Forescout (FSCT) 10-K 1 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 15, 2019	Jun. 29, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	FORESCOUT TECHNOLOGIES, INC
Entity Central Index Key	1,145,057
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		44,523,438
Entity Public Float			$ 1,187,927,026

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 66,895	$ 63,009
Marketable securities	47,632	123,384
Accounts receivable	79,255	64,686
Inventory	1,501	3,660
Deferred commissions - current	12,543	10,957
Prepaid expenses and other current assets	13,353	9,213
Total current assets	221,179	274,909
Deferred commissions - non-current	22,831	21,795
Property and equipment, net	24,349	23,260
Restricted cash - non current	1,266	4,146
Intangible assets	19,002	0
Goodwill	92,482	0
Other assets	7,369	4,608
Total assets	388,478	328,718
Current liabilities:
Accounts payable	12,118	7,348
Accrued compensation	32,649	25,358
Accrued expenses	14,558	11,031
Deferred revenue - current	101,900	79,631
Notes payable - current	7,331	7,245
Total current liabilities	168,556	130,613
Deferred revenue - non-current	69,618	55,228
Notes payable - non-current	8,248	15,579
Other liabilities	14,335	11,807
Total liabilities	260,757	213,227
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.001 par value; 100,000 shares authorized; zero shares issued and outstanding at December 31, 2018 and 2017.	0	0
Common stock, $0.001 par value; 1,000,000 shares authorized; 43,403 and 38,122 shares issued and outstanding at December 31, 2018 and 2017, respectively.	43	38
Additional paid-in capital	639,237	551,986
Accumulated other comprehensive loss	(302)	(112)
Accumulated deficit	(511,257)	(436,421)
Total stockholders’ equity	127,721	115,491
Total liabilities and stockholders' equity	$ 388,478	$ 328,718

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (shares)	100,000	100,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (shares)	1,000,000	1,000,000
Common stock, shares issued (shares)	43,403	38,122
Common stock, shares outstanding (shares)	43,403	38,122

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Cost of revenue:
Cost of revenue	17,486	19,197	14,713	16,486	16,073	15,928	14,088	12,523	67,882	58,612	48,403
Total gross profit	67,246	66,431	52,881	43,211	46,834	53,412	35,893	29,653	229,769	165,792	119,143
Operating expenses:
Research and development	17,161	15,062	14,803	14,687	14,801	10,985	10,702	10,947	61,713	47,435	31,490
Sales and marketing	50,464	46,098	45,039	42,279	41,769	34,028	33,556	35,045	183,880	144,398	119,071
General and administrative	16,849	13,880	13,260	13,732	23,941	9,148	8,902	9,215	57,721	51,206	30,731
Total operating expenses	84,474	75,040	73,102	70,698	80,511	54,161	53,160	55,207	303,314	243,039	181,292
Loss from operations	(17,228)	(8,609)	(20,221)	(27,487)	(33,677)	(749)	(17,267)	(25,554)	(73,545)	(77,247)	(62,149)
Interest expense	(237)	(208)	(225)	(243)	(270)	(290)	(318)	(345)	(913)	(1,223)	(2,577)
Other income (expense), net	527	865	513	662	382	160	(82)	(144)	2,567	316	(607)
Revaluation of warrant liabilities	0	0	0	0	(385)	0	50	(392)	0	(727)	1,104
Loss before income taxes	(16,938)	(7,952)	(19,933)	(27,068)	(33,950)	(879)	(17,617)	(26,435)	(71,891)	(78,881)	(64,229)
Income tax provision	1,010	334	473	1,128	618	412	174	635	2,945	1,839	1,250
Net loss	(17,948)	(8,286)	(20,406)	(28,196)	(34,568)	(1,291)	(17,791)	(27,070)	(74,836)	(80,720)	(65,479)
Deemed dividend on the conversion of Series G redeemable convertible preferred stock	0	0	0	0	12,810	0	0	0	0	12,810	0
Net loss attributable to common stockholders	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (47,378)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (93,530)	$ (65,479)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.42)	$ (0.20)	$ (0.50)	$ (0.74)	$ (1.73)	$ (0.21)	$ (2.95)	$ (4.57)	$ (1.83)	$ (8.20)	$ (11.67)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	43,016	42,064	40,457	38,313	27,349	6,140	6,031	5,924	40,980	11,405	5,609
Product
Revenue:
Revenue	$ 47,482	$ 51,082	$ 34,323	$ 29,780	$ 34,994	$ 43,204	$ 26,842	$ 20,308	$ 162,667	$ 125,348	$ 97,994
Cost of revenue:
Cost of revenue	6,852	8,947	4,919	7,136	6,964	7,240	5,545	4,092	27,854	23,841	21,832
Maintenance and professional services
Revenue:
Revenue	37,250	34,546	33,271	29,917	27,913	26,136	23,139	21,868	134,984	99,056	69,552
Cost of revenue:
Cost of revenue	$ 10,634	$ 10,250	$ 9,794	$ 9,350	$ 9,109	$ 8,688	$ 8,543	$ 8,431	$ 40,028	$ 34,771	$ 26,571

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (74,836)	$ (80,720)	$ (65,479)
Other comprehensive loss, net of tax:
Change in unrealized gains (losses) on marketable securities	9	(112)	0
Foreign currency translation adjustments	(199)	0	0
Comprehensive loss	$ (75,026)	$ (80,832)	$ (65,479)

Consolidated Statements of Rede

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit As Adjusted
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 41,175				$ 41,175
Redeemable convertible preferred stock, beginning balance (in shares) at Dec. 31, 2015	18,300,000
Redeemable convertible preferred stock, beginning balance at Dec. 31, 2015	$ 279,913
Increase (Decrease) in Temporary Equity [Roll Forward]
Net proceeds from issuance of Series G redeemable convertible preferred stock (in shares)	169,000
Net proceeds from issuance of Series G redeemable convertible preferred stock	$ 3,941
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2016	18,469,000
Redeemable convertible preferred stock, ending balance at Dec. 31, 2016	$ 283,854
Stockholders' (deficit) equity, beginning balance (in shares) at Dec. 31, 2015		5,067,000
Stockholders' (deficit) equity, beginning balance at Dec. 31, 2015	(252,802)	$ 5	$ 65,814	$ 0	(318,621)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss, net of tax	0
Stock-based compensation	16,834		16,834
Issuance of common stock in connection with employee equity incentive plans (in shares)		644,000
Issuance of common stock in connection with employee equity incentive plans	1,071	$ 1	1,070
Vesting of early exercised stock options (in shares)		143,000
Vesting of early exercised stock options	1,074		1,074
Net loss	(65,479)				(65,479)
Stockholders' (deficit) equity, ending balance (in shares) at Dec. 31, 2016		5,854,000
Stockholders' (deficit) equity, ending balance at Dec. 31, 2016	(258,127)	$ 6	84,792	0	(342,925)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 34				34
Conversion of redeemable convertible preferred stock to common stock in connection with the initial public offering (in shares)	(18,525,000)
Conversion of redeemable convertible preferred stock to common stock in connection with the initial public offering	$ (283,854)
Shares issued for preferred stock warrant exercise (in shares)	56,000
Shares issued for preferred stock warrant exercise	$ 0
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2017	0
Redeemable convertible preferred stock, ending balance at Dec. 31, 2017	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss, net of tax	(112)			(112)
Stock-based compensation	$ 42,562		42,562
Issuance of common stock in connection with employee equity incentive plans (in shares)	306,000	306,000
Issuance of common stock in connection with employee equity incentive plans	$ 1,626	$ 0	1,626
Issuance of common stock in connection with public offering, net of underwriter discounts and commissions and offering costs (in shares)		6,072,000
Issuance of common stock in connection with public offering, net of underwriter discounts and commissions and offering costs	119,684	$ 6	119,678
Conversion of redeemable convertible preferred stock to common stock in connection with the initial public offering (in shares)		24,845,000
Conversion of redeemable convertible preferred stock to common stock in connection with the initial public offering	283,854	$ 25	283,829
Conversion of preferred stock warrants to common stock warrants in connection with initial public offering	4,173		4,173
Vesting of early exercised stock options (in shares)		183,000
Vesting of early exercised stock options	1,089		1,089
Issuance of common stock upon exercise of common stock warrants (in shares)		280,000
Shares issued for preferred stock warrant exercise	1,428		1,428
Deemed dividend on the conversion of Series G redeemable convertible preferred stock (in shares)		582,000
Deemed dividend on the conversion of Series G redeemable convertible preferred stock	0	$ 1	12,809		(12,810)
Net loss	$ (80,720)				(80,720)
Stockholders' (deficit) equity, ending balance (in shares) at Dec. 31, 2017	38,122	38,122,000
Stockholders' (deficit) equity, ending balance at Dec. 31, 2017	$ 115,491	$ 38	551,986	(112)	(436,421)
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2018	0
Redeemable convertible preferred stock, ending balance at Dec. 31, 2018	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss, net of tax	9
Other comprehensive loss, net of tax	(190)			(190)
Stock-based compensation	$ 53,497		53,497
Issuance of common stock in connection with employee equity incentive plans (in shares)	2,979,000	4,616,000
Issuance of common stock in connection with employee equity incentive plans	$ 20,347	$ 5	20,342
Issuance of common stock in connection with public offering, net of underwriter discounts and commissions and offering costs (in shares)		500,000
Issuance of common stock in connection with public offering, net of underwriter discounts and commissions and offering costs	12,572	$ 0	12,572
Vesting of early exercised stock options (in shares)		98,000
Vesting of early exercised stock options	840		840
Issuance of common stock upon exercise of common stock warrants (in shares)		67,000
Net loss	$ (74,836)				(74,836)
Stockholders' (deficit) equity, ending balance (in shares) at Dec. 31, 2018	43,403	43,403,000
Stockholders' (deficit) equity, ending balance at Dec. 31, 2018	$ 127,721	$ 43	$ 639,237	$ (302)	$ (511,257)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net loss	$ (74,836)	$ (80,720)	$ (65,479)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Stock-based compensation	53,497	42,596	16,834
Depreciation and amortization	8,003	6,068	3,610
Revaluation of warrant liabilities	0	727	(1,104)
Other	461	(127)	694
Changes in operating assets and liabilities, net of business acquisition
Accounts receivable	(10,899)	(19,992)	(14,608)
Inventory	2,168	(2,719)	(450)
Deferred commissions	(2,621)	(7,469)	(9,624)
Prepaid expenses and other current assets	(3,084)	(141)	(4,772)
Other assets	(3,543)	60	(992)
Accounts payable	4,632	1,734	596
Accrued compensation	7,057	8,072	4,134
Accrued expenses	2,667	(599)	2,045
Deferred revenue	30,366	49,569	23,888
Other liabilities	(379)	206	6,937
Net cash provided by (used in) operating activities	13,489	(2,735)	(38,291)
Cash flows from investing activities
Purchases of property and equipment	(7,628)	(4,517)	(22,006)
Purchases of marketable securities	(54,530)	(123,032)	(23,983)
Proceeds from maturities of marketable securities	130,633	0	12,000
Proceeds from sales of marketable securities	0	0	11,979
Business acquisition, net of cash acquired	(105,425)	0	0
Net cash used in investing activities	(36,950)	(127,549)	(22,010)
Cash flows from financing activities
Net borrowings of notes payable	0	0	29,977
Repayments of notes payable	(7,500)	(7,500)	(20,130)
Payment of accrued success fees	0	(350)	0
Net proceeds from issuance of redeemable convertible preferred stock	0	0	2,399
Proceeds from sales of shares through employee equity incentive plans	31,790	1,626	1,071
Payment related to shares withheld for taxes on vesting of restricted stock units	(11,443)	0	0
Payments of deferred offering costs	(1,542)	(4,245)	(7)
Proceeds from public offering, net of underwriting discounts and commissions	13,818	124,233	0
Net cash provided by financing activities	25,123	113,764	13,310
Effect of exchange rate changes on cash and cash equivalents	(7)	0	0
Net change in cash, cash equivalents, and restricted cash for period	1,655	(16,520)	(46,991)
Cash, cash equivalents, and restricted cash at beginning of period	67,357	83,877	130,868
Cash, cash equivalents, and restricted cash at end of period	69,012	67,357	83,877
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,447	1,634	1,012
Cash paid for interest	628	819	2,014
Noncash disclosure of investing and financing activities:
Change in liability for early exercise of stock options, net of vested portion	840	1,089	1,075
Deferred offering costs included in accrued expenses	0	296	1,435
Conversion of preferred stock warrants to common stock warrants in connection with initial public offering	0	4,173	0
Cashless exercise of preferred stock warrants	0	1,428	0
Reconciliation of cash, cash equivalents, and restricted cash within the consolidated balance sheets to the amounts shown in the statements of cash flows above:
Total cash, cash equivalents, and restricted cash	$ 67,357	$ 83,877	$ 130,868

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Company and Background Forescout Technologies, Inc. (the “Company”) was incorporated in the State of Delaware and commenced operations in April 2000. The Company provides an agentless approach to network security that discovers and classifies IP-based devices in real time as the devices connect to the network and continuously monitors and assesses the devices’ security posture. The Company’s agentless approach supports heterogeneous wired and wireless networks, as well as both virtual and cloud infrastructures, while scaling to meet the needs of globally distributed organizations. The Company offers its solution across two product groups: (i) products for visibility and control capabilities, and (ii) products for orchestration capabilities. The Company’s products for visibility and control capabilities are comprised of CounterACT and SilentDefense. CounterACT provides for visibility and control capabilities across campus IT and IoT devices, OT devices, data center physical and virtual devices and cloud virtual devices. SilentDefense provides for visibility and control capabilities deeper within an OT portion of the network. Our products for orchestration capabilities are comprised of our portfolio of Extended Modules. The Company offers its solution across two product types: software products and hardware products. The Company’s software products include CounterACT, Extended Modules, CounterACT Virtual Appliance, CounterACT Enterprise Manager Virtual Appliances, SilentDefense and SilentDefense Command Center (“Software Products”). The Company’s hardware products include hardware that is sold separately for use with CounterACT or SilentDefense, CounterACT Appliances (hardware appliances that are embedded with CounterACT), and CounterACT Enterprise Manager Appliances (“Hardware Products”). The Company sells its products, maintenance, and professional services to end-customers through distributors and resellers, who are supported by the Company’s sales and marketing organization, and to a lesser extent directly to end-customers. Initial Public Offering On October 31, 2017 , the Company closed its initial public offering (“IPO”), in which it issued and sold 6,072,000 shares of common stock inclusive of the underwriters’ option to purchase additional shares that was exercised in full. The price per share to the public was $22.00 . The Company received aggregate proceeds of $124.2 million from the IPO, net of underwriters’ discounts and commissions, and before deducting offering costs of approximately $4.5 million . Upon the closing of the IPO, all shares of the Company's outstanding redeemable convertible preferred stock automatically converted into 25,370,616 shares of common stock. Follow-On Offering The Company closed its follow-on offering (the “Offering”) in March 2018, in which it issued and sold 500,000 shares of its common stock. Further, an additional 4,572,650 shares of its common stock were sold by certain stockholders in the Offering, inclusive of the underwriters’ option to purchase additional shares from certain of the selling stockholders. The price to the public was $29.00 per share. The Company received aggregate proceeds of $16.4 million from the Offering, net of underwriters’ discounts and commissions of $0.7 million and inclusive of approximately $2.6 million received by the Company in connection with the exercise by certain selling stockholders of options to purchase an aggregate of 425,436 shares of common stock that were sold in the Offering. The Company incurred offering costs of approximately $1.2 million . The Company did not receive any proceeds from the sale of shares by the selling stockholders in the Offering. Basis of Presentation The consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The Company’s consolidated financial statements include the results of Forescout Technologies, Inc. and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make use of estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. These estimates form the basis of judgments made about carrying values of assets and liabilities, which are not readily apparent from other sources. The areas where management has made estimates requiring judgment include, but are not limited to, the best estimate of selling prices for products and related support, the period over which deferred sales commissions are amortized to expense, sales return reserve, accruals, stock-based compensation including the fair value of common stock, redeemable convertible preferred stock warrant liabilities, provision for income taxes, including related reserves, identified intangibles and goodwill, and purchase price allocation of an acquired business. Actual results could differ materially from those estimates. Reverse Stock Split On October 16, 2017, the Company amended its amended and restated certificate of incorporation to effect a two-to-one reverse stock split of its common stock and convertible preferred stock (the “Reverse Stock Split”). Upon the filing of the amended and restated certificate of incorporation in the state of Delaware, (i) each two shares of outstanding convertible preferred stock and each two shares of outstanding common stock were exchanged and combined into one share of convertible preferred stock and one share of common stock, respectively; (ii) the number of shares of common stock issuable under each outstanding option to purchase common stock and issuable upon vesting under each restricted stock unit was proportionately reduced on a two -to-one basis; (iii) the exercise price of each outstanding option to purchase common stock was proportionately increased on a two -to-one basis; (iv) the number of shares of convertible preferred stock issuable under outstanding warrants was proportionally reduced on a two -to-one basis and the exercise price of such warrants was proportionally increased on a two -to-one basis; and (v) corresponding adjustments in the per share conversion prices, dividend rates and liquidation preferences of the convertible preferred stock were made on a two -to-one basis. Accordingly, all share and per share information presented in the consolidated financial statements herein, and notes thereto, have been retroactively adjusted to reflect the Reverse Stock Split. Segment Information The chief operating decision maker (“CODM”) is the Chief Executive Officer who reviews financial information presented on a consolidated basis. The Company has one business activity and there are no segment managers who are held accountable by the CODM for operations, operating results and planning for levels or components below the consolidated level. The Company operates in one segment. Concentrations Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, accounts receivable, and restricted cash. The Company maintains all of its cash and cash equivalents in interest-bearing bank accounts and money market accounts. Management believes that the financial institutions that hold the Company’s cash and cash equivalents are financially sound and exposed to minimal credit risk. Deposits held with banks generally exceed the amount of insurance provided on such deposits. Accounts receivable are primarily derived from the Company’s customers, including distributors and resellers representing various geographical locations. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable, and, if necessary, an allowance for doubtful accounts is maintained for estimated potential credit losses. As of December 31, 2018 and 2017 , four customers represented 17% , 15% , 11% , and 11% of total accounts receivable, and two customers represented 33% and 17% of total accounts receivable, respectively. For the year ended December 31, 2018 , three customers represented 22% , 18% , and 13% of the Company’s total revenue. For the year ended December 31, 2017 , three customers represented 31% , 22% , and 16% of the Company’s total revenue. For the year ended December 31, 2016 , 24% , 16% , and 14% of the Company’s total revenue. The Company purchases its hardware appliances from one contract manufacturer that assembles all of its products. Foreign Currency The Company’s functional currency is the U.S. dollar for the majority of its foreign operations except for SecurityMatters, B.V. (“SecurityMatters”) whose functional currency is the Euro. Transactions denominated in currencies other than the applicable functional currency are converted to the functional currency at the exchange rate on the transaction date. At period end, monetary assets and liabilities are remeasured using the current exchange rate at the balance sheet date. Non-monetary assets and liabilities and capital accounts are remeasured using historical exchange rates. Revenue and expenses have been remeasured using the average exchange rates in effect during each period. Resulting foreign currency remeasurement gains and losses are recorded in other income (expense), net on the consolidated statements of operations. Where a non-U.S. currency is the functional currency, translation from that functional currency to the U.S. dollar is performed for balance sheet accounts using exchange rates in effect at the balance sheet date and for revenue and expense accounts using an average exchange rate for the period. Resulting translation adjustments are reported as a component of accumulated other comprehensive loss on the consolidated balance sheets. Cash and Cash Equivalents The Company considers all highly liquid investments held at financial institutions with original maturities of three months or less at date of purchase to be cash equivalents. Cash and cash equivalents are stated at cost, which approximates fair value. Marketable Securities The Company’s marketable securities consist primarily of commercial paper, corporate debt securities, and U.S. government agency securities. The Company’s marketable securities are classified as available-for-sale and are reported at fair value. The Company determines any realized gains or losses on the sale of available-for-sale securities on a specific identification method, and such gains and losses are recorded as a component of other income (expense), net on the consolidated statements of operations. Unrealized gains and losses of the available-for-sale securities are excluded from earnings and reported as a component of accumulated other comprehensive loss. The Company has classified and accounted for its marketable securities as available-for-sale. After consideration of the Company’s risk versus reward objectives, as well as the Company’s liquidity requirements, the Company may sell these securities prior to their stated maturities. As the Company views these securities as available to support current operations, the Company classifies highly liquid securities with maturities beyond 12 months as current assets under the caption marketable securities in the consolidated balance sheets. Marketable securities are considered impaired when a decline in fair value is judged to be other-than-temporary. The Company considers available quantitative and qualitative evidence in evaluating potential impairment of the marketable securities on a quarterly basis. If the cost of an individual investment exceeds its fair value, the Company evaluates, among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investment. Once a decline in fair value is determined to be other-than-temporary, the Company will record an impairment charge and establish a new cost basis in the investment. As of December 31, 2018 , the Company did not consider any of its marketable securities to be other-than-temporarily impaired. Restricted Cash As of December 31, 2018 and 2017 , the Company had restricted cash of $0.9 million and $0.2 million recorded as prepaid expenses and other current assets, respectively, and $1.3 million and $4.1 million recorded as non-current restricted cash, respectively. Restricted cash primarily consists of letters of credit issued as security deposits required for facility leases. Accounts Receivable Trade accounts receivable are recorded at the invoiced amount, net of allowances for doubtful accounts. The Company assesses its trade accounts receivable for doubtful accounts based on the collectability of accounts. Management regularly reviews the adequacy of the allowance for doubtful accounts by considering the age of each outstanding invoice, each customer’s expected ability to pay, and the collection history with each customer, to determine whether a specific allowance is appropriate. Accounts receivable that are deemed uncollectible are charged against the allowance for doubtful accounts. Based on management’s assessment of its trade accounts receivable, the Company did not record an allowance for doubtful accounts as of December 31, 2018 and 2017 . Inventory Inventory primarily consists of finished goods hardware appliances and production materials. Inventory is stated at the lower of cost or market determined using the specific identification method. Inventory that is obsolete or in excess of forecasted demand is written down to its estimated realizable value. Inventory write-downs, once established, are not reversed as they establish a new cost basis for the inventory. There were no material inventory write-downs for the years ended December 31, 2018 , 2017 , and 2016 . Property and Equipment Property and equipment is stated at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years. Demonstration units are not resold after use and are depreciated over the estimated useful life of three years or less. Leasehold improvements are depreciated over the shorter of the estimated useful lives of the improvements or the remaining lease term. Business Combinations The Company accounts for acquisitions using the acquisition method of accounting for business combinations . When the Company acquires a business, the purchase price is allocated to the net tangible and identifiable intangible assets acquired based on their estimated fair values. Any residual purchase price is recorded as goodwill. The allocation of the purchase price requires management to make significant estimates in determining the fair values of assets acquired and liabilities assumed, especially with respect to intangible assets. These estimates can include, but are not limited to, the cash flows that an asset is expected to generate in the future, the appropriate weighted-average cost of capital, and the cost savings expected to be derived from acquiring an asset. These estimates are inherently uncertain and unpredictable. During the measurement period, which may be up to one year from the acquisition date, adjustments to the fair value of these tangible and intangible assets acquired and liabilities assumed may be recorded, with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations. Goodwill and Other Long-Lived Assets The excess of the purchase price over the estimated fair value of net assets of businesses acquired in a business combination is recognized as goodwill. Goodwill is tested for impairment annually on October 1st or more frequently if certain indicators are present. For the year ended December 31, 2018, the Company performed its goodwill impairment test on December 31, 2018 as the SecurityMatters acquisition was completed on November 7, 2018. Management reviews long-lived assets, such as property and equipment and finite-lived intangible assets subject to amortization, for events and changes in circumstances that may indicate that carrying amounts of long-lived assets may not be recoverable. When such events or circumstances occur, recoverability of these assets is measured by a comparison of the carrying value to the future undiscounted cash flows the assets are expected to generate. If long-lived assets are considered to be impaired, the impairment to be recognized would equal the amount by which the carrying value of the asset exceeds its fair market value. To date, the Company has not recorded any significant impairment to its goodwill and other long-lived assets. Deferred Offering Costs Deferred offering costs consisted of fees and expenses incurred in connection with the sale of the Company’s common stock in its IPO and Offering, including direct incremental legal, consulting, accounting fees, and other offering-related costs. Upon completion of the Company’s IPO or Offering, these deferred offering costs were reclassified to stockholders’ equity and offset against the proceeds of the offerings. Product Warranty The Company provides a standard 90 day warranty on its hardware and software products. The Company also offers its customers post-contract support (“PCS”), which includes a warranty of between one to five -years on hardware. The Company will also provide its customers software releases or updates during the PCS term. The Company accrues for estimated standard warranty costs for those customers that do not purchase PCS at the time of product shipment. These potential warranty claims are accrued as a component of product cost of revenue based on historical experience and other data, which is reviewed periodically for adequacy. Warranty costs associated with PCS are expensed as incurred. To date, the Company has not incurred nor accrued any significant costs associated with product warranty. Contract Manufacturer Liabilities Manufacturing, repair, and supply chain management operations are outsourced to a third-party contract manufacturer. These costs are a significant portion of product cost of revenue. Although the Company is contractually obligated to purchase manufactured products, the Company generally does not own the manufactured products as product title transfers from the contract manufacturer to the Company and immediately to the customer upon shipment. The contract manufacturer assembles the Company’s products using design specifications, quality assurance programs, and standards that the Company establishes. Components are procured and assembled based on the Company’s demand forecasts. These forecasts represent management’s best estimates of future demand for the products based upon historical trends and analysis from sales and operations functions as adjusted for overall market conditions. The Company accrues for costs for contractual manufacturing commitments in excess of its forecasted demand, including costs incurred for excess components or for the carrying costs incurred by the contract manufacturer. To date, the Company has not accrued any significant contract manufacturer liabilities. Redeemable Convertible Preferred and Common Stock Warrant Liabilities Upon completion of the Company's IPO in October 2017, there were no freestanding warrants to purchase shares of convertible preferred stock. As such, no preferred stock warrant liability remained outstanding after the IPO. Before the Company's IPO, freestanding warrants related to shares that are redeemable or contingently redeemable were classified as a liability in the Company’s consolidated balance sheet. The convertible preferred stock warrants were subject to re-measurement at each balance sheet date, and any change in fair value was recognized in the consolidated statements of operations. The Company adjusted the redeemable convertible preferred stock warrant liability to the estimated fair value of the warrants until either the exercise or the completion of the Company’s IPO, at which time the redeemable convertible preferred stock issuable upon exercise of the warrants became warrants to purchase common stock and the related liability was reclassified to additional paid-in capital in stockholders' equity. Severance Pay Deposits and Accrued Severance Pay Liability The Company records a severance pay asset and liability on its consolidated balance sheets related to its employees located in Israel. Under Israeli law and labor agreements, the Company is required to make severance and pension payments to retired or dismissed employees and to employees leaving employment in certain other circumstances. Liabilities for severance pay are calculated pursuant to Israeli severance pay law using the most recent monthly salary for the employees, multiplied by the number of years of employment, and are included in accrued expenses and other liabilities in the Company’s consolidated balance sheets for the current and non-current portions, respectively. The Company’s liability at each respective balance sheet date for its Israeli employees is fully accrued in the accompanying consolidated financial statements. The severance liability is funded through monthly deposits to the employee’s pension and management insurance carriers. The fair value of this deposit is recorded in prepaid expenses and other current assets, and other assets in the Company’s consolidated balance sheets for the current and non-current portions, respectively. Revenue Recognition Effective January 1, 2018, the Company adopted Topic 606 using the full retrospective method. Refer to Note 2 for a detailed discussion of accounting policies related to revenue recognition, including deferred revenue and commissions. Software Development Costs Software development costs are not capitalized as the software development process is essentially completed concurrent with the establishment of technological feasibility. As such, all software development costs are expensed as incurred and included in research and development expense in the accompanying consolidated statements of operations. Advertising Costs Advertising costs include costs incurred on print, broadcast, and online advertising. Advertising costs are expensed as incurred and included in sales and marketing expense in the accompanying consolidated statements of operations. Stock-Based Compensation Stock-based compensation for employees is measured based on the grant date fair value of the award and is expensed over the requisite service period, which is generally the vesting period. The fair value of option awards is determined on the date of grant using the Black-Scholes option pricing model. In applying the Black-Scholes option pricing model, the Company’s determination of the fair value of the option award on the grant date prior to its IPO is affected by the Company’s estimated fair value of the underlying common stock, as well as assumptions relating to subjective variables. Subsequent to its IPO, the Company uses the market closing price for its common stock as reported on the NASDAQ Global Select Market. These variables include the expected term of the award, the expected volatility of the common stock price, the risk-free interest rate, and the expected dividend yield of common stock. Prior to the IPO, the fair value of restricted stock units (“RSUs”) is determined on the date of grant using the Company’s estimated fair value of the underlying common stock. Subsequent to its IPO, the Company uses the market closing price for its common stock as reported on the NASDAQ Global Select Market. Prior to January 1, 2017, for awards with a service condition only, the Company recognized stock-based compensation expense over the service period on a straight-line basis, net of forfeitures. For awards with both a service and performance condition, stock-based compensation expense is recognized over the service period using an accelerated attribution method once the performance conditions become probable. Beginning January 1, 2017 with the adoption of ASU 2016-09, the Company elected to recognize forfeitures as they occur, and no longer estimates a forfeiture rate when calculating the stock-based compensation for equity awards. Stock-based compensation for the year ended December 31, 2016 was calculated using an estimated forfeiture rate based on an analysis of the Company’s actual historical forfeitures. Income Taxes Deferred income taxes are recognized using the asset and liability method, whereby deferred tax assets and liabilities are recognized for the expected future tax consequences attributable to differences between the Company’s (1) financial statement carrying amounts and their respective tax bases and (2) operating loss and tax credit carryforwards. Valuation allowances are provided when the expected realization of tax assets does not meet a more-likely-than-not criterion. Due to the Company’s lack of earnings history, the U.S. net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes tax benefits from uncertain tax positions if it is more likely than not that the tax position will be sustained upon examination by a taxing authority based on the technical merits of the position. The tax benefits recognized from such positions are measured based on the largest benefit that has a greater than 50% likelihood to be realized upon settlement. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in income tax expense in the accompanying consolidated statements of operations, when and if incurred. On December 22, 2017, the President of the United States signed the Tax Cuts and Jobs Act (the “Tax Act”) into law. The legislation significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a mandatory repatriation tax on earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. Staff Accounting Bulletin No. 118 (“SAB 118”) was issued to address the application of GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Act. In accordance with SAB 118, the measurement period is now closed and the Company has determined that provisional estimates of the impact recorded in the fourth quarter of 2017 in connection with the revaluation of deferred taxes and the transition tax on the mandatory deemed repatriation of foreign earnings is now final. No material adjustments from the provisional amounts were recorded in 2018. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The Company adopted Topic 606 effective January 1, 2018 using the full retrospective method, which required the Company to restate each prior reporting period presented. See Note 2 for the details of any impacts to previously reported results. In November 2016, the FASB issued ASU No. 2016-18 (Topic 230), Statement of Cash Flows: Restricted Cash . The new standard requires an entity to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows, and an entity will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. The standard is effective for annual and interim periods within those fiscal years, beginning after December 15, 2017, and should be applied retrospectively. The Company adopted this standard effective January 1, 2018 and as a result of adopting this standard, the Company no longer includes the changes in its restricted cash in net cash used in investing activities. The Company’s restricted cash primarily consists of letters of credit issued as security deposits required for facility leases. Recently Issued and Not Yet Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases (“ASU 2016-02”). The new standard requires lessees to recognize leases on their balance sheet as a right-of-use asset and a lease liability. The guidance also requires qualitative and quantitative disclosures to assess the amount, timing and uncertainty of cash flows arising from leases. The standard requires a modified retrospective transition approach and provides certain optional transitional relief. In July 2018, the FASB issued ASU No. 2018-10 (Topic 842), Codification Improvements to Topic 842, Leases (“ASU 2018-10”), and ASU No. 2018-11 (Topic 842), Targeted Improvements (“ASU 2018-11”) which provide a transition method to apply the new lease standards at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption . The Company will apply the transition method, whereby prior comparative periods will not be retrospectively presented. The new standard provides a number of optional practical expedients in transition. The Company plans to elect the following practical expedients and accounting policies: • Practical expedients not to reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs, • Practical expedient for lessees to combine lease and non-lease components, • Accounting policy to not record right-of-use assets and lease liabilities for a lease with an initial term of 12 months or less. The standard is effective for the Company in the first quarter of fiscal 2019. The Company is currently evaluating the lease portfolio, process, control and policy change requirements as part of the adoption. The Company expects the adoption of the new guidance to have a material impact on the total assets and liabilities reported on the Company’s consolidated balance sheets, and estimates an increase in long-term assets and total liabilities of approximately $15 million to $25 million as of January 1, 2019. The Company does not anticipate that the adoption of this standard will have a material impact on its consolidated statements of operations.

Revenue, Deferred Revenue and D

Revenue, Deferred Revenue and Deferred Commissions	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue, Deferred Revenue and Deferred Commissions	Revenue, Deferred Revenue and Deferred Commissions The Company adopted Topic 606 effective January 1, 2018 using the full retrospective method, which required the Company to restate each prior reporting period presented to be consistent with the standard. The most significant impact to revenue recognized related to the accounting for the sale of Extended Modules and to a lesser extent the sale of CounterACT. Under previously reported GAAP, the Company established Vendor Specific Objective Evidence (“VSOE”) for professional services, and support and maintenance on Software Products, except Extended Modules, beginning January 1, 2016. Under previously reported GAAP, Software Product related revenue was recognized ratably over the contractually committed support and maintenance period when VSOE was not established. Professional services sold in conjunction with such Software Products were also recognized ratably over the contractually committed support and maintenance period. Under ASC 606, the requirement to have VSOE for undelivered elements is eliminated and the Company now generally recognizes Software Product revenue at the time of delivery, and any related professional services revenue as services are provided to the customers. Further, revenue allocated from future deliverables (primarily support and maintenance) to Hardware Products is now recognized upon delivery under ASC 606 when the standalone selling price is different from the contract price. Under previously reported GAAP, such differences were recognized over the contractual support and maintenance period. Additionally, Topic 606 requires the capitalization of costs to obtain a contract, primarily sales commissions, and the amortization of these costs over the contract period or estimated customer life, which resulted in the recognition of a deferred charge on the Company’s consolidated balance sheets. Under previously reported GAAP, the Company expensed all sales commissions and other incremental costs to acquire contracts as they were incurred. Impacts on Financial Statements The Company adjusted its consolidated financial statements from amounts previously reported due to the adoption of Topic 606. Selected consolidated balance sheet line items, which reflect the adoption of Topic 606, are as follows (in thousands): December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Assets Accounts receivable $ 65,428 $ (742 ) $ 64,686 Deferred commission - current $ — $ 10,957 $ 10,957 Prepaid expenses and other current assets $ 8,655 $ 558 $ 9,213 Deferred commission - non-current $ — $ 21,795 $ 21,795 Other assets $ 4,120 $ 488 $ 4,608 Liabilities and stockholders’ equity Deferred revenue - current $ 98,027 $ (18,396 ) $ 79,631 Deferred revenue - non-current $ 64,731 $ (9,503 ) $ 55,228 Accumulated deficit $ (497,376 ) $ 60,955 $ (436,421 ) Selected consolidated statement of operations line items, which reflect the adoption of Topic 606, are as follows (in thousands, except per share data): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Revenue: Product $ 121,413 $ 3,935 $ 125,348 Maintenance and professional services $ 99,458 $ (402 ) $ 99,056 Cost of revenue: Product $ 24,098 $ (257 ) $ 23,841 Operating expenses: Sales and marketing $ 151,093 $ (6,695 ) $ 144,398 Loss from operations $ (87,732 ) $ 10,485 $ (77,247 ) Net loss $ (91,205 ) $ 10,485 $ (80,720 ) Net loss attributable to common stockholders $ (104,015 ) $ 10,485 $ (93,530 ) Net loss per share attributable to common stockholders, basic and diluted $ (9.12 ) $ 0.92 $ (8.20 ) Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Revenue: Product $ 98,655 $ (661 ) $ 97,994 Maintenance and professional services $ 68,186 $ 1,366 $ 69,552 Cost of revenue: Product $ 21,678 $ 154 $ 21,832 Operating expenses: Sales and marketing $ 127,815 $ (8,744 ) $ 119,071 Loss from operations $ (71,444 ) $ 9,295 $ (62,149 ) Net loss $ (74,774 ) $ 9,295 $ (65,479 ) Net loss attributable to common stockholders $ (74,774 ) $ 9,295 $ (65,479 ) Net loss per share attributable to common stockholders, basic and diluted $ (13.33 ) $ 1.66 $ (11.67 ) Revenue by geographic area based on the billing address of the customer, which reflects the adoption of Topic 606, is as follows (in thousands): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 162,479 $ 2,661 $ 165,140 Other Americas 6,176 (54 ) 6,122 Total Americas 168,655 2,607 171,262 Europe, Middle East, and Africa 36,300 364 36,664 Asia Pacific and Japan 15,916 562 16,478 Total revenue $ 220,871 $ 3,533 $ 224,404 Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 133,615 $ (1,399 ) $ 132,216 Other Americas 4,949 1,017 5,966 Total Americas 138,564 (382 ) 138,182 Europe, Middle East, and Africa 18,918 463 19,381 Asia Pacific and Japan 9,359 624 9,983 Total revenue $ 166,841 $ 705 $ 167,546 The adoption of Topic 606 impacted certain line items in the cash flows from operating activities as follows (in thousands): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Cash flows from operating activities: Net loss $ (91,205 ) $ 10,485 $ (80,720 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Accounts receivable $ (20,734 ) $ 742 $ (19,992 ) Deferred commissions $ — $ (7,469 ) $ (7,469 ) Prepaid expenses and other current assets $ (63 ) $ (78 ) $ (141 ) Other assets $ (535 ) $ 595 $ 60 Deferred revenue $ 53,844 $ (4,275 ) $ 49,569 Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Cash flows from operating activities: Net loss $ (74,774 ) $ 9,295 $ (65,479 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Accounts receivable $ (15,469 ) $ 861 $ (14,608 ) Deferred commissions $ — $ (9,624 ) $ (9,624 ) Prepaid expenses and other current assets $ (5,032 ) $ 260 $ (4,772 ) Other assets $ (1,767 ) $ 775 $ (992 ) Deferred revenue $ 25,455 $ (1,567 ) $ 23,888 Additionally, the adoption of Topic 606 did not have a material impact on income tax provision. The adoption adjustments impacted the deferred income taxes pertaining to the U.S. entity which are subject to a full valuation allowance. Revenue Recognition The Company derives its revenue from sales of products and associated maintenance and professional services. The Company offers its solution across two product groups: (i) products for visibility and control capabilities, and (ii) products for orchestration capabilities and across two product types: (i) software products, and (ii) hardware products. Following the adoption of Topic 606, the Company determines revenue recognition through the following steps, which are described in more detail below: • Identification of the contract, or contracts, with a customer — A contract with a customer exists when (i) the Company enters into an enforceable contract with a customer that defines each party’s rights regarding the goods or services to be transferred and identifies the payment terms related to these goods or services, (ii) the contract has commercial substance, and (iii) the Company determines that collection of substantially all consideration for goods or services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s ability and intention to pay, which is based on a variety of factors, including the customer’s historical payment experience or, in the case of a new customer, published credit and financial information pertaining to the customer. The Company’s payment terms typically range between 30 to 90 days. • Identification of the performance obligation(s) in the contract — Performance obligations promised in a contract are identified based on the goods or services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the goods or services either on their own or together with other resources that are readily available from third parties or from the Company, and are distinct in the context of the contract, whereby the transfer of the goods or services is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised goods or services, the Company applies judgment to determine whether promised goods or services are capable of being distinct, and are distinct in the context of the contract. If these criteria are not met, the promised goods or services are accounted for as a combined performance obligation. • Determination of the transaction price — The transaction price is determined based on the consideration that the Company will be entitled to in exchange for transferring goods or services to the customer. In determining the transaction price, the Company considers uncertainties such as historical rates of product returns and/or concessions. • Allocation of the transaction price to the performance obligation(s) in the contract — If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation based on a relative standalone selling price (“SSP”) basis. The Company determines standalone selling price based on the price at which the performance obligation is sold separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price taking into account available information such as market conditions and internally approved pricing guidelines related to the performance obligations. • Recognition of revenue when, or as, a performance obligation is satisfied — The Company satisfies performance obligations either over time or at a point in time as discussed in further detail below. Revenue is recognized at the time the related performance obligation is satisfied by transferring a promised good or service to a customer. Revenue is recorded net of sales taxes. The following describes the nature of the Company’s primary types of revenue and the revenue recognition policies as they pertain to the types of transactions the Company enters into with its customers. Product Revenue Product revenue consists of sales of CounterACT, SilentDefense, and Extended Modules. Revenue is recognized at the time of transfer of control, which is generally upon delivery of access to software downloads or shipment, provided that all other revenue recognition criteria have been met. Support and Maintenance Revenue The majority of the products are sold with a support and maintenance contract. Support and maintenance contracts are generally offered as renewable, fixed fee contracts where payments are typically due in advance and generally have a term of one or three years, but can be up to five years . Support and maintenance revenue is recognized ratably over the term of the support and maintenance contract and any unearned support and maintenance revenue is included in deferred revenue. Professional Services Revenue Professional services revenue is derived primarily from customer fees for optional installation of the Company’s products or training. Generally, the Company recognizes revenue for professional services as the services are performed. Contract Costs The Company capitalizes contract origination costs that are incremental and recoverable costs of obtaining a contract with a customer. The Company expects that sales commissions and associated payroll taxes and third-party referral fees related to customer contracts are both incremental and recoverable. The contract origination costs are capitalized and amortized to sales and marketing expense when the related performance obligations are met. Incremental contract origination costs relating to products are expensed as the related products are delivered. Incremental contract origination costs relating to support and maintenance contracts are capitalized and amortized over either the contractual performance period or on a straight-line basis over the average customer life of five years , depending on whether the costs relate to a specific support and maintenance contract or the customer relationship. The Company determines its average customer life by taking into consideration its customer contracts, technology, and other factors. Capitalized costs are periodically reviewed for impairment. Capitalized contract costs were $35.9 million and $33.8 million as of December 31, 2018 and December 31, 2017 , respectively. For the years ended December 31, 2018 , 2017 , and 2016 , amortization expense for the contract costs was $14.9 million , $11.4 million , and $11.4 million , respectively. There were no impairment loss in relation to the costs capitalized for the years ended December 31, 2018 , 2017 , and 2016 . Revenue from Contracts with Customers Contract Assets and Contract Liabilities A contract asset is a right to consideration in exchange for products or services that the Company has transferred to a customer when that right is conditional and is not just subject to the passage of time. The Company has no material contract assets. A receivable will be recorded on the consolidated balance sheets when the Company has unconditional rights to consideration. A contract liability is an obligation to transfer products or services for which the Company has received consideration, or for which an amount of consideration is due from the customer. Contract liabilities include customer deposits under non-cancelable contracts and current and non-current deferred revenue balances. The Company’s contract balances are reported in a net contract asset or liability position on a contract-by-contract basis at the end of each reporting period. Significant changes in contract liabilities during the periods presented are as follows (in thousands): Contract Liabilities Balance as of December 31, 2016 $ 86,405 Additions 274,468 Gross revenue recognized (225,006 ) Balance as of December 31, 2017 135,867 Additions 327,650 Assumed in a business combination 6,297 Gross revenue recognized (297,783 ) Balance as of December 31, 2018 $ 172,031 During the years ended December 31, 2018 and 2017 , the Company recognized revenue of $80.0 million and $52.4 million that was included in the contract liabilities balance as of December 31, 2017 and 2016 , respectively. Contract modifications entered into during the year ended December 31, 2018 and 2017 did not have a significant impact on the Company’s contract assets or contract liabilities. Performance Obligations The majority of the contracted but not invoiced performance obligations are subject to cancellation terms. Revenue allocated to remaining performance obligations represent contracted revenue that has not yet been recognized (“contracted not recognized”), which includes deferred revenue, certain customer deposits, and non-cancelable amounts that will be invoiced and recognized as revenue in future periods and excludes performance obligations that are subject to cancellation terms. Contracted not recognized revenue was $177.6 million as of December 31, 2018 , of which the Company expects to recognize approximately 60% of the revenue over the next 12 months and the remainder thereafter. Practical Expedients The Company does not disclose the value of consideration associated with unsatisfied or partially unsatisfied performance obligations for contracts for which the Company recognizes revenue at the amount to which it will have the right to invoice for services performed. The Company also reflects the aggregate effect of all modifications to a contract that occurred before the earliest period presented in the current period’s financial statements instead of retrospectively restating contracts for all previous contract modifications. Disaggregation of Revenue The Company generates revenue from the sale of Software Products, Hardware Products, support and maintenance, and professional services. All revenue recognized in the consolidated statement of operations is considered to be revenue from contracts with customers. The following table depicts the disaggregation of revenue according to revenue type and is consistent with how the Company evaluates its financial performance (in thousands): Year Ended December 31, Revenue: 2018 2017 2016 Software products $ 106,978 $ 49,405 $ 22,346 Hardware products 55,689 75,943 75,648 Support and maintenance 118,572 86,691 60,374 Professional services 16,412 12,365 9,178 Total revenue $ 297,651 $ 224,404 $ 167,546

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial assets and liabilities are recorded at fair value on the consolidated balance sheets and are categorized based upon the level of judgment associated with inputs used to measure their fair value. Fair value reflects the price that would be received on the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value measurements, the Company considers the principal or most advantageous market and also market-based risk. The accounting guidance for fair value measurements requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The accounting guidance also establishes a fair value hierarchy based on the independence of the source and objective evidence of the inputs used. There are three fair value hierarchies based upon the level of inputs that are significant to fair value measurement: • Level 1 —Observable inputs that reflect quoted prices in active markets for identical assets or liabilities. • Level 2 —Observable inputs that reflect quoted prices for identical assets and liabilities in markets that are not active, quoted prices for similar assets or liabilities in active markets, inputs other than quoted prices that are observable for the assets or liabilities, or inputs that are derived principally from or corroborated by observable market data by correlation or other means. • Level 3 —Inputs that are generally unobservable and are supported by little or no market activity, and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. There have been no transfers between fair value measurement levels during the periods presented. The following table presents the fair value of the Company’s financial assets and liabilities according to the fair value hierarchy (in thousands): December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Financial Assets Cash and cash equivalents: Cash $ 46,017 $ — $ — $ 24,526 $ — $ — Money market accounts 20,878 — — 38,483 — — Total cash and cash equivalents 66,895 — — 63,009 — — Marketable securities: Commercial paper — 3,991 — — 40,610 — Corporate debt securities — 35,639 — — 58,948 — U.S. government securities — 8,002 — — 23,826 — Total marketable securities — 47,632 — — 123,384 — Restricted cash (current and non-current) 2,117 — — 4,348 — — Total financial assets $ 69,012 $ 47,632 $ — $ 67,357 $ 123,384 $ —

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities The following table summarizes the unrealized losses and fair value of the Company’s marketable securities as of December 31, 2018 and 2017 (in thousands): December 31, 2018 December 31, 2017 Amortized Cost Unrealized Losses Fair Value Amortized Cost Unrealized Losses Fair Value Marketable securities: Available-for-sale: Commercial paper $ 3,991 $ — $ 3,991 $ 40,610 $ — $ 40,610 Corporate debt securities 35,730 (90 ) 35,640 59,031 (83 ) 58,948 U.S. government securities 8,012 (11 ) 8,001 23,855 (29 ) 23,826 Total marketable securities $ 47,733 $ (101 ) $ 47,632 $ 123,496 $ (112 ) $ 123,384 The following table summarizes the amortized cost and fair value of the Company’s available-for-sale securities as of December 31, 2018 and 2017 , by the contractual maturity date (in thousands): December 31, 2018 December 31, 2017 Amortized Cost Fair Value Amortized Cost Fair Value Due within one year $ 47,733 $ 47,632 $ 83,419 $ 83,374 Due between one and five years — — 40,077 40,010 Total $ 47,733 $ 47,632 $ 123,496 $ 123,384 The Company had 13 and 20 marketable securities in unrealized loss positions as of December 31, 2018 and 2017 , respectively. For individual marketable securities that were in an unrealized loss position as of December 31, 2018 and 2017 , the fair value and gross unrealized loss for these securities aggregated by investment category and length of time in an unrealized loss position are presented in the following tables (in thousands): December 31, 2018 Less Than 12 Months Greater Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate debt securities $ 4,020 $ (3 ) $ 31,620 $ (87 ) $ 35,640 $ (90 ) U.S. government securities — — 8,001 (11 ) 8,001 (11 ) Total $ 4,020 $ (3 ) $ 39,621 $ (98 ) $ 43,641 $ (101 ) December 31, 2017 Less Than 12 Months Greater Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate debt securities $ 58,581 $ (83 ) $ — $ — $ 58,581 $ (83 ) U.S. government securities 23,771 (29 ) — — 23,771 (29 ) Total $ 82,352 $ (112 ) $ — $ — $ 82,352 $ (112 ) Unrealized losses related to these marketable securities are due to interest rate fluctuations as opposed to credit quality. In addition, the Company does not intend to sell and it is not likely that the Company would be required to sell these marketable securities before recovery of their amortized cost basis, which may be at maturity. As a result, there are no other-than-temporary impairments for these marketable securities at December 31, 2018 and 2017 .

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): December 31, 2018 2017 Leasehold improvements $ 19,832 $ 18,631 Computer, equipment and software 14,591 9,835 Furniture and fixtures 4,361 3,577 Demonstration units 3,262 2,528 Total property and equipment 42,046 34,571 Less: accumulated depreciation (17,697 ) (11,311 ) Total property and equipment, net $ 24,349 $ 23,260 Depreciation expense related to property and equipment for the years ended December 31, 2018 , 2017 , and 2016 was approximately $7.5 million , $6.1 million and $3.6 million , respectively.

Acquisitions, Goodwill, and Int

Acquisitions, Goodwill, and Intangible Assets	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions, Goodwill, and Intangible Assets	Acquisitions, Goodwill, and Intangible Assets On November 7, 2018, the Company acquired 100% of the equity interests of SecurityMatters B.V. (“SecurityMatters”), a privately-held entity that develops cybersecurity solutions for the operational technology market, through a share purchase agreement (the “Purchase Agreement”) in exchange for cash consideration (the “Acquisition”). This Acquisition has been accounted for as a business combination and is intended to enhance the Company’s market-leading solutions with deeper visibility into the operational technology network stack. The total consideration transferred as part of the closing of the Acquisition for all of the vested and outstanding equity interests of SecurityMatters consisted of cash payments (adjusted for customary closing adjustments) of $109.3 million (the “Purchase Consideration”). There were no other components of Purchase Consideration other than cash payments. Also, as part of the Purchase Agreement, the Company agreed to pay cash on the closing date of the Acquisition of $6.2 million to be held by a third-party escrow agent and to be released to a continuing employee of SecurityMatters (the “Holdback Amounts”). Such Holdback Amounts were recorded as prepaid expenses and other current assets for the current portion and other assets for the non-current portion, and would be released at future dates following the one and two-year anniversaries of the Acquisition in exchange for future employee services to the Company (assuming the employee provides the required service). In addition, as part of the Purchase Agreement, the Company agreed to pay cash on future dates of $1.2 million to continuing employees of SecurityMatters in exchange for such employees’ equity awards that were unvested as of the closing of the Acquisition. Such cash payments would be paid on future dates that are consistent with the original SecurityMatters equity awards’ vesting terms (assuming the employees provide employee services to the Company through such future dates). Such amounts were not included as Purchase Consideration, but instead will be recognized as post-combination compensation expense over the period the employees provide the required services. Also in connection with the Acquisition, the Company issued RSUs with a grant date fair value of $5.9 million to continuing employees of SecurityMatters in exchange for future employee services to the Company, which vest annually over four years from the grant date. Such amounts are recorded as post-combination compensation expense over the period the employees provide the requisite service. Additionally, the Company recognized $2.7 million of acquisition transaction costs as general and administrative expense in the Company’s consolidated statements of operations during the year ended December 31, 2018. The Purchase Consideration of $109.3 million was preliminary allocated as follows (in thousands): Amount Net tangible assets acquired $ 686 Intangible assets 19,500 Deferred tax liabilities, net (3,486 ) Goodwill 92,648 Total purchase price allocation $ 109,348 The Company is still finalizing the allocation of the purchase price, which may be subject to change as additional information becomes available. The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition (in thousands, except useful life): Intangible Assets Cost Weighted Average Useful Life (in years) Developed technology $ 13,300 7.0 Customer relationships 6,200 5.0 Total intangible assets acquired $ 19,500 6.4 Goodwill represents the excess of the preliminary estimated Purchase Consideration over the preliminary estimates of the fair value of the net tangible and intangible assets acquired and has been allocated to the Company’s one operating segment. Goodwill is primarily attributable to expected post-acquisition synergies from integrating SecurityMatters’ technology into the Company’s security solutions and product offerings and cross-selling opportunities. None of the goodwill recorded is deductible for income tax purposes. The results of operations of SecurityMatters have been included in the Company’s consolidated statements of operations from the acquisition date. Pro forma results of operations for the transaction have not been presented as they were not material to the consolidated statements of operations. Goodwill and Acquired Intangible Assets There was no goodwill related to acquisitions as of December 31, 2017 and in prior periods. The changes in the carrying amount of goodwill during the year ended December 31, 2018 are as follows (in thousands): Amount Balance as of December 31, 2017 $ — Goodwill acquired 92,648 Foreign currency translation adjustments (166 ) Balance as of December 31, 2018 $ 92,482 There were no intangible assets acquired as of December 31, 2017 and in prior periods. Intangible assets subject to amortization realized from acquisitions as of December 31, 2018 are as follows (in thousands): Intangible Assets Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Developed technology $ 13,300 $ (280 ) $ (24 ) $ 12,996 Customer relationships 6,200 (183 ) (11 ) 6,006 $ 19,500 $ (463 ) $ (35 ) $ 19,002 Amortization expense of intangible assets during the year ended December 31, 2018 was $0.5 million , which was recognized in the consolidated statements of operations, within product cost of revenue and sales and marketing expenses. There was no amortization expense of intangible assets during the years ended December 31, 2017 and 2016 . The expected future annual amortization expense of intangible assets as of December 31, 2018 is presented below (in thousands): Year Ending December 31, Amount 2019 $ 3,122 2020 3,122 2021 3,122 2022 3,122 2023 and thereafter 6,514 Total $ 19,002

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company leases office space under various non-cancelable operating leases, which expire through the year ending October 31, 2026. The facility lease agreements include rent holidays and generally provide for rental payments on a graduated basis. The agreements also generally provide for options to renew, which could increase future minimum lease payments if exercised. Lease renewals are not included in the lease term unless the renewals are reasonably assured at lease inception. Rent expense is recognized on a straight-line basis over the lease term. The Company records the difference between cash rent payments and the recognition of rent expense as deferred rent in the consolidated balance sheets. In October 2015, the Company entered into an 11 year lease agreement for corporate office space in San Jose, California. This lease allows for one five -year option to extend the lease term. This option to extend was not assumed in the determination of the lease term as the extension is not reasonably assured at the inception of the lease. This lease contains an incentive for tenant improvements, in addition to a one year rent holiday and escalating rent payments. Consistent with the Company’s other operating leases, rent expense begins on the date legal right to use and control the leased space occurs. This lease contains an incentive for tenant improvements of up to $4.8 million , of which the entire $4.8 million was approved and recognized as a reduction of rent expense on a straight-line basis over the term of the lease. As of December 31, 2018 , the future minimum lease payments by fiscal year under non-cancelable leases are as follows (in thousands): Years Ending December 31, Operating 2019 $ 5,551 2020 4,188 2021 4,307 2022 4,435 2023 4,461 2024 and thereafter 11,933 Total $ 34,875 Rent expense was approximately $6.4 million , $5.6 million , and $5.3 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Contract Manufacturer Commitments As of December 31, 2018 , the Company had contract manufacturer commitments of $8.0 million to purchase components and products from the Company’s third-party contract manufacturer. The contract manufacturer commitments result from the Company’s contractual obligation to order or build inventory in advance of anticipated sales. Purchase Obligations As of December 31, 2018 , the Company had purchase obligations of $6.5 million primarily related to non-cancelable license obligations for software licenses. Litigation The Company is a party to various legal proceedings and claims which arise in the ordinary course of business. The Company records a liability when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. If the Company determines that a loss is possible and a range of the loss can be reasonably estimated, the range of the possible loss is disclosed. On October 24, 2017, Network Security Technologies, LLC, or NST, filed a lawsuit against the Company in the United States District Court for the District of Delaware, alleging that the Company infringe U.S. Patent Nos. 8,234,705 and 9,516,048 and is seeking compensatory damages and attorneys’ fees. The Company believed it had meritorious defenses and intended to vigorously defend the claims against the Company. Subsequently, on February 1, 2018, NST filed a notice of voluntary dismissal without prejudice to dismiss the Company from the complaint. Indemnification The Company enters into indemnification provisions in its standard sales contracts with its customers in which it agrees to defend its channel partners and end-customers against third-party claims asserting infringement of certain intellectual property rights, which may include patents, copyrights, trademarks, or trade secrets, and the responsibility to pay judgments entered on such claims. In addition, we indemnify our officers, directors and certain key employees while they are serving in good faith in their respective capacities. To date, there have been no claims under any indemnification provisions.

Debt Agreements

Debt Agreements	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt Agreements	Debt Agreements On December 22, 2016, the Company amended its amended and restated loan and security agreement, which was originally entered into in May 2009 (the “Amended and Restated 2009 Loan and Security Agreement”) to increase the maximum amount of credit available for borrowing under the revolving line of credit to 80% of qualified accounts receivable up to $40.0 million . Additionally, the Company borrowed $30.0 million under the Amended and Restated 2009 Loan and Security Agreement, which carries a maturity date of December 2020 . The combined outstanding balances of the revolving line of credit and the term loan cannot exceed $40.0 million . The agreement is subject to the Company maintaining an adjusted quick ratio of 1.25 . The agreement requires equal monthly installments of principal of $625,000 and monthly interest payments at a fixed interest rate per annum of 3.25% . Concurrent with the final monthly installment payment on the maturity date in December 2020, the Company is required to pay an additional payment of $825,000 . The amortization expense related to the total discount of the Company’s debt for the years ended December 31, 2018 , 2017 , and 2016 was $0.3 million , $0.3 million , and $0.7 million , respectively. As of December 31, 2018 and 2017 , there was no outstanding balance under the revolving line of credit. The following table presents the carrying value of the Company’s notes payable (in thousands): December 31, 2018 2017 Principal amount of notes payable $ 15,825 $ 23,325 Unamortized debt discount (246 ) (501 ) Net carrying amount of notes payable 15,579 22,824 Less current portion (7,331 ) (7,245 ) Non-current portion of notes payable $ 8,248 $ 15,579 The Amended and Restated 2009 Loan and Security Agreement provides certain financial-related covenants, among others, relating to delivery of audited financial statements to the lenders. The Company was in compliance with respect to all financial-related covenants under its loan agreements as of December 31, 2018 and 2017 . As of December 31, 2018 , the future principal payments on the Company’s notes payable were as follows (in thousands): Years Ending December 31, Amount 2019 $ 7,500 2020 8,325 Total $ 15,825

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Common Stock and Stockholders' Equity	Common Stock and Stockholders’ Equity Redeemable Convertible Preferred Stock Upon the closing of the IPO in October 2017, all shares of the Company's then-outstanding redeemable convertible preferred stock automatically converted into 25,370,616 shares of common stock, including 582,254 additional shares issuable upon conversion of our Series G redeemable convertible preferred stock based on the initial public offering price of $22.00 per share. As of December 31, 2018 and 2017 , there were no shares of redeemable convertible preferred stock issued and outstanding. Redeemable Convertible Preferred Stock Warrants Concurrent with the closing of the IPO, all shares of outstanding redeemable convertible preferred stock warrants were either exercised or converted to common stock warrants. In connection with the conversion of the redeemable convertible preferred stock warrants, the Company re-measured the redeemable convertible preferred stock warrant liability as of the date of conversion and recorded an increase of $0.3 million to other income (expense), net. The Company also reclassified approximately $4.2 million from redeemable convertible preferred stock warrant liability to additional paid-in capital for the estimated fair value of the warrant on the date of conversion. Additionally, the Company recorded $0.1 million to other income (expense), net upon the exercise of redeemable convertible preferred stock warrants. All of the above warrants were exercised as of December 31, 2017. In lieu of payment of the aggregate warrant price, the warrant holders elected a "cashless exercise", whereby a portion of the shares equal to the aggregate warrant price were withheld. The average fair market value at the time of exercise was $25.12 , which resulted in 224,691 shares being issued by the Company. Common Stock Warrants During the year ended December 31, 2018 and 2017 , 83,163 and 149,786 common stock warrants were exercised, respectively. In lieu of payment of the aggregate warrant price, the warrant holders elected a "cashless exercise", whereby a portion of the shares equal to the aggregate warrant price were withheld. The average fair market value per share at the time exercise was $33.36 and $25.28 , which resulted in 66,661 and 111,147 shares being issued by the Company for the warrants exercised during the year ended December 31, 2018 and 2017 , respectively. As of December 31, 2018 , 74 common stock warrants remained outstanding and exercisable. Common Stock As of December 31, 2018 and 2017 , 3.9 million shares and 3.7 million shares of our common stock were reserved for future grants under the 2017 Plan, respectively. As of December 31, 2018 , common stock reserved, on an as-if converted basis for issuance are as follows: December 31, 2018 Reserved for future issuance under equity award plans 3,905,796 Common stock options outstanding 6,012,830 Restricted stock units outstanding 5,709,472 Common stock warrants outstanding 74 Total common stock reserved for issuance 15,628,172 Stock Option and Incentive Plan The 2000 Stock Option and Incentive Plan (the “2000 Plan”) allows for the issuance of stock options and RSUs to employees, non-employees and directors. The Plan provides for incentive stock options to be granted to employees at an exercise price at least equal to 100% of the fair value at the grant date as determined by the Company’s Board of Directors. If a stock-based award is issued to an executive officer that owns more than 10% of the Company’s outstanding common stock, the exercise price will be 110% of the fair market value. The Plan also provides for nonqualified stock options to be issued to employees, non-employees and directors. Options granted generally have a maximum term of 10 years from grant date, allow for early exercise unless otherwise designated by the Board of Directors at the time of grant. Stock options and RSUs generally vest over a four -year period. In October 2017, the Company’s stockholders approved the Company’s 2017 Equity Incentive Plan (the “2017 Plan”). The 2017 Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance stock units, performance shares, and performance awards. A total of 3,800,000 shares of the Company’s common stock are reserved for future issuance pursuant to the 2017 Plan. In addition, shares subject to outstanding awards granted under the 2000 Plan, that are canceled, expire, or otherwise terminate without having been exercised in full and shares previously issued under the 2000 Plan that are forfeited to the Company, tendered to or withheld by the Company for the payment of an award’s exercise price or for tax withholding, or repurchased by the Company, may be added to the 2017 Plan (provided that the maximum number of shares that may be added to the Company’s 2017 Plan pursuant to the provision in this sentence is 12,500,000 shares). The number of shares available for future issuance under the Company’s 2017 Plan also includes automatic annual increases on the first day of the Company’s fiscal year beginning with 2018, equal to the lesser of: 3,800,000 shares; 5% of the outstanding shares of common stock as of the last day of the Company’s immediately preceding fiscal year; or such lower number of shares as determined by the administrator of the 2017 Plan. Prior to the IPO, options granted allowed for early exercise unless otherwise designated by the Board of Directors at the time of grant. The Company had an early exercise liability of approximately $0.4 million and $1.2 million as at December 31, 2018 and 2017 , respectively. Including early exercises, the Company has 43,450,819 and 38,266,450 shares of legally outstanding common stock as at December 31, 2018 and 2017 , respectively. 2017 Employee Stock Purchase Plan In October 2017, the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “ESPP”). The ESPP allows eligible employees to purchase shares of the Company’s common stock through payroll deductions and is intended to qualify under Section 423 of the Internal Revenue Code. A total of 800,000 shares of the Company’s common stock are available for sale under the ESPP. The number of shares available for issuance under the Company’s ESPP will also include an automatic, annual increase on the first day of each fiscal year of the Company beginning in 2018, equal to the lesser of: 800,000 shares; 1% of the total number of shares of the Company’s common stock outstanding on the last day of the Company’s immediately preceding fiscal year; or such lower number of shares as determined by the Administrator. The Company’s ESPP provides for consecutive, six -month offering periods. The offering periods are scheduled to start on the first trading day on or after May 20 and November 20 of each year, except for the first offering period which began following the closing of the IPO, and will end on the first trading day on May 18, 2018. Participants may purchase the Company’s common stock through payroll deductions, of up to a maximum of 15% of their eligible compensation. Participation will end automatically upon termination of employment with the Company. The purchase price of the shares will be 85% of the lower of the fair market value of the Company’s common stock on the first trading day of each offering period or on the exercise date. As of December 31, 2018 , 387,602 shares of common stock were purchased under the ESPP at a weighted-average price of $19.53 per share, resulting in cash proceeds of $7.6 million . The Company selected the Black-Scholes option-pricing model as the method for determining the estimated fair value for the Company’s ESPP. As of December 31, 2018 , total unrecognized compensation cost related to the ESPP was $1.2 million , which will be amortized over a period of 0.4 years. As of December 31, 2018 , 793,617 shares of our common stock were reserved for future grants under the 2017 ESPP Plan. Stock Option Activity The following table summarizes option activity under the Plan and related information (in thousands, except per share and contractual life amounts): Options Outstanding Number Weighted- Weighted- Aggregate Balance—December 31, 2016 9,588 $ 10.13 8.0 $ 61,865 Options granted 549 $ 20.05 Options forfeited (517 ) $ 14.58 Options exercised (306 ) $ 5.32 Balance—December 31, 2017 9,314 $ 10.63 7.2 $ 198,012 Options granted 44 $ 30.81 Options exercised (2,979 ) $ 8.13 Options forfeited (366 ) $ 16.59 Balance—December 31, 2018 6,013 $ 11.65 6.4 $ 86,624 Options vested and exercisable—December 31, 2018 4,525 $ 10.26 6.1 $ 71,237 The weighted-average fair value per share for all options granted was $14.95 , $9.79 , and $8.24 for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The aggregate intrinsic value of employee options exercised was $71.9 million , $4.4 million , and $6.0 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The aggregate intrinsic value represents the difference between the Company’s estimated fair value of its common stock and the exercise price of the outstanding options. As of December 31, 2018 , total unrecognized compensation cost related to unvested options was $11.5 million , net of estimated forfeitures, which was expected to be amortized over a weighted-average period of approximately 1.4 years. Restricted Stock Unit Activity The following table summarizes RSU activity under the Plan and related information (in thousands, except per share and contractual life amounts): RSUs Outstanding Number Weighted- Weighted- Aggregate Balance—December 31, 2016 1,899 $ 14.83 1.7 $ 30,720 RSUs granted 2,355 $ 25.20 RSUs forfeited (38 ) $ 20.44 Balance—December 31, 2017 4,216 $ 20.57 1.7 $ 134,448 RSUs granted 3,354 $ 30.94 RSUs released (1,607 ) $ 14.78 RSUs forfeited (254 ) $ 26.80 Balance—December 31, 2018 5,709 $ 28.01 1.8 $ 148,389 As of December 31, 2018 , total unrecognized compensation cost related to unvested RSUs was $124.3 million , which was expected to be amortized over a weighted-average period of approximately 2.9 years. On April 25, 2018 , an aggregate of 892,996 shares underlying the RSUs held by the Company’s directors and then-current employees vested and settled. Substantially all of the RSUs vested upon the satisfaction of both a service-based vesting condition and a performance-based vesting condition. The performance-based vesting condition became probable on October 26, 2017, which was the effective date of the registration statement for the Company’s IPO, and was satisfied on the Settlement Date. For the Company’s executive officers, 227,044 of the vested shares were withheld to satisfy the tax obligations due for the RSUs that settled on the Settlement Date. The closing price of the Company’s common stock on the Settlement Date was $32.76 per share, resulting in tax obligations of $7.4 million in the aggregate. For RSUs held by the Company’s non-executive employees, subject to tax withholding obligations, 55,904 shares were sold on the Settlement Date to cover tax obligations of $1.8 million in the aggregate. Stock-Based Compensation Stock-based compensation expense for both employees and non-employees included in the accompanying consolidated statements of operations is as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenue: Product $ 253 $ 103 $ 30 Maintenance and professional services 3,015 2,291 1,123 Research and development 10,161 6,213 2,311 Sales and marketing 24,999 14,451 8,084 General and administrative 15,069 19,538 5,286 Total $ 53,497 $ 42,596 $ 16,834 Prior to the IPO, certain employees and advisors have been granted stock options with vesting subject to a future liquidity event. Upon the liquidity event, these stock options became fully exercisable, and all of the associated stock-based compensation expense was recognized. Prior to the IPO, the Company granted RSUs to participants that included both a service-based vesting condition and a performance-based vesting condition. The awards generally vest annually over four years, but were subject to a liquidity event prior to any of the shares vesting. Further, in the case of a liquidity event that is an IPO, participants must provide services through 181 days post-IPO before any of the “accrued” time-based shares can vest. Since these options and awards were tied to a liquidity event, and in accordance with the accounting guidance, the liquidity event was not deemed probable until occurrence, the Company did not record any expense for these grants until the completion of the Company’s IPO. Upon the closing of the Company’s IPO on October 31, 2017 , the Company recognized stock-based compensation expense of approximately $21.2 million related to these performance-based stock options and RSUs. During the year ended December 31, 2017 , the Company amended its Chief Executive Officer's (“CEO”) employment agreement to provide for accelerated vesting of all of the CEO’s equity awards upon his termination due to death or disability while executing his employment duties. As a result of this modification to the CEO’s vesting terms, the Company expects to record an incremental $7.6 million in stock-based compensation expense over the service period beginning in October 2017 (following the completion of the Company’s IPO), $6.5 million of which was recorded by the Company during the three months ended December 31, 2017 . The remaining $1.1 million was recorded by the Company in the year ended December 31, 2018 . During the year ended December 31, 2016 , the Company entered into separation agreements with three employees that resulted in the acceleration of the vesting for stock options. As a result of the modification, the Company recorded stock-based compensation expense of $2.3 million to sales and marketing expense. Determining the Fair Value of Stock Options The fair value of stock option awards granted to employees and to be purchased under ESPP are estimated using the Black-Scholes option-pricing model. The key assumptions within the model are described as follows: Fair Value of Common Stock Prior to the Company’s IPO, the Company’s Board of Directors considered numerous objective and subjective factors to determine the fair value of its common stock. These factors included, but were not limited to (i) contemporaneous third-party valuations of common stock; (ii) the rights and preferences of redeemable convertible preferred stock relative to common stock; (iii) the lack of marketability of common stock; (iv) developments in the business; and (v) the likelihood of achieving a liquidity event, such as an initial public offering or sale of the Company, given prevailing market conditions. Subsequent to its IPO, the Company uses the market closing price for its common stock as reported on the NASDAQ Global Select Market on the date of grant. Risk-Free Interest Rate The risk-free interest rate is based on the rate for a U.S. Treasury zero-coupon issue with a term that approximates the expected life of the option on the date of grant. Expected Term The expected term represents the period that stock-based awards are expected to be outstanding. The expected term is calculated using the simplified method for stock options issued at-the-money. For stock options that have been issued out-of-the-money, the expected term was determined by calculating the midpoint of the simplified method and the contractual life of the option of 10 years , as neither historical experience nor other relevant data was available to estimate the future exercise behavior of out-of-the money stock options. The Company uses the remaining contractual life as the expected term for non-employee awards. Volatility The expected volatility is based on the average historic price volatility for the Company’s publicly traded industry peers based on daily price observations over a period equivalent to the expected term of stock-based awards. The historical volatility data of a peer group is used as there is insufficient trading history for the Company’s common stock. Dividend Yield The Company has never paid dividends and at present, does not expect to pay dividends in the foreseeable future. The assumptions used to determine the grant date fair value of employee stock options and ESPP purchase rights for the periods presented are as follows: Year Ended December 31, 2018 2017 2016 Employee Stock Options Fair value of common stock $29.92 – $30.97 $16.73 – $31.16 $15.78 – $21.56 Risk-free interest rate 2.4% – 2.8% 1.9% – 2.2% 1.2% – 2.1% Expected term (in years) 6.1 6.0 – 6.1 6.0 – 8.1 Volatility 48% 46% – 49% 47% – 51% Dividend yield —% —% —% Employee Stock Purchase Plan Fair value of common stock $24.65 – $31.00 $25.12 $— Risk-free interest rate 2.14% – 2.52% 1.4% —% Expected term (in years) 0.5 0.5 0 Volatility 30% – 43% 30% —% Dividend yield —% —% —%

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of loss before provision for income taxes are as follows (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Domestic $ (85,252 ) $ (82,292 ) $ (66,810 ) Foreign 13,361 3,411 2,581 Total $ (71,891 ) $ (78,881 ) $ (64,229 ) * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. The provision for income taxes consists of the following (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Current Federal $ 1 $ 17 $ 4 State 56 50 66 Foreign 3,263 1,788 1,273 Total current 3,320 1,855 1,343 Deferred Foreign (375 ) (16 ) (93 ) Total deferred $ (375 ) $ (16 ) $ (93 ) Total $ 2,945 $ 1,839 $ 1,250 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and tax effects of net operating loss and credit carryforwards. Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): December 31, 2018 2017 *As Adjusted Deferred tax assets: Federal and state net operating losses $ 59,803 $ 43,410 Research/other credits 2,913 1,060 Non-deductible and accrued expenses 4,756 4,485 Deferred revenue 14,040 3,725 Property and equipment 506 — Stock-based compensation 10,323 9,507 Other 1,024 610 Gross deferred tax assets 93,365 62,797 Valuation allowance (83,376 ) (54,233 ) Net deferred tax assets 9,989 8,564 Deferred tax liabilities: Acquired intangible assets (4,117 ) — Property and equipment — (13 ) Deferred commission (8,691 ) (8,375 ) Others (116 ) — Net deferred tax liabilities (12,924 ) (8,388 ) Total $ (2,935 ) $ 176 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. Reconciliation of the statutory federal income tax to the Company’s effective tax (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Tax at federal statutory rate $ (15,097 ) $ (30,385 ) $ (21,838 ) State, net of federal benefit 61 60 61 Stock-based compensation (6,215 ) 4,097 3,225 Non-deductible warrant expenses — 272 (365 ) Tax Reform federal rate change — 36,460 — Change in valuation allowance 23,929 (10,512 ) 19,225 Other 267 1,847 942 Total $ 2,945 $ 1,839 $ 1,250 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. On December 22, 2017, the President of the United States signed the Tax Act into law. The legislation significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a mandatory repatriation tax on earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. As a result of the change in the U.S. tax rate, the Company’s deferred tax assets and liabilities were remeasured, resulting in an unfavorable change of $36.5 million , which was offset by a corresponding change in the valuation allowance in its income tax expense for the year ended December 31, 2017. The Tax Act also provided for a one-time deemed mandatory repatriation of post-1986 undistributed foreign subsidiary earnings and profits ("E&P") through the year ended December 31, 2017. The Company had a provisional $6.9 million of undistributed foreign E&P subject to repatriation, however, no tax liability was recognized as of December 31, 2017 because the deemed repatriation is expected to be fully offset by net operating losses. The effects of the Tax Act may be adjusted within a one-year measurement period from the enactment date for items that were previously reported as provisional, or where a provisional estimate could not be made. In the fourth quarter of 2018, the Company finalized its provisional estimate of undistributed E&P that was subject to repatriation and recorded an adjustment of $5.9 million . This change to the provisional estimate originally recorded in the financial statement period ending December 31, 2017, did not have an impact on the Company’s income statement or balance sheet as the income inclusion was fully offset by net operating loss deferred tax assets, which are subject to a full valuation allowance. The Tax Act provides for new international rules for Global Intangible Low-Tax Income (“GILTI”), Base Erosion Anti-Abuse Tax (“BEAT”), and Foreign Derived Intangible Income (“FDII”), which are effective for tax years beginning after December 31, 2017. For the year ended December 31, 2018 , BEAT and FDII were not applicable to the Company and there was no income inclusion associated with GILTI. A valuation allowance has been provided to reduce the deferred tax asset to an amount management believes is more likely than not to be realized. The valuation allowance increased by $29.1 million and decreased by $0.9 million for the years ended December 31, 2018 and 2017 , respectively. As of December 31, 2018 , the Company had net operating loss carryforwards for federal income tax purposes of approximately $243.8 million , which begin to expire in 2021 if not utilized. The Company also has California net operating loss carryforwards of approximately $29.3 million , which begin to expire in 2028 if not utilized. The Company also has other state net operating loss carryforwards of approximately $102.9 million , which begin to expire in 2019 if not utilized. The Company has federal, California, and Texas research and development credit carryforwards of $1.8 million , $1.2 million , and $0.1 million respectively. The federal research and development credits will begin to expire in 2035 , if not utilized. California research and development credits can be carried forward indefinitely. Utilization of the Company’s net operating loss carryforwards may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Such a limitation could result in the expiration of the net operating loss carryforwards before utilization. The Company performed an ownership change analysis from inception to the balance sheet date of December 31, 2018 and $2.8 million of net operating loss carryforwards were written off due to the limitation. The Company provides U.S. income taxes on the earnings of foreign subsidiaries, unless the subsidiaries’ earnings are considered indefinitely reinvested outside the United States. As of December 31, 2018 , there is no U.S. income tax impact of undistributed earnings from its foreign subsidiaries. Any earnings if distributed by the foreign subsidiary would not result in any material liability since they would be offset by net operating losses. Uncertain Tax Positions For benefits to be realized, a tax position must be more likely than not to be sustained upon examination. The amount recognized is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement. As a result of the implementation of these provisions, the Company did not recognize any adjustments to retained earnings for uncertain tax positions. A reconciliation of the gross unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2018 2017 2016 Unrecognized tax benefits at the beginning of the period $ 1,727 $ 1,050 $ 254 Additions for tax positions taken in prior years 104 248 185 Additions for tax positions taken in current year 195 845 611 Reductions for tax positions taken in prior years (759 ) — — Settlements with taxing authorities — (416 ) — Unrecognized tax benefits at the end of the period $ 1,267 $ 1,727 $ 1,050 It is the Company’s policy to recognize interest and penalties related to income tax matters in income tax expense. During the years ended December 31, 2018 , 2017 , and 2016 , the Company did not recognize any significant accrued interest and penalties related to uncertain tax positions. The Company is subject to federal income tax as well as income tax in multiple state and foreign jurisdictions. Due to the Company’s net operating loss carryforwards, all tax years since inception remain subject to examination for United States federal tax returns, and fiscal year 2016 remains subject to examination for Israel. There are tax years which remain subject to examination in various other jurisdictions that are not material to the Company’s financial statements. When considering the outcomes and the timing of tax examinations, the Company is unable to determine the amount of uncertain tax positions that will significantly change within the next 12 months. On April 22, 2018, the Supreme Court of Israel ruled to uphold a decision for stock based compensation to be included within Israeli entities’ transfer pricing reimbursement arrangements. As a result, the Company changed its tax return filing position for fiscal year 2017 and the uncertain tax position associated with this liability decreased by approximately $0.4 million , there was a corresponding increase to current income tax payable included in accrued expenses.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss per Share Net loss per share of common stock is computed using the two-class method required for participating securities based on their participation rights. All series of redeemable convertible preferred stock are participating securities as the holders are entitled to participate in common stock dividends with common stock on an as converted basis. Basic net loss per share is computed by dividing net loss attributable to common stockholders by basic weighted-average shares outstanding during the period. All participating securities are excluded from basic weighted-average shares outstanding. In computing diluted net loss attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing net loss attributable to common stockholders by diluted weighted-average shares outstanding, including potentially dilutive securities, unless anti-dilutive. The following table presents the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share amounts): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Net loss $ (74,836 ) $ (80,720 ) $ (65,479 ) Deemed dividend on the conversion of Series G redeemable convertible preferred stock — 12,810 — Net loss attributable to common stockholders $ (74,836 ) $ (93,530 ) $ (65,479 ) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 40,980 11,405 5,609 Net loss per share attributable to common stockholders, basic and diluted $ (1.83 ) $ (8.20 ) $ (11.67 ) * Adjusted to include the impact of ASC 606. Refer to Note 2 for more details on the impact of the adoption of this standard. The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because their inclusion would reduce the net loss per share (in thousands). Year Ended December 31, 2018 2017 2016 Options to purchase common stock 6,013 9,314 9,588 Unvested early exercised common shares 47 146 330 Unvested restricted stock units 5,709 4,216 1,899 Shares estimated under ESPP 233 221 — Warrants to purchase common stock — 83 233 Redeemable convertible preferred stock — — 24,788 Warrants to purchase redeemable convertible preferred stock — — 293

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Israeli labor laws and agreements require the Company’s Israeli subsidiary to make severance payments to retired or dismissed Israeli employees, as well as to employees leaving employment under certain other circumstances. The Company’s severance obligations to employees are measured based upon length of service and latest monthly salary amount. The Company has recorded a non-current liability of $2.5 million and $2.6 million as of December 31, 2018 and 2017 , respectively, for the estimated amount of accrued severance benefits in other liabilities in the accompanying consolidated balance sheet. The current portion of the liability was immaterial as of December 31, 2018 and 2017 . The deposits are held with a severance pay fund in order to fund the obligation, which totaled $2.0 million and $2.1 million as of December 31, 2018 and 2017 , respectively, and are recorded as a non-current asset in other assets in the accompanying consolidated balance sheets. The current portion of the deposit was immaterial as of December 31, 2018 and 2017. A 401(k) tax-deferred savings plan (the “401(k) Plan”) was established that covers substantially all of the Company’s U.S. employees. The 401(k) plan permits participants to make contributions by salary deduction pursuant to Section 401(k) of the Internal Revenue Code. The Company is responsible for administrative costs of the 401(k) Plan. The Company provided for a match of 50% of the first 6% of an eligible employee’s compensation contributed, up to a maximum matching dollar amount of $2,000 for a year. Matching contributions under the 401(k) Plan are 100% vested when made. Pre-tax 401(k) and post-tax Roth 401(k) contributions are allocated to each participant’s individual account and are then invested in selected investment alternatives according to the participants’ directions. The 401(k) Plan is intended to qualify under Sections 401(a) and 501(a) of the Code. As a tax-qualified retirement plan, pre-tax contributions are not taxable to the employees until distributed from the 401(k) Plan, and post-tax contributions are not exempt from taxes at the time of contribution but the earnings accumulated are tax-free and are not taxable upon distribution. All contributions are deductible by the Company when made. The Company’s contributions to the 401(k) Plan were $1.3 million , $1.1 million , and $1.0 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s business is conducted globally. The Company’s chief operating decision maker is the Chief Executive Officer who reviews financial information presented on a consolidated basis accompanied by information about revenue by geographic region for purposes of allocating resources and evaluating financial performance. There is one business activity and there are no segment managers who are held accountable for operations, operating results, and plans for levels, components, or types of products or services below the consolidated unit level. Accordingly, there is a single reporting segment and operating unit structure. Revenue by geographic area is attributed based on the billing address of the customer and is as follows (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Revenue: Americas United States $ 215,322 $ 165,140 $ 132,216 Other Americas 6,883 6,122 5,966 Total Americas 222,205 171,262 138,182 Europe, Middle East, and Africa (“EMEA”) 52,214 36,664 19,381 Asia Pacific and Japan (“APJ”) 23,232 16,478 9,983 Total revenue $ 297,651 $ 224,404 $ 167,546 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. Long-lived assets, net by geographic area are attributed based on legal entity structure and are as follows (in thousands): December 31, 2018 2017 Long-lived assets, net: United States $ 18,570 $ 18,989 Israel 5,057 3,453 Other 722 818 Total long-lived assets, net $ 24,349 $ 23,260

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) The following tables set forth selected unaudited quarterly consolidated statements of operations data for each of the eight quarters in the period ended December 31, 2018 . The information for each of these quarters has been prepared on the same basis as the audited annual consolidated financial statements included elsewhere in this report and, in the opinion of management, includes all adjustments, which consist only of normal recurring adjustments, necessary for the fair presentation of the results of operations for these periods in accordance with GAAP. This data should be read in conjunction with our audited consolidated financial statements and related notes included elsewhere in this report. These quarterly operating results are not necessarily indicative of our operating results for a full year or any future period. Three Months Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 December 31, 2017 (1) September 30, 2017 June 30, 2017 March 31, 2017 (In thousands, except per share amounts) Revenue: Product $ 47,482 $ 51,082 $ 34,323 $ 29,780 $ 34,994 $ 43,204 $ 26,842 $ 20,308 Maintenance and professional services 37,250 34,546 33,271 29,917 27,913 26,136 23,139 21,868 Total revenue 84,732 85,628 67,594 59,697 62,907 69,340 49,981 42,176 Cost of revenue: Product (2) 6,852 8,947 4,919 7,136 6,964 7,240 5,545 4,092 Maintenance and professional services (2) 10,634 10,250 9,794 9,350 9,109 8,688 8,543 8,431 Total cost of revenue 17,486 19,197 14,713 16,486 16,073 15,928 14,088 12,523 Total gross profit 67,246 66,431 52,881 43,211 46,834 53,412 35,893 29,653 Operating expenses: Research and development (2) 17,161 15,062 14,803 14,687 14,801 10,985 10,702 10,947 Sales and marketing (2) 50,464 46,098 45,039 42,279 41,769 34,028 33,556 35,045 General and administrative (2) 16,849 13,880 13,260 13,732 23,941 9,148 8,902 9,215 Total operating expenses 84,474 75,040 73,102 70,698 80,511 54,161 53,160 55,207 Loss from operations (17,228 ) (8,609 ) (20,221 ) (27,487 ) (33,677 ) (749 ) (17,267 ) (25,554 ) Interest expense (237 ) (208 ) (225 ) (243 ) (270 ) (290 ) (318 ) (345 ) Other income (expense), net 527 865 513 662 382 160 (82 ) (144 ) Revaluation of warrant liabilities — — — — (385 ) — 50 (392 ) Loss before income taxes (16,938 ) (7,952 ) (19,933 ) (27,068 ) (33,950 ) (879 ) (17,617 ) (26,435 ) Income tax provision 1,010 334 473 1,128 618 412 174 635 Net loss $ (17,948 ) $ (8,286 ) $ (20,406 ) $ (28,196 ) $ (34,568 ) $ (1,291 ) $ (17,791 ) $ (27,070 ) Deemed dividend on the conversion of Series G redeemable convertible preferred stock — — — — 12,810 — — — Net loss attributable to common stockholders $ (17,948 ) $ (8,286 ) $ (20,406 ) $ (28,196 ) $ (47,378 ) $ (1,291 ) $ (17,791 ) $ (27,070 ) Net loss per share attributable to common stockholders, basic and diluted $ (0.42 ) $ (0.20 ) $ (0.50 ) $ (0.74 ) $ (1.73 ) $ (0.21 ) $ (2.95 ) $ (4.57 ) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 43,016 42,064 40,457 38,313 27,349 6,140 6,031 5,924 _____________________ (1) Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. (2) Includes stock-based compensation expense as follows: Three Months Ended December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31, (In thousands) Cost of revenue: Product $ 79 $ 67 $ 54 $ 53 $ 43 $ 19 $ 20 $ 21 Maintenance and professional services 804 715 723 773 1,361 286 319 325 Research and development 2,688 2,613 2,513 2,347 4,170 630 613 800 Sales and marketing 6,804 6,165 5,850 6,180 9,583 1,602 1,609 1,657 General and administrative 3,578 3,458 3,796 4,237 15,379 1,372 1,372 1,415 Total $ 13,953 $ 13,018 $ 12,936 $ 13,590 $ 30,536 $ 3,909 $ 3,933 $ 4,218

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The Company’s consolidated financial statements include the results of Forescout Technologies, Inc. and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	The preparation of financial statements in conformity with GAAP requires management to make use of estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. These estimates form the basis of judgments made about carrying values of assets and liabilities, which are not readily apparent from other sources. The areas where management has made estimates requiring judgment include, but are not limited to, the best estimate of selling prices for products and related support, the period over which deferred sales commissions are amortized to expense, sales return reserve, accruals, stock-based compensation including the fair value of common stock, redeemable convertible preferred stock warrant liabilities, provision for income taxes, including related reserves, identified intangibles and goodwill, and purchase price allocation of an acquired business. Actual results could differ materially from those estimates.
Segment information	The chief operating decision maker (“CODM”) is the Chief Executive Officer who reviews financial information presented on a consolidated basis. The Company has one business activity and there are no segment managers who are held accountable by the CODM for operations, operating results and planning for levels or components below the consolidated level. The Company operates in one segment.
Concentrations	Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, accounts receivable, and restricted cash. The Company maintains all of its cash and cash equivalents in interest-bearing bank accounts and money market accounts. Management believes that the financial institutions that hold the Company’s cash and cash equivalents are financially sound and exposed to minimal credit risk. Deposits held with banks generally exceed the amount of insurance provided on such deposits. Accounts receivable are primarily derived from the Company’s customers, including distributors and resellers representing various geographical locations. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable, and, if necessary, an allowance for doubtful accounts is maintained for estimated potential credit losses.
Foreign Currency	The Company’s functional currency is the U.S. dollar for the majority of its foreign operations except for SecurityMatters, B.V. (“SecurityMatters”) whose functional currency is the Euro. Transactions denominated in currencies other than the applicable functional currency are converted to the functional currency at the exchange rate on the transaction date. At period end, monetary assets and liabilities are remeasured using the current exchange rate at the balance sheet date. Non-monetary assets and liabilities and capital accounts are remeasured using historical exchange rates. Revenue and expenses have been remeasured using the average exchange rates in effect during each period. Resulting foreign currency remeasurement gains and losses are recorded in other income (expense), net on the consolidated statements of operations. Where a non-U.S. currency is the functional currency, translation from that functional currency to the U.S. dollar is performed for balance sheet accounts using exchange rates in effect at the balance sheet date and for revenue and expense accounts using an average exchange rate for the period. Resulting translation adjustments are reported as a component of accumulated other comprehensive loss on the consolidated balance sheets.
Cash and Cash Equivalents	The Company considers all highly liquid investments held at financial institutions with original maturities of three months or less at date of purchase to be cash equivalents. Cash and cash equivalents are stated at cost, which approximates fair value.
Marketable Securities	The Company’s marketable securities consist primarily of commercial paper, corporate debt securities, and U.S. government agency securities. The Company’s marketable securities are classified as available-for-sale and are reported at fair value. The Company determines any realized gains or losses on the sale of available-for-sale securities on a specific identification method, and such gains and losses are recorded as a component of other income (expense), net on the consolidated statements of operations. Unrealized gains and losses of the available-for-sale securities are excluded from earnings and reported as a component of accumulated other comprehensive loss. The Company has classified and accounted for its marketable securities as available-for-sale. After consideration of the Company’s risk versus reward objectives, as well as the Company’s liquidity requirements, the Company may sell these securities prior to their stated maturities. As the Company views these securities as available to support current operations, the Company classifies highly liquid securities with maturities beyond 12 months as current assets under the caption marketable securities in the consolidated balance sheets. Marketable securities are considered impaired when a decline in fair value is judged to be other-than-temporary. The Company considers available quantitative and qualitative evidence in evaluating potential impairment of the marketable securities on a quarterly basis. If the cost of an individual investment exceeds its fair value, the Company evaluates, among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investment. Once a decline in fair value is determined to be other-than-temporary, the Company will record an impairment charge and establish a new cost basis in the investment.
Accounts Receivable	Trade accounts receivable are recorded at the invoiced amount, net of allowances for doubtful accounts. The Company assesses its trade accounts receivable for doubtful accounts based on the collectability of accounts. Management regularly reviews the adequacy of the allowance for doubtful accounts by considering the age of each outstanding invoice, each customer’s expected ability to pay, and the collection history with each customer, to determine whether a specific allowance is appropriate. Accounts receivable that are deemed uncollectible are charged against the allowance for doubtful accounts.
Inventory	Inventory primarily consists of finished goods hardware appliances and production materials. Inventory is stated at the lower of cost or market determined using the specific identification method. Inventory that is obsolete or in excess of forecasted demand is written down to its estimated realizable value. Inventory write-downs, once established, are not reversed as they establish a new cost basis for the inventory.
Property and Equipment	Property and equipment is stated at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years. Demonstration units are not resold after use and are depreciated over the estimated useful life of three years or less. Leasehold improvements are depreciated over the shorter of the estimated useful lives of the improvements or the remaining lease term.
Business Combinations	The Company accounts for acquisitions using the acquisition method of accounting for business combinations . When the Company acquires a business, the purchase price is allocated to the net tangible and identifiable intangible assets acquired based on their estimated fair values. Any residual purchase price is recorded as goodwill. The allocation of the purchase price requires management to make significant estimates in determining the fair values of assets acquired and liabilities assumed, especially with respect to intangible assets. These estimates can include, but are not limited to, the cash flows that an asset is expected to generate in the future, the appropriate weighted-average cost of capital, and the cost savings expected to be derived from acquiring an asset. These estimates are inherently uncertain and unpredictable. During the measurement period, which may be up to one year from the acquisition date, adjustments to the fair value of these tangible and intangible assets acquired and liabilities assumed may be recorded, with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations.
Goodwill	The excess of the purchase price over the estimated fair value of net assets of businesses acquired in a business combination is recognized as goodwill. Goodwill is tested for impairment annually on October 1st or more frequently if certain indicators are present.
Other Long-Lived Assets	Management reviews long-lived assets, such as property and equipment and finite-lived intangible assets subject to amortization, for events and changes in circumstances that may indicate that carrying amounts of long-lived assets may not be recoverable. When such events or circumstances occur, recoverability of these assets is measured by a comparison of the carrying value to the future undiscounted cash flows the assets are expected to generate. If long-lived assets are considered to be impaired, the impairment to be recognized would equal the amount by which the carrying value of the asset exceeds its fair market value.
Deferred Offering Costs	Deferred offering costs consisted of fees and expenses incurred in connection with the sale of the Company’s common stock in its IPO and Offering, including direct incremental legal, consulting, accounting fees, and other offering-related costs. Upon completion of the Company’s IPO or Offering, these deferred offering costs were reclassified to stockholders’ equity and offset against the proceeds of the offerings.
Product Warranty	The Company provides a standard 90 day warranty on its hardware and software products. The Company also offers its customers post-contract support (“PCS”), which includes a warranty of between one to five -years on hardware. The Company will also provide its customers software releases or updates during the PCS term. The Company accrues for estimated standard warranty costs for those customers that do not purchase PCS at the time of product shipment. These potential warranty claims are accrued as a component of product cost of revenue based on historical experience and other data, which is reviewed periodically for adequacy. Warranty costs associated with PCS are expensed as incurred. To date, the Company has not incurred nor accrued any significant costs associated with product warranty.
Contract Manufacturer Liabilities	Manufacturing, repair, and supply chain management operations are outsourced to a third-party contract manufacturer. These costs are a significant portion of product cost of revenue. Although the Company is contractually obligated to purchase manufactured products, the Company generally does not own the manufactured products as product title transfers from the contract manufacturer to the Company and immediately to the customer upon shipment. The contract manufacturer assembles the Company’s products using design specifications, quality assurance programs, and standards that the Company establishes. Components are procured and assembled based on the Company’s demand forecasts. These forecasts represent management’s best estimates of future demand for the products based upon historical trends and analysis from sales and operations functions as adjusted for overall market conditions. The Company accrues for costs for contractual manufacturing commitments in excess of its forecasted demand, including costs incurred for excess components or for the carrying costs incurred by the contract manufacturer. To date, the Company has not accrued any significant contract manufacturer liabilities.
Redeemable Convertible Preferred and Common Stock Warrant Liabilities	Upon completion of the Company's IPO in October 2017, there were no freestanding warrants to purchase shares of convertible preferred stock. As such, no preferred stock warrant liability remained outstanding after the IPO. Before the Company's IPO, freestanding warrants related to shares that are redeemable or contingently redeemable were classified as a liability in the Company’s consolidated balance sheet. The convertible preferred stock warrants were subject to re-measurement at each balance sheet date, and any change in fair value was recognized in the consolidated statements of operations. The Company adjusted the redeemable convertible preferred stock warrant liability to the estimated fair value of the warrants until either the exercise or the completion of the Company’s IPO, at which time the redeemable convertible preferred stock issuable upon exercise of the warrants became warrants to purchase common stock and the related liability was reclassified to additional paid-in capital in stockholders' equity.
Severance Pay Deposits and Accrued Severance Pay Liability	The Company records a severance pay asset and liability on its consolidated balance sheets related to its employees located in Israel. Under Israeli law and labor agreements, the Company is required to make severance and pension payments to retired or dismissed employees and to employees leaving employment in certain other circumstances. Liabilities for severance pay are calculated pursuant to Israeli severance pay law using the most recent monthly salary for the employees, multiplied by the number of years of employment, and are included in accrued expenses and other liabilities in the Company’s consolidated balance sheets for the current and non-current portions, respectively. The Company’s liability at each respective balance sheet date for its Israeli employees is fully accrued in the accompanying consolidated financial statements. The severance liability is funded through monthly deposits to the employee’s pension and management insurance carriers. The fair value of this deposit is recorded in prepaid expenses and other current assets, and other assets in the Company’s consolidated balance sheets for the current and non-current portions, respectively.
Revenue Recognition	Effective January 1, 2018, the Company adopted Topic 606 using the full retrospective method. The Company adopted Topic 606 effective January 1, 2018 using the full retrospective method, which required the Company to restate each prior reporting period presented to be consistent with the standard. The most significant impact to revenue recognized related to the accounting for the sale of Extended Modules and to a lesser extent the sale of CounterACT. Under previously reported GAAP, the Company established Vendor Specific Objective Evidence (“VSOE”) for professional services, and support and maintenance on Software Products, except Extended Modules, beginning January 1, 2016. Under previously reported GAAP, Software Product related revenue was recognized ratably over the contractually committed support and maintenance period when VSOE was not established. Professional services sold in conjunction with such Software Products were also recognized ratably over the contractually committed support and maintenance period. Under ASC 606, the requirement to have VSOE for undelivered elements is eliminated and the Company now generally recognizes Software Product revenue at the time of delivery, and any related professional services revenue as services are provided to the customers. Further, revenue allocated from future deliverables (primarily support and maintenance) to Hardware Products is now recognized upon delivery under ASC 606 when the standalone selling price is different from the contract price. Under previously reported GAAP, such differences were recognized over the contractual support and maintenance period. Additionally, Topic 606 requires the capitalization of costs to obtain a contract, primarily sales commissions, and the amortization of these costs over the contract period or estimated customer life, which resulted in the recognition of a deferred charge on the Company’s consolidated balance sheets. Under previously reported GAAP, the Company expensed all sales commissions and other incremental costs to acquire contracts as they were incurred. Revenue from Contracts with Customers Contract Assets and Contract Liabilities A contract asset is a right to consideration in exchange for products or services that the Company has transferred to a customer when that right is conditional and is not just subject to the passage of time. The Company has no material contract assets. A receivable will be recorded on the consolidated balance sheets when the Company has unconditional rights to consideration. A contract liability is an obligation to transfer products or services for which the Company has received consideration, or for which an amount of consideration is due from the customer. Contract liabilities include customer deposits under non-cancelable contracts and current and non-current deferred revenue balances. The Company’s contract balances are reported in a net contract asset or liability position on a contract-by-contract basis at the end of each reporting period. Performance Obligations The majority of the contracted but not invoiced performance obligations are subject to cancellation terms. Revenue allocated to remaining performance obligations represent contracted revenue that has not yet been recognized (“contracted not recognized”), which includes deferred revenue, certain customer deposits, and non-cancelable amounts that will be invoiced and recognized as revenue in future periods and excludes performance obligations that are subject to cancellation terms. Contracted not recognized revenue was $177.6 million as of December 31, 2018 , of which the Company expects to recognize approximately 60% of the revenue over the next 12 months and the remainder thereafter. Practical Expedients The Company does not disclose the value of consideration associated with unsatisfied or partially unsatisfied performance obligations for contracts for which the Company recognizes revenue at the amount to which it will have the right to invoice for services performed. The Company also reflects the aggregate effect of all modifications to a contract that occurred before the earliest period presented in the current period’s financial statements instead of retrospectively restating contracts for all previous contract modifications. Disaggregation of Revenue The Company generates revenue from the sale of Software Products, Hardware Products, support and maintenance, and professional services. All revenue recognized in the consolidated statement of operations is considered to be revenue from contracts with customers. Revenue Recognition The Company derives its revenue from sales of products and associated maintenance and professional services. The Company offers its solution across two product groups: (i) products for visibility and control capabilities, and (ii) products for orchestration capabilities and across two product types: (i) software products, and (ii) hardware products. Following the adoption of Topic 606, the Company determines revenue recognition through the following steps, which are described in more detail below: • Identification of the contract, or contracts, with a customer — A contract with a customer exists when (i) the Company enters into an enforceable contract with a customer that defines each party’s rights regarding the goods or services to be transferred and identifies the payment terms related to these goods or services, (ii) the contract has commercial substance, and (iii) the Company determines that collection of substantially all consideration for goods or services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s ability and intention to pay, which is based on a variety of factors, including the customer’s historical payment experience or, in the case of a new customer, published credit and financial information pertaining to the customer. The Company’s payment terms typically range between 30 to 90 days. • Identification of the performance obligation(s) in the contract — Performance obligations promised in a contract are identified based on the goods or services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the goods or services either on their own or together with other resources that are readily available from third parties or from the Company, and are distinct in the context of the contract, whereby the transfer of the goods or services is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised goods or services, the Company applies judgment to determine whether promised goods or services are capable of being distinct, and are distinct in the context of the contract. If these criteria are not met, the promised goods or services are accounted for as a combined performance obligation. • Determination of the transaction price — The transaction price is determined based on the consideration that the Company will be entitled to in exchange for transferring goods or services to the customer. In determining the transaction price, the Company considers uncertainties such as historical rates of product returns and/or concessions. • Allocation of the transaction price to the performance obligation(s) in the contract — If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation based on a relative standalone selling price (“SSP”) basis. The Company determines standalone selling price based on the price at which the performance obligation is sold separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price taking into account available information such as market conditions and internally approved pricing guidelines related to the performance obligations. • Recognition of revenue when, or as, a performance obligation is satisfied — The Company satisfies performance obligations either over time or at a point in time as discussed in further detail below. Revenue is recognized at the time the related performance obligation is satisfied by transferring a promised good or service to a customer. Revenue is recorded net of sales taxes. The following describes the nature of the Company’s primary types of revenue and the revenue recognition policies as they pertain to the types of transactions the Company enters into with its customers. Product Revenue Product revenue consists of sales of CounterACT, SilentDefense, and Extended Modules. Revenue is recognized at the time of transfer of control, which is generally upon delivery of access to software downloads or shipment, provided that all other revenue recognition criteria have been met. Support and Maintenance Revenue The majority of the products are sold with a support and maintenance contract. Support and maintenance contracts are generally offered as renewable, fixed fee contracts where payments are typically due in advance and generally have a term of one or three years, but can be up to five years . Support and maintenance revenue is recognized ratably over the term of the support and maintenance contract and any unearned support and maintenance revenue is included in deferred revenue. Professional Services Revenue Professional services revenue is derived primarily from customer fees for optional installation of the Company’s products or training. Generally, the Company recognizes revenue for professional services as the services are performed. Contract Costs The Company capitalizes contract origination costs that are incremental and recoverable costs of obtaining a contract with a customer. The Company expects that sales commissions and associated payroll taxes and third-party referral fees related to customer contracts are both incremental and recoverable. The contract origination costs are capitalized and amortized to sales and marketing expense when the related performance obligations are met. Incremental contract origination costs relating to products are expensed as the related products are delivered. Incremental contract origination costs relating to support and maintenance contracts are capitalized and amortized over either the contractual performance period or on a straight-line basis over the average customer life of five years , depending on whether the costs relate to a specific support and maintenance contract or the customer relationship. The Company determines its average customer life by taking into consideration its customer contracts, technology, and other factors. Capitalized costs are periodically reviewed for impairment.
Software Development Costs	Software development costs are not capitalized as the software development process is essentially completed concurrent with the establishment of technological feasibility. As such, all software development costs are expensed as incurred and included in research and development expense in the accompanying consolidated statements of operations.
Advertising Costs	Advertising costs include costs incurred on print, broadcast, and online advertising. Advertising costs are expensed as incurred and included in sales and marketing expense in the accompanying consolidated statements of operations.
Stock-Based Compensation	Stock-based compensation for employees is measured based on the grant date fair value of the award and is expensed over the requisite service period, which is generally the vesting period. The fair value of option awards is determined on the date of grant using the Black-Scholes option pricing model. In applying the Black-Scholes option pricing model, the Company’s determination of the fair value of the option award on the grant date prior to its IPO is affected by the Company’s estimated fair value of the underlying common stock, as well as assumptions relating to subjective variables. Subsequent to its IPO, the Company uses the market closing price for its common stock as reported on the NASDAQ Global Select Market. These variables include the expected term of the award, the expected volatility of the common stock price, the risk-free interest rate, and the expected dividend yield of common stock. Prior to the IPO, the fair value of restricted stock units (“RSUs”) is determined on the date of grant using the Company’s estimated fair value of the underlying common stock. Subsequent to its IPO, the Company uses the market closing price for its common stock as reported on the NASDAQ Global Select Market. Prior to January 1, 2017, for awards with a service condition only, the Company recognized stock-based compensation expense over the service period on a straight-line basis, net of forfeitures. For awards with both a service and performance condition, stock-based compensation expense is recognized over the service period using an accelerated attribution method once the performance conditions become probable. Beginning January 1, 2017 with the adoption of ASU 2016-09, the Company elected to recognize forfeitures as they occur, and no longer estimates a forfeiture rate when calculating the stock-based compensation for equity awards. Stock-based compensation for the year ended December 31, 2016 was calculated using an estimated forfeiture rate based on an analysis of the Company’s actual historical forfeitures.
Income Taxes	Deferred income taxes are recognized using the asset and liability method, whereby deferred tax assets and liabilities are recognized for the expected future tax consequences attributable to differences between the Company’s (1) financial statