary of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 118,082	$ 112,282	$ 107,209	$ 102,648	$ 97,049	$ 91,852	$ 85,384	$ 80,301	$ 440,221	$ 354,586	$ 267,360
License
Disaggregation of Revenue [Line Items]
Revenue									377,354	290,549	205,827
License and Maintenance
Disaggregation of Revenue [Line Items]
Revenue									50,594	54,173	54,622
Professional services and other revenue
Disaggregation of Revenue [Line Items]
Revenue									$ 12,273	$ 9,864	$ 6,911

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
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-Paragraph 4
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
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-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Revenue - Concentrations (Details)	12 Months Ended
Revenue - Concentrations (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue \| Sales method risk
Concentration Risk [Line Items]
Concentration risk (in percent)	91.00%	90.00%	88.00%
One distributor \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (in percent)	43.00%	43.00%	46.00%
One distributor \| Accounts receivable \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (in percent)	41.00%	40.00%

Revenue - Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue recognized that was included in deferred revenue	$ 274.3	$ 214.0	$ 154.9

Revenue - Remaining Performance Obligations (Details) $ in Millions	Dec. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 443.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected recognized percentage over succeeding 12 months	76.00%
Expected timing of satisfaction	4 years

Revenue - Activity of Deferred Contract Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 72,265	$ 59,434
Capitalization of contract acquisition costs	38,756	40,172
Amortization of deferred contract acquisition costs	(32,145)	(27,341)
Ending balance	$ 78,876	$ 72,265

Cash and Cash Equivalents and Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 48,653	$ 22,575
Debt securities, available-for-sale, amortized cost	113,613	137,854
Debt Securities, available-for-sale, accumulated gross unrealized gain, before tax	10	52
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(2)
Short-term investments	113,623	137,904
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	44,153	13,588
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	4,500	8,987
Cash Equivalents
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	48,653	22,575
Commercial paper
Cash and Cash Equivalents [Line Items]
Debt securities, available-for-sale, amortized cost	71,425	61,371
Debt Securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Short-term investments	71,425	61,371
Corporate Bond Securities
Cash and Cash Equivalents [Line Items]
Debt securities, available-for-sale, amortized cost	4,502	23,856
Debt Securities, available-for-sale, accumulated gross unrealized gain, before tax	3	14
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(1)
Short-term investments	4,505	23,869
US Treasury and Government
Cash and Cash Equivalents [Line Items]
Debt securities, available-for-sale, amortized cost	37,686	52,627
Debt Securities, available-for-sale, accumulated gross unrealized gain, before tax	7	38
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(1)
Short-term investments	$ 37,693	$ 52,664

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 48,653	$ 22,575
Short-term investments	113,623	137,904
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	44,153	13,588
Short-term investments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	4,500	8,987
Short-term investments	113,623	137,904
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investments	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	71,425	61,371
Commercial paper \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Commercial paper \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	71,425	61,371
Commercial paper \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	4,505	23,869
Corporate bonds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Corporate bonds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	4,505	23,869
Corporate bonds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. Treasury and agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	37,693	52,664
U.S. Treasury and agency obligations \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. Treasury and agency obligations \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	37,693	52,664
U.S. Treasury and agency obligations \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	44,153	13,588
Money market funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	44,153	13,588
Money market funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Money market funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	4,500	8,987
Commercial paper \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Commercial paper \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	4,500	8,987
Commercial paper \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0	$ 0

Property and Equipment, Net - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Right-of-use assets under finance leases	$ 1,571	$ 1,866
Total	56,722	44,557
Less: accumulated depreciation and amortization	(17,802)	(17,710)
Property and equipment, net	38,920	26,847
Computer software and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	22,930	21,234
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,011	4,504
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 26,210	$ 16,953

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 8.1	$ 6.3	$ 5.6

Acquisition, Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 02, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Payments to acquire businesses, net cash acquired		$ 276	$ 74,911	$ 0
Working capital adjustment		276
Acquisition-related transaction costs		300	4,000
Expense related to the intercompany transfer of intellectual property			2,100
Amortization of intangible assets		$ 2,300	$ 600	$ 600
INDEGY LTD.
Business Acquisition [Line Items]
Payments to acquire businesses, net cash acquired	$ 80,300
Cash acquired	5,500
Working capital adjustment	300
Stock-based compensation expense for unvested options	$ 1,800

Acquisition, Goodwill and Intangible Assets - Schedule of Assets Acquired (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 02, 2019
Business Acquisition [Line Items]
Goodwill	$ 54,414	$ 54,138
INDEGY LTD.
Business Acquisition [Line Items]
Cash acquired			$ 5,500
Other net tangible assets acquired			735
Deferred tax assets, net			4,243
Intangible assets			15,700
Goodwill			54,149
Total purchase price allocation			$ 80,327

