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Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2020	May 01, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
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	7021 Columbia Gateway Drive
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Columbia
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21046
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		100,080,320
Entity Central Index Key	0001660280
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 107,769	$ 74,363
Short-term investments	118,924	137,904
Accounts receivable (net of allowance for doubtful accounts of $399 and $764 at March 31, 2020 and December 31, 2019, respectively)	74,378	94,827
Deferred commissions	28,751	28,499
Prepaid expenses and other current assets	25,632	27,369
Total current assets	355,454	362,962
Property and equipment, net	30,534	26,847
Deferred commissions (net of current portion)	41,991	43,766
Operating lease right-of-use assets	41,283	42,847
Acquired intangible assets, net	14,929	15,508
Goodwill	54,138	54,138
Other assets	11,245	12,544
Total assets	549,574	558,612
Current liabilities:
Accounts payable	4,404	1,732
Accrued expenses	14,536	8,436
Accrued compensation	23,357	36,634
Deferred revenue	270,916	274,348
Operating lease liabilities	4,866	5,209
Other current liabilities	750	1,284
Total current liabilities	318,829	327,643
Deferred revenue (net of current portion)	87,175	88,779
Operating lease liabilities (net of current portion)	40,301	40,663
Other liabilities	2,893	2,622
Total liabilities	449,198	459,707
Stockholders’ equity:
Common stock (par value: $0.01; 500,000 shares authorized; 100,003 and 98,587 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively)	1,000	986
Additional paid-in capital	687,311	662,990
Accumulated other comprehensive income	163	50
Accumulated deficit	(588,098)	(565,121)
Total stockholders’ equity	100,376	98,905
Total liabilities and stockholders’ equity	$ 549,574	$ 558,612

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 399	$ 764
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)	100,003,000	98,587,000
Common stock, shares outstanding (in shares)	100,003,000	98,587,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue	$ 102,648	$ 80,301
Cost of revenue	18,701	13,226
Gross profit	83,947	67,075
Operating expenses:
Sales and marketing	59,855	52,689
Research and development	26,831	21,935
General and administrative	18,933	15,136
Total operating expenses	105,619	89,760
Loss from operations	(21,672)	(22,685)
Interest income, net	734	1,556
Other expense, net	(960)	(214)
Loss before income taxes	(21,898)	(21,343)
Provision for income taxes	1,079	97
Net loss	$ (22,977)	$ (21,440)
Net loss per share, basic and diluted (in usd per share)	$ (0.23)	$ (0.23)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)	98,855	93,738

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (22,977)	$ (21,440)
Other comprehensive income, net of tax:
Unrealized gains on available-for-sale securities	113	21
Other comprehensive income	113	21
Comprehensive loss	$ (22,864)	$ (21,419)

- Definition

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

+ References + Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance (in shares) at Dec. 31, 2018		93,126
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)		2,638
Exercise of stock options	9,878	$ 26	9,852
Issuance of common stock under employee stock purchase plan (in shares)		439
Issuance of common stock under employee stock purchase plan	8,579	$ 5	8,574
Stock-based compensation	9,408		9,408
Other comprehensive income	21			21
Net loss	(21,440)				(21,440)
Balance (in shares) at Mar. 31, 2019		96,203
Balance at Mar. 31, 2019	$ 128,209	$ 962	614,774	21	(487,548)
Balance (in shares) at Dec. 31, 2019	98,587	98,587
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)	635	635
Exercise of stock options	$ 3,978	$ 6	3,972
Vesting of restricted stock units (in shares)		403
Vesting of restricted stock units	0	$ 4	(4)
Issuance of common stock under employee stock purchase plan (in shares)		378
Issuance of common stock under employee stock purchase plan	7,307	$ 4	7,303
Stock-based compensation	13,050		13,050
Other comprehensive income	113			113
Net loss	$ (22,977)				(22,977)
Balance (in shares) at Mar. 31, 2020	100,003	100,003
Balance at Mar. 31, 2020	$ 100,376	$ 1,000	$ 687,311	$ 163	$ (588,098)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (22,977)	$ (21,440)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	2,678	1,622
Stock-based compensation	13,035	9,319
Deferred income taxes	41	0
Other	474	(284)
Changes in operating assets and liabilities:
Accounts receivable	20,813	11,104
Prepaid expenses and other current assets	1,663	1,374
Deferred commissions	1,523	(377)
Other assets	2,155	54
Accounts payable and accrued expenses	3,669	3,372
Accrued compensation	(13,277)	(7,233)
Deferred revenue	(5,036)	2,002
Other current liabilities	(535)	(429)
Other liabilities	266	42
Net cash provided by (used in) operating activities	4,492	(874)
Cash flows from investing activities:
Purchases of property and equipment	(614)	(2,306)
Purchases of short-term investments	(58,831)	(53,915)
Sales and maturities of short-term investments	78,175	41,750
Net cash provided by (used in) investing activities	18,730	(14,471)
Cash flows from financing activities:
Principal payments under finance lease obligations	(4)	(4)
Proceeds from stock issued in connection with the employee stock purchase plan	7,307	8,579
Proceeds from the exercise of stock options	3,978	9,878
Net cash provided by financing activities	11,281	18,453
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(1,097)	(258)
Net increase in cash and cash equivalents and restricted cash	33,406	2,850
Cash and cash equivalents and restricted cash at beginning of period	74,665	165,378
Cash and cash equivalents and restricted cash at end of period	108,071	168,228
Supplemental disclosure of cash flow information:
Cash paid for interest	41	24
Cash paid for income taxes	1,203	416
Supplemental cash flow information related to leases:
Operating cash payments for operating leases	1,263	1,195
Supplemental disclosure of non-cash flow investing and financing activities:
Construction in progress	$ 5,107	$ 186

Business and Summary of Significant Accounting Policies	3 Months Ended
Business and Summary of Significant Accounting Policies	Mar. 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 enterprise software platform enables broad visibility into an organization’s cyber exposure across the modern attack surface and deep insights that help organizations translate technical data into business insights to understand and reduce their cybersecurity risk. Basis of Presentation The accompanying consolidated financial statements include the accounts of Tenable Holdings, Inc. and our wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with United States generally accepted accounting principles (“GAAP”) for interim financial information. The consolidated statements are unaudited and should be read in conjunction with the consolidated financial statements and related notes included in our 2019 Annual Report on Form 10-K ("10-K") filed with the Securities and Exchange Commission on February 28, 2020. The consolidated financial statements have been prepared on a basis consistent with the audited annual consolidated financial statements included in the 10-K and, in the opinion of management, include all adjustments of a normal recurring nature necessary to fairly state our financial position, our results of operations, and cash flows. The results for the three months ended March 31, 2020 are not necessarily indicative of the operating results expected for the year ending December 31, 2020 or any other future period. 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. Significant Accounting Policies Our significant accounting policies are described in our 10-K. During the three months ended March 31, 2020, there were no material changes to our significant accounting policies other than those described below. 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. Under the new standard, our allowance for doubtful accounts reflects our best estimate of expected future credit losses based on various factors, 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 that may impact our ability to collect our accounts receivable. Additionally, the new standard requires us to evaluate impairments of available-for-sale debt securities due to credit-related and non-credit-related factors. Identified credit-related impairments are recognized as a charge in the statement of operations. The adoption of this guidance did not have a material impact on our condensed consolidated financial statements.

Revenue Recognition

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

Revenue Recognition

Disaggregation of Revenue

The following table presents a summary of revenue:



	Three Months Ended March 31,
(in thousands)	2020		2019
Subscription revenue	$	86,390	$	64,737
Perpetual license and maintenance revenue	13,419		13,527
Professional services and other revenue	2,839		2,037
Revenue	$	102,648	$	80,301

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%, and 90% of revenue through our channel network in the three months ended March 31, 2020 and 2019, respectively. One of our distributors accounted for 43% and 44% of revenue in the three months ended March 31, 2020 and 2019, respectively. That same distributor accounted for 41% and 40% of accounts receivable at March 31, 2020 and December 31, 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 the three months ended March 31, 2020 and 2019, we recognized revenue of $95.3 million and $74.6 million, respectively, that was included in the deferred revenue balance at the beginning of each of the respective periods.

Remaining Performance Obligations

At March 31, 2020, the future estimated revenue related to unsatisfied performance obligations was $363.9 million, with approximately 75% 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:



	Three Months Ended March 31,
(in thousands)	2020			2019
Beginning balance	$	72,265		$	59,434
Capitalization of contract acquisition costs	6,121			6,626
Amortization of deferred contract acquisition costs	(7,644		)	(6,249		)
Ending balance	$	70,742		$	59,811

Cash and Cash Equivalents and Short-Term Investments

3 Months Ended

Mar. 31, 2020

Cash and Cash Equivalents [Abstract]

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:



	March 31, 2020
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Cash equivalents:
Money market funds	$	40,395	$	—	$	—		$	40,395
Total cash equivalents	$	40,395	$	—	$	—		$	40,395

Short-term investments:
Commercial paper	$	52,984	$	—	$	—		$	52,984
Corporate bonds	20,775		6		(109		)	20,672
U.S. Treasury and agency obligations	45,002		266		—			45,268
Total short-term investments	$	118,761	$	272	$	(109	)	$	118,924



	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

Gross unrealized losses were not material at March 31, 2020 and December 31, 2019, respectively. At March 31, 2020, we considered the extent to which any unrealized losses on our short-term investments were driven by credit risk and other 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. Based on our assessment, we do not believe any unrealized losses represent credit losses at March 31, 2020.

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

At March 31, 2020 and December 31, 2019, cash and cash equivalents included $0.4 million of restricted cash, that was related to collateral for a lease and credit card deposits, and excluded $0.3 million of restricted cash, that was related to an account established as collateral for a lease arrangement and was included in other assets on the consolidated balance sheets.

Fair Value Measurements

3 Months Ended

Mar. 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:



	March 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	40,395	$	—	$	—	$	40,395
	$	40,395	$	—	$	—	$	40,395

Short-term investments
Commercial paper	$	—	$	52,984	$	—	$	52,984
Corporate bonds	—		20,672		—		20,672
U.S. Treasury and agency obligations	—		45,268		—		45,268
	$	—	$	118,924	$	—	$	118,924



	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 March 31, 2020 or December 31, 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

3 Months Ended

Mar. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following:



(in thousands)	March 31, 2020			December 31, 2019
Computer software and equipment	$	21,763		$	21,234
Furniture and fixtures	4,618			4,504
Leasehold improvements	21,701			16,953
Right-of-use assets under finance leases	1,866			1,866
Total	49,948			44,557
Less: accumulated depreciation and amortization	(19,414		)	(17,710		)
Property and equipment, net	$	30,534		$	26,847

Depreciation and amortization related to property and equipment was $2.0 million and $1.5 million in the three months ended March 31, 2020 and 2019, respectively.

Goodwill and Acquired Intangible Assets

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Acquired Intangible Assets

On December 2, 2019, we acquired Indegy, Ltd. We have not yet finalized the allocation of the purchase price, which may change as additional information becomes available related to any working capital adjustment and income taxes.

At March 31, 2020 and December 31, 2019, our goodwill balance was $54.1 million, respectively.

Acquired intangible assets subject to amortization are as follows:



	March 31, 2020							December 31, 2019
(in thousands)	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired technology	$	17,325	$	(2,563	)	$	14,762	$	17,325	$	(2,009	)	$	15,316
Trade name	200		(33		)	167		200		(8		)	192
	$	17,525	$	(2,596	)	$	14,929	$	17,525	$	(2,017	)	$	15,508

Amortization of acquired intangible assets was $0.6 million and $0.2 million in the three months ended March 31, 2020 and 2019, respectively.

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



(in thousands)
Year ending December 31,
2020⁽¹⁾	$	1,735
2021	2,306
2022	2,214
2023	2,214
2024	2,214
Thereafter	4,246
Total	$	14,929

_______________

(1) Represents the nine months ending December 31, 2020.

Leases

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Leases

We have operating leases for office facilities and finance leases for computer and office equipment. The components of lease expense were as follows:



	Three Months Ended March 31,
(in thousands)	2020		2019
Operating lease cost	$	2,484	$	981

Finance lease cost
Amortization of ROU assets	$	110	$	153
Interest on lease liabilities	2		2
Total finance lease cost	$	112	$	155

Rent expense for short-term leases in the three months ended March 31, 2020 and 2019 was not material.

Supplemental information related to leases was as follows:



	March 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	9.9 years	10.0 years
Weighted average discount rate	5.8%	5.8%



	Three Months Ended March 31,
(in thousands)	2020		2019
ROU assets obtained in exchange for lease obligations
Operating leases	$	—	$	2,198
Finance leases	—		11

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



(in thousands)
Year ending December 31,
2020⁽¹⁾	$	3,866
2021	6,749
2022	6,985
2023	6,993
2024	7,129
Thereafter	50,935
Total lease payments	82,657
Less: Imputed interest	(22,985		)
Less: Tenant incentives	(14,505		)
Total	$	45,167

_______________

(1) Represents the nine months ending December 31, 2020.

Leases

We have operating leases for office facilities and finance leases for computer and office equipment. The components of lease expense were as follows:



	Three Months Ended March 31,
(in thousands)	2020		2019
Operating lease cost	$	2,484	$	981

Finance lease cost
Amortization of ROU assets	$	110	$	153
Interest on lease liabilities	2		2
Total finance lease cost	$	112	$	155

Rent expense for short-term leases in the three months ended March 31, 2020 and 2019 was not material.

Supplemental information related to leases was as follows:



	March 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	9.9 years	10.0 years
Weighted average discount rate	5.8%	5.8%



	Three Months Ended March 31,
(in thousands)	2020		2019
ROU assets obtained in exchange for lease obligations
Operating leases	$	—	$	2,198
Finance leases	—		11

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



(in thousands)
Year ending December 31,
2020⁽¹⁾	$	3,866
2021	6,749
2022	6,985
2023	6,993
2024	7,129
Thereafter	50,935
Total lease payments	82,657
Less: Imputed interest	(22,985		)
Less: Tenant incentives	(14,505		)
Total	$	45,167

_______________

(1) Represents the nine months ending December 31, 2020.

