Cloudflare (NET) 10-K 4 Mar 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Sep. 17, 2019
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-39039
Entity Registrant Name	Cloudflare, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-0805829
Entity Address, Address Line One	101 Townsend Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94107
City Area Code	888
Local Phone Number	993-5273
Title of 12(b) Security	Class A Common Stock, $0.001 par value
Trading Symbol	NET
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 1,905
Documents Incorporated by Reference	Portions of the registrant's definitive Proxy Statement relating to the 2020 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December 31, 2019.
Amendment Flag	false
Entity Central Index Key	0001477333
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--12-31
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		94,569,695
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		208,066,163

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 138,976	$ 25,055
Available-for-sale securities	497,972	135,602
Accounts receivable, net	33,867	25,155
Contract assets	2,063	1,552
Prepaid expenses and other current assets	16,994	9,373
Total current assets	689,872	196,737
Property and equipment, net	101,466	73,210
Goodwill	4,083	4,083
Acquired intangible assets, net	31	156
Deferred contract acquisition costs, noncurrent	25,184	15,940
Restricted cash	6,660	6,371
Other noncurrent assets	3,528	1,883
Total assets	830,824	298,380
Current liabilities:
Accounts payable	11,463	14,285
Accrued expenses and other current liabilities	28,314	15,699
Note payable, current portion	0	255
Liability for early exercise of unvested stock options	13,263	14,323
Deferred revenue	30,843	16,817
Total current liabilities	83,883	61,379
Build-to-suit lease financing obligation	10,506	10,443
Deferred revenue, noncurrent	804	220
Redeemable convertible preferred stock warrant liability	0	1,618
Other noncurrent liabilities	9,803	6,704
Total liabilities	104,996	80,364
Commitments and contingencies (Note 7)
Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock; $0.001 par value; zero and 168,108 shares authorized as of December 31, 2019 and 2018, respectively; zero and 165,658 shares issued and outstanding with aggregate liquidation preference of zero and $332,041 as of December 31, 2019 and 2018, respectively	0	331,521
Stockholders’ Equity (Deficit)
Additional paid-in capital	1,027,179	82,345
Accumulated deficit	(301,706)	(195,878)
Accumulated other comprehensive income (loss)	61	(57)
Total stockholders’ equity (deficit)	725,828	(113,505)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	830,824	298,380
Class A common stock
Stockholders’ Equity (Deficit)
Common stock	87	0
Class B common stock
Stockholders’ Equity (Deficit)
Common stock	$ 207	$ 85

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized (in shares)	0	168,108,000
Redeemable convertible preferred stock, shares issued (in shares)	0	165,658,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	165,658,000
Aggregate liquidation preference	$ 0	$ 332,041,000
Class A common stock
Stockholders’ Equity (Deficit)
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	2,250,000,000	550,000,000
Common stock, shares issued (in shares)	87,071,783	0
Common stock, shares outstanding (in shares)	87,071,783	0
Class B common stock
Stockholders’ Equity (Deficit)
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	315,000,000	300,000,000
Common stock, shares issued (in shares)	213,101,364	91,542,243
Common stock, shares outstanding (in shares)	213,101,364	91,542,243

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 287,022	$ 192,674	$ 134,915
Cost of revenue	63,423	43,537	28,788
Gross profit	223,599	149,137	106,127
Operating expenses:
Sales and marketing	159,298	94,394	61,899
Research and development	90,669	54,463	33,650
General and administrative	81,578	85,179	20,308
Total operating expenses	331,545	234,036	115,857
Loss from operations	(107,946)	(84,899)	(9,730)
Non-operating income (expense):
Interest income	5,787	1,895	762
Interest expense	(1,112)	(992)	(862)
Other income (expense), net	(1,442)	(2,091)	115
Total non-operating income (expense), net	3,233	(1,188)	15
Loss before income taxes	(104,713)	(86,087)	(9,715)
Provision for income taxes	1,115	1,077	1,033
Net loss	$ (105,828)	$ (87,164)	$ (10,748)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.72)	$ (1.08)	$ (0.14)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	146,306	80,981	77,147

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (105,828)	$ (87,164)	$ (10,748)
Other comprehensive income (loss):
Change in unrealized gain (loss) on investments, net of tax	118	49	(17)
Other comprehensive income (loss)	118	49	(17)
Comprehensive loss	$ (105,710)	$ (87,115)	$ (10,765)

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Redeemable convertible preferred stock	Class A common stock	Class A common stockCommon Stock	Class B common stock	Class B common stockCommon Stock
Beginning balance (in shares) at Dec. 31, 2016						152,022,000
Beginning balance at Dec. 31, 2016						$ 181,546
Ending balance (in shares) at Dec. 31, 2017						152,022,000
Ending balance at Dec. 31, 2017						$ 181,546
Beginning balance (in shares) at Dec. 31, 2016								0		76,593,000
Beginning balance at Dec. 31, 2016	$ (53,390)		$ 44,588	$ (97,966)	$ (89)			$ 0		$ 77
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	2,458,000									1,461,000
Issuance of common stock upon exercise of stock options	$ 1,055		1,053							$ 2
Repurchases of unvested common stock (in shares)										(11,000)
Issuance of common stock related to early exercised stock options (in shares)										997,000
Vesting of shares issued upon early exercise of stock options	455		455
Vesting of restricted stock (in shares)										76,000
Vesting of restricted common stock	5		5
Stock-based compensation	2,806		2,806
Net loss	(10,748)	$ (10,748)		(10,748)
Other comprehensive income (loss)	(17)				(17)
Ending balance (in shares) at Dec. 31, 2017								0		79,116,000
Ending balance at Dec. 31, 2017	$ (59,834)		48,907	(108,714)	(106)			$ 0		$ 79
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series D redeemable convertible preferred stock, net of issuance costs of $25 (in shares)						13,636,000
Issuance of Series D redeemable convertible preferred stock, net of issuance costs of $25						$ 149,975
Ending balance (in shares) at Dec. 31, 2018	165,658,000					165,658,000
Ending balance at Dec. 31, 2018	$ 331,521					$ 331,521
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	12,387,000									5,481,000
Issuance of common stock upon exercise of stock options	$ 4,412		4,406							$ 6
Repurchases of unvested common stock (in shares)										(36,000)
Issuance of common stock related to early exercised stock options (in shares)										6,906,000
Vesting of shares issued upon early exercise of stock options	1,415		1,415
Vesting of restricted stock (in shares)										75,000
Vesting of restricted common stock	3		3
Stock-based compensation	27,614		27,614
Net loss	(87,164)	$ (87,164)		(87,164)
Other comprehensive income (loss)	49				49
Ending balance (in shares) at Dec. 31, 2018							0	0	91,542,243	91,542,000
Ending balance at Dec. 31, 2018	$ (113,505)		82,345	(195,878)	(57)			$ 0		$ 85
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)						(165,658,000)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering						$ (331,521)
Ending balance (in shares) at Dec. 31, 2019	0					0
Ending balance at Dec. 31, 2019	$ 0					$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon initial public offering, net of underwriting discounts and issuance costs (in shares)								40,250,000
Issuance of common stock upon initial public offering, net of underwriting discounts and issuance costs	565,041		565,001					$ 40
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)								31,381,000		134,277,000
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	331,521		331,355					$ 31		$ 135
Conversion of redeemable convertible preferred stock warrants into common stock warrants and issuance of common stock upon net exercise of common stock warrants (in shares)									174,347	174,000
Conversion of redeemable convertible preferred stock warrants into common stock warrants and issuance of common stock upon net exercise of common stock warrants	3,135		3,135
Issuance of common stock in connection with acquisition (in shares)										7,000
Issuance of common stock in connection with acquisition	$ 18		18
Issuance of common stock upon exercise of stock options (in shares)	2,665,000							27,000		1,736,000
Issuance of common stock upon exercise of stock options	$ 3,058		3,055					$ 1		$ 2
Repurchases of unvested common stock (in shares)										(123,000)
Issuance of common stock related to early exercised stock options (in shares)										902,000
Vesting of shares issued upon early exercise of stock options	3,668		3,668
Conversion of Class B to Class A common stock (in shares)								15,414,000		(15,414,000)
Conversion of Class B to Class A common stock	0							$ 15		$ (15)
Stock-based compensation	38,602		38,602
Net loss	(105,828)			(105,828)				$ (18,259)		$ (87,569)
Other comprehensive income (loss)	118				118
Ending balance (in shares) at Dec. 31, 2019							87,071,783	87,072,000	213,101,364	213,101,000
Ending balance at Dec. 31, 2019	$ 725,828		$ 1,027,179	$ (301,706)	$ 61			$ 87		$ 207

CONSOLIDATED STATEMENTS OF RE_2

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Issuance costs	$ 0
Redeemable convertible preferred stock
Issuance costs	$ 25