Acquisition, Goodwill and Intangible Assets - Schedule of Finite-lived Intangible Assets Acquired (Details) - INDEGY LTD. $ in Thousands	Dec. 02, 2019 USD ($)
Business Acquisition [Line Items]
Finite-lived intangible assets acquired	$ 15,700
Purchased technology
Business Acquisition [Line Items]
Finite-lived intangible assets acquired	$ 15,500
Weighted Average Useful Life	7 years
Trade name
Business Acquisition [Line Items]
Finite-lived intangible assets acquired	$ 200
Weighted Average Useful Life	2 years

Acquisition, Goodwill and Intangible Assets - Schedule of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Business Combinations [Abstract]
Balance at December 31, 2019	$ 54,138
Working capital adjustment	276
Balance at December 31, 2020	$ 54,414

Acquisition, Goodwill and Intangible Assets - Schedule of Finite-lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 17,525	$ 17,525
Accumulated amortization	(4,332)	(2,017)
Net carrying amount	13,193	15,508
Amortization of intangible assets	2,300	600	$ 600
Purchased technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	17,325	17,325
Accumulated amortization	(4,224)	(2,009)
Net carrying amount	13,101	15,316
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	200	200
Accumulated amortization	(108)	(8)
Net carrying amount	$ 92	$ 192

Acquisition, Goodwill and Intangible Assets - Schedule of Future Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
2021	$ 2,306
2022	2,214
2023	2,214
2024	2,214
2025	2,214
Thereafter	2,031
Net carrying amount	$ 13,193	$ 15,508

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Leased Assets [Line Items]
Renewal term on lease	5 years
Proceeds from tenant incentives	$ 14,200
Operating leases	$ 3,188	$ 39,170	$ 1,525
Minimum
Operating Leased Assets [Line Items]
Remaining terms of leases	1 year
Option to terminate lease	1 year
Maximum
Operating Leased Assets [Line Items]
Remaining terms of leases	11 years
Option to terminate lease	4 years

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease cost	$ 9,870	$ 6,045	$ 3,694
Finance leases
Amortization of ROU assets	242	607	614
Interest on lease liabilities	6	7	35
Total finance lease cost	$ 248	$ 614	$ 649

Leases - Supplemental Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Weighted average remaining lease term	10 years	10 years
Weighted average discount rate	5.60%	5.80%
ROU assets obtained in exchange for lease obligations:
Operating leases	$ 3,188	$ 39,170	$ 1,525
Finance leases	$ 0	$ 11	$ 15

Leases - Operating Lease Liability Maturities (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Leases [Abstract]
2021	$ 3,891
2022	8,050
2023	7,711
2024	7,866
2025	7,435
Thereafter	44,525
Total lease payments	79,478
Less: Imputed interest	(21,134)
Total	$ 58,344

Debt (Details) - USD ($)		12 Months Ended
Debt (Details) - USD ($)	Jul. 24, 2020	Dec. 31, 2020	May 04, 2017
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			$ 25,000,000.0
Percent of capital stock	65.00%
Arrears paid on average unused portion	0.35%
Borrowings against debt instrument		$ 0
Debt instrument, covenant, quick ratio required, minimum	1.5
Outstanding balance of credit facility, amount requiring covenant compliance		$ 5,500,000
Revolving Credit Facility \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 45,000,000.0
Uncommitted expansion, limit	45,000,000.0
Letter of Credit \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	10,000,000.0
Bridge Loan \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 10,000,000.0
LIBOR \| Revolving Credit Facility \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Line of Credit \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.00%
Line of Credit \| Prime Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%

Redeemable Convertible Preferred Stock and Common Stock (Details)		1 Months Ended
	Jul. 30, 2018 shares	Dec. 31, 2015 $ / shares shares	Oct. 31, 2012 shares	Dec. 31, 2020 shares	Dec. 31, 2019 shares
Class of Stock [Line Items]
Redeemable convertible preferred stock, conversion ratio		1
Issuance of common stock upon conversion of redeemable convertible preferred stock (in shares)	55,385,854
Common stock, authorized (in shares)	500,000,000			500,000,000	500,000,000
Preferred stock, authorized (in shares)	10,000,000
Preferred stock, issued (in shares)				0	0
Preferred stock, outstanding (in shares)				0	0
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Stock sold (in shares)		15,847,500	15,847,500
Redeemable convertible preferred stock, par value (in usd per share) \| $ / shares		$ 0.01
Series B Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Stock sold (in shares)		39,538,354
Redeemable convertible preferred stock, par value (in usd per share) \| $ / shares		$ 0.01
Redeemable convertible preferred stock, shares authorized (in shares)		42,000,000

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense, outstanding stock options	$ 10.4
Stock options vested and expected to vest (in shares)	9,400,000
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	17,766,262
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, stock incentive plans, maximum term (in years)	10 years
Estimated remaining weighted average period	1 year 3 months 18 days
Weighted average grant date fair value (in USD per share)		$ 6.84
Stock options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, stock incentive plan, vesting period (in years)	3 years
Stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, stock incentive plan, vesting period (in years)	4 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated remaining weighted average period	2 years 9 months 18 days
Unrecognized stock-based compensation expense, unvested restricted stock or RSUs	$ 107.5
RSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, stock incentive plan, vesting period (in years)	2 years
RSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, stock incentive plan, vesting period (in years)	4 years
Stock-based awards \| 2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)			4,929,361
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)			1,478,808
Shares available for grant (in shares)	5,431,176
Estimated remaining weighted average period	7 months 6 days

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 59,573	$ 43,443	$ 22,875
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	3,158	2,817	1,707
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	19,842	16,032	6,911
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	14,794	8,911	5,804
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 21,779	$ 15,683	$ 8,453

Stock-Based Compensation - Restricted Stock and Restricted Stock Units (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Number of shares unvested, beginning of period (in shares)	495	890
Number of shares unvested, end of period (in shares)	99	495	890
Restricted stock
Number of Shares
Number of shares unvested, beginning of period (in shares)			1,583
Number of shares, granted (in shares)	0	0	0
Number of shares, vested (in shares)	(396)	(395)	(693)
Number of shares, forfeited (in shares)	0	0	0
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning of period (in USD per share)	$ 4.25	$ 4.25	$ 4.25
Weighted average grant date fair value, granted (in USD per share)	0	0	0
Weighted average grant date fair value, vested (in USD per share)	4.25	4.25	4.25
Weighted average grant date fair value, forfeited (in USD per share)	0	0	0
Weighted average grant date fair value, end of period (in USD per share)	$ 4.25	$ 4.25	$ 4.25
RSUs
Number of Shares
Number of shares unvested, beginning of period (in shares)	2,894	1,129	0
Number of shares, granted (in shares)	3,570	2,715	1,200
Number of shares, vested (in shares)	(1,504)	(479)	0
Number of shares, forfeited (in shares)	(470)	(471)	(71)
Number of shares unvested, end of period (in shares)	4,490	2,894	1,129
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning of period (in USD per share)	$ 26.34	$ 18.90	$ 0
Weighted average grant date fair value, granted (in USD per share)	28.23	27.81	18.75
Weighted average grant date fair value, vested (in USD per share)	25.37	18.28	0
Weighted average grant date fair value, forfeited (in USD per share)	26.68	25.21	16.27
Weighted average grant date fair value, end of period (in USD per share)	$ 28.13	$ 26.34	$ 18.90

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Number of shares outstanding, beginning of period (in shares)	12,939	19,219	14,573
Number of shares, granted (in shares)	0	0	6,108
Number of shares, exercised (in shares)	(2,956)	(4,205)	(740)
Number of shares, forfeited/canceled (in shares)	(542)	(2,075)	(722)
Number of shares outstanding, end of period (in shares)	9,441	12,939	19,219	14,573
Number of shares exercisable (in shares)	6,189
Weighted Average Exercise Price
Weighted average exercise price, outstanding, beginning of period (in USD per share)	$ 8.38	$ 7.78	$ 4.38
Weighted average exercise price, granted (in USD per share)	0	0	15.17
Weighted average exercise price, exercised (in USD per share)	7.34	4.53	2.26
Weighted average exercise price, forfeited/canceled (in USD per share)	10.80	10.63	7.23
Weighted average exercise price, outstanding, end of period (in USD per share)	8.56	$ 8.38	$ 7.78	$ 4.38
Weighted average exercise price, exercisable (in USD per share)	$ 6.53
Weighted average remaining contractual term (in years), outstanding	6 years 4 months 24 days	7 years 1 month 6 days	8 years	8 years 2 months 12 days
Weighted average remaining contractual term (in years), exercisable	6 years 1 month 6 days
Aggregate intrinsic value, outstanding, beginning of period	$ 201,608	$ 277,114	$ 77,020
Aggregate intrinsic value, exercised	73,277	98,378	9,902
Aggregate intrinsic value, outstanding, end of period	412,547	$ 201,608	$ 277,114	$ 77,020
Aggregate intrinsic value, exercisable	$ 283,024

Stock-Based Compensation - Fair Value of Stock Options Assumptions (Details) - Stock options	12 Months Ended
	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 3 months 18 days
Expected volatility, minimum	41.30%
Expected volatility, maximum	43.30%
Risk - free interest rate, minimum	2.70%
Risk - free interest rate, maximum	290.00%
Expected dividend yield	0.00%
Expected forfeiture rate	0.00%

Stock-Based Compensation - 2018 Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from stock issued in connection with the employee stock purchase plan	$ 13,040	$ 15,129	$ 0
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)				1,478,808
Shares available for grant (in shares)	5,431,176
Percentage of employee earnings allowed	15.00%
Discount price percentage	85.00%
Offering period (up to)	27 months
Common stock purchased (in shares)	667,719	776,809
Weighted-average purchase price per share (in USD per share)	$ 19.53	$ 19.48
Employee contributions	$ 6,500	$ 5,400
Unrecognized stock-based compensation expense	$ 4,100
Remaining offering period	7 months 6 days

Stock-Based Compensation - Fair Value of ESPP Purchase Rights (Details) - Employee stock purchase plan	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	41.60%	34.40%	31.90%
Expected volatility, maximum	60.10%	44.60%	33.50%
Risk - free interest rate, minimum	0.10%	1.50%	2.30%
Risk - free interest rate, maximum	0.90%	2.50%	2.70%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	7 months 6 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	2 years	2 years	2 years 1 month 6 days

Net Loss Per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net loss attributable to common stockholders									$ (42,731)	$ (99,013)	$ (73,955)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)									101,009	96,014	53,669
Net loss per share attributable to common stockholders, basic and diluted (in usd per share)	$ (0.02)	$ (0.06)	$ (0.12)	$ (0.23)	$ (0.39)	$ (0.18)	$ (0.23)	$ (0.23)	$ (0.42)	$ (1.03)	$ (1.38)

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1377-109256

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
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+ Details

Net Loss Per Share Attributable to Common Stockholders - Schedule of Potentially Dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	14,351	16,606	21,558
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	9,441	12,939	19,219
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	4,490	2,894	1,129
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	99	495	890
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	321	278	320

Income Taxes - Components of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. (loss) income									$ (6,719)	$ (21,644)	$ 1,429
Foreign loss									(30,355)	(64,005)	(72,586)
Loss before income taxes	$ (730)	$ (4,038)	$ (10,408)	$ (21,898)	$ (26,504)	$ (17,040)	$ (20,762)	$ (21,343)	$ (37,074)	$ (85,649)	$ (71,157)

Income Taxes - Components of the Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal									$ 3	$ (224)	$ 0
State									17	100	58
Foreign									5,476	9,245	2,306
Total current tax expense									5,496	9,121	2,364
Deferred
Federal									102	0	0
State									59	0	0
Foreign									0	4,243	0
Total deferred tax expense									161	4,243	0
Total provision for income taxes	$ 1,206	$ 1,820	$ 1,552	$ 1,079	$ 11,801	$ 600	$ 866	$ 97	$ 5,657	$ 13,364	$ 2,364

Income Taxes - Differences Between Federal and Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	21.00%	21.00%	21.00%
State and local taxes	10.80%	4.80%	(1.50%)
Research and development tax credit	11.10%	3.10%	1.90%
Stock-based compensation	34.40%	19.00%	0.50%
Uncertain tax positions	0.10%	(0.50%)	(1.00%)
Foreign tax rate differential	(10.60%)	(7.90%)	(9.40%)
Change in valuation allowance	(81.20%)	(40.80%)	(12.60%)
Gain on sale of intellectual property	0.00%	(12.30%)	0.00%
Foreign withholding tax	(3.30%)	(1.40%)	(1.10%)
Other	2.40%	(0.60%)	(1.10%)
Effective tax rate	(15.30%)	(15.60%)	(3.30%)

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating losses	$ 89,053	$ 65,494
Deferred revenue	13,454	13,891
Stock-based compensation	11,846	10,032
Tax credits	11,565	7,585
Leases	15,238	10,451
Accrued compensation	1,271	918
Other	379	263
Total deferred tax assets	142,806	108,634
Valuation allowance	(112,363)	(82,237)
Net deferred tax assets	30,443	26,397
Deferred tax liabilities:
Deferred commissions	(15,987)	(15,003)
Property and equipment	(13,257)	(10,086)
Intangible assets	(962)	(919)
Other	(398)	(389)
Total deferred tax liabilities	(30,604)	(26,397)
Net deferred tax liabilities	$ (161)	$ 0

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Tax credits carryforwards	$ 13,900
Tax expense from intercompany transfer	5,476	$ 9,245	$ 2,306
Deferred taxes from intercompany transfer	0	4,243	0
Unrecognized tax benefits	7,123	7,163	4,814	$ 1,199
Effective tax rate impact	100	100	$ 100
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	254,700
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	188,500
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	209,800
ISRAEL
Operating Loss Carryforwards [Line Items]
Tax expense from intercompany transfer		$ 6,300
Deferred taxes from intercompany transfer	$ 4,200

Income Taxes - Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at the beginning of the period	$ 7,163	$ 4,814	$ 1,199
Additions for tax positions in the current year	232	2,306	3,571
Increase in prior year positions	62	90	102
Decrease in prior year positions	(334)	(89)	(58)
Acquisitions	0	42	0
Unrecognized tax benefits at the end of the period	$ 7,123	$ 7,163	$ 4,814

Geographic Information - Narrative (Details) - segment	12 Months Ended
Geographic Information - Narrative (Details) - segment	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting [Abstract]
Number of operating segments	1
United States \| Revenue \| Geographic concentration risk
Concentration Risk [Line Items]
Concentration risk (in percent)	61.00%	63.00%	67.00%

Geographic Information - Revenue by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 118,082	$ 112,282	$ 107,209	$ 102,648	$ 97,049	$ 91,852	$ 85,384	$ 80,301	$ 440,221	$ 354,586	$ 267,360
The Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									293,734	243,616	191,204
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									102,155	77,676	53,839
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									$ 44,332	$ 33,294	$ 22,317

- Definition

+ References

+ Details

Geographic Information - Property And Equipment, Net By Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 38,920	$ 26,847
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	35,406	21,464
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 3,514	$ 5,383

Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
Benefit Plans (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Contribution expense	$ 6.5	$ 6.2	$ 4.8

Subsequent Events (Details) $ in Millions	Feb. 10, 2021 USD ($)
Subsequent event \| Alsid
Subsequent Event [Line Items]
Business combination, consideration transferred	$ 98

Quarterly Results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 118,082	$ 112,282	$ 107,209	$ 102,648	$ 97,049	$ 91,852	$ 85,384	$ 80,301	$ 440,221	$ 354,586	$ 267,360
Cost of revenue	20,317	19,394	19,142	18,701	18,429	15,245	13,918	13,226	77,554	60,818	43,167
Gross profit	97,765	92,888	88,067	83,947	78,620	76,607	71,466	67,075	362,667	293,768	224,193
Operating expenses:
Sales and marketing	55,934	53,045	55,443	59,855	62,632	56,699	56,015	52,689	224,277	228,035	173,344
Research and development	24,418	25,128	25,310	26,831	22,668	20,763	21,698	21,935	101,687	87,064	76,698
General and administrative	18,144	18,180	17,879	18,933	20,873	17,472	15,987	15,136	73,136	69,468	46,732
Total operating expenses	98,496	96,353	98,632	105,619	106,173	94,934	93,700	89,760	399,100	384,567	296,774
Loss from operations	(731)	(3,465)	(10,565)	(21,672)	(27,553)	(18,327)	(22,234)	(22,685)	(36,433)	(90,799)	(72,581)
Interest income, net	67	(12)	455	734	1,153	1,527	1,594	1,556	1,244	5,830	2,355
Other expense, net	(66)	(561)	(298)	(960)	(104)	(240)	(122)	(214)	(1,885)	(680)	(931)
Loss before income taxes	(730)	(4,038)	(10,408)	(21,898)	(26,504)	(17,040)	(20,762)	(21,343)	(37,074)	(85,649)	(71,157)
Provision for income taxes	1,206	1,820	1,552	1,079	11,801	600	866	97	5,657	13,364	2,364
Net loss	$ (1,936)	$ (5,858)	$ (11,960)	$ (22,977)	$ (38,305)	$ (17,640)	$ (21,628)	$ (21,440)	$ (42,731)	$ (99,013)	$ (73,521)
Net loss per share attributable to common stockholders, basic and diluted (in usd per share)	$ (0.02)	$ (0.06)	$ (0.12)	$ (0.23)	$ (0.39)	$ (0.18)	$ (0.23)	$ (0.23)	$ (0.42)	$ (1.03)	$ (1.38)

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 764	$ 188	$ 160
Additions Charged to Costs and Expenses	336	967	149
Deductions	(839)	(391)	(121)
Balance at End of Year	$ 261	$ 764	$ 188