Debt	3 Months Ended
Debt	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt	Debt There were no amounts outstanding under our $25.0 million revolving credit facility (“Credit Facility”) with Silicon Valley Bank in the three months ended March 31, 2020 or in 2019. Our borrowing capacity at March 31, 2020 was reduced by $2.5 million related to a standby letter of credit for the security deposit on our new headquarters lease. In April 2020, the maturity date of the Credit Facility was extended by 60 days until July 3, 2020. Additionally, the Credit Facility was amended to increase the maximum amount of letters of credit that may be issued from $5.0 million to $6.5 million.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

Under the evergreen provision in our 2018 Equity Incentive Plan ("2018 Plan"), we reserved an additional 4,929,361 shares of our common stock for issuance in January 2020. At March 31, 2020, there were 17,555,416 shares available for grant under the 2018 Plan.

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



	Three Months Ended March 31,
(in thousands)	2020		2019
Cost of revenue	$	747	$	652
Sales and marketing	4,496		3,366
Research and development	2,948		2,030
General and administrative	4,844		3,271
Total stock-based compensation expense	$	13,035	$	9,319

At March 31, 2020, the unrecognized stock-based compensation expense related to unvested restricted stock units was $134.5 million, which is expected to be recognized over an estimated remaining weighted average period of 3.4 years.

At March 31, 2020, the total unrecognized stock-based compensation expense related to outstanding stock options was $20.3 million, which is expected to be recognized over an estimated remaining weighted average period of 1.9 years.

At March 31, 2020, the unrecognized stock-based compensation expense related to unvested awards of restricted stock was $1.3 million, which is expected to be recognized over an estimated remaining period of 0.8 years.

Restricted Stock and Restricted Stock Units

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



	Restricted Stock				Restricted Stock Units
(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, 2019	495		$	4.25	2,894		$	26.34
Granted	—		—		3,082		28.00
Vested	(99	)	4.25		(403	)	29.14
Forfeited	—		—		(123	)	26.16
Unvested balance at March 31, 2020	396		4.25		5,450		27.07

Stock Options

A summary of our stock option activity is presented 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, 2019	12,939	$	8.38	7.1	$	201,608
Granted	—	—
Exercised	(635)	6.27			12,383
Forfeited/canceled	(190)	10.78
Outstanding at March 31, 2020	12,114	8.45		7.0	162,596
Exercisable at March 31, 2020	6,783	6.12		6.5	106,847

At March 31, 2020, there were 12.1 million stock options that were vested and expected to vest.

2018 Employee Stock Purchase Plan

Under the evergreen provision in our 2018 Employee Stock Purchase Plan ("2018 ESPP"), we reserved an additional 1,478,808 shares of our common stock for issuance in January 2020. At March 31, 2020, there were 5,721,517 shares reserved for issuance under the 2018 ESPP.

In the three months ended March 31, 2020, employees purchased 377,378 shares of our common stock at a weighted average price of $19.36 per share, resulting in $7.3 million of cash proceeds.

At March 31, 2020, there was $1.7 million of employee contributions to the 2018 ESPP included in accrued compensation. The unrecognized stock-based compensation expense related to our 2018 ESPP was $8.7 million, which is expected to be recognized over the remaining weighted average period of 0.8 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:



	Three Months Ended March 31,
	2020	2019
Expected term (in years)	0.5 — 2.0	0.5 — 2.0
Expected volatility	41.6% — 47.9%	35.4% — 44.6%
Risk-free interest rate	0.8% — 0.9%	2.5% — 2.6%
Expected dividend yield	—	—

Net Loss Per Share

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

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



	Three Months Ended March 31,
(in thousands, except per share data)	2020			2019
Net loss	$	(22,977	)	$	(21,440	)

Weighted-average shares used to compute net loss per share	98,855			93,738
Net loss per share, basic and diluted	$	(0.23	)	$	(0.23	)

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



	Three Months Ended March 31,
(in thousands)	2020	2019
Stock options	12,114	15,632
Restricted stock units	5,450	2,934
Restricted shares	396	791
Shares to be issued under the 2018 ESPP	87	65
Total	18,047	19,422

Geographic Information

3 Months Ended

Mar. 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:



	Three Months Ended March 31,
(in thousands)	2020		2019
Americas	$	69,314	$	56,091
Europe, Middle East and Africa	23,550		17,307
Asia Pacific	9,784		6,903
Revenue	$	102,648	$	80,301

Customers located in the United States accounted for 62%, and 65% of revenue in the three months ended March 31, 2020 and 2019, 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:



(in thousands)	March 31, 2020		December 31, 2019
United States	$	25,734	$	21,464
International	4,800		5,383
Property and equipment, net	$	30,534	$	26,847

Business and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidations	The accompanying consolidated financial statements include the accounts of Tenable Holdings, Inc. and our wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Basis of Accounting	The consolidated financial statements have been prepared in conformity with United States generally accepted accounting principles (“GAAP”) for interim financial information. The consolidated statements are unaudited and should be read in conjunction with the consolidated financial statements and related notes included in our 2019 Annual Report on Form 10-K ("10-K") filed with the Securities and Exchange Commission on February 28, 2020. The consolidated financial statements have been prepared on a basis consistent with the audited annual consolidated financial statements included in the 10-K and, in the opinion of management, include all adjustments of a normal recurring nature necessary to fairly state our financial position, our results of operations, and cash flows.
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.
Recently Adopted 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. Under the new standard, our allowance for doubtful accounts reflects our best estimate of expected future credit losses based on various factors, 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 that may impact our ability to collect our accounts receivable. Additionally, the new standard requires us to evaluate impairments of available-for-sale debt securities due to credit-related and non-credit-related factors. Identified credit-related impairments are recognized as a charge in the statement of operations. The adoption of this guidance did not have a material impact on our condensed consolidated financial statements.

Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

Summary of revenue

The following table presents a summary of revenue:



	Three Months Ended March 31,
(in thousands)	2020		2019
Subscription revenue	$	86,390	$	64,737
Perpetual license and maintenance revenue	13,419		13,527
Professional services and other revenue	2,839		2,037
Revenue	$	102,648	$	80,301

Activity of deferred contract costs

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



	Three Months Ended March 31,
(in thousands)	2020			2019
Beginning balance	$	72,265		$	59,434
Capitalization of contract acquisition costs	6,121			6,626
Amortization of deferred contract acquisition costs	(7,644		)	(6,249		)
Ending balance	$	70,742		$	59,811

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

3 Months Ended

Mar. 31, 2020

Cash and Cash Equivalents [Abstract]

Summary of amortized cost, unrealized gain and loss and estimated fair value

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



	March 31, 2020
(in thousands)	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Cash equivalents:
Money market funds	$	40,395	$	—	$	—		$	40,395
Total cash equivalents	$	40,395	$	—	$	—		$	40,395

Short-term investments:
Commercial paper	$	52,984	$	—	$	—		$	52,984
Corporate bonds	20,775		6		(109		)	20,672
U.S. Treasury and agency obligations	45,002		266		—			45,268
Total short-term investments	$	118,761	$	272	$	(109	)	$	118,924



	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)

3 Months Ended

Mar. 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:



	March 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	40,395	$	—	$	—	$	40,395
	$	40,395	$	—	$	—	$	40,395

Short-term investments
Commercial paper	$	—	$	52,984	$	—	$	52,984
Corporate bonds	—		20,672		—		20,672
U.S. Treasury and agency obligations	—		45,268		—		45,268
	$	—	$	118,924	$	—	$	118,924



	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

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Property and Equipment, Net (Tables)

3 Months Ended

Mar. 31, 2020

Property, Plant and Equipment [Abstract]

Property and equipment, net

Property and equipment, net consisted of the following:



(in thousands)	March 31, 2020			December 31, 2019
Computer software and equipment	$	21,763		$	21,234
Furniture and fixtures	4,618			4,504
Leasehold improvements	21,701			16,953
Right-of-use assets under finance leases	1,866			1,866
Total	49,948			44,557
Less: accumulated depreciation and amortization	(19,414		)	(17,710		)
Property and equipment, net	$	30,534		$	26,847

Goodwill and Acquired Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of finite-lived intangible assets

Acquired intangible assets subject to amortization are as follows:



	March 31, 2020							December 31, 2019
(in thousands)	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired technology	$	17,325	$	(2,563	)	$	14,762	$	17,325	$	(2,009	)	$	15,316
Trade name	200		(33		)	167		200		(8		)	192
	$	17,525	$	(2,596	)	$	14,929	$	17,525	$	(2,017	)	$	15,508

Schedule of finite-lived intangible assets, future amortization expense

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



(in thousands)
Year ending December 31,
2020⁽¹⁾	$	1,735
2021	2,306
2022	2,214
2023	2,214
2024	2,214
Thereafter	4,246
Total	$	14,929

_______________

(1) Represents the nine months ending December 31, 2020.

Leases (Tables)

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Components of leases

Supplemental information related to leases was as follows:



	March 31, 2020	December 31, 2019
Operating leases
Weighted average remaining lease term	9.9 years	10.0 years
Weighted average discount rate	5.8%	5.8%



	Three Months Ended March 31,
(in thousands)	2020		2019
ROU assets obtained in exchange for lease obligations
Operating leases	$	—	$	2,198
Finance leases	—		11

The components of lease expense were as follows:



	Three Months Ended March 31,
(in thousands)	2020		2019
Operating lease cost	$	2,484	$	981

Finance lease cost
Amortization of ROU assets	$	110	$	153
Interest on lease liabilities	2		2
Total finance lease cost	$	112	$	155

Schedule of maturities of operating lease liabilities

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



(in thousands)
Year ending December 31,
2020⁽¹⁾	$	3,866
2021	6,749
2022	6,985
2023	6,993
2024	7,129
Thereafter	50,935
Total lease payments	82,657
Less: Imputed interest	(22,985		)
Less: Tenant incentives	(14,505		)
Total	$	45,167

_______________

(1) Represents the nine months ending December 31, 2020.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 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:



	Three Months Ended March 31,
(in thousands)	2020		2019
Cost of revenue	$	747	$	652
Sales and marketing	4,496		3,366
Research and development	2,948		2,030
General and administrative	4,844		3,271
Total stock-based compensation expense	$	13,035	$	9,319

Stock option activity

A summary of our stock option activity is presented 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, 2019	12,939	$	8.38	7.1	$	201,608
Granted	—	—
Exercised	(635)	6.27			12,383
Forfeited/canceled	(190)	10.78
Outstanding at March 31, 2020	12,114	8.45		7.0	162,596
Exercisable at March 31, 2020	6,783	6.12		6.5	106,847

Summary of restricted stock and restricted stock units

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



	Restricted Stock				Restricted Stock Units
(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, 2019	495		$	4.25	2,894		$	26.34
Granted	—		—		3,082		28.00
Vested	(99	)	4.25		(403	)	29.14
Forfeited	—		—		(123	)	26.16
Unvested balance at March 31, 2020	396		4.25		5,450		27.07

ESPP 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:



	Three Months Ended March 31,
	2020	2019
Expected term (in years)	0.5 — 2.0	0.5 — 2.0
Expected volatility	41.6% — 47.9%	35.4% — 44.6%
Risk-free interest rate	0.8% — 0.9%	2.5% — 2.6%
Expected dividend yield	—	—

Net Loss Per Share (Tables)

3 Months Ended

Mar. 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:



	Three Months Ended March 31,
(in thousands, except per share data)	2020			2019
Net loss	$	(22,977	)	$	(21,440	)

Weighted-average shares used to compute net loss per share	98,855			93,738
Net loss per share, basic and diluted	$	(0.23	)	$	(0.23	)

Potentially dilutive securities

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



	Three Months Ended March 31,
(in thousands)	2020	2019
Stock options	12,114	15,632
Restricted stock units	5,450	2,934
Restricted shares	396	791
Shares to be issued under the 2018 ESPP	87	65
Total	18,047	19,422

Geographic Information (Tables)

3 Months Ended

Mar. 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:



	Three Months Ended March 31,
(in thousands)	2020		2019
Americas	$	69,314	$	56,091
Europe, Middle East and Africa	23,550		17,307
Asia Pacific	9,784		6,903
Revenue	$	102,648	$	80,301

Property and equipment, net by geographic area

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



(in thousands)	March 31, 2020		December 31, 2019
United States	$	25,734	$	21,464
International	4,800		5,383
Property and equipment, net	$	30,534	$	26,847

Revenue Recognition - Summary of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 102,648	$ 80,301
Subscription revenue
Disaggregation of Revenue [Line Items]
Revenue	86,390	64,737
Perpetual license and maintenance revenue
Disaggregation of Revenue [Line Items]
Revenue	13,419	13,527
Professional services and other revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 2,839	$ 2,037

Revenue Recognition - Concentrations (Details)	3 Months Ended		12 Months Ended
Revenue Recognition - Concentrations (Details)	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
One distributor \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk, percentage	43.00%	44.00%
One distributor \| Accounts receivable \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk, percentage	41.00%		40.00%
Channel network \| Revenue \| Sales method risk
Concentration Risk [Line Items]
Concentration risk, percentage	91.00%	90.00%

Revenue Recognition - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue recognized that was included in deferred revenue	$ 95.3	$ 74.6

Revenue Recognition - Remaining Performance Obligations (Details) $ in Millions	Mar. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Future estimated revenue	$ 363.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected recognized percentage over succeeding 12 months	75.00%
Expected timing of satisfaction	4 years

Revenue Recognition - Activity of Deferred Contract Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 72,265	$ 59,434
Capitalization of contract acquisition costs	6,121	6,626
Amortization of deferred contract acquisition costs	(7,644)	(6,249)
Ending balance	$ 70,742	$ 59,811

Cash and Cash Equivalents and Short-Term Investments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Collateral for Lease and Credit Card Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 0.4	$ 0.4
Collateral for Lease Arrangement
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 0.3	$ 0.3

Cash and Cash Equivalents and Short-Term Investments - Summary of Amortized Cost, Unrealized Gain and Loss and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Amortized Cost	$ 118,761	$ 137,854
Unrealized Gain	272	52
Unrealized Loss	(109)	(2)
Estimated Fair Value	118,924	137,904
Commercial paper
Cash and Cash Equivalents [Line Items]
Amortized Cost	52,984	61,371
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	52,984	61,371
Corporate bonds
Cash and Cash Equivalents [Line Items]
Amortized Cost	20,775	23,856
Unrealized Gain	6	14
Unrealized Loss	(109)	(1)
Estimated Fair Value	20,672	23,869
U.S. Treasury and agency obligations
Cash and Cash Equivalents [Line Items]
Amortized Cost	45,002	52,627
Unrealized Gain	266	38
Unrealized Loss	0	(1)
Estimated Fair Value	45,268	52,664
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	40,395	13,588
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		8,987
Cash equivalents
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 40,395	$ 22,575

Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total	$ 49,948		$ 44,557
Less: accumulated depreciation and amortization	(19,414)		(17,710)
Property and equipment, net	30,534		26,847
Depreciation and amortization	2,000	$ 1,500
Computer software and equipment
Property, Plant and Equipment [Line Items]
Total	21,763		21,234
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	4,618		4,504
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	21,701		16,953
Right-of-use assets under finance leases
Property, Plant and Equipment [Line Items]
Total	$ 1,866		$ 1,866

Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 54,138		$ 54,138
Amortization of acquired intangible assets	$ 600	$ 200

Goodwill and Acquired Intangible Assets - Schedule of Finite-lived Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 17,525	$ 17,525
Accumulated Amortization	(2,596)	(2,017)
Total	14,929	15,508
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,325	17,325
Accumulated Amortization	(2,563)	(2,009)
Total	14,762	15,316
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	200	200
Accumulated Amortization	(33)	(8)
Total	$ 167	$ 192

Goodwill and Acquired Intangible Assets - Schedule of Future Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
2020	$ 1,735
2021	2,306
2022	2,214
2023	2,214
2024	2,214
Thereafter	4,246
Total	$ 14,929	$ 15,508

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating lease cost	$ 2,484	$ 981
Amortization of ROU assets	110	153
Interest on lease liabilities	2	2
Total finance lease cost	$ 112	$ 155

Leases - Supplemental Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating leases
Weighted average remaining lease term	9 years 10 months 24 days		10 years
Weighted average discount rate	5.80%		5.80%
ROU assets obtained in exchange for lease obligations
Operating leases	$ 0	$ 2,198
Finance leases	$ 0	$ 11

Leases - Operating Lease Liability Maturities (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Leases [Abstract]
2020	$ 3,866
2021	6,749
2022	6,985
2023	6,993
2024	7,129
Thereafter	50,935
Total lease payments	82,657
Less: Imputed interest	(22,985)
Less: Tenant incentives	(14,505)
Total	$ 45,167

Debt (Details) - Silicon Valley Bank - USD ($)		3 Months Ended
Debt (Details) - Silicon Valley Bank - USD ($)	Apr. 22, 2020	Mar. 31, 2020	Mar. 31, 2019	Apr. 21, 2020
Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings outstanding		$ 0	$ 0
Credit facility, maximum borrowing capacity		25,000,000.0
Revolving Credit Facility \| Subsequent Event
Line of Credit Facility [Line Items]
Credit facility, extension period	60 days
Standby Letters of Credit
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity		$ 2,500,000
Letter of Credit \| Subsequent Event
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity	$ 6,500,000			$ 5,000,000.0

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense, outstanding stock options	$ 20.3
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated remaining weighted average period	1 year 10 months 24 days
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated remaining weighted average period	9 months 18 days
Unrecognized stock-based compensation expense, unvested restricted stock or RSUs	$ 1.3
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated remaining weighted average period	3 years 4 months 24 days
Unrecognized stock-based compensation expense, unvested restricted stock or RSUs	$ 134.5
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
Shares available for grant (in shares)	17,555,416

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 13,035	$ 9,319
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	747	652
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	4,496	3,366
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	2,948	2,030
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 4,844	$ 3,271

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Number of Shares
Number of shares outstanding, beginning of period (in shares)	12,939
Number of shares, granted (in shares)	0
Number of shares, exercised (in shares)	(635)
Number of shares, forfeited/canceled (in shares)	(190)
Number of shares outstanding, end of period (in shares)	12,114	12,939
Number of shares exercisable (in shares)	6,783
Weighted Average Exercise Price
Weighted average exercise price, outstanding, beginning of period (in usd per share)	$ 8.38
Weighted average exercise price, granted (in usd per share)	0
Weighted average exercise price, exercised (in usd per share)	6.27
Weighted average exercise price, forfeited/canceled (in usd per share)	10.78
Weighted average exercise price, outstanding, end of period (in usd per share)	8.45	$ 8.38
Weighted average exercise price, exercisable (in usd per share)	$ 6.12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term (in years), outstanding	7 years	7 years 1 month 6 days
Weighted average remaining contractual term (in years), exercisable	6 years 6 months
Aggregate intrinsic value, outstanding	$ 162,596	$ 201,608
Aggregate intrinsic value, exercised	12,383
Aggregate intrinsic value, exercisable	$ 106,847

Stock-Based Compensation - Stock Option Activity (Narrative) (Details) shares in Millions	Mar. 31, 2020 shares
Share-based Payment Arrangement [Abstract]
Stock options vested and expected to vest (in shares)	12.1

Stock-Based Compensation - Restricted Stock and Restricted Stock Units (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Restricted shares
Number of Shares
Number of shares unvested, beginning of period (in shares) \| shares	495
Number of shares, granted (in shares) \| shares	0
Number of shares, vested (in shares) \| shares	(99)
Number of shares, forfeited (in shares) \| shares	0
Number of shares unvested, end of period (in shares) \| shares	396
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning of period (in usd per share) \| $ / shares	$ 4.25
Weighted average grant date fair value, granted (in usd per share) \| $ / shares	0
Weighted average grant date fair value, vested (in usd per share) \| $ / shares	4.25
Weighted average grant date fair value, forfeited (in usd per share) \| $ / shares	0
Weighted average grant date fair value, end of period (in usd per share) \| $ / shares	$ 4.25
Restricted stock units
Number of Shares
Number of shares unvested, beginning of period (in shares) \| shares	2,894
Number of shares, granted (in shares) \| shares	3,082
Number of shares, vested (in shares) \| shares	(403)
Number of shares, forfeited (in shares) \| shares	(123)
Number of shares unvested, end of period (in shares) \| shares	5,450
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning of period (in usd per share) \| $ / shares	$ 26.34
Weighted average grant date fair value, granted (in usd per share) \| $ / shares	28.00
Weighted average grant date fair value, vested (in usd per share) \| $ / shares	29.14
Weighted average grant date fair value, forfeited (in usd per share) \| $ / shares	26.16
Weighted average grant date fair value, end of period (in usd per share) \| $ / shares	$ 27.07

Stock-Based Compensation - Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	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	$ 7,307	$ 8,579
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)	5,721,517		1,478,808
Common stock purchased (in shares)	377,378
Share price (in usd per share)	$ 19.36
Employee contributions	$ 1,700
Unrecognized stock-based compensation expense	$ 8,700
Remaining offering period	9 months 18 days

Stock-Based Compensation - Fair Value Assumptions (Details) - Employee stock purchase plan	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	41.60%	35.40%
Expected volatility, maximum	47.90%	44.60%
Risk - free interest rate, minimum	0.80%	2.50%
Risk - free interest rate, maximum	0.90%	2.60%
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	2 years	2 years

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (22,977)	$ (21,440)
Weighted-average shares used to compute net loss per share (in shares)	98,855	93,738
Net loss per share, basic and diluted (in usd per share)	$ (0.23)	$ (0.23)

- Definition

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

+ References + Details

Net Loss Per Share - Schedule of Potentially Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	18,047	19,422
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	12,114	15,632
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	5,450	2,934
Restricted shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	396	791
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	87	65

Geographic Information - Narrative (Details) - segment	3 Months Ended
Geographic Information - Narrative (Details) - segment	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting [Abstract]
Number of operating segments	1
United States \| Revenue \| Geographic concentration risk
Concentration Risk [Line Items]
Concentration risk, percentage	62.00%	65.00%

Geographic Information - Revenue by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 102,648	$ 80,301
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	69,314	56,091
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	23,550	17,307
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 9,784	$ 6,903

Geographic Information - Property And Equipment, Net By Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 30,534	$ 26,847
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	25,734	21,464
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 4,800	$ 5,383

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 118,924	$ 137,904
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	52,984	61,371
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	20,672	23,869
U.S. Treasury and agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45,268	52,664
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	40,395	13,588
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		8,987
Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	40,395	22,575
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| U.S. Treasury and agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	40,395	13,588
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Level 1 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	40,395	13,588
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	118,924	137,904
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	52,984	61,371
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	20,672	23,869
Level 2 \| U.S. Treasury and agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45,268	52,664
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		8,987
Level 2 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	8,987
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| U.S. Treasury and agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Level 3 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0	$ 0