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows From Operating Activities
Net loss	$ (105,828,000)	$ (87,164,000)	$ (10,748,000)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:
Depreciation and amortization expense	29,479,000	18,905,000	12,174,000
Amortization of deferred contract acquisition costs	10,821,000	7,060,000	3,955,000
Stock-based compensation expense	36,627,000	27,347,000	2,755,000
Net accretion of discounts and amortization of premiums on available-for-sale securities	(1,801,000)	(570,000)	338,000
Deferred income taxes	370,000	385,000	(135,000)
Provision for bad debt	2,488,000	1,080,000	0
Change in fair value of redeemable convertible preferred stock warrant liability	1,517,000	1,220,000	50,000
Other	304,000	46,000	9,000
Changes in operating assets and liabilities, net of effect of acquisitions:
Accounts receivable, net	(11,200,000)	(14,758,000)	(2,073,000)
Contract assets	(511,000)	2,158,000	(3,075,000)
Deferred contract acquisition costs	(20,065,000)	(12,235,000)	(8,976,000)
Prepaid expenses and other current assets	(7,621,000)	(5,942,000)	941,000
Other noncurrent assets	(1,575,000)	(352,000)	(1,261,000)
Accounts payable	(1,328,000)	4,386,000	(957,000)
Accrued expenses and other current liabilities	12,334,000	6,824,000	3,982,000
Deferred revenue	14,610,000	4,903,000	5,500,000
Other noncurrent liabilities	2,462,000	3,426,000	688,000
Net cash provided by (used in) operating activities	(38,917,000)	(43,281,000)	3,167,000
Cash Flows From Investing Activities
Purchases of property and equipment	(43,289,000)	(25,466,000)	(19,031,000)
Capitalized internal-use software	(13,990,000)	(9,373,000)	(3,944,000)
Cash paid for acquisitions, net of cash acquired	0	0	(250,000)
Purchases of available-for-sale securities	(537,382,000)	(145,269,000)	(47,090,000)
Sales of available-for-sale securities	1,978,000	0	0
Maturities of available-for-sale securities	174,998,000	59,249,000	79,831,000
Other investing activities	44,000	64,000	28,000
Net cash provided by (used in) investing activities	(417,641,000)	(120,795,000)	9,544,000
Cash Flows From Financing Activities
Proceeds from issuance of preferred stock, net of issuance costs	0	149,975,000	0
Proceeds from initial public offering, net of underwriting discounts and commissions	570,544,000	0	0
Proceeds from the exercise of stock options	3,058,000	4,412,000	1,085,000
Proceeds from the early exercise of stock options	2,909,000	14,525,000	1,675,000
Repurchases of unvested common stock	(283,000)	(65,000)	(16,000)
Payments on note payable	(255,000)	(356,000)	(345,000)
Payments on related party promissory note payable	0	0	(4,750,000)
Proceeds from build-to-suit lease financing obligation drawdown	63,000	130,000	2,202,000
Payments of deferred offering costs	(5,268,000)	0	0
Net cash provided by (used in) financing activities	570,768,000	168,621,000	(149,000)
Net increase in cash, cash equivalents, and restricted cash	114,210,000	4,545,000	12,562,000
Cash, cash equivalents, and restricted cash, beginning of period	31,426,000	26,881,000	14,319,000
Cash, cash equivalents, and restricted cash, end of period	145,636,000	31,426,000	26,881,000
Supplemental Disclosure of Cash Flow Information:
Cash paid for interest	786,000	786,000	812,000
Cash paid for taxes	2,391,000	2,658,000	825,000
Supplemental Disclosure of Non-cash Investing and Financing Activities:
Stock-based compensation capitalized for software development	1,975,000	267,000	51,000
Accounts payable and accrued expenses related to property and equipment additions	3,571,000	5,757,000	563,000
Vesting of early exercised stock options	3,668,000	1,415,000	455,000
Deferred offering costs, accrued but not paid	236,000	0	0
Conversion of redeemable convertible preferred stock to common stock	331,521,000	0	0
Conversion of redeemable convertible preferred stock warrant liability reclassified to additional paid-in capital	$ 3,135,000	$ 0	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Organization and Description of Business Cloudflare, Inc. (the Company, Cloudflare, we, us, or our) has built a global cloud platform that delivers a broad range of network services to businesses of all sizes and geographies, making them more secure, enhancing the performance of their business-critical applications, and eliminating the cost and complexity of managing individual network hardware. Cloudflare provides businesses with a scalable, easy-to-use, unified control plane to deliver security, performance, and reliability across their on-premise, hybrid, cloud, and SaaS applications. The Company was incorporated in Delaware in July 2009. The Company is headquartered in San Francisco, California. Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements and accompanying notes have been prepared in conformity with accounting principles generally accepted in the United States (U.S. GAAP) and include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company’s fiscal year ends on December 31. Initial Public Offering In September 2019, the Company completed an IPO in which it issued and sold 40,250,000 shares of Class A common stock, which included 5,250,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of $15.00 per share. The Company received net proceeds of $570.5 million from sales of its shares in the IPO, after deducting underwriting discounts and commissions, but before deducting offering costs of $5.5 million. The net proceeds included proceeds of $74.4 million, net of underwriters' discounts and commissions, from the exercise of the underwriters' option to purchase an additional 5,250,000 shares of the Company's Class A common stock. Upon completion of the IPO, 31,381,152 shares of redeemable convertible preferred stock were automatically converted into an equal number of shares of Class A common stock, 134,276,690 shares of redeemable convertible preferred stock were automatically converted into an equal number of shares of Class B common stock, outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into outstanding warrants to purchase shares of Class B common stock, and 15,198,587 shares of Class B common stock held by former employees were automatically converted into an equal number of shares of Class A common stock. Deferred Offering Costs Deferred offering costs are capitalized and consist of fees and expenses incurred in connection with the sale of the Company's Class A common stock in the IPO, including the legal, accounting, printing and other IPO-related costs. As of December 31, 2018, the Company had not incurred such costs. During 2019, the Company capitalized $5.5 million of offering costs. In September 2019, upon completion of the IPO, the Company reclassified $5.5 million of offering costs into stockholders' equity (deficit) as a reduction of the net proceeds received from the IPO. During the year ended December 31, 2019, the Company paid $5.3 million of the deferred offering costs. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes to the consolidated financial statements. Such estimates include, but are not limited to, deferred contract acquisitions costs, the period of benefit generated from the Company’s deferred contract acquisition costs, the capitalization and estimated useful life of internal-use software, useful lives of property and equipment, the valuation and recognition of stock-based compensation expense, uncertain tax positions, and the recognition and measurement of current and deferred income tax assets and liabilities. Management bases these estimates and assumptions on historical experience and on various other assumptions that are believed to be reasonable. Actual results could differ materially from these estimates.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Concentrations of Risks The Company’s revenue is reliant on its customers utilizing Internet-based services. These services can be prone to rapid changes in technology and government regulation. If the Company were unable to keep pace with customers’ needs and continue to improve its technological capabilities, or if another firm were to introduce competitive products, or a government jurisdiction were to enact legislation detrimental to the Company’s business, such an event or events could adversely affect the Company’s operating results. The Company serves its customers from co-location facilities located in various cities and countries around the world. The Company has internal procedures to restore services in the event of disasters at its current co-location facilities. Even with these procedures for disaster recovery in place, the Company’s services could be significantly interrupted during the implementation of restoration procedures. The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash, cash equivalents, available-for-sale securities, and accounts receivable. Although the Company maintains cash deposits, cash equivalent balances, and available-for-sale securities with multiple financial institutions, the deposits, at times, may exceed federally insured limits. Cash and cash equivalents may be withdrawn or redeemed on demand. The Company believes that the financial institutions that hold its cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these balances. The Company also maintains investments in U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds that carry high credit ratings and accordingly, minimal credit risk exists with respect to these balances. Cash equivalents consist of money market funds, commercial paper, and corporate bonds which are invested through financial institutions in the United States. The Company’s accounts receivable are derived from net revenue to customers located throughout the world. The Company grants credit to its customers in the normal course of business. For the years ended December 31, 2019, 2018, and 2017, no customer accounted for more than 10% of the Company’s revenue. No customer represented 10% or more of accounts receivable, net as of December 31, 2019 and 2018. Revenue Recognition In accordance with Accounting Standards Codification (ASC) Topic 606, Revenue From Contracts With Customers (ASC 606), revenue is recognized when a customer obtains control of promised services. Refer to Note 3 to these consolidated financial statements for additional information. Accounts Receivable and Allowance Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts. Credit is extended to customers based on an evaluation of their financial condition and other factors. The Company establishes a sales allowance at the time of revenue recognition based on its history of adjustments and credits provided to customers. In determining the necessary allowance for doubtful accounts, the Company considers the current aging and financial condition of its customers, the amount of receivables in dispute, and current payment patterns. Accounts receivable are written off against the allowance when management determines a balance is uncollectible and the Company no longer actively pursues collection of the receivable. The Company does not have any off-balance-sheet credit exposure related to its customers. Cost of Revenue Cost of revenue consists primarily of expenses that are directly related to providing the Company's service to its paying customers. These expenses include expenses related to operating in co-location facilities, network and bandwidth costs, depreciation of the Company's equipment located in co-location facilities, certificate authority services costs for paying customers, related overhead costs, the amortization of the Company's capitalized internal-use software, and the amortization of acquired developed technologies. Cost of revenue also includes employee-related costs, including salaries, bonuses, benefits, and stock-based compensation for employees whose primary responsibilities relate to supporting the Company's paying customers and delivering paid customer support. Other costs included in cost of revenue include credit card fees related to processing customer transactions and allocated overhead costs. Research and Development The Company charges costs related to research, design, and development of products to research and development expense in the consolidated statements of operations as incurred. Research and development expenses support the Company's efforts to add new features to its existing offerings and to ensure the security, performance, and reliability of its global cloud platform. The majority of the Company's research and development expenses result from employee-related costs, including salaries, bonuses and benefits, consulting costs, depreciation of equipment used in research and development, and allocated overhead costs. Advertising Expense Advertising costs are charged to sales and marketing expense in the consolidated statements of operations as incurred. Advertising expense for the years ended December 31, 2019, 2018, and 2017 was $18.8 million, $10.4 million, and $5.9 million, respectively. Stock-based Compensation The Company measures and recognizes stock-based compensation expense based on the grant date fair value of the awards. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model. The grant date fair value of restricted stock units (RSUs) is estimated based on the fair value of the Company's underlying common stock. The grant date fair value and the stock-based compensation expense related to purchase rights issued under the 2019 Employee Stock Purchase Plan (ESPP) is estimated using the Black-Scholes option pricing model and is based on the estimated number of awards as of the beginning of the offering period, respectively. The Black-Scholes option pricing model requires the use of highly subjective assumptions, including the award’s expected term, the fair value of the underlying common stock, the expected volatility of the price of the common stock, risk-free interest rates, and the expected dividend yield of the common stock. The assumptions used to determine the fair value of the stock-based awards are management’s best estimates and involve inherent uncertainties and the application of judgment. The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. As the Company does not have sufficient historical experience for determining the expected term of the stock option awards granted, it has based its expected term on the simplified method available under U.S. GAAP. Stock-based compensation expense for awards with service-based vesting only is recognized on a straight-line basis over the requisite service period of the awards, which is generally four years. The Company accounts for forfeitures as they occur. Prior to the IPO, the fair value of the Company's common stock for financial reporting purposes was determined considering numerous objective and subjective factors and required judgment to determine the fair value of common stock as of each grant date. Subsequent to the IPO, the Company determines the fair value using the market closing price of its Class A common stock on the date of grant. The Company granted qualified event options (QE Options) and qualified event restricted stock units (QE RSUs) to employees and contractors which vest on the satisfaction of both a service-based condition and a performance condition. For QE Options, the performance condition was deemed satisfied upon the Company's Class A common stock being listed on a public exchange. For QE Options, the service-based condition is satisfied by rendering service from the date of grant through the qualifying event, as well as a four four Income Taxes The Company accounts for income taxes using the asset and liability method. Deferred income taxes are recognized by applying the enacted statutory tax rates applicable to future years to differences between the carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The measurement of deferred tax assets is reduced, if necessary, by a valuation allowance to amounts that are more likely than not to be realized. The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Foreign Currency Remeasurement The Company's functional currency of its foreign subsidiaries is the U.S. dollar. The monetary assets and liabilities that are denominated in a currency other than the U.S. dollar of the Company's foreign subsidiaries are remeasured into U.S. dollars at the exchange rate on the balance sheet date, while nonmonetary items are remeasured at historical rates. Revenue and expenses are remeasured at average exchange rates during the period. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations. The Company recognized remeasurement losses of $0.2 million and $0.3 million for the years ended December 31, 2019 and 2018, respectively and a remeasurement gain of $0.2 million for the year ended December 31, 2017. Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with an original maturity from the date of purchase of 90 days or less. Available-for-sale securities The Company’s available-for-sale securities consist of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds. The Company has designated all securities held by it as available-for-sale and therefore, such securities are reported at fair value, with unrealized gains and losses recorded in accumulated other comprehensive loss on the consolidated balance sheets. For securities sold prior to maturity, the cost of securities sold is based on the specific identification method. Realized gains and losses on the sale of available-for-sale securities are recorded in other income (expense), net in the consolidated statements of operations. Historically, securities with original maturities greater than three months and remaining maturities less than one year were classified as marketable securities; and securities with remaining maturities greater than one year were classified as long-term investments. Effective as of December 31, 2019, all securities are classified within current assets as such securities can be liquidated to fund current operations without penalty. Other-than-temporary impairment All of the Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is determined to be other-than-temporary. Factors considered in determining whether a loss is temporary include the extent and length of time the investment’s fair value has been lower than its cost basis, the financial condition and near-term prospects of the investee, the extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security, and whether or not the Company will be required to sell the security prior to the expected recovery of the investment’s amortized cost basis. No such impairment charges were recorded during the years ended December 31, 2019, 2018, and 2017. Fair Value Measurements The carrying value of the Company’s financial instruments, including cash equivalents, available-for-sale securities, accounts receivable, accounts payable, and accrued expenses, approximates fair value due to their short-term nature. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows: Useful Lives Servers—network infrastructure 4 years Buildings 30 years Office and computer equipment 2 years Office furniture 3 years Software 3 years Leasehold improvements Lesser of useful life or term of lease Asset retirement obligation Lesser of useful life or term of lease Expenditures for maintenance and repairs are expensed as incurred. Build-to-Suit Leases The Company capitalizes construction in progress and records a corresponding long-term liability for build-to-suit lease agreements where the Company is considered the accounting owner during the construction period. For the building under build-to-suit lease arrangements where the Company has taken occupancy, the Company determined that it continued to be the deemed owner of this building. This is principally due to the Company’s significant investment in tenant improvements. As a result, the building is being depreciated over the useful life. At occupancy, the long-term construction obligations are considered long-term finance lease obligations. Assets capitalized under build-to-suit leases were $13.0 million as of December 31, 2019 and 2018. Depreciation expense for these assets was $0.4 million for the years ended December 31, 2019, 2018, and 2017. Capitalized Internal-Use Software Development Costs Certain development costs related to the Company’s global cloud platform during the application development stage are capitalized. Costs incurred in the preliminary stages of development are analogous to research and development activities and are expensed as incurred. The preliminary stage includes such activities as conceptual formulation of alternatives, evaluation of alternatives, determination of existence of needed technology, and final selection of alternatives. Once the application development stage is reached, internal and external costs are capitalized until the software is substantially complete and ready for its intended use. Capitalized costs are recorded as part of property and equipment, net. Capitalized internal-use software is amortized on a straight-line basis over its estimated useful life, which is generally three years, and is recorded as cost of revenue in the consolidated statements of operations. Capitalization of costs associated with the development of software for internal-use totaled $16.0 million, $9.6 million, and $4.0 million for the years ended December 31, 2019, 2018, and 2017, respectively. Amortization expense for capitalized internal-use software totaled $6.7 million, $3.3 million, and $1.0 million for the years ended December 31, 2019, 2018, and 2017, respectively. Business Combinations The Company includes the results of operations of the businesses that the Company acquires from the date of acquisition. The fair value of the assets acquired and liabilities assumed is based on their estimated fair values as of the respective date of acquisition. The excess purchase price over the fair value of the net assets acquired and liabilities assumed is recorded as goodwill. Determining the fair value of assets acquired and liabilities assumed requires significant judgment and estimates including the selection of valuation methodologies, future expected cash flows, discount rates, and useful lives. The Company’s estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed with a corresponding offset to goodwill. At the conclusion of the measurement period, or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are reflected in the consolidated statements of operations. When the Company issues payments or grants of equity to selling stockholders in connection with an acquisition, the Company evaluates whether the payments or awards are compensatory. This evaluation includes whether cash payments or stock award vesting is contingent on the continued employment of the selling stockholder beyond the acquisition date. If continued employment is required for the cash to be paid or stock awards to vest, the award is treated as compensation for post-acquisition services and is recognized as compensation expense. Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expense in the Company’s consolidated statements of operations. Goodwill and Intangible Assets Goodwill represents the excess of the purchase price of an acquired business over the fair value of the net tangible and identifiable intangible assets acquired. The carrying amount of goodwill is reviewed for impairment at least annually, in the fourth quarter, or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. At December 31, 2019 and 2018, the Company had a single operating segment and reporting unit structure. As part of the annual goodwill impairment test, the Company first performs a qualitative assessment to determine whether further impairment testing is necessary. If, as a result of the qualitative assessment, it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the quantitative impairment test will be required. If the Company has determined it necessary to perform a quantitative impairment assessment, the Company will compare the fair value of the reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the total amount of goodwill of the reporting unit. The Company did not recognize any goodwill impairment charges for any of the periods presented. Intangible assets are carried at cost, net of accumulated amortization. Intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company estimates the useful life by estimating the expected period of economic benefit. The estimated useful life of the Company’s acquired developed technology intangible assets is two years. Indefinite lived intangibles are assessed annually for impairment, which includes an assessment of whether there were any triggering events that required an impairment assessment of the Company’s definite lived intangible assets, and whether it was more likely than not that the Company’s indefinite lived intangible asset was impaired. The Company’s indefinite lived intangible asset arose from an asset acquisition in November 2017. As a result of acquiring assets the Company recognized $0.3 million of in-process research and development. The Company began amortizing the in-process research and development as developed technology in 2018. The Company performed an evaluation for impairment and determined there was no impairment for the years ended December 31, 2019, 2018, and 2017. Impairment of Long-Lived Assets The Company evaluates long-lived assets, which include depreciable tangible assets, for impairment whenever events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable. The recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows these assets are expected to generate. The Company recognizes an impairment in the event the carrying amount of such assets exceeds the fair value attributable to such assets. There were no events or changes in circumstances that indicated the long-lived assets were impaired during any of the periods presented. Operating Leases The Company recognizes rent expense on a straight-line basis over the non-cancelable term of the operating lease. The difference between rent expense and rent paid is recorded as deferred rent in accrued expenses and other current liabilities and other noncurrent liabilities on the consolidated balance sheets. Legal Contingencies The Company accrues a liability for an estimated loss for legal contingencies if the potential loss from any claim or legal proceeding is considered probable, and the amount can be reasonably estimated. The Company believes there are no legal proceedings pending that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition. Redeemable Convertible Preferred Stock Warrant Liability Warrants to purchase shares of the Company’s redeemable convertible preferred stock were classified as noncurrent liabilities on the consolidated balance sheets at fair value upon issuance because the underlying shares of redeemable convertible preferred stock were redeemable at the option of the holders upon the occurrence of certain deemed liquidation events considered not solely within the Company’s control. The warrants were subject to remeasurement to fair value at each balance sheet date and any change in fair value was recognized as a component of other income (expense), net, in the consolidated statements of operations. Net Loss per Share Attributable to Common Stockholders Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for multiple classes of common stock and participating securities. The Company considers its previously outstanding redeemable convertible preferred stock to be participating securities. The Company also considers any shares issued on the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have nonforfeitable dividend rights in the event a dividend is paid on common stock. Under the two-class method, net income is attributed to common stockholders and participating securities based on their participation rights. The holders of the redeemable convertible preferred stock, as well as the holders of early exercised shares subject to repurchase, do not have a contractual obligation to share in the losses of the Company. As such, the Company’s net losses for the years ended December 31, 2019, 2018, and 2017 were not allocated to these participating securities. The rights, including the liquidation and dividend rights, of the Class A common stock and Class B common stock are substantially identical, other than voting rights. Accordingly, the Class A common stock and Class B common stock shared proportionately in the Company’s net losses. Prior to the completion of the IPO, there were no shares of Class A common stock issued and outstanding. 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, less shares subject to repurchase. Vested RSUs that have not been settled have been included in the appropriate common share class used to calculate basic net loss per share. Diluted net loss per share attributable to common stockholders adjusts basic net loss per share for the effect of dilutive securities, including awards under the Company's equity incentive plans. As the Company has reported losses for all periods presented, all potentially dilutive securities are antidilutive and accordingly, basic net loss per share equals diluted net loss per share. Upon completion of the IPO, all shares of redeemable convertible preferred stock then outstanding were automatically converted into an equivalent number of shares of common stock on a one-to-one basis and their carrying amount reclassified into stockholders' equity (deficit). As of December 31, 2019, there were no shares of redeemable convertible preferred stock issued and outstanding. Segment and Geographic Information The Company has one reportable and operating segment. Financial information about the Company’s operating segment and geographic areas is presented in Note 14 to t hese consolidated financial statements. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In July 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. This ASU reduces the complexity associated with an issuer’s accounting for certain financial instruments with characteristics of liabilities and equity. Specifically, the FASB determined that a down round feature would no longer cause a freestanding equity-linked financial instrument (or an embedded conversion option) to be accounted for as a derivative liability at fair value with changes in fair value recognized in current earnings. For public business entities, it is effective for fiscal years beginning after December 15, 2018, and interim periods therein. For all other entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company adopted this guidance effective September 30, 2019 using the prospective approach. The adoption of ASU 2017-11 did not have a material impact on the consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which provides financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. For all entities, it is effective for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The amendments in this ASU should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Company adopted this ASU effective January 1, 2019, noting no material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), and since that date, has issued several ASUs to further clarify certain aspects of ASU 2016-02 and provide entities with practical expedients that may be elected upon adoption. ASU 2016-02 introduces the recognition of right-of-use assets and lease liabilities by lessees for all leases on the consolidated balance sheets. For the consolidated statements of operations, the ASU retains the distinction between finance leases and operating leases, with the classification criteria for distinguishing between finance leases and operating leases are substantially similar to the previous lease guidance. During the transition period for this ASU, lessees and lessors are required to recognize and measure leases at either the beginning of the earliest period presented using a modified retrospective approach, or at the adoption date recognizing the cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. The effective date and transition requirements of ASU 2016-02, for public business entities, is interim and annual periods beginning on or after December 15, 2018, with early adoption permitted. For all other entities, ASU 2016-02 is effective for annual periods beginning on or after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. The Company intends to adopt the ASU beginning January 1, 2020, and has elected to apply the alternate transition method by recording a cumulative-effect adjustment to the opening balance of retained earnings (accumulated deficit) in the period of adoption. Under the new standard, lessees will be required to record a right-of-use asset and liability for all leases, with certain exceptions, on their balance sheets. The Company is currently evaluating its lease portfolio and expects the adoption of this standard to have a material impact on its consolidated balance sheet. In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement . This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. For public business entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. For all other entities, it is effective for fiscal years beginning after December 15, 2020, and interim periods beginning after December 15, 2021. Early adoption of the amendments in this update is permitted, including adoption in any interim period, for all entities. The Company is currently evaluating the potential impact of this ASU on its consolidated financial statements. In November 2019, the FASB issued ASU 2019-10 , Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842). This ASU revises, and staggers, the effective dates for various major updates that have been issued since 2014 to alleviate the burden on both larger public companies as well as private companies, smaller public companies, not-for-profit organizations, and employee benefit plans. Most notably, the amendments for Topic 326 are now effective for the Company beginning January 1, 2020. The Company is currently evaluating the impact of this ASU on its consolidated financial statements, which is not expected to be material. In December 2019, the FASB issued ASU 2019-12 (ASC Topic 740), Simplifying the Accounting for Income Taxes . This ASU simplifies accounting for income taxes by removing certain exceptions to the general principles and amending existing guidance to improve consistent application. The amendments in this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption of the amendments is permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company is in the process of evaluating the impact, if any, of this ASU on its consolidated financial statements.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue Recognition In accordance with ASC 606, revenue is recognized when a customer obtains control of promised services. The amount of revenue recognized reflects the consideration that the Company expects to be entitled to receive in exchange for these services. To achieve this standard, the Company applies the following five steps: 1. Identify the contract with a customer The Company considers the terms and conditions of the contracts and its customary business practices in identifying its contracts under ASC 606. The Company determines it has a contract with a customer when the contract is approved, the Company can identify each party’s rights regarding the services to be transferred, the Company can identify the payment terms, the Company has determined that collectibility is probable, and the contract has commercial substance. The Company applies judgment in determining that collectibility is probable, which is based on a variety of factors, including the customer’s historical payment experience or, in the case of a new customer, credit and financial information relevant to the customer. 2. Identify the performance obligations in the contract Performance obligations promised in a contract are identified based on the services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the service either on its own or together with other resources that are readily available to the Company, and are distinct in the context of the contract, whereby the transfer of the services is separately identifiable from other promises in the contract. The Company’s performance obligation primarily consists of subscription and support services, as they are provided over the same service period. 3. Determine the transaction price The transaction price is determined based on the consideration to which the Company expects to be entitled in exchange for transferring services to the customer. Usage-based variable consideration is recognized in the period it is incurred. None of the Company’s contracts contain a significant financing component. 4. Allocate the transaction price to performance obligations in the contract The subscription and support services in the Company’s contracts are considered a single performance obligation, and thus the entire transaction price is allocated to the single performance obligation. 5. Recognize revenue when or as the Company satisfies a performance obligation Revenue is recognized at the time the related performance obligation is satisfied by transferring the service to a customer. Revenue is recognized when control of the services is transferred to the Company’s customers, in an amount that reflects the consideration that the Company expects to be entitled to receive in exchange for those services. The Company generates sales directly through its sales team and through its channel partners. Revenue from sales to channel partners are recorded once all revenue recognition criteria above are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company. Payment from channel partners is not contingent on the partner’s collection from end-customers. The Company has determined that it is acting as an agent in these arrangements and records this revenue on a net basis. Subscription and Support Revenue The Company generates revenue primarily from sales to its customers of subscriptions to access its platform, together with related support services. Arrangements with customers generally do not provide the customer with the right to take possession of the Company’s software operating its global cloud platform at any time. Instead, customers are granted continuous access to the Company’s global cloud platform over the contractual period. Access to the Company’s platform and products is considered a monthly series comprising one performance obligation. A time-elapsed output method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription and support revenue is generally recognized on a straight-line basis over the contract term beginning on the date that the Company’s service is made available to the customer. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s platform in a given period and is recognized as revenue in the period in which the usage occurs. The typical subscription and support term for the Company’s contracted customers, which consist of customers that enter into contracts for the Company's Enterprise subscription plan (and which the Company previously referred to as enterprise customers), is one year and subscription and support term lengths range from one Variable Consideration If the Company’s services do not meet certain service level commitments, its customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of these forms of variable consideration to the extent that a significant reversal of cumulative revenue will not occur in a future period. The Company has historically not experienced any incidents that had a material impact on its consolidated financial statements. Accordingly, any estimated refunds related to these agreements in the consolidated financial statements are not material during the periods presented. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s platform in a given period and is recognized as revenue in the period in which the usage occurs. Disaggregation of Revenue Subscription and support revenue is recognized over time and accounted for substantially all of the Company’s revenue for the years ended December 31, 2019, 2018, and 2017. The following table summarizes the revenue by region based on the billing address of customers who have contracted to use the Company’s global cloud platform: Year Ended December 31, 2019 2018 2017 (in thousands) Amount Percentage Amount Percentage Amount Percentage United States $ 144,575 50 % $ 92,652 48 % $ 64,940 48 % Europe, Middle East, and Africa 68,418 24 % 48,438 25 % 31,882 24 % Asia Pacific 42,253 15 % 26,305 14 % 15,465 11 % China 12,878 4 % 12,546 6 % 14,425 11 % Other 18,898 7 % 12,733 7 % 8,203 6 % Total $ 287,022 100 % $ 192,674 100 % $ 134,915 100 % The following table summarizes the revenue from contracts by type of customer: Year Ended December 31, 2019 2018 2017 (in thousands) Amount Percentage Amount Percentage Amount Percentage Channel partners $ 26,496 9 % $ 13,231 7 % $ 7,849 6 % Direct customers 260,526 91 % 179,443 93 % 127,066 94 % Total $ 287,022 100 % $ 192,674 100 % $ 134,915 100 % Contract Balances Contract liabilities consist of deferred revenue and include payments received in advance of performance under the contract. Such amounts are recognized as revenue over the contractual period. For the years ended December 31, 2019, 2018, and 2017 the Company recognized revenue of $16.8 million, $11.9 million, and $6.6 million, respectively, that was included in the corresponding contract liability balance at the beginning of the periods presented. The Company receives payments from customers based upon contractual billing schedules; accounts receivable are recorded when the right to consideration becomes unconditional. Standard payment terms are due upon receipt. Contract assets include amounts related to the Company’s contractual right to consideration for both completed and partially completed performance obligations that have not been invoiced. Costs to Obtain and Fulfill a Contract The Company capitalizes sales commission and associated payroll taxes paid to internal sales personnel that are incremental to the acquisition of channel partner and direct customer contracts. These costs are recorded as deferred contract acquisition costs on the consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are in fact incremental and would not have occurred absent the customer contract. Sales commissions for renewal of a contract are not considered commensurate with the commissions paid for the acquisition of the initial contract. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of three years while commissions paid for renewal contracts are amortized over the contractual term of the renewals. Amortization of deferred contract acquisition costs is recognized on a straight-line basis commensurate with the pattern of revenue recognition and included in sales and marketing expense in the consolidated statements of operations. The Company determines the period of benefit for commissions paid for the acquisition of the initial contract by taking into consideration the expected subscription term and expected renewals of its customer contracts, the duration of its relationships with its customers, customer retention data, its technology development lifecycle, and other factors. The Company periodically reviews the carrying amount of deferred contract acquisition costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these deferred costs. The Company did not recognize any impairment losses of deferred contract acquisition costs during the periods presented. The following table summarizes the activity of the deferred contract acquisition costs: Year Ended December 31, 2019 2018 2017 (in thousands) Beginning balance $ 15,940 $ 10,765 $ 5,744 Capitalization of contract acquisition costs 20,065 12,235 8,976 Amortization of deferred contract acquisition costs (10,821) (7,060) (3,955) Ending balance $ 25,184 $ 15,940 $ 10,765 Remaining Performance Obligations As of December 31, 2019, the aggregate amount of the transaction price allocated to remaining performance obligations was $219.2 million. As of December 31, 2019, the Company expected to recognize 82% of its remaining performance obligations as revenue over the next 12 months and 18% of its remaining performance obligations as revenue over the next three years. Nonmonetary Transactions From time to time, the Company enters into nonmonetary arrangements. In the years ended December 31, 2019 and 2018, the Company did not participate in any significant nonmonetary transactions. In the year ended December 31, 2017, the Company participated in nonmonetary transactions with three of its customers in exchange for those customers agreeing to become vendors providing services to the Company. In accordance with ASC 606, at contract inception, the Company measures and records the transaction price for nonmonetary transactions that meet certain criteria at the estimated fair value of the non-cash consideration received from the customer; if the Company cannot reasonably estimate the fair value of the non-cash consideration, the Company will measure the consideration indirectly by reference to the standalone selling price of the goods or services promised to the customer in exchange for the consideration. Services delivered to the Company and provided by the Company are recognized as the services or capacity is delivered, which also may require estimates. The estimated fair value of the services was derived from internal margin metrics and third-party comparable pricing. Nonmonetary transaction revenue was $7.0 million for the year ended December 31, 2017. Nonmonetary transaction expense, recognized as a component of cost of revenue and of sales and marketing expense in the consolidated statements of operations, was $7.0 million for the year ended December 31, 2017. The Company concluded that one of the three arrangements was not in scope of ASC 606 and could not be recognized at fair value as the transaction did not have commercial substance. There were no significant exchanges of services under that contract during the periods presented.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the exchange price that would be received from sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Assets and liabilities measured at fair value are classified into the following categories: • Level I: Observable inputs are unadjusted quoted prices in active markets for identical assets or liabilities; • Level II: Observable inputs are quoted prices for similar assets and liabilities in active markets or inputs other than quoted prices that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments; and • Level III: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs are based on the Company’s own assumptions used to measure assets and liabilities at fair value and require significant management judgment or estimation. The Company's cash equivalents are comprised of highly liquid money market funds, U.S. government agency securities, and commercial paper. The Company classifies money market funds within Level I of the fair value hierarchy because they are valued based on quoted market prices in active markets. The Company classifies its investments, which are comprised of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds, within Level II of the fair value hierarchy because the fair value of these securities is priced by using inputs based on non-binding market consensus prices that are primarily corroborated by observable market data or quoted market prices for similar instruments. The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each period. There were no transfers between levels during the periods presented. The following table summarizes the Company’s cash and available-for-sale securities’ amortized cost, unrealized gains (losses), and fair value by significant investment category reported as cash and cash equivalents, restricted cash, or available-for-sale securities as of December 31, 2019 and 2018. (in thousands) Reported as: December 31, 2019 Amortized Unrealized Unrealized Fair Value Cash & Cash Equivalents Available-for-sale Securities Long-term Restricted Cash Cash $ 24,631 $ — $ — $ 24,631 $ 24,631 $ — $ — Level I: Money market funds 32,856 — — 32,856 26,196 — 6,660 Level II: Corporate bonds 84,054 22 (30) 84,046 — 84,046 — U.S. treasury securities 311,083 151 (23) 311,211 — 311,211 — U.S. government agency securities 95,380 17 — 95,397 22,549 72,848 — Commercial paper 95,467 — — 95,467 65,600 29,867 — Subtotal 585,984 190 (53) 586,121 88,149 497,972 — Total assets measured at fair value on a recurring basis $ 643,471 $ 190 $ (53) $ 643,608 $ 138,976 $ 497,972 $ 6,660 (in thousands) Reported as: December 31, 2018 Amortized Unrealized Unrealized Fair Value Cash & Cash Equivalents Available-for-sale Securities Long-term Restricted Cash Cash $ 4,151 $ — $ — $ 4,151 $ 4,151 $ — $ — Level I: Money market funds 23,278 — — 23,278 16,907 — 6,371 Level II: Corporate bonds 17,291 1 (16) 17,276 — 17,276 — U.S. treasury securities 102,360 8 (20) 102,348 — 102,348 — U.S. government agency securities 1,099 — — 1,099 — 1,099 — Commercial paper 18,876 — — 18,876 3,997 14,879 — Subtotal 139,626 9 (36) 139,599 3,997 135,602 — Total assets measured at fair value on a recurring basis $ 167,055 $ 9 $ (36) $ 167,028 $ 25,055 $ 135,602 $ 6,371 The aggregate fair value of the Company’s money market funds approximated amortized cost and, as such, there were no unrealized gains or losses on money market funds as of December 31, 2019 and 2018. Realized gains and losses, net of tax, were not material for any of the periods presented. The amortized cost of available-for-sale investments with maturities less than one year was $450.2 million and $135.6 million as of December 31, 2019 and 2018, respectively. The amortized cost of available-for-sale investments with maturities greater than one year was $47.7 million and zero as of December 31, 2019 and 2018, respectively. As of December 31, 2019, net unrealized gains on investments were $0.1 million net of tax and were included in accumulated other comprehensive income (loss) on the consolidated balance sheets. As of December 31, 2018, net unrealized losses on investments were $0.1 million net of tax and were included in accumulated other comprehensive income (loss) on the consolidated balance sheets. The unrealized gains and losses on available-for-sale investments are related to U.S. treasury securities, U.S. government agency securities, and corporate bonds. The Company determined these unrealized losses to be temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the investment’s fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, the extent of the loss related to the credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security, and whether or not the Company will be required to sell the security before the recovery of its amortized cost. The Company classifies financial instruments in Level III of the fair value hierarchy when there is reliance on at least one significant unobservable input to the valuation model. In addition to these unobservable inputs, the valuation models for Level III financial instruments typically also rely on a number of inputs that are readily observable, either directly or indirectly. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The gains and losses presented below include changes in the fair value related to both observable and unobservable inputs. Prior to the IPO, the Company's only Level III financial instruments were its redeemable convertible preferred stock warrants. Upon the completion of the IPO, the warrant to purchase shares of Series B redeemable convertible preferred stock was converted into a warrant to purchase shares of Class B common stock. As a result, the warrant liability was remeasured and reclassified to additional paid-in capital within stockholders' equity (deficit). The following tables summarize the Company’s redeemable convertible preferred stock warrant liability measured and recorded at fair value as of December 31, 2019 and 2018: December 31, 2019 Fair Value Reported as (in thousands) Fair value using Level III inputs Redeemable convertible preferred stock warrant liability $ 3,135 $ 3,135 Reclassification to stockholders' equity (deficit) (3,135) (3,135) Balance as of December 31, 2019 $ — $ — December 31, 2018 Fair Value Reported as (in thousands) Fair value using Level III inputs Redeemable convertible preferred stock warrant liability $ 1,618 $ 1,618 Balance as of December 31, 2018 $ 1,618 $ 1,618 Redeemable (in thousands) Fair value using Level III inputs Balance as of December 31, 2016 $ 348 Addition — Change in fair value 50 Balance as of December 31, 2017 398 Addition — Change in fair value 1,220 Balance as of December 31, 2018 1,618 Addition — Change in fair value 1,517 Conversion of redeemable convertible preferred stock warrants into Class B common stock warrants (3,135) Balance as of December 31, 2019 $ — Refer to Note 8 to these consolidated financial statements for further information on the redeemable convertible preferred stock warrants, including the assumptions used to determine their fair value and further information on the exercise of such warrants in the year ended December 31, 2019.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Accounts Receivable, Net Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts. Activity in the allowance for doubtful accounts was as follows: December 31, 2019 2018 (in thousands) Beginning balance $ 160 $ — Provision for bad debt 2,488 1,080 Write-off of uncollectible accounts receivable (2,115) (920) Ending balance $ 533 $ 160 There was no bad debt expense or write-off of uncollectible accounts receivable for the year ended December 31, 2017. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following: December 31, 2019 2018 (in thousands) Prepaid expenses $ 10,913 $ 5,581 Deposits 2,773 2,635 Other 3,308 1,157 Total prepaid expenses and other current assets $ 16,994 $ 9,373 Property and Equipment, Net Property and equipment, net consisted of the following: December 31, 2019 2018 (in thousands) Property and equipment: Servers—network infrastructure $ 84,979 $ 57,089 Buildings 13,035 13,035 Construction in progress 8,692 14,848 Capitalized internal-use software 31,171 16,344 Office and computer equipment 13,528 6,552 Office furniture 6,124 3,573 Software 1,025 847 Leasehold improvements 9,870 772 Asset retirement obligation 231 49 Gross property and equipment 168,655 113,109 Less accumulated depreciation and amortization (67,189) (39,899) Total property and equipment, net $ 101,466 $ 73,210 Depreciation and amortization expense on property and equipment for the years ended December 31, 2019, 2018, and 2017 was $29.4 million, $18.4 million, and $11.7 million, respectively. Acquired Intangible Assets, Net Acquired intangible assets, net consisted of the following: December 31, 2019 Gross Carrying Accumulated Net Book (in thousands) Developed technology $ 250 $ 219 $ 31 Total acquired intangible assets, net $ 250 $ 219 $ 31 December 31, 2018 Gross Carrying Accumulated Net Book (in thousands) Developed technology $ 250 $ 94 $ 156 Total acquired intangible assets, net $ 250 $ 94 $ 156 The Company recorded, at the time of the acquisition, acquired in-process research and development for projects in progress that had not yet reached technological feasibility. The Company began amortizing the in-process research and development as developed technology in 2018 using the straight-line method over its estimated useful life. Amortization of acquired intangible assets for the years ended December 31, 2019, 2018, and 2017 was $0.1 million, $0.5 million, and $0.5 million, respectively. As of December 31, 2019, the estimated future amortization expense of acquired intangible assets was as follows: Estimated (in thousands) Year ending December 31, 2020 $ 31 Total $ 31 Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: December 31, 2019 2018 (in thousands) Accrued compensation and benefits $ 14,970 $ 7,075 Accrued expenses 5,331 4,072 Customer refunds and credits 3,328 2,336 Accrued co-location and bandwidth 2,696 1,119 Other 1,989 1,097 Total accrued expenses and other current liabilities $ 28,314 $ 15,699 Other Noncurrent Liabilities Other noncurrent liabilities consisted of the following: December 31, 2019 2018 (in thousands) Accrued taxes $ 4,862 $ 4,137 Deferred rent 2,342 1,659 Other 2,599 908 Total other noncurrent liabilities $ 9,803 $ 6,704

Note Payable

Note Payable	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Note Payable	Note PayableIn July 2015 and November 2015, the Company entered into three separate Installment Purchase Agreements (the IPA Agreements) totaling $1.7 million for computer equipment and maintenance with one of its suppliers. The IPA Agreements are collateralized by the equipment purchased from the supplier and bear interest ranging from 2.9% to 5.0%. As of December 31, 2019 and 2018, the Company had zero and $0.3 million, respectively, outstanding under this facility.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company has entered into various non-cancelable operating lease agreements for certain of its offices and co-location facilities with lease periods expiring between the years ending December 31, 2019 and 2027. Certain of these arrangements have free or escalating rent payment provisions. The Company recognizes rent expense on a straight-line basis over the lease period. The difference between the rent paid and the straight-line rent is recorded as deferred rent, which is included in accrued expenses and other current liabilities and other noncurrent liabilities on the consolidated balance sheets. Rent expense was $11.2 million, $7.3 million, and $3.9 million for the years ended December 31, 2019, 2018, and 2017, respectively. Refer to the table below for the aggregate future minimum lease payments under non-cancelable operating leases as of December 31, 2019. As of December 31, 2019 and 2018, the Company had $6.7 million and $6.4 million, respectively, in restricted cash related to irrevocable standby letters of credit established according to the requirements under lease agreements. Bandwidth & Co-location Commitments The Company enters into long-term non-cancelable agreements with providers in various countries to purchase capacity, such as bandwidth and co-location space, for the Company’s global cloud platform. Bandwidth and co-location costs for paying customers are recorded as cost of revenue in the consolidated statements of operations and as sales and marketing expense in the consolidated statements of operations for free customers. Such costs totaled $37.0 million, $27.5 million, and $19.2 million for the years ended December 31, 2019, 2018, and 2017, respectively. Refer to the table below for long-term bandwidth and co-location commitments under non-cancelable contracts with various networks and Internet service providers as of December 31, 2019. Purchase Commitments Open purchase commitments are for the purchase of services under non-cancelable contracts. They are not recorded as liabilities on the consolidated balance sheet as of December 31, 2019 as the Company has not yet received the related services. Refer to the table below for purchase commitments under non-cancelable contracts with various vendors as of December 31, 2019. Payments Due by Period as of December 31, 2019 Total 2020 2021 2022 2023 2024 Thereafter (in thousands) Non-cancelable: Open purchase agreements (1) $ 13,684 $ 2,430 $ 2,400 $ 1,810 $ 1,377 $ 685 $ 4,982 Bandwidth and co-location commitments (2) 32,776 18,517 9,515 3,099 1,260 384 1 Operating lease obligations (3) 51,359 11,385 11,329 8,746 5,499 4,096 10,304 Total $ 97,819 $ 32,332 $ 23,244 $ 13,655 $ 8,136 $ 5,165 $ 15,287 (1) Open purchase commitments are for the purchase of services under non-cancelable contracts. They were not recorded as liabilities on the consolidated balance sheet as of December 31, 2019 as the Company had not yet received the related services. (2) Long-term commitments for bandwidth usage and co-location with various networks and Internet service providers. The costs for services not yet received were not recorded as liabilities on the consolidated balance sheet as of December 31, 2019. (3) Office space and equipment under non-cancelable operating leases. Total payments listed represent total minimum future lease payments. Build-to-Suit Lease Financing Obligation The Company entered into a lease whereby the Company is deemed the accounting owner under build-to-suit lease accounting. The fair value of the leased property and corresponding financing obligation are included in property and equipment, net and build-to-suit lease financing obligation, respectively, on the consolidated balance sheets as of December 31, 2019 and 2018. As of December 31, 2019, the Company’s future minimum lease payments required under this non-cancelable obligation were as follows: Build-to-Suit Lease (in thousands) Year ending December 31, 2020 $ 2,673 2021 2,753 2022 2,355 Total minimum lease payments $ 7,781 The Company recognizes an increase in the fair value of the asset as additional building costs are incurred during the construction period and a corresponding increase in the build-to-suit lease financing obligation for any construction costs to be reimbursed by the landlord. As of December 31, 2019 and 2018, $10.5 million and $10.4 million, respectively, of build-to-suit lease financing obligation was included on the consolidated balance sheets. Legal Matters From time to time the Company is a party to various legal proceedings that arise in the ordinary course of business. In addition, third parties may from time to time assert claims against the Company in the form of letters and other communications. Management currently believes that there is no pending or threatened legal proceeding to which the Company is a party that is likely to have a material adverse effect on the Company’s consolidated financial statements. However, the results of legal proceedings are inherently unpredictable and if an unfavorable ruling were to occur in any of the legal proceedings there exists the possibility of a material adverse effect on the Company’s financial position, results of operations, and cash flows. The Company accrues for legal proceedings that it considers probable and for which the loss can be reasonably estimated. The Company discloses potential losses when they are reasonably possible. Legal costs incurred and expected to be incurred related to litigation matters are expensed as incurred. The Company’s platform and associated products are subject to various restrictions under U.S. export control and sanctions laws and regulations, including the U.S. Department of Commerce’s Export Administration Regulations (EAR) and various economic and trade sanctions regulations administered by the U.S. Department of the Treasury’s Office of Foreign Assets Controls (OFAC). The U.S. export control laws and U.S. economic sanctions laws include restrictions or prohibitions on the sale or supply of certain products and services to U.S. embargoed or sanctioned countries, governments, persons and entities and also require authorization for the export of certain encryption items. In addition, various countries regulate the import of certain encryption technology, including through import permitting and licensing requirements and have enacted or could enact laws that could limit the Company’s ability to distribute its platform. Although the Company takes precautions to prevent its platform and associated products from being accessed or used in violation of such laws, the Company may have inadvertently allowed its platform and associated products to be accessed or used by some customers in apparent violation of U.S. economic sanctions laws, including by users in embargoed or sanctioned countries, and the Company may have exported or allowed the download of certain software prior to making required filings with the U.S. Department of Commerce’s Bureau of Industry and Security. As a result, the Company has submitted to OFAC and to the Bureau of Industry and Security a voluntary self-disclosure concerning potential violations, and the Company has submitted a voluntary self-disclosure to the Census Bureau regarding potential violations of the Foreign Trade Regulations related to some incorrect electronic export information statements to the U.S. government for certain hardware exports, which were authorized. The voluntary self-disclosure to the Census Bureau was completed with no penalties in November 2019, while the other voluntary self-disclosures are still under review. If the Company is found to be in violation of U.S. economic sanctions or export control laws, it could result in substantial fines and penalties for the Company and for the individuals working for the Company. The Company may also be adversely affected through other penalties, reputational harm, loss of access to certain markets or otherwise. No loss has been recognized in the consolidated financial statements for this loss contingency as it is not probable a loss has been incurred and the range of a possible loss is not yet estimable. Guarantees and Indemnifications If the Company's services do not meet certain service level commitments, its contracted customers and certain of its pay-as-you-go customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. To date, the Company has not incurred any material costs as a result of such commitments. The Company’s arrangements generally include certain provisions for indemnifying customers against liabilities if its products or services infringe a third-party’s intellectual property rights. It is not possible to determine the maximum potential amount under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. To date, the Company has not incurred any material costs as a result of such obligations and has not accrued any liabilities related to such obligations in the consolidated financial statements. The Company has also agreed to indemnify its directors, executive officers, and certain other employees for costs associated with any fees, expenses, judgments, fines, and settlement amounts incurred by them in any action or proceeding to which any of them are, or are threatened to be, made a party by reason of their service as a director or officer. The Company maintains director and officer insurance coverage that would generally enable it to recover a portion of any future amounts paid. The Company also may be subject to indemnification obligations by law with respect to the actions of its employees under certain circumstances and in certain jurisdictions.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2019
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock Redeemable Convertible Preferred Stock Upon completion of the IPO, all shares of Series A, Series B, and Series C redeemable convertible preferred stock then outstanding, totaling 134,276,690 shares, were automatically converted into an equivalent number of shares of Class B common stock on a one-to-one basis and all shares of Series D redeemable convertible preferred stock outstanding, totaling 31,381,152 shares, were automatically converted into an equivalent number of shares of Class A common stock on a one-to-one basis. The carrying value of $331.5 million was reclassified into stockholders' equity (deficit). As of December 31, 2019, there were no shares of redeemable convertible preferred stock issued and outstanding. In connection with the IPO, the Company's amended and restated certificate of incorporation became effective, which authorized the issuance of 225,000,000 shares of preferred stock with a par value of $0.001 per share with rights and preferences, including voting rights, designated from time to time by the Company's Board of Directors. As of December 31, 2018, the Company's redeemable convertible preferred stock consisted of the following: Shares Authorized Shares Issued and Outstanding Carrying Value Aggregate Liquidation Preference (in thousands) Series A 50,041 50,041 $ 1,985 $ 2,050 Series B 59,286 59,109 19,927 19,991 Series C 25,127 25,127 49,942 50,000 Series D 33,654 31,381 259,667 260,000 168,108 165,658 $ 331,521 $ 332,041 Redeemable Convertible Preferred Stock Warrants In connection with the terms of a loan and security agreement entered into by the Company in April 2011, the Company issued a warrant to purchase 59,140 shares of Series B redeemable convertible preferred stock upon execution of the agreement, an additional warrant to purchase 94,510 shares of Series B redeemable convertible preferred stock in connection with the Company’s drawdown of $1.6 million under the facility during October 2011, and a warrant to purchase 23,760 shares of Series B redeemable convertible preferred stock in connection with the final drawdown of $0.4 million in January 2012. The warrants had an exercise price of $0.34 per share. The warrants were considered a liability and carried at fair value with any changes in fair value recognized in other income (expense), net in the consolidated statements of operations. Upon completion of the IPO, the warrants to purchase Series B redeemable convertible preferred stock were automatically converted to warrants to purchase an equal number of shares of Class B common stock. As a result, the warrant liability was remeasured and reclassified to additional paid-in capital within stockholders' equity (deficit). During the years ended December 31, 2019 and 2018, the Company recorded a loss of $1.5 million and $1.2 million, respectively, related to the change in fair value of the redeemable convertible preferred stock warrants. The fair value of the redeemable convertible preferred stock warrants was determined using the following assumptions: December 31, 2018 Remaining contractual life (in years) 2.3 Expected volatility 39.2 % Risk-free interest rate 2.5 % Expected dividend rate — In the year ended December 31, 2019, the warrants were exercised and such shares were settled via the net settlement method, resulting in the issuance of 174,347 shares of the Company's Class B common stock.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Common Stock	Common Stock The Company’s amended and restated certificate of incorporation authorizes the issuance of Class A common stock and Class B common stock. The holder of each share of Class A common stock is entitled to one vote per share, while the holder of each share of Class B common stock is entitled to 10 votes per share. As of December 31, 2019 and 2018, the Company was authorized to issue 2,250,000,000 and 550,000,000 shares of Class A common stock, respectively, and 315,000,000 and 300,000,000 shares of Class B common stock, respectively, each with a par value of $0.001 per share. There were 87,071,783 and zero shares of Class A common stock issued and outstanding as of December 31, 2019 and 2018, respectively. The number of shares of Class B common stock issued and outstanding was 213,101,364 and 91,542,243, as of December 31, 2019 and 2018, respectively. Holders of the Company’s Class A common stock and Class B common stock are entitled to dividends when, as and if, declared by the Company’s Board of Directors, subject to the rights of the holders of all classes of stock outstanding having priority rights to dividends. Any dividends paid to the holders of the Class A common stock and Class B common stock will be paid on a pro rata basis. As of December 31, 2019 and 2018, the Company had not declared any dividends. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Shares of our Class B common stock are convertible into an equivalent number of shares of our Class A common stock and generally convert into shares of our Class A common stock upon cessation of employment or transfer, except for certain transfers described in the Company's amended and restated certificate of incorporation. Class A common stock and Class B common stock are referred to, collectively, as common stock throughout the notes to these consolidated financial statements, unless otherwise indicated. Common Stock Reserved for Future Issuance Shares of common stock reserved for future issuance, on an as-if converted basis, are as follows: December 31, 2019 2018 (in thousands) Conversion of redeemable convertible preferred stock — 165,658 Stock options issued and outstanding 21,191 25,087 Remaining shares available for issuance under the 2010 Plan — 13,356 Remaining shares available for issuance under the 2019 Plan 29,048 — Redeemable convertible preferred stock warrants outstanding — 177 Outstanding and unsettled RSUs 7,175 — Shares available for issuance under the ESPP 5,870 — Total shares of common stock reserved 63,284 204,278

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock-based Compensation	Stock-based Compensation Equity Incentive Plans In 2010, the Company's Board of Directors adopted and stockholders approved the 2010 Equity Incentive Plan (2010 Plan). The 2010 Plan is a broad-based retention program and is intended to attract and retain talented employees, directors, and non-employee consultants. The 2010 Plan provides for the granting of stock options, restricted stock, RSUs, and stock appreciation rights to employees, directors, and consultants. Incentive stock options may be granted only to employees. All other awards under the 2010 Plan, including non-qualified stock options, may be granted to employees, directors, and consultants. Except for qualifying assumptions and substitutions of options, the exercise price of an incentive stock option and non-qualified stock option shall not be less than 100% of the fair market value of such shares on the date of grant. The number of shares of common stock authorized for issuance under the 2010 Plan was 75,008,088 as of December 31, 2018. Prior to the Company's IPO, stock-based awards forfeited, canceled, or repurchased generally were returned to the pool of shares of common stock available for issuance under the 2010 Plan. The number of shares of common stock available for issuance under the 2010 Plan was zero and 13,355,967 as of December 31, 2019 and 2018, respectively. In connection with the IPO, the 2010 Plan was terminated effective immediately prior to the effectiveness of the 2019 Equity Incentive Plan (2019 Plan) and the Company ceased granting any additional awards under the 2010 Plan. All outstanding awards under the 2010 Plan at the time of the termination of the 2010 Plan remain subject to the terms of the 2010 Plan, and any shares underlying stock options that expire or terminate or are forfeited or repurchased by the Company under the 2010 Plan will be automatically transferred to the 2019 Plan. In 2019, the Company's Board of Directors adopted and stockholders approved the 2019 Plan, which became effective one business day prior to the effective date of the Company's registration statement on Form S-1 for the IPO. The 2019 Plan provides for the granting of stock options, restricted stock, RSUs, stock appreciation rights, performance shares, performance stock units, and performance awards for the Company's Class A common stock to the Company's employees, directors, and consultants. Except as otherwise indicated below, the maximum number of shares of Class A common stock that may be issued under the 2019 Plan will not exceed 66,661,953 shares of the Company's Class A common stock, which is the sum of (1) 29,335,000 new shares, plus (2) an additional number of shares of Class A common stock not to exceed 37,326,953, consisting of the total number of shares of Class A or Class B common stock subject to outstanding awards granted under the 2010 Plan that, on or after the 2019 Plan became effective, are canceled, expire, or otherwise terminate prior to exercise or settlement; are repurchased by the Company because of the failure to vest; or are forfeited, tendered to, or withheld by the Company (or not issued) to satisfy a tax withholding obligation or the payment of an exercise price, if any, as such shares become available from time to time. Stock-based awards under the 2019 Plan that expire or are forfeited, canceled, or repurchased generally are returned to the pool of shares of Class A common stock available for issuance under the 2019 Plan. In addition, the number of shares of the Company's Class A common stock reserved for issuance under the 2019 Plan will automatically increase on January 1 of each calendar year, starting on January 1, 2021 through January 1, 2029, in an amount equal to the least of (i) 29,335,000 shares, (ii) 5% of the total number of shares of Class A and Class B common stock outstanding on December 31 of the fiscal year before the date of each automatic increase, or (iii) a lesser number of shares determined by the com pensation committee of the Company's Board of Directors prior to the applicable January 1. As of December 31, 2019, 1,112,681 shares of Class A common stock underlying RSUs were granted under the 2019 Plan and the number of shares of Class A common stock available for issuance under the 2019 Plan was 29,047,799. Stock Options Under the 2010 Plan and 2019 Plan, at exercise, stock option awards entitle the holder to receive one share of Class B or Class A common stock, in the case of the 2010 Plan, or one share of Class A common stock, in the case of the 2019 Plan. Stock options granted under the 2010 Plan and the 2019 Plan generally vest over a four The following table summarizes the stock options activity under the 2010 Plan: Stock Options Outstanding (in thousands, except year and per share data) Shares Subject Weighted- Weighted- Aggregate Balances as of December 31, 2016 13,319 $ 0.99 7.8 $ 9,283 Options granted 17,937 $ 2.02 Options exercised (2,458) $ 1.12 $ 2,115 Repurchase of unvested shares — Options canceled/forfeited/expired (671) $ 1.60 Balances as of December 31, 2017 28,127 $ 1.62 8.5 $ 11,684 Options granted 10,527 $ 2.91 Options exercised (12,387) $ 1.53 $ 15,433 Repurchase of unvested shares — Options canceled/forfeited/expired (1,180) $ 2.24 Balances as of December 31, 2018 25,087 $ 2.18 8.4 $ 159,945 Options granted 394 $ 9.60 Options exercised (2,665) $ 2.24 $ 22,306 Repurchase of unvested shares — Options canceled/forfeited/expired (1,625) $ 2.35 Balances as of December 31, 2019 21,191 $ 2.30 7.4 $ 312,720 Vested and expected to vest as of December 31, 2019 21,191 $ 2.30 7.4 $ 312,720 Exercisable as of December 31, 2019 21,184 $ 2.30 7.4 $ 312,622 The weighted-average assumptions used to determine the fair value of stock options granted during the periods presented were as follows: Year ended December 31, 2019 2018 2017 Expected term (in years) 6.2 6.5 6.5 Expected volatility 40.3 % 43.5 % 45.8 % Risk-free interest rate 2.3 % 2.9 % 2.1 % Dividend yield — — — The weighted-average grant date fair value of options granted during the years ended December 31, 2019, 2018, and 2017 was $4.10, $1.38, and $0.97 per share, respectively. The aggregate intrinsic value is the difference between the exercise price of the option and the estimated fair value of the underlying common stock. Options exercisable include 15,477,903 and 20,697,847 options that were unvested as of December 31, 2019 and 2018, respectively. The total grant date fair value for vested options in the years ended December 31, 2019, 2018, and 2017 was $5.2 million, $3.4 million, and $2.3 million, respectively. As of December 31, 2019 and 2018, there was $15.8 million and $28.9 million, respectively, of unrecognized stock-based compensation expense related to unvested stock options that is expected to be recognized over a weighted-average period of 2.7 years and 3.8 years, respectively. Early Exercises of Stock Options The 2010 Plan allows for the early exercise of stock options for certain individuals as determined by the Company’s Board of Directors. Shares of common stock issued upon early exercises of unvested options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules and accordingly, the consideration received for early exercises is initially recorded as a liability and reclassified to common stock and additional paid-in capital as the underlying awards vest. Stock options that are early exercised are subject to a repurchase option that allows the Company to repurchase any unvested shares within six months of an individual’s termination for any reason, including death and disability (or in the case of shares issued upon exercise of an option after termination, within six months of the date of exercise), at the price equal to the lower of the amount paid by the purchaser and the fair market value at the time of repurchase, except that after the IPO the repurchase price will be the amount paid by the purchaser. As of December 31, 2019 and 2018, the Company had $13.3 million and $14.3 million, respectively, recorded in liability for early exercise of unvested stock options, and the related number of unvested shares subject to repurchase was 5,945,083 and 6,737,971, respectively. Restricted Stock Units RSUs granted under the 2010 Plan generally vest upon the satisfaction of both a service-based vesting condition and a performance vesting condition, as defined below, occurring before these RSUs expire. RSUs granted under the 2019 Plan generally vest upon the satisfaction of a service-based vesting condition. The service-based vesting condition for employees under both the 2010 Plan and the 2019 Plan is typically satisfied over a four three four RSU activity for the year ended December 31, 2019 was as follows: RSUs Weighted-Average (in thousands, except per share data) Unvested and outstanding as of December 31, 2018 Granted 7,578 $ 10.78 Vested (668) $ 8.93 Forfeited (402) $ 9.13 Unvested as of December 31, 2019 6,508 $ 11.08 Vested and not yet released 667 $ 8.93 Outstanding as of December 31, 2019 7,175 $ 10.88 The total grant date fair value for vested RSUs for the year ended December 31, 2019 was $6.0 million, and zero for the years ended December 31, 2018 and 2017. The total stock-based compensation expense for RSUs for the year ended December 31, 2019 was $24.9 million, and zero for the years ended December 31, 2018 and 2017. As of December 31, 2019 and 2018, the total unrecognized stock-based compensation expense related to RSUs was $53.1 million and zero, respectively, that is expected to be recognized over a weighted-average period of 2.5 and zero years, respectively. 2019 Employee Stock Purchase Plan In September 2019, the Company's Board of Directors adopted and stockholders approved the 2019 Employee Stock Purchase Plan (ESPP), which became effective one business day prior to the effective date of the Company's registration statement on Form S-1 filed with the SEC in connection with the IPO. A total of 5,870,000 shares of Class A common stock were initially reserved for sale under the ESPP. The number of shares of Class A common stock reserved for issuance includes an annual increase on the first day of each fiscal year, beginning on January 1, 2021, by the least of (1) 5,870,000 shares of Class A common stock, (2) 1% of the total number of shares of Class A and Class B common stock outstanding on December 31 of the fiscal year before the date of each automatic increase; or (3) such lesser amount as the compensation committee of the Company's Board of Directors may determine prior to the applicable January 1. Generally, all regular employees, including executive officers, employed by the Company or by any of its designated subsidiaries, except for those holding 5% or more of the total combined voting power or value of all classes of common stock, may participate in the ESPP and may contribute, normally through payroll deductions, up to 10% of their eligible compensation for the purchase of Class A common stock under the ESPP. Unless otherwise determined by the compensation committee of the Board of Directors, Class A common stock will be purchased for the accounts of employees participating in the ESPP at a price per share that is the lesser of (1) 85% of the fair market value of a share of the Company's Class A common stock on the first date of an offering period, or (2) 85% of the fair market value of a share of the Company's Class A common stock on the date of purchase. The initial offering period began on September 13, 2019 and will end on May 15, 2020, with the purchase date of May 15, 2020. In addition, a second offering period began on November 15, 2019 and will also end on May 15, 2020, with a purchase date of May 15, 2020. The ESPP generally provides for six six As of December 31, 2019, no shares of Class A common stock have been purchased under the ESPP. As of December 31, 2019 and 2018, the total unrecognized stock-based compensation expense related to the ESPP was $1.0 million and zero, respectively, that is expected to be recognized over a weighted-average period of 0.4 and zero The weighted-average assumptions used to determine the fair value of the ESPP during the periods presented were as follows: Year ended December 31, 2019 2018 Expected term (in years) 0.7 N/A Risk-free interest rate 1.8 % N/A Expected volatility 35.5 % N/A Dividend yield — N/A Stock-based Compensation Expense The following table sets forth the total stock-based compensation expense included in the Company’s consolidated statements of operations: Year Ended December 31, 2019 2018 2017 (in thousands) Cost of revenue $ 716 $ 119 $ 47 Sales and marketing 8,709 979 488 Research and development 13,037 1,532 969 General and administrative 14,165 24,717 1,251 Total stock-based compensation expense $ 36,627 $ 27,347 $ 2,755 Total stock-based compensation expense for the year ended December 31, 2018 includes charges related to a secondary sale of the Company’s Class B common stock of $23.3 million. Refer t o Note 13

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	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, 2019 2018 2017 Class A Class B Common Common (in thousands, except per share data) Net loss attributable to common stockholders $ (18,259) $ (87,569) $ (87,164) $ (10,748) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 25,243 121,063 80,981 77,147 Net loss per share attributable to common stockholders, basic and diluted $ (0.72) $ (0.72) $ (1.08) $ (0.14) Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share as the inclusion of all potential common shares outstanding would have been antidilutive. The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive are as follows: December 31, 2019 2018 2017 (in thousands) Redeemable convertible preferred stock — 165,658 152,022 Redeemable convertible preferred stock warrants — 177 177 Shares subject to repurchase 5,945 6,738 748 Unexercised stock options 21,191 25,087 28,127 Unvested restricted stock and RSUs 6,508 — 78 Shares issuable pursuant to the ESPP 438 — — Total 34,082 197,660 181,152

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of the Company's income (loss) before income taxes for the years ended December 31, 2019, 2018, and 2017 were as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Domestic $ (117,401) $ (87,615) $ (11,633) Foreign 12,688 1,528 1,918 Total income (loss) before income taxes $ (104,713) $ (86,087) $ (9,715) The components of the Company's provision for income taxes for the years ended December 31, 2019, 2018, and 2017 were as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Current expense (benefit): Federal $ 391 $ 402 $ 699 State 29 42 23 Foreign 325 248 446 Total current provision for income taxes $ 745 $ 692 $ 1,168 Deferred expense (benefit): Federal — (1) 1 State — — — Foreign 370 386 (136) Total deferred provision for income taxes $ 370 $ 385 $ (135) Total provision for income taxes $ 1,115 $ 1,077 $ 1,033 A reconciliation of the U.S. federal statutory rate to the Company's effective tax rate is as follows: Year Ended December 31, 2019 2018 2017 Expected benefit at U.S. federal statutory rate 21.0 % 21.0 % 34.0 % State income taxes, net of federal tax benefits — — (0.2) Foreign income or losses taxed at different rates 0.6 (1.3) 2.1 Stock-based compensation (1.2) (5.5) 2.1 Change in valuation allowance (20.5) (14.0) (36.5) Withholding taxes (0.4) (0.5) (7.2) Transition tax — — (3.3) Miscellaneous permanent items (0.6) (1.0) (1.6) Total provision for income taxes (1.1) % (1.3) % (10.6) % In 2019, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets and income taxes from profitable jurisdictions outside of the U.S. In 2018 and 2017, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was also primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets and income taxes from profitable jurisdictions outside of the U.S. The components of the Company's deferred tax assets and liabilities as of December 31, 2019 and 2018 were as follows: Year Ended December 31, 2019 2018 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 53,536 $ 31,701 Tax credit carryforwards 11,969 8,699 Accrued expenses and reserves 168 1,069 Fixed assets 85 — Stock-based compensation 6,852 — Unrealized loss on investments 43 617 Other 1,703 1,062 Gross deferred tax assets 74,356 43,148 Valuation allowance (63,487) (37,924) Total deferred tax assets $ 10,869 $ 5,224 Deferred tax liabilities: Capitalized internal-use software (4,668) (3,111) Deferred commissions (5,487) (493) Fixed assets (1,228) (1,269) Stock-based compensation — (514) Unrealized gain on investments (32) (13) Total deferred tax liabilities $ (11,415) $ (5,400) Net deferred tax assets (liabilities) $ (546) $ (176) In determining the need for a valuation allowance, the Company weighs both positive and negative evidence in the various jurisdictions in which it operates to determine whether it is more likely than not that its deferred tax assets are recoverable. Accordingly, a full valuation allowance has been established in the U.S. and no deferred tax assets and related tax benefit have been recognized in the consolidated financial statements. There is however, no valuation allowance on the foreign jurisdictions, as the foreign entities have cumulative income and expected future income. The valuation allowance as of December 31, 2019 and 2018 was $63.5 million and $37.9 million, respectively. The net change in the valuation allowance for the years ended December 31, 2019, 2018, and 2017 was an increase of $25.6 million, an increase of $15.5 million, and a decrease of $2.5 million, respectively. The increase in the Company’s valuation allowance compared to the prior year was primarily due to an increase in U.S. deferred tax assets from an increased U.S. taxable loss. As of December 31, 2019 and 2018, the Company had net operating loss carryforwards for federal income tax purposes of $221.5 million and $122.3 million, net of uncertain tax positions, respectively. The federal net operating loss carryforwards for tax years before December 31, 2017 will expire, if not utilized, beginning in the year 2029. Under the Tax Cuts and Jobs Act (The Tax Act), the federal net operating loss carryforwards for tax years after December 31, 2017 are carried forward indefinitely but are limited to 80% of taxable income. Federal research and development tax credit carryforwards as of December 31, 2019 of $8.5 million will expire, if not utilized, beginning in the year 2029. In addition, as of December 31, 2019 and 2018, the Company had net operating loss carryforwards for state income tax purposes of $104.7 million and $89.8 million, net of uncertain tax positions, respectively. The state net operating loss carryforwards will expire, if not utilized, beginning in the year 2026. The Company had state research and development tax credit carryforwards as of December 31, 2019 of $6.5 million. The state research and development tax credits do not expire. As of December 31, 2019 and 2018, the Company had foreign tax credit carryforwards for federal income tax purposes of $1.8 million. The federal foreign tax credit carryforwards will expire, if not utilized, beginning in the year 2025. The Tax Reform Act of 1986 and similar California legislation impose substantial restrictions on the utilization of net operating losses and tax credit carryforwards in the event that there is a change in ownership as provided by Section 382 of the Internal Revenue Code and similar state provisions. Such a limitation could result in the expiration of the net operating loss carryforwards and tax credits before utilization. A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Balance as of the beginning of the period $ 2,549 $ 2,247 $ 1,153 Decreases for tax positions related to the prior year (120) (613) — Additions for tax positions related to the current year 1,311 915 1,094 Balance as of the end of the period $ 3,740 $ 2,549 $ 2,247 As of December 31, 2019, no amount of unrecognized tax benefits, if recognized, would impact the Company's effective income tax rate given the Company's full valuation allowance position. The Company does not expect any unrecognized tax benefits to be recognized within the next 12 months. The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. The Company did not recognize any income tax expense related to interest and penalties in the years ended December 31, 2019, 2018, and 2017, respectively. As of December 31, 2019, 2018, and 2017, the Company had no liabilities for interest and penalties. The Company’s significant tax jurisdictions include the U.S., Australia, Germany, Singapore, and the United Kingdom. Because of the net operating loss carryforwards, substantially all of the Company’s tax years remain open to federal and state tax examination. The Company’s foreign tax returns are open to audit under the statutes of limitations of the respective foreign countries in which the subsidiaries are located. As of December 31, 2019, no other income taxes (state or foreign) have been provided on the undistributed earnings of $18.6 million from the Company’s international subsidiaries as these earnings have been, and under current plans, will continue to be indefinitely reinvested outside of the U.S. However, if such earnings were distributed, the Company would not incur a material amount of foreign withholding taxes and U.S. taxes.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsIn September 2018, certain third-party investment funds purchased 8,909,092 shares of common stock from certain of the Company’s founders for a total purchase price of $98.0 million. Since the purchasing investment funds were entities affiliated with holders of economic interests in the Company and the funds acquired shares from the founders at a price in excess of the fair value of such shares, the amount paid in excess of the fair value of the shares at the time of the purchase was recorded as stock-based compensation expense. The Company recorded $23.3 million of stock-based compensation expense to general and administrative expense in the consolidated statement of operations during the year ended December 31, 2018 related to the purchases. There were no such transactions in the year ended December 31, 2019.

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment and Geographic Information	Segment and Geographic Information The Company’s chief operating decision maker (CODM) is its CEO, COO, and CFO. Collectively, the CODM reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has no segment managers who are held accountable by the CODM for operations, operating results, and planning for levels or components below the consolidated unit level. Accordingly, the Company has determined it has a single operating segment. Refer to Note 3 to these consolidated financial statements for revenue by geography. The Company’s property and equipment, net, by geographic area were as follows: December 31, 2019 2018 (in thousands) United States $ 59,688 $ 46,012 Rest of the world 41,778 27,198 Total property and equipment, net $ 101,466 $ 73,210

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsOn January 1, 2020, the Company acquired S2 Systems Corporation, a company based in Kirkland, Washington that has developed patented browser isolation technology, for approximately $39.2 million. The purchase accounting for this acquisition is in progress.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	The accompanying consolidated financial statements and accompanying notes have been prepared in conformity with accounting principles generally accepted in the United States (U.S. GAAP) and include the accounts of the Company and its wholly-owned subsidiaries.
Principles of Consolidation	All intercompany balances and transactions have been eliminated in consolidation.
Fiscal Period	The Company’s fiscal year ends on December 31.
Deferred Offering Costs	Deferred offering costs are capitalized and consist of fees and expenses incurred in connection with the sale of the Company's Class A common stock in the IPO, including the legal, accounting, printing and other IPO-related costs.
Use of Estimates	The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes to the consolidated financial statements. Such estimates include, but are not limited to, deferred contract acquisitions costs, the period of benefit generated from the Company’s deferred contract acquisition costs, the capitalization and estimated useful life of internal-use software, useful lives of property and equipment, the valuation and recognition of stock-based compensation expense, uncertain tax positions, and the recognition and measurement of current and deferred income tax assets and liabilities. Management bases these estimates and assumptions on historical experience and on various other assumptions that are believed to be reasonable. Actual results could differ materially from these estimates.
Concentration of Risks	The Company’s revenue is reliant on its customers utilizing Internet-based services. These services can be prone to rapid changes in technology and government regulation. If the Company were unable to keep pace with customers’ needs and continue to improve its technological capabilities, or if another firm were to introduce competitive products, or a government jurisdiction were to enact legislation detrimental to the Company’s business, such an event or events could adversely affect the Company’s operating results. The Company serves its customers from co-location facilities located in various cities and countries around the world. The Company has internal procedures to restore services in the event of disasters at its current co-location facilities. Even with these procedures for disaster recovery in place, the Company’s services could be significantly interrupted during the implementation of restoration procedures. The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash, cash equivalents, available-for-sale securities, and accounts receivable. Although the Company maintains cash deposits, cash equivalent balances, and available-for-sale securities with multiple financial institutions, the deposits, at times, may exceed federally insured limits. Cash and cash equivalents may be withdrawn or redeemed on demand. The Company believes that the financial institutions that hold its cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these balances. The Company also maintains investments in U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds that carry high credit ratings and accordingly, minimal credit risk exists with respect to these balances. Cash equivalents consist of money market funds, commercial paper, and corporate bonds which are invested through financial institutions in the United States.
Revenue Recognition	In accordance with Accounting Standards Codification (ASC) Topic 606, Revenue From Contracts With Customers (ASC 606), revenue is recognized when a customer obtains control of promised services. Refer to Note 3 to these consolidated financial statements for additional information. In accordance with ASC 606, revenue is recognized when a customer obtains control of promised services. The amount of revenue recognized reflects the consideration that the Company expects to be entitled to receive in exchange for these services. To achieve this standard, the Company applies the following five steps: 1. Identify the contract with a customer The Company considers the terms and conditions of the contracts and its customary business practices in identifying its contracts under ASC 606. The Company determines it has a contract with a customer when the contract is approved, the Company can identify each party’s rights regarding the services to be transferred, the Company can identify the payment terms, the Company has determined that collectibility is probable, and the contract has commercial substance. The Company applies judgment in determining that collectibility is probable, which is based on a variety of factors, including the customer’s historical payment experience or, in the case of a new customer, credit and financial information relevant to the customer. 2. Identify the performance obligations in the contract Performance obligations promised in a contract are identified based on the services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the service either on its own or together with other resources that are readily available to the Company, and are distinct in the context of the contract, whereby the transfer of the services is separately identifiable from other promises in the contract. The Company’s performance obligation primarily consists of subscription and support services, as they are provided over the same service period. 3. Determine the transaction price The transaction price is determined based on the consideration to which the Company expects to be entitled in exchange for transferring services to the customer. Usage-based variable consideration is recognized in the period it is incurred. None of the Company’s contracts contain a significant financing component. 4. Allocate the transaction price to performance obligations in the contract The subscription and support services in the Company’s contracts are considered a single performance obligation, and thus the entire transaction price is allocated to the single performance obligation. 5. Recognize revenue when or as the Company satisfies a performance obligation Revenue is recognized at the time the related performance obligation is satisfied by transferring the service to a customer. Revenue is recognized when control of the services is transferred to the Company’s customers, in an amount that reflects the consideration that the Company expects to be entitled to receive in exchange for those services. The Company generates sales directly through its sales team and through its channel partners. Revenue from sales to channel partners are recorded once all revenue recognition criteria above are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company. Payment from channel partners is not contingent on the partner’s collection from end-customers. The Company has determined that it is acting as an agent in these arrangements and records this revenue on a net basis. Subscription and Support Revenue The Company generates revenue primarily from sales to its customers of subscriptions to access its platform, together with related support services. Arrangements with customers generally do not provide the customer with the right to take possession of the Company’s software operating its global cloud platform at any time. Instead, customers are granted continuous access to the Company’s global cloud platform over the contractual period. Access to the Company’s platform and products is considered a monthly series comprising one performance obligation. A time-elapsed output method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription and support revenue is generally recognized on a straight-line basis over the contract term beginning on the date that the Company’s service is made available to the customer. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s platform in a given period and is recognized as revenue in the period in which the usage occurs. The typical subscription and support term for the Company’s contracted customers, which consist of customers that enter into contracts for the Company's Enterprise subscription plan (and which the Company previously referred to as enterprise customers), is one year and subscription and support term lengths range from one Variable Consideration If the Company’s services do not meet certain service level commitments, its customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of these forms of variable consideration to the extent that a significant reversal of cumulative revenue will not occur in a future period. The Company has historically not experienced any incidents that had a material impact on its consolidated financial statements. Accordingly, any estimated refunds related to these agreements in the consolidated financial statements are not material during the periods presented. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s platform in a given period and is recognized as revenue in the period in which the usage occurs. Disaggregation of Revenue Subscription and support revenue is recognized over time and accounted for substantially all of the Company’s revenue for the years ended December 31, 2019, 2018, and 2017. Contract Balances Contract liabilities consist of deferred revenue and include payments received in advance of performance under the contract. Such amounts are recognized as revenue over the contractual period. For the years ended December 31, 2019, 2018, and 2017 the Company recognized revenue of $16.8 million, $11.9 million, and $6.6 million, respectively, that was included in the corresponding contract liability balance at the beginning of the periods presented. The Company receives payments from customers based upon contractual billing schedules; accounts receivable are recorded when the right to consideration becomes unconditional. Standard payment terms are due upon receipt. Contract assets include amounts related to the Company’s contractual right to consideration for both completed and partially completed performance obligations that have not been invoiced. Costs to Obtain and Fulfill a Contract The Company capitalizes sales commission and associated payroll taxes paid to internal sales personnel that are incremental to the acquisition of channel partner and direct customer contracts. These costs are recorded as deferred contract acquisition costs on the consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are in fact incremental and would not have occurred absent the customer contract.
Accounts Receivable and Allowance	Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts. Credit is extended to customers based on an evaluation of their financial condition and other factors. The Company establishes a sales allowance at the time of revenue recognition based on its history of adjustments and credits provided to customers. In determining the necessary allowance for doubtful accounts, the Company considers the current aging and financial condition of its customers, the amount of receivables in dispute, and current payment patterns. Accounts receivable are written off against the allowance when management determines a balance is uncollectible and the Company no longer actively pursues collection of the receivable. The Company does not have any off-balance-sheet credit exposure related to its customers.
Cost of Revenue	Cost of revenue consists primarily of expenses that are directly related to providing the Company's service to its paying customers. These expenses include expenses related to operating in co-location facilities, network and bandwidth costs, depreciation of the Company's equipment located in co-location facilities, certificate authority services costs for paying customers, related overhead costs, the amortization of the Company's capitalized internal-use software, and the amortization of acquired developed technologies. Cost of revenue also includes employee-related costs, including salaries, bonuses, benefits, and stock-based compensation for employees whose primary responsibilities relate to supporting the Company's paying customers and delivering paid customer support. Other costs included in cost of revenue include credit card fees related to processing customer transactions and allocated overhead costs.
Research and Development	The Company charges costs related to research, design, and development of products to research and development expense in the consolidated statements of operations as incurred. Research and development expenses support the Company's efforts to add new features to its existing offerings and to ensure the security, performance, and reliability of its global cloud platform. The majority of the Company's research and development expenses result from employee-related costs, including salaries, bonuses and benefits, consulting costs, depreciation of equipment used in research and development, and allocated overhead costs.
Advertising Expense	Advertising costs are charged to sales and marketing expense in the consolidated statements of operations as incurred.
Stock-based Compensation	The Company measures and recognizes stock-based compensation expense based on the grant date fair value of the awards. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model. The grant date fair value of restricted stock units (RSUs) is estimated based on the fair value of the Company's underlying common stock. The grant date fair value and the stock-based compensation expense related to purchase rights issued under the 2019 Employee Stock Purchase Plan (ESPP) is estimated using the Black-Scholes option pricing model and is based on the estimated number of awards as of the beginning of the offering period, respectively. The Black-Scholes option pricing model requires the use of highly subjective assumptions, including the award’s expected term, the fair value of the underlying common stock, the expected volatility of the price of the common stock, risk-free interest rates, and the expected dividend yield of the common stock. The assumptions used to determine the fair value of the stock-based awards are management’s best estimates and involve inherent uncertainties and the application of judgment. The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. As the Company does not have sufficient historical experience for determining the expected term of the stock option awards granted, it has based its expected term on the simplified method available under U.S. GAAP. Stock-based compensation expense for awards with service-based vesting only is recognized on a straight-line basis over the requisite service period of the awards, which is generally four years. The Company accounts for forfeitures as they occur. Prior to the IPO, the fair value of the Company's common stock for financial reporting purposes was determined considering numerous objective and subjective factors and required judgment to determine the fair value of common stock as of each grant date. Subsequent to the IPO, the Company determines the fair value using the market closing price of its Class A common stock on the date of grant. The Company granted qualified event options (QE Options) and qualified event restricted stock units (QE RSUs) to employees and contractors which vest on the satisfaction of both a service-based condition and a performance condition. For QE Options, the performance condition was deemed satisfied upon the Company's Class A common stock being listed on a public exchange. For QE Options, the service-based condition is satisfied by rendering service from the date of grant through the qualifying event, as well as a four four
Income Taxes	The Company accounts for income taxes using the asset and liability method. Deferred income taxes are recognized by applying the enacted statutory tax rates applicable to future years to differences between the carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The measurement of deferred tax assets is reduced, if necessary, by a valuation allowance to amounts that are more likely than not to be realized.The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position.
Foreign Currency Remeasurement	The Company's functional currency of its foreign subsidiaries is the U.S. dollar. The monetary assets and liabilities that are denominated in a currency other than the U.S. dollar of the Company's foreign subsidiaries are remeasured into U.S. dollars at the exchange rate on the balance sheet date, while nonmonetary items are remeasured at historical rates. Revenue and expenses are remeasured at average exchange rates during the period. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations.
Cash and Cash Equivalents	Cash and cash equivalents consist of highly liquid investments with an original maturity from the date of purchase of 90 days or less.
Available-for-sale securities and Other-than-temporary impairment	The Company’s available-for-sale securities consist of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds. The Company has designated all securities held by it as available-for-sale and therefore, such securities are reported at fair value, with unrealized gains and losses recorded in accumulated other comprehensive loss on the consolidated balance sheets. For securities sold prior to maturity, the cost of securities sold is based on the specific identification method. Realized gains and losses on the sale of available-for-sale securities are recorded in other income (expense), net in the consolidated statements of operations. Historically, securities with original maturities greater than three months and remaining maturities less than one year were classified as marketable securities; and securities with remaining maturities greater than one year were classified as long-term investments. Effective as of December 31, 2019, all securities are classified within current assets as such securities can be liquidated to fund current operations without penalty.
Fair Value Measurements	The carrying value of the Company’s financial instruments, including cash equivalents, available-for-sale securities, accounts receivable, accounts payable, and accrued expenses, approximates fair value due to their short-term nature.
Property and Equipment	Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows: Useful Lives Servers—network infrastructure 4 years Buildings 30 years Office and computer equipment 2 years Office furniture 3 years Software 3 years Leasehold improvements Lesser of useful life or term of lease Asset retirement obligation Lesser of useful life or term of lease Expenditures for maintenance and repairs are expensed as incurred.
Built-to-Suit Leases	The Company capitalizes construction in progress and records a corresponding long-term liability for build-to-suit lease agreements where the Company is considered the accounting owner during the construction period. For the building under build-to-suit lease arrangements where the Company has taken occupancy, the Company determined that it continued to be the deemed owner of this building. This is principally due to the Company’s significant investment in tenant improvements. As a result, the building is being depreciated over the useful life. At occupancy, the long-term construction obligations are considered long-term finance lease obligations.
Capitalized Internal-Use Software Development Costs	Certain development costs related to the Company’s global cloud platform during the application development stage are capitalized. Costs incurred in the preliminary stages of development are analogous to research and development activities and are expensed as incurred. The preliminary stage includes such activities as conceptual formulation of alternatives, evaluation of alternatives, determination of existence of needed technology, and final selection of alternatives. Once the application development stage is reached, internal and external costs are capitalized until the software is substantially complete and ready for its intended use. Capitalized costs are recorded as part of property and equipment, net. Capitalized internal-use software is amortized on a straight-line basis over its estimated useful life, which is generally three years, and is recorded as cost of revenue in the consolidated statements of operations.
Business Combinations	The Company includes the results of operations of the businesses that the Company acquires from the date of acquisition. The fair value of the assets acquired and liabilities assumed is based on their estimated fair values as of the respective date of acquisition. The excess purchase price over the fair value of the net assets acquired and liabilities assumed is recorded as goodwill. Determining the fair value of assets acquired and liabilities assumed requires significant judgment and estimates including the selection of valuation methodologies, future expected cash flows, discount rates, and useful lives. The Company’s estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed with a corresponding offset to goodwill. At the conclusion of the measurement period, or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are reflected in the consolidated statements of operations. When the Company issues payments or grants of equity to selling stockholders in connection with an acquisition, the Company evaluates whether the payments or awards are compensatory. This evaluation includes whether cash payments or stock award vesting is contingent on the continued employment of the selling stockholder beyond the acquisition date. If continued employment is required for the cash to be paid or stock awards to vest, the award is treated as compensation for post-acquisition services and is recognized as compensation expense. Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expense in the Company’s consolidated statements of operations.
Goodwill and Intangible Assets	Goodwill represents the excess of the purchase price of an acquired business over the fair value of the net tangible and identifiable intangible assets acquired. The carrying amount of goodwill is reviewed for impairment at least annually, in the fourth quarter, or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. At December 31, 2019 and 2018, the Company had a single operating segment and reporting unit structure. As part of the annual goodwill impairment test, the Company first performs a qualitative assessment to determine whether further impairment testing is necessary. If, as a result of the qualitative assessment, it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the quantitative impairment test will be required. If the Company has determined it necessary to perform a quantitative impairment assessment, the Company will compare the fair value of the reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the total amount of goodwill of the reporting unit. The Company did not recognize any goodwill impairment charges for any of the periods presented. Intangible assets are carried at cost, net of accumulated amortization. Intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company estimates the useful life by estimating the expected period of economic benefit. The estimated useful life of the Company’s acquired developed technology intangible assets is two years.
Impairment of Long-Lived Assets	The Company evaluates long-lived assets, which include depreciable tangible assets, for impairment whenever events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable. The recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows these assets are expected to generate. The Company recognizes an impairment in the event the carrying amount of such assets exceeds the fair value attributable to such assets. There were no events or changes in circumstances that indicated the long-lived assets were impaired during any of the periods presented.
Operating Leases	The Company recognizes rent expense on a straight-line basis over the non-cancelable term of the operating lease. The difference between rent expense and rent paid is recorded as deferred rent in accrued expenses and other current liabilities and other noncurrent liabilities on the consolidated balance sheets.
Legal Contingencies	The Company accrues a liability for an estimated loss for legal contingencies if the potential loss from any claim or legal proceeding is considered probable, and the amount can be reasonably estimated. The Company believes there are no legal proceedings pending that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition.
Redeemable Convertible Preferred Stock Warrant Liability	Warrants to purchase shares of the Company’s redeemable convertible preferred stock were classified as noncurrent liabilities on the consolidated balance sheets at fair value upon issuance because the underlying shares of redeemable convertible preferred stock were redeemable at the option of the holders upon the occurrence of certain deemed liquidation events considered not solely within the Company’s control. The warrants were subject to remeasurement to fair value at each balance sheet date and any change in fair value was recognized as a component of other income (expense), net, in the consolidated statements of operations.
Net Loss per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for multiple classes of common stock and participating securities. The Company considers its previously outstanding redeemable convertible preferred stock to be participating securities. The Company also considers any shares issued on the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have nonforfeitable dividend rights in the event a dividend is paid on common stock. Under the two-class method, net income is attributed to common stockholders and participating securities based on their participation rights. The holders of the redeemable convertible preferred stock, as well as the holders of early exercised shares subject to repurchase, do not have a contractual obligation to share in the losses of the Company. As such, the Company’s net losses for the years ended December 31, 2019, 2018, and 2017 were not allocated to these participating securities. The rights, including the liquidation and dividend rights, of the Class A common stock and Class B common stock are substantially identical, other than voting rights. Accordingly, the Class A common stock and Class B common stock shared proportionately in the Company’s net losses. Prior to the completion of the IPO, there were no shares of Class A common stock issued and outstanding. 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, less shares subject to repurchase. Vested RSUs that have not been settled have been included in the appropriate common share class used to calculate basic net loss per share. Diluted net loss per share attributable to common stockholders adjusts basic net loss per share for the effect of dilutive securities, including awards under the Company's equity incentive plans. As the Company has reported losses for all periods presented, all potentially dilutive securities are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.
Segment and Geographic Information	The Company has one reportable and operating segment.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In July 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. This ASU reduces the complexity associated with an issuer’s accounting for certain financial instruments with characteristics of liabilities and equity. Specifically, the FASB determined that a down round feature would no longer cause a freestanding equity-linked financial instrument (or an embedded conversion option) to be accounted for as a derivative liability at fair value with changes in fair value recognized in current earnings. For public business entities, it is effective for fiscal years beginning after December 15, 2018, and interim periods therein. For all other entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company adopted this guidance effective September 30, 2019 using the prospective approach. The adoption of ASU 2017-11 did not have a material impact on the consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which provides financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. For all entities, it is effective for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The amendments in this ASU should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Company adopted this ASU effective January 1, 2019, noting no material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), and since that date, has issued several ASUs to further clarify certain aspects of ASU 2016-02 and provide entities with practical expedients that may be elected upon adoption. ASU 2016-02 introduces the recognition of right-of-use assets and lease liabilities by lessees for all leases on the consolidated balance sheets. For the consolidated statements of operations, the ASU retains the distinction between finance leases and operating leases, with the classification criteria for distinguishing between finance leases and operating leases are substantially similar to the previous lease guidance. During the transition period for this ASU, lessees and lessors are required to recognize and measure leases at either the beginning of the earliest period presented using a modified retrospective approach, or at the adoption date recognizing the cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. The effective date and transition requirements of ASU 2016-02, for public business entities, is interim and annual periods beginning on or after December 15, 2018, with early adoption permitted. For all other entities, ASU 2016-02 is effective for annual periods beginning on or after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. The Company intends to adopt the ASU beginning January 1, 2020, and has elected to apply the alternate transition method by recording a cumulative-effect adjustment to the opening balance of retained earnings (accumulated deficit) in the period of adoption. Under the new standard, lessees will be required to record a right-of-use asset and liability for all leases, with certain exceptions, on their balance sheets. The Company is currently evaluating its lease portfolio and expects the adoption of this standard to have a material impact on its consolidated balance sheet. In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement . This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. For public business entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. For all other entities, it is effective for fiscal years beginning after December 15, 2020, and interim periods beginning after December 15, 2021. Early adoption of the amendments in this update is permitted, including adoption in any interim period, for all entities. The Company is currently evaluating the potential impact of this ASU on its consolidated financial statements. In November 2019, the FASB issued ASU 2019-10 , Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842). This ASU revises, and staggers, the effective dates for various major updates that have been issued since 2014 to alleviate the burden on both larger public companies as well as private companies, smaller public companies, not-for-profit organizations, and employee benefit plans. Most notably, the amendments for Topic 326 are now effective for the Company beginning January 1, 2020. The Company is currently evaluating the impact of this ASU on its consolidated financial statements, which is not expected to be material. In December 2019, the FASB issued ASU 2019-12 (ASC Topic 740), Simplifying the Accounting for Income Taxes . This ASU simplifies accounting for income taxes by removing certain exceptions to the general principles and amending existing guidance to improve consistent application. The amendments in this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption of the amendments is permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company is in the process of evaluating the impact, if any, of this ASU on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of Property and Equipment	Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows: Useful Lives Servers—network infrastructure 4 years Buildings 30 years Office and computer equipment 2 years Office furniture 3 years Software 3 years Leasehold improvements Lesser of useful life or term of lease Asset retirement obligation Lesser of useful life or term of lease Property and equipment, net consisted of the following: December 31, 2019 2018 (in thousands) Property and equipment: Servers—network infrastructure $ 84,979 $ 57,089 Buildings 13,035 13,035 Construction in progress 8,692 14,848 Capitalized internal-use software 31,171 16,344 Office and computer equipment 13,528 6,552 Office furniture 6,124 3,573 Software 1,025 847 Leasehold improvements 9,870 772 Asset retirement obligation 231 49 Gross property and equipment 168,655 113,109 Less accumulated depreciation and amortization (67,189) (39,899) Total property and equipment, net $ 101,466 $ 73,210

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following table summarizes the revenue by region based on the billing address of customers who have contracted to use the Company’s global cloud platform: Year Ended December 31, 2019 2018 2017 (in thousands) Amount Percentage Amount Percentage Amount Percentage United States $ 144,575 50 % $ 92,652 48 % $ 64,940 48 % Europe, Middle East, and Africa 68,418 24 % 48,438 25 % 31,882 24 % Asia Pacific 42,253 15 % 26,305 14 % 15,465 11 % China 12,878 4 % 12,546 6 % 14,425 11 % Other 18,898 7 % 12,733 7 % 8,203 6 % Total $ 287,022 100 % $ 192,674 100 % $ 134,915 100 % The following table summarizes the revenue from contracts by type of customer: Year Ended December 31, 2019 2018 2017 (in thousands) Amount Percentage Amount Percentage Amount Percentage Channel partners $ 26,496 9 % $ 13,231 7 % $ 7,849 6 % Direct customers 260,526 91 % 179,443 93 % 127,066 94 % Total $ 287,022 100 % $ 192,674 100 % $ 134,915 100 %
Summary of Deferred Contract Acquisition Costs	The following table summarizes the activity of the deferred contract acquisition costs: Year Ended December 31, 2019 2018 2017 (in thousands) Beginning balance $ 15,940 $ 10,765 $ 5,744 Capitalization of contract acquisition costs 20,065 12,235 8,976 Amortization of deferred contract acquisition costs (10,821) (7,060) (3,955) Ending balance $ 25,184 $ 15,940 $ 10,765

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value by Significant Investment Category	The following table summarizes the Company’s cash and available-for-sale securities’ amortized cost, unrealized gains (losses), and fair value by significant investment category reported as cash and cash equivalents, restricted cash, or available-for-sale securities as of December 31, 2019 and 2018. (in thousands) Reported as: December 31, 2019 Amortized Unrealized Unrealized Fair Value Cash & Cash Equivalents Available-for-sale Securities Long-term Restricted Cash Cash $ 24,631 $ — $ — $ 24,631 $ 24,631 $ — $ — Level I: Money market funds 32,856 — — 32,856 26,196 — 6,660 Level II: Corporate bonds 84,054 22 (30) 84,046 — 84,046 — U.S. treasury securities 311,083 151 (23) 311,211 — 311,211 — U.S. government agency securities 95,380 17 — 95,397 22,549 72,848 — Commercial paper 95,467 — — 95,467 65,600 29,867 — Subtotal 585,984 190 (53) 586,121 88,149 497,972 — Total assets measured at fair value on a recurring basis $ 643,471 $ 190 $ (53) $ 643,608 $ 138,976 $ 497,972 $ 6,660 (in thousands) Reported as: December 31, 2018 Amortized Unrealized Unrealized Fair Value Cash & Cash Equivalents Available-for-sale Securities Long-term Restricted Cash Cash $ 4,151 $ — $ — $ 4,151 $ 4,151 $ — $ — Level I: Money market funds 23,278 — — 23,278 16,907 — 6,371 Level II: Corporate bonds 17,291 1 (16) 17,276 — 17,276 — U.S. treasury securities 102,360 8 (20) 102,348 — 102,348 — U.S. government agency securities 1,099 — — 1,099 — 1,099 — Commercial paper 18,876 — — 18,876 3,997 14,879 — Subtotal 139,626 9 (36) 139,599 3,997 135,602 — Total assets measured at fair value on a recurring basis $ 167,055 $ 9 $ (36) $ 167,028 $ 25,055 $ 135,602 $ 6,371
Schedule of Redeemable Convertible Preferred Stock Warrant Liability Measured and Recorded at Fair Value	The following tables summarize the Company’s redeemable convertible preferred stock warrant liability measured and recorded at fair value as of December 31, 2019 and 2018: December 31, 2019 Fair Value Reported as (in thousands) Fair value using Level III inputs Redeemable convertible preferred stock warrant liability $ 3,135 $ 3,135 Reclassification to stockholders' equity (deficit) (3,135) (3,135) Balance as of December 31, 2019 $ — $ — December 31, 2018 Fair Value Reported as (in thousands) Fair value using Level III inputs Redeemable convertible preferred stock warrant liability $ 1,618 $ 1,618 Balance as of December 31, 2018 $ 1,618 $ 1,618 Redeemable (in thousands) Fair value using Level III inputs Balance as of December 31, 2016 $ 348 Addition — Change in fair value 50 Balance as of December 31, 2017 398 Addition — Change in fair value 1,220 Balance as of December 31, 2018 1,618 Addition — Change in fair value 1,517 Conversion of redeemable convertible preferred stock warrants into Class B common stock warrants (3,135) Balance as of December 31, 2019 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Activity in Allowance for Doubtful Accounts	Activity in the allowance for doubtful accounts was as follows: December 31, 2019 2018 (in thousands) Beginning balance $ 160 $ — Provision for bad debt 2,488 1,080 Write-off of uncollectible accounts receivable (2,115) (920) Ending balance $ 533 $ 160
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: December 31, 2019 2018 (in thousands) Prepaid expenses $ 10,913 $ 5,581 Deposits 2,773 2,635 Other 3,308 1,157 Total prepaid expenses and other current assets $ 16,994 $ 9,373
Schedule of Property and Equipment, Net	Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows: Useful Lives Servers—network infrastructure 4 years Buildings 30 years Office and computer equipment 2 years Office furniture 3 years Software 3 years Leasehold improvements Lesser of useful life or term of lease Asset retirement obligation Lesser of useful life or term of lease Property and equipment, net consisted of the following: December 31, 2019 2018 (in thousands) Property and equipment: Servers—network infrastructure $ 84,979 $ 57,089 Buildings 13,035 13,035 Construction in progress 8,692 14,848 Capitalized internal-use software 31,171 16,344 Office and computer equipment 13,528 6,552 Office furniture 6,124 3,573 Software 1,025 847 Leasehold improvements 9,870 772 Asset retirement obligation 231 49 Gross property and equipment 168,655 113,109 Less accumulated depreciation and amortization (67,189) (39,899) Total property and equipment, net $ 101,466 $ 73,210
Schedule of Acquired Intangible Assets, Net	Acquired intangible assets, net consisted of the following: December 31, 2019 Gross Carrying Accumulated Net Book (in thousands) Developed technology $ 250 $ 219 $ 31 Total acquired intangible assets, net $ 250 $ 219 $ 31 December 31, 2018 Gross Carrying Accumulated Net Book (in thousands) Developed technology $ 250 $ 94 $ 156 Total acquired intangible assets, net $ 250 $ 94 $ 156
Schedule of Estimated Future Amortization Expense of Acquired Intangible Assets	As of December 31, 2019, the estimated future amortization expense of acquired intangible assets was as follows: Estimated (in thousands) Year ending December 31, 2020 $ 31 Total $ 31
Schedule of Accrued Expenses	Accrued expenses and other current liabilities consisted of the following: December 31, 2019 2018 (in thousands) Accrued compensation and benefits $ 14,970 $ 7,075 Accrued expenses 5,331 4,072 Customer refunds and credits 3,328 2,336 Accrued co-location and bandwidth 2,696 1,119 Other 1,989 1,097 Total accrued expenses and other current liabilities $ 28,314 $ 15,699
Schedule of Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: December 31, 2019 2018 (in thousands) Accrued compensation and benefits $ 14,970 $ 7,075 Accrued expenses 5,331 4,072 Customer refunds and credits 3,328 2,336 Accrued co-location and bandwidth 2,696 1,119 Other 1,989 1,097 Total accrued expenses and other current liabilities $ 28,314 $ 15,699
Schedule of Other Noncurrent Liabilities	Other noncurrent liabilities consisted of the following: December 31, 2019 2018 (in thousands) Accrued taxes $ 4,862 $ 4,137 Deferred rent 2,342 1,659 Other 2,599 908 Total other noncurrent liabilities $ 9,803 $ 6,704

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Purchase Commitments	Refer to the table below for purchase commitments under non-cancelable contracts with various vendors as of December 31, 2019. Payments Due by Period as of December 31, 2019 Total 2020 2021 2022 2023 2024 Thereafter (in thousands) Non-cancelable: Open purchase agreements (1) $ 13,684 $ 2,430 $ 2,400 $ 1,810 $ 1,377 $ 685 $ 4,982 Bandwidth and co-location commitments (2) 32,776 18,517 9,515 3,099 1,260 384 1 Operating lease obligations (3) 51,359 11,385 11,329 8,746 5,499 4,096 10,304 Total $ 97,819 $ 32,332 $ 23,244 $ 13,655 $ 8,136 $ 5,165 $ 15,287 (1) Open purchase commitments are for the purchase of services under non-cancelable contracts. They were not recorded as liabilities on the consolidated balance sheet as of December 31, 2019 as the Company had not yet received the related services. (2) Long-term commitments for bandwidth usage and co-location with various networks and Internet service providers. The costs for services not yet received were not recorded as liabilities on the consolidated balance sheet as of December 31, 2019.
Schedule of Future Minimum Lease Payments Required Under Build-to-Suit Leases	As of December 31, 2019, the Company’s future minimum lease payments required under this non-cancelable obligation were as follows: Build-to-Suit Lease (in thousands) Year ending December 31, 2020 $ 2,673 2021 2,753 2022 2,355 Total minimum lease payments $ 7,781

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2019
Temporary Equity Disclosure [Abstract]
Schedule of Shares of Redeemable Convertible Preferred Stock and Liquidation Preferences	As of December 31, 2018, the Company's redeemable convertible preferred stock consisted of the following: Shares Authorized Shares Issued and Outstanding Carrying Value Aggregate Liquidation Preference (in thousands) Series A 50,041 50,041 $ 1,985 $ 2,050 Series B 59,286 59,109 19,927 19,991 Series C 25,127 25,127 49,942 50,000 Series D 33,654 31,381 259,667 260,000 168,108 165,658 $ 331,521 $ 332,041
Schedule of Fair Value Assumptions	The fair value of the redeemable convertible preferred stock warrants was determined using the following assumptions: December 31, 2018 Remaining contractual life (in years) 2.3 Expected volatility 39.2 % Risk-free interest rate 2.5 % Expected dividend rate — In the year ended December 31, 2019, the warrants were exercised and such shares were settled via the net settlement method, resulting in the issuance of 174,347 shares of the Company's Class B common stock.

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Shares of common stock reserved for future issuance, on an as-if converted basis, are as follows: December 31, 2019 2018 (in thousands) Conversion of redeemable convertible preferred stock — 165,658 Stock options issued and outstanding 21,191 25,087 Remaining shares available for issuance under the 2010 Plan — 13,356 Remaining shares available for issuance under the 2019 Plan 29,048 — Redeemable convertible preferred stock warrants outstanding — 177 Outstanding and unsettled RSUs 7,175 — Shares available for issuance under the ESPP 5,870 — Total shares of common stock reserved 63,284 204,278

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Stock-based Awards	The following table summarizes the stock options activity under the 2010 Plan: Stock Options Outstanding (in thousands, except year and per share data) Shares Subject Weighted- Weighted- Aggregate Balances as of December 31, 2016 13,319 $ 0.99 7.8 $ 9,283 Options granted 17,937 $ 2.02 Options exercised (2,458) $ 1.12 $ 2,115 Repurchase of unvested shares — Options canceled/forfeited/expired (671) $ 1.60 Balances as of December 31, 2017 28,127 $ 1.62 8.5 $ 11,684 Options granted 10,527 $ 2.91 Options exercised (12,387) $ 1.53 $ 15,433 Repurchase of unvested shares — Options canceled/forfeited/expired (1,180) $ 2.24 Balances as of December 31, 2018 25,087 $ 2.18 8.4 $ 159,945 Options granted 394 $ 9.60 Options exercised (2,665) $ 2.24 $ 22,306 Repurchase of unvested shares — Options canceled/forfeited/expired (1,625) $ 2.35 Balances as of December 31, 2019 21,191 $ 2.30 7.4 $ 312,720 Vested and expected to vest as of December 31, 2019 21,191 $ 2.30 7.4 $ 312,720 Exercisable as of December 31, 2019 21,184 $ 2.30 7.4 $ 312,622
Schedule of Assumptions Used to Determine the Fair Value of Stock Options Granted	The weighted-average assumptions used to determine the fair value of stock options granted during the periods presented were as follows: Year ended December 31, 2019 2018 2017 Expected term (in years) 6.2 6.5 6.5 Expected volatility 40.3 % 43.5 % 45.8 % Risk-free interest rate 2.3 % 2.9 % 2.1 % Dividend yield — — —
Schedule of Restricted Stock Units Activity	RSU activity for the year ended December 31, 2019 was as follows: RSUs Weighted-Average (in thousands, except per share data) Unvested and outstanding as of December 31, 2018 Granted 7,578 $ 10.78 Vested (668) $ 8.93 Forfeited (402) $ 9.13 Unvested as of December 31, 2019 6,508 $ 11.08 Vested and not yet released 667 $ 8.93 Outstanding as of December 31, 2019 7,175 $ 10.88
Schedule of Fair Value Assumptions for Employee Stock Purchase Plan	The weighted-average assumptions used to determine the fair value of the ESPP during the periods presented were as follows: Year ended December 31, 2019 2018 Expected term (in years) 0.7 N/A Risk-free interest rate 1.8 % N/A Expected volatility 35.5 % N/A Dividend yield — N/A
Schedule of Stock-based Compensation Expense	The following table sets forth the total stock-based compensation expense included in the Company’s consolidated statements of operations: Year Ended December 31, 2019 2018 2017 (in thousands) Cost of revenue $ 716 $ 119 $ 47 Sales and marketing 8,709 979 488 Research and development 13,037 1,532 969 General and administrative 14,165 24,717 1,251 Total stock-based compensation expense $ 36,627 $ 27,347 $ 2,755

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted 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, 2019 2018 2017 Class A Class B Common Common (in thousands, except per share data) Net loss attributable to common stockholders $ (18,259) $ (87,569) $ (87,164) $ (10,748) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 25,243 121,063 80,981 77,147 Net loss per share attributable to common stockholders, basic and diluted $ (0.72) $ (0.72) $ (1.08) $ (0.14)
Schedule of Potential Shares of Common Stock Excluded from Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders	The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive are as follows: December 31, 2019 2018 2017 (in thousands) Redeemable convertible preferred stock — 165,658 152,022 Redeemable convertible preferred stock warrants — 177 177 Shares subject to repurchase 5,945 6,738 748 Unexercised stock options 21,191 25,087 28,127 Unvested restricted stock and RSUs 6,508 — 78 Shares issuable pursuant to the ESPP 438 — — Total 34,082 197,660 181,152

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Components of Income (Loss) Before Income Taxes	The components of the Company's income (loss) before income taxes for the years ended December 31, 2019, 2018, and 2017 were as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Domestic $ (117,401) $ (87,615) $ (11,633) Foreign 12,688 1,528 1,918 Total income (loss) before income taxes $ (104,713) $ (86,087) $ (9,715)
Components of Provision for Income Taxes	The components of the Company's provision for income taxes for the years ended December 31, 2019, 2018, and 2017 were as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Current expense (benefit): Federal $ 391 $ 402 $ 699 State 29 42 23 Foreign 325 248 446 Total current provision for income taxes $ 745 $ 692 $ 1,168 Deferred expense (benefit): Federal — (1) 1 State — — — Foreign 370 386 (136) Total deferred provision for income taxes $ 370 $ 385 $ (135) Total provision for income taxes $ 1,115 $ 1,077 $ 1,033
Reconciliation of U.S. Federal Statutory Rate to Effective Tax Rate	A reconciliation of the U.S. federal statutory rate to the Company's effective tax rate is as follows: Year Ended December 31, 2019 2018 2017 Expected benefit at U.S. federal statutory rate 21.0 % 21.0 % 34.0 % State income taxes, net of federal tax benefits — — (0.2) Foreign income or losses taxed at different rates 0.6 (1.3) 2.1 Stock-based compensation (1.2) (5.5) 2.1 Change in valuation allowance (20.5) (14.0) (36.5) Withholding taxes (0.4) (0.5) (7.2) Transition tax — — (3.3) Miscellaneous permanent items (0.6) (1.0) (1.6) Total provision for income taxes (1.1) % (1.3) % (10.6) %
Components of Deferred Tax Assets and Liabilities	The components of the Company's deferred tax assets and liabilities as of December 31, 2019 and 2018 were as follows: Year Ended December 31, 2019 2018 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 53,536 $ 31,701 Tax credit carryforwards 11,969 8,699 Accrued expenses and reserves 168 1,069 Fixed assets 85 — Stock-based compensation 6,852 — Unrealized loss on investments 43 617 Other 1,703 1,062 Gross deferred tax assets 74,356 43,148 Valuation allowance (63,487) (37,924) Total deferred tax assets $ 10,869 $ 5,224 Deferred tax liabilities: Capitalized internal-use software (4,668) (3,111) Deferred commissions (5,487) (493) Fixed assets (1,228) (1,269) Stock-based compensation — (514) Unrealized gain on investments (32) (13) Total deferred tax liabilities $ (11,415) $ (5,400) Net deferred tax assets (liabilities) $ (546) $ (176)
Reconciliation of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows: Year Ended December 31, 2019 2018 2017 (in thousands) Balance as of the beginning of the period $ 2,549 $ 2,247 $ 1,153 Decreases for tax positions related to the prior year (120) (613) — Additions for tax positions related to the current year 1,311 915 1,094 Balance as of the end of the period $ 3,740 $ 2,549 $ 2,247

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Schedule of Property and Equipment, Net by Geographic Area	The Company’s property and equipment, net, by geographic area were as follows: December 31, 2019 2018 (in thousands) United States $ 59,688 $ 46,012 Rest of the world 41,778 27,198 Total property and equipment, net $ 101,466 $ 73,210

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Offering costs		$ 5,268	$ 0	$ 0
Deferred offering costs		$ 5,500
Offering costs reclassified as a reduction of proceeds received from IPO	$ 5,500
Class A common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	31,381,152
Series D
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(31,381,152)
Series A, Series B, And Series C, Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(134,276,690)
Class B common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	134,276,690
Initial Public Offering | Class A common stock
Class of Stock [Line Items]
Shares issued in initial public offering (in shares)	40,250,000
Aggregate proceeds received from initial public offering, net of underwriters' discounts and commissions	$ 570,500
Offering costs	$ 5,500
Underwriters' Option | Class A common stock
Class of Stock [Line Items]
Shares issued in initial public offering (in shares)	5,250,000
Price per share in initial public offering (in dollars per share)	$ 15
Aggregate proceeds received from initial public offering, net of underwriters' discounts and commissions	$ 74,400
Former Employees | Class A common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	15,198,587
Former Employees | Class B common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(15,198,587)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)	1 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)	Nov. 30, 2017USD ($)	Dec. 31, 2019USD ($)segmentshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Advertising expense			$ 18,800,000	$ 10,400,000	$ 5,900,000
Stock-based compensation expense	$ 21,000,000		36,627,000	27,347,000	2,755,000,000
Foreign currency remeasurement gain (loss)			(200,000)	(300,000)	200,000
Restricted cash			6,660,000	6,371,000
Other-than-temporary impairment			0	0	0
Assets capitalized from build-to-suit leases			13,000,000	13,000,000
Depreciation expense from build-to-suit leases			400,000	400,000	400,000
Capitalization of internal-use software costs			16,000,000	9,600,000	4,000,000
Amortization expense for capitalized internal-use software			6,700,000	3,300,000	1,000,000
Goodwill impairment charges			0	0	0
In-process research and development recognized		$ 300,000
Impairment of intangible assets, finite-lived			$ 0	$ 0	0
Redeemable convertible preferred stock, shares issued (in shares) | shares			0	165,658,000
Redeemable convertible preferred stock, shares outstanding (in shares) | shares			0	165,658,000
Number of reportable segments | segment			1
Number of operating segments | segment			1
Developed technology
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated useful life			2 years
Capitalized internal-use software
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Useful Lives			3 years
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of awards			4 years
Vesting period			4 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Stock-based compensation expense			$ 24,900,000	$ 0	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Servers—network infrastructure
Property, Plant and Equipment [Line Items]
Useful Lives	4 years
Buildings
Property, Plant and Equipment [Line Items]
Useful Lives	30 years
Office and computer equipment
Property, Plant and Equipment [Line Items]
Useful Lives	2 years
Office furniture
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Software
Property, Plant and Equipment [Line Items]
Useful Lives	3 years

Revenue - Additional Informatio

Revenue - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)arrangement	Dec. 31, 2018USD ($)arrangement	Dec. 31, 2017USD ($)arrangement
Disaggregation of Revenue [Line Items]
Subscription and support term length	1 year
Revenue recognized	$ 16,800,000	$ 11,900,000	$ 6,600,000
Amortization period	3 years
Impairment losses of deferred contract acquisition costs	$ 0	$ 0	$ 0
Exchange of Respective Services
Disaggregation of Revenue [Line Items]
Number of nonmonetary transaction arrangements | arrangement	0	0	3
Nonmonetary transaction revenue			$ 7,000,000
Nonmonetary transaction expense			$ 7,000,000
Number of nonmonetary transaction arrangements not in scope of ASC 606 | arrangement			1
Minimum
Disaggregation of Revenue [Line Items]
Subscription and support term length	1 year
Maximum
Disaggregation of Revenue [Line Items]
Subscription and support term length	3 years

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 287,022	$ 192,674	$ 134,915
Sales Channel Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	100.00%	100.00%	100.00%
Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	100.00%	100.00%	100.00%
Channel partners
Disaggregation of Revenue [Line Items]
Revenue	$ 26,496	$ 13,231	$ 7,849
Channel partners | Sales Channel Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	9.00%	7.00%	6.00%
Direct customers
Disaggregation of Revenue [Line Items]
Revenue	$ 260,526	$ 179,443	$ 127,066
Direct customers | Sales Channel Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	91.00%	93.00%	94.00%
United States
Disaggregation of Revenue [Line Items]
Revenue	$ 144,575	$ 92,652	$ 64,940
United States | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	50.00%	48.00%	48.00%
Europe, Middle East, and Africa
Disaggregation of Revenue [Line Items]
Revenue	$ 68,418	$ 48,438	$ 31,882
Europe, Middle East, and Africa | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	24.00%	25.00%	24.00%
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	$ 42,253	$ 26,305	$ 15,465
Asia Pacific | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	15.00%	14.00%	11.00%
China
Disaggregation of Revenue [Line Items]
Revenue	$ 12,878	$ 12,546	$ 14,425
China | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	4.00%	6.00%	11.00%
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 18,898	$ 12,733	$ 8,203
Other | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage of Revenue	7.00%	7.00%	6.00%

Revenue - Deferred Contract Acq

Revenue - Deferred Contract Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 15,940	$ 10,765	$ 5,744
Capitalization of contract acquisition costs	20,065	12,235	8,976
Amortization of deferred contract acquisition costs	(10,821)	(7,060)	(3,955)
Ending balance	$ 25,184	$ 15,940	$ 10,765

Revenue - Remaining Performance

Revenue - Remaining Performance Obligations (Details) $ in Millions	Dec. 31, 2019USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation, amount	$ 219.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	82.00%
Remaining performance obligation, expected timing of satisfaction	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	18.00%
Remaining performance obligation, expected timing of satisfaction	3 years

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Cash and Available-for-sale Debt Securities' Amortized Cost, Unrealized Gains (Losses) and Fair Value by Significant Investment Category (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$ 138,976,000	$ 25,055,000
Amortized Cost	643,471,000	167,055,000
Unrealized Gain	190,000	9,000
Unrealized (Loss)	(53,000)	(36,000)
Fair Value	643,608,000	167,028,000
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	24,631,000	4,151,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	24,631,000	4,151,000
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Level I | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	32,856,000	23,278,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	32,856,000	23,278,000
Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	585,984,000	139,626,000
Unrealized Gain	190,000	9,000
Unrealized (Loss)	(53,000)	(36,000)
Fair Value	586,121,000	139,599,000
Level II | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	84,054,000	17,291,000
Unrealized Gain	22,000	1,000
Unrealized (Loss)	(30,000)	(16,000)
Fair Value	84,046,000	17,276,000
Level II | U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	311,083,000	102,360,000
Unrealized Gain	151,000	8,000
Unrealized (Loss)	(23,000)	(20,000)
Fair Value	311,211,000	102,348,000
Level II | U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	95,380,000	1,099,000
Unrealized Gain	17,000	0
Unrealized (Loss)	0	0
Fair Value	95,397,000	1,099,000
Level II | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	95,467,000	18,876,000
Unrealized Gain	0	0
Unrealized (Loss)	0	0
Fair Value	95,467,000	18,876,000
Cash & Cash Equivalents | Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	138,976,000	25,055,000
Cash & Cash Equivalents | Fair Value, Recurring | Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	24,631,000	4,151,000
Cash & Cash Equivalents | Fair Value, Recurring | Level I | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	26,196,000	16,907,000
Cash & Cash Equivalents | Fair Value, Recurring | Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	88,149,000	3,997,000
Cash & Cash Equivalents | Fair Value, Recurring | Level II | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Cash & Cash Equivalents | Fair Value, Recurring | Level II | U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Cash & Cash Equivalents | Fair Value, Recurring | Level II | U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	22,549,000	0
Cash & Cash Equivalents | Fair Value, Recurring | Level II | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	65,600,000	3,997,000
Available-for-sale Securities | Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	497,972,000	135,602,000
Available-for-sale Securities | Fair Value, Recurring | Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Available-for-sale Securities | Fair Value, Recurring | Level I | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Available-for-sale Securities | Fair Value, Recurring | Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	497,972,000	135,602,000
Available-for-sale Securities | Fair Value, Recurring | Level II | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	84,046,000	17,276,000
Available-for-sale Securities | Fair Value, Recurring | Level II | U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	311,211,000	102,348,000
Available-for-sale Securities | Fair Value, Recurring | Level II | U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	72,848,000	1,099,000
Available-for-sale Securities | Fair Value, Recurring | Level II | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	29,867,000	14,879,000
Long-term Restricted Cash | Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	6,660,000	6,371,000
Long-term Restricted Cash | Fair Value, Recurring | Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Long-term Restricted Cash | Fair Value, Recurring | Level I | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	6,660,000	6,371,000
Long-term Restricted Cash | Fair Value, Recurring | Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Long-term Restricted Cash | Fair Value, Recurring | Level II | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Long-term Restricted Cash | Fair Value, Recurring | Level II | U.S. treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Long-term Restricted Cash | Fair Value, Recurring | Level II | U.S. government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Long-term Restricted Cash | Fair Value, Recurring | Level II | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized cost of available-for-sale investments with maturities less than one year	$ 450,200,000	$ 135,600,000
Amortized cost of available-for-sale investments with maturities greater than one year	47,700,000	0
Net unrealized gains (losses) on investments, net of tax	100,000	(100,000)
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized gain	0	0
Unrealized loss	$ 0	$ 0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Redeemable Convertible Preferred Stock Warrant Liability Measured and Recorded at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Redeemable Convertible Preferred Stock Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of December 31, 2018	$ 1,618	$ 398	$ 348
Addition	0	0	0
Change in fair value	1,517	1,220	50
Conversion of redeemable convertible preferred stock warrants into Class B common stock warrants	(3,135)
Balance as of September 30, 2019	0	1,618	$ 398
Level III
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Redeemable convertible preferred stock warrant liability, before reclassification	3,135
Reclassification to stockholders' equity (deficit)	(3,135)
Redeemable convertible preferred stock warrant liability	0	1,618
Long-Term Liability [Member] | Level III
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Redeemable convertible preferred stock warrant liability, before reclassification	3,135
Reclassification to stockholders' equity (deficit)	(3,135)
Redeemable convertible preferred stock warrant liability	$ 0	$ 1,618

Balance Sheet Components - Acti

Balance Sheet Components - Activity in Allowance for Doubtful Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 160,000	$ 0
Provision for bad debt	2,488,000	1,080,000	$ 0
Write-off of uncollectible accounts receivable	(2,115,000)	(920,000)	0
Ending balance	$ 533,000	$ 160,000	$ 0

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid expenses	$ 10,913	$ 5,581
Deposits	2,773	2,635
Other	3,308	1,157
Total prepaid expenses and other current assets	$ 16,994	$ 9,373

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 168,655	$ 113,109
Less accumulated depreciation and amortization	(67,189)	(39,899)
Total property and equipment, net	101,466	73,210
Depreciation and amortization expense	29,400	18,400	$ 11,700
Servers—network infrastructure
Property, Plant and Equipment [Line Items]
Gross property and equipment	84,979	57,089
Buildings
Property, Plant and Equipment [Line Items]
Gross property and equipment	13,035	13,035
Construction in progress
Property, Plant and Equipment [Line Items]
Gross property and equipment	8,692	14,848
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Gross property and equipment	31,171	16,344
Office and computer equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment	13,528	6,552
Office furniture
Property, Plant and Equipment [Line Items]
Gross property and equipment	6,124	3,573
Software [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	1,025	847
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross property and equipment	9,870	772
Asset retirement obligation
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 231	$ 49

Balance Sheet Components - Acqu

Balance Sheet Components - Acquired Intangible Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 250	$ 250
Accumulated Amortization	219	94
Net Book Value	31	156
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	250	250
Accumulated Amortization	219	94
Net Book Value	$ 31	$ 156

Balance Sheet Components - Amor

Balance Sheet Components - Amortization Expense and Estimated Future Amortization Expense of Acquired Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Amortization of acquired intangible assets	$ 100	$ 500	$ 500
Year ending December 31, 2020	31
Net Book Value	$ 31	$ 156

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation and benefits	$ 14,970	$ 7,075
Accrued expenses	5,331	4,072
Customer refunds and credits	3,328	2,336
Accrued co-location and bandwidth	2,696	1,119
Other	1,989	1,097
Total accrued expenses and other current liabilities	$ 28,314	$ 15,699

Balance Sheet Components - Othe

Balance Sheet Components - Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued taxes	$ 4,862	$ 4,137
Deferred rent	2,342	1,659
Other	2,599	908
Total other noncurrent liabilities	$ 9,803	$ 6,704

Note Payable - Narrative (Detai

Note Payable - Narrative (Details) - Notes Payable - IPA Agreements	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Nov. 30, 2015USD ($)supplierinstallment_purchase_agreement
Line of Credit Facility [Line Items]
Number of IPA agreements | installment_purchase_agreement			3
Face amount			$ 1,700,000
Number of suppliers | supplier			1
Amount outstanding	$ 0	$ 300,000
Minimum
Line of Credit Facility [Line Items]
Interest rate			2.90%
Maximum
Line of Credit Facility [Line Items]
Interest rate			5.00%

Commitment and Contingencies -

Commitment and Contingencies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 11,200	$ 7,300	$ 3,900
Restricted cash related to irrevocable standby letters of credit	6,700	6,400
Cost and expenses related to bandwidth and other co-location commitments	37,000	27,500	$ 19,200
Build-to-suit lease financing obligation	$ 10,506	$ 10,443

Commitment and Contingencies _2

Commitment and Contingencies - Schedule of Purchase Commitments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Open Purchase Agreements
Total payments due, purchase agreements	$ 13,684
2020	2,430
2021	2,400
2022	1,810
2023	1,377
2024	685
Thereafter	4,982
Bandwidth and Co-Location Commitments
Total payments due, bandwidth and co-location commitments	32,776
2020	18,517
2021	9,515
2022	3,099
2023	1,260
2024	384
Thereafter	1
Operating Lease Obligations
Total payments due, operating leases	51,359
2020	11,385
2021	11,329
2022	8,746
2023	5,499
2024	4,096
Thereafter	10,304
Total Purchase Commitments
Total payments due, purchase commitments	97,819
2020	32,332
2021	23,244
2022	13,655
2023	8,136
2024	5,165
Thereafter	$ 15,287

Commitment and Contingencies _3

Commitment and Contingencies - Build-to-Suit Lease Financing Obligation (Details) $ in Thousands	Dec. 31, 2019USD ($)
Build-to-Suit Lease
2020	$ 2,673
2021	2,753
2022	2,355
Total minimum lease payments	$ 7,781

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended	12 Months Ended
	Sep. 30, 2019	Jan. 31, 2012	Oct. 31, 2011	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2011
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	$ 331,500				$ 331,521
Redeemable convertible preferred stock, shares issued (in shares)				0	0	165,658,000
Redeemable convertible preferred stock, shares outstanding (in shares)				0	0	165,658,000
Preferred stock, shares authorized (in shares)	225,000,000
Preferred stock, par value (in dollars per share)	$ 0.001
Change in fair value of redeemable convertible preferred stock warrant liability					$ 1,517	$ 1,220	$ 50
Warrant To Purchase Series B Redeemable Preferred Stock
Class of Stock [Line Items]
Number of shares subject to purchase from warrant (in shares)		23,760	94,510						59,140
Proceeds from drawdown		$ 400	$ 1,600
Exercise price of warrants (in dollars per share)									$ 0.34
Class B common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	134,276,690
Number of shares issued from exercise of warrants (in shares)				174,347	174,347
Redeemable convertible preferred stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)					(165,658,000)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	$ (331,500)				$ (331,521)
Redeemable convertible preferred stock, shares issued (in shares)				0	0
Redeemable convertible preferred stock, shares outstanding (in shares)				0	0	165,658,000	152,022,000	152,022,000
Series A, Series B, And Series C, Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(134,276,690)
Series D
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(31,381,152)
Redeemable convertible preferred stock, shares issued (in shares)						31,381,000
Redeemable convertible preferred stock, shares outstanding (in shares)						31,381,000
Class A common stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	31,381,152

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock - Shares of Redeemable Convertible Preferred Stock and Liquidation Preferences (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Shares Authorized (in shares)	0	168,108,000
Shares Issued (in shares)	0	165,658,000
Shares Outstanding (in shares)	0	165,658,000
Carrying Value	$ 0	$ 331,521,000
Aggregate Liquidation Preference	$ 0	$ 332,041,000
Series A
Class of Stock [Line Items]
Shares Authorized (in shares)		50,041,000
Shares Issued (in shares)		50,041,000
Shares Outstanding (in shares)		50,041,000
Carrying Value		$ 1,985,000
Aggregate Liquidation Preference		$ 2,050,000
Series B
Class of Stock [Line Items]
Shares Authorized (in shares)		59,286,000
Shares Issued (in shares)		59,109,000
Shares Outstanding (in shares)		59,109,000
Carrying Value		$ 19,927,000
Aggregate Liquidation Preference		$ 19,991,000
Series C
Class of Stock [Line Items]
Shares Authorized (in shares)		25,127,000
Shares Issued (in shares)		25,127,000
Shares Outstanding (in shares)		25,127,000
Carrying Value		$ 49,942,000
Aggregate Liquidation Preference		$ 50,000,000
Series D
Class of Stock [Line Items]
Shares Authorized (in shares)		33,654,000
Shares Issued (in shares)		31,381,000
Shares Outstanding (in shares)		31,381,000
Carrying Value		$ 259,667,000
Aggregate Liquidation Preference		$ 260,000,000

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock - Schedule of Fair Value Assumptions of Redeemable Convertible Preferred Stock Warrants (Details)	Dec. 31, 2018
Remaining contractual life (in years)
Class of Stock [Line Items]
Redeemable convertible preferred stock warrant, measurement input, term	2 years 3 months 18 days
Expected volatility
Class of Stock [Line Items]
Redeemable convertible preferred stock warrant, measurement input	0.392
Risk-free interest rate
Class of Stock [Line Items]
Redeemable convertible preferred stock warrant, measurement input	0.025
Expected dividend rate
Class of Stock [Line Items]
Redeemable convertible preferred stock warrant, measurement input	0

Common Stock - Narrative (Detai

Common Stock - Narrative (Details)	Dec. 31, 2019vote$ / sharesshares	Dec. 31, 2018$ / sharesshares
Class A common stock
Class of Stock [Line Items]
Common stock, number of votes per share | vote	1
Common stock, shares authorized (in shares)	2,250,000,000	550,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	87,071,783	0
Common stock, shares outstanding (in shares)	87,071,783	0
Class B common stock
Class of Stock [Line Items]
Common stock, number of votes per share | vote	10
Common stock, shares authorized (in shares)	315,000,000	300,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	213,101,364	91,542,243
Common stock, shares outstanding (in shares)	213,101,364	91,542,243

Common Stock - Schedule of Comm

Common Stock - Schedule of Common Stock Reserved for Future Issuance (Details) - shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	63,284	204,278
2010 Plan
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	0	13,356
2019 Plan
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	29,048	0
Options
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	21,191	25,087
Restricted Stock Units (RSUs)
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	7,175	0
ESPP
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	5,870	0
Redeemable convertible preferred stock warrants outstanding
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	0	177
Redeemable convertible preferred stock
Class of Stock [Line Items]
Shares of common stock reserved (in shares)	0	165,658

Stock-based Compensation - Narr

Stock-based Compensation - Narrative (Details) - USD ($)	Dec. 31, 2019	Sep. 13, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant date fair value for vested options					$ 5,200,000	$ 3,400,000	$ 2,300,000
Stock-based compensation expense			$ 21,000,000		$ 36,627,000	$ 27,347,000	$ 2,755,000,000
Shares of common stock reserved (in shares)	63,284,000				63,284,000	204,278,000
Common Stock | 2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)						75,008,088
Number of shares available for issuance (in shares)	0				0	13,355,967
Class A common stock | 2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)	66,661,953				66,661,953
Number of shares available for issuance (in shares)	29,047,799				29,047,799
Number of new shares authorized for issuance (in shares)	29,335,000				29,335,000
Number of additional shares authorized for issuance (in shares)	37,326,953				37,326,953
Class A and Class B Common Stock | 2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential increase in number of shares authorized, as a percentage of total common stock outstanding					5.00%
Class B common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense						$ 23,300,000
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Weighted-average grant date fair value for options granted (in dollars per share)					$ 4.10	$ 1.38	$ 0.97
Unvested options exercisable (in shares)	15,477,903				15,477,903	20,697,847
Options unrecognized stock-based compensation expense	$ 15,800,000				$ 15,800,000	$ 28,900,000
Weighted-average remaining vesting period					2 years 8 months 12 days	3 years 9 months 18 days
Liability for early exercise of stock options	$ 13,300,000				$ 13,300,000	$ 14,300,000
Number of unvested shares expected to be repurchased (in shares)					5,945,083	6,737,971
Shares of common stock reserved (in shares)	21,191,000				21,191,000	25,087,000
Options | 2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Expiration period					10 years
Options | Common Stock | 2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of common stock, percentage of fair market value					100.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)					7,578,000
Vesting period					4 years
Weighted-average remaining vesting period				0 days	2 years 6 months
Vesting percentage					25.00%
Total grant date fair value for vested shares					$ 6,000,000	$ 0	$ 0
Stock-based compensation expense					24,900,000	0	$ 0
Unrecognized stock-based compensation expense	$ 53,100,000				$ 53,100,000	$ 0
Shares of common stock reserved (in shares)	7,175,000				7,175,000	0
Restricted Stock Units (RSUs) | Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					1 year
Restricted Stock Units (RSUs) | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					3 years
Restricted Stock Units (RSUs) | Class A common stock | 2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)					1,112,681
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (in shares)	5,870,000				5,870,000	0
ESPP | 2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining vesting period					4 months 24 days	0 years
Unrecognized stock-based compensation expense	$ 1,000,000				$ 1,000,000	$ 0
Maximum ownership percentage threshold for participation		5.00%
Maximum contribution percentage per employee		10.00%
ESPP | Class A common stock | 2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (in shares)		5,870,000
Number of additional shares allowable under the plan (in shares)		5,870,000
Purchase price of common stock, percentage of fair value		85.00%
Offering period		6 months
Purchase period		6 months
Maximum number of shares available for repurchase for each employee (in shares)		1,500
Maximum value of shares available for repurchase for each employee		$ 25,000
Number of shares repurchased (in shares)	0
ESPP | Class A and Class B Common Stock | 2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential increase in number of share authorized, as a percentage of total common stock outstanding		1.00%
Initial Public Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 21,000,000

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Stock-based Awards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares Subject to Options Outstanding
Stock options outstanding, beginning balance (in shares)	25,087	28,127	13,319
Stock options granted (in shares)	394	10,527	17,937
Stock options exercised (in shares)	(2,665)	(12,387)	(2,458)
Repurchases of unvested shares (in shares)	0	0	0
Stock options cancelled, forfeited, expired (in shares)	(1,625)	(1,180)	(671)
Stock options outstanding, ending balance (in shares)	21,191	25,087	28,127	13,319
Stock options vested and expected to vest (in shares)	21,191
Stock options exercisable (in shares)	21,184
Weighted- Average Exercise Price per Option
Stock options outstanding, weighted-average exercise price, beginning balance (in dollars per share)	$ 2.18	$ 1.62	$ 0.99
Stock options granted, weighted-average exercise price (in dollars per share)	9.60	2.91	2.02
Stock options exercised, weighted-average exercise price (in dollars per share)	2.24	1.53	1.12
Stock options cancelled, forfeited, expired, weighted-averaged exercise price (in dollars per share)	2.35	2.24	1.60
Stock options outstanding, weighted-average exercise price, ending balance (in dollars per share)	2.30	$ 2.18	$ 1.62	$ 0.99
Stock options vested and expected to vest, weighted-average exercise price (in dollars per share)	2.30
Stock options exercisable, weighted-average exercise price (in dollars per share)	$ 2.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock options outstanding, weighted-average remaining contractual term	7 years 4 months 24 days	8 years 4 months 24 days	8 years 6 months	7 years 9 months 18 days
Stock options vested and expected to vest, weighted-average remaining contractual term	7 years 4 months 24 days
Stock options exercisable, weighted-average remaining contractual term	7 years 4 months 24 days
Share-Based Payment Award, Options, Aggregate Intrinsic Value [Abstract]
Stock options outstanding, aggregate intrinsic value	$ 312,720	$ 159,945	$ 11,684	$ 9,283
Stock options exercised, aggregate intrinsic value	22,306	$ 15,433	$ 2,115
Stock options vested and expected to vest, aggregate intrinsic value	312,720
Stock options exercisable, aggregate intrinsic value	$ 312,622

Stock-based Compensation - Sc_2

Stock-based Compensation - Schedule of Assumptions Used to Determine the Fair Value of Stock Options Granted (Details) - Options	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 2 months 12 days	6 years 6 months	6 years 6 months
Expected volatility	40.30%	43.50%	45.80%
Risk-free interest rate	2.30%	2.90%	2.10%
Dividend yield	0.00%	0.00%	0.00%

Stock-based Compensation - Sc_3

Stock-based Compensation - Schedule of Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) shares in Thousands	12 Months Ended
	Dec. 31, 2019$ / sharesshares
RSUs
Granted (in shares) | shares	7,578
Vested (in shares) | shares	(668)
Forfeited (in shares) | shares	(402)
Unvested, ending balance (in shares) | shares	6,508
Vested and not yet released (in shares) | shares	667
Outstanding at end of period (in shares) | shares	7,175
Weighted-Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 10.78
Vested (in dollars per share) | $ / shares	8.93
Forfeited (in dollars per share) | $ / shares	9.13
Unvested, weighted average grant date fair value, ending balance (in dollars per share) | $ / shares	11.08
Vested and not yet released, weighted-average grant date fair value (in dollars per share) | $ / shares	8.93
Outstanding at end of period, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 10.88

Stock-based Compensation - Sc_4

Stock-based Compensation - Schedule of Fair Value Assumptions for Employee Stock Purchase Plan (Details) - ESPP	12 Months Ended
	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	8 months 12 days
Risk-free interest rate	1.80%
Expected volatility	35.50%
Dividend yield	0.00%

Stock-based Compensation - Sc_5

Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 21,000	$ 36,627	$ 27,347	$ 2,755,000
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense		716	119	47,000
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense		8,709	979	488,000
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense		13,037	1,532	969,000
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense		$ 14,165	$ 24,717	$ 1,251,000

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Earnings per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (105,828)	$ (87,164)	$ (10,748)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	146,306	80,981	77,147
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.72)	$ (1.08)	$ (0.14)
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders		$ (87,164)	$ (10,748)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)		80,981	77,147
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)		$ (1.08)	$ (0.14)
Class A common stock | Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (18,259)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	25,243
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.72)
Class B common stock | Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (87,569)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	121,063
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.72)

Net Loss per Share Attributab_4

Net Loss per Share Attributable to Common Stockholders - Schedule of Potential Shares of Common Stock Excluded from Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	34,082	197,660	181,152
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	0	165,658	152,022
Redeemable convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	0	177	177
Shares subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	5,945	6,738	748
Unexercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	21,191	25,087	28,127
Unvested restricted stock and RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	6,508	0	78
Shares issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares)	438	0	0

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Domestic	$ (117,401)	$ (87,615)	$ (11,633)
Foreign	12,688	1,528	1,918
Loss before income taxes	$ (104,713)	$ (86,087)	$ (9,715)

Income Taxes - Components of Pr

Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense (benefit):
Federal	$ 391	$ 402	$ 699
State	29	42	23
Foreign	325	248	446
Total current provision for income taxes	745	692	1,168
Deferred expense (benefit):
Federal	0	(1)	1
State	0	0	0
Foreign	370	386	(136)
Total deferred provision for income taxes	370	385	(135)
Total provision for income taxes	$ 1,115	$ 1,077	$ 1,033

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Expected benefit at U.S. federal statutory rate	21.00%	21.00%	34.00%
State income taxes, net of federal tax benefits	0.00%	0.00%	(0.20%)
Foreign income or losses taxed at different rates	0.60%	(1.30%)	2.10%
Stock-based compensation	(1.20%)	(5.50%)	2.10%
Change in valuation allowance	(20.50%)	(14.00%)	(36.50%)
Withholding taxes	(0.40%)	(0.50%)	(7.20%)
Transition tax	0	0	(0.033)
Miscellaneous permanent items	(0.60%)	(1.00%)	(1.60%)
Total provision for income taxes	(1.10%)	(1.30%)	(10.60%)

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 53,536	$ 31,701
Tax credit carryforwards	11,969	8,699
Accrued expenses and reserves	168	1,069
Fixed assets	85	0
Stock-based compensation	6,852	0
Unrealized loss on investments	43	617
Other	1,703	1,062
Gross deferred tax assets	74,356	43,148
Valuation allowance	(63,487)	(37,924)
Total deferred tax assets	10,869	5,224
Deferred tax liabilities:
Capitalized internal-use software	(4,668)	(3,111)
Deferred commissions	(5,487)	(493)
Fixed assets	(1,228)	(1,269)
Stock-based compensation	0	(514)
Unrealized gain on investments	(32)	(13)
Total deferred tax liabilities	(11,415)	(5,400)
Net deferred tax assets (liabilities)	$ (546)	$ (176)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Valuation allowance	$ 63,487,000	$ 37,924,000
Increase (decrease) in valuation allowance	25,600,000	15,500,000	$ (2,500,000)
Amount of unrecognized tax benefits that would impact the effective income tax rate	0
Income tax expense related to interest and penalties	0	0	0
Liabilities for interest and penalties	0	0	$ 0
Undistributed earnings of international subsidiaries	18,600,000
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	221,500,000	122,300,000
Federal | Research and development tax credit carryforward
Income Tax Contingency [Line Items]
Tax credit carryforwards	8,500,000
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	104,700,000	89,800,000
State | Research and development tax credit carryforward
Income Tax Contingency [Line Items]
Tax credit carryforwards	6,500,000
Foreign
Income Tax Contingency [Line Items]
Tax credit carryforwards	$ 1,800,000	$ 1,800,000

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of the beginning of the period	$ 2,549	$ 2,247	$ 1,153
Decreases for tax positions related to the prior year	(120)	(613)	0
Additions for tax positions related to the current year	1,311	915	1,094
Balance as of the end of the period	$ 3,740	$ 2,549	$ 2,247

Related Party Transactions (Det

Related Party Transactions (Details) - Affiliated Entity - Purchase of Common Stock from Founders - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Number of shares purchased (in shares)	8,909,092
Purchase price	$ 98,000,000
Stock-based compensation expense recorded		$ 0	$ 23,300,000

Segment and Geographic Inform_3

Segment and Geographic Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2019segment
Segment Reporting [Abstract]
Number of operating segments	1

Segment and Geographic Inform_4

Segment and Geographic Information - Schedule of Property and Equipment, Net by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Property and equipment, net	$ 101,466	$ 73,210
United States
Segment Reporting Information [Line Items]
Property and equipment, net	59,688	46,012
Rest of the world
Segment Reporting Information [Line Items]
Property and equipment, net	$ 41,778	$ 27,198

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Jan. 01, 2020USD ($)
Subsequent Event | S2 Systems Corporation
Subsequent Event [Line Items]
Consideration transferred	$ 39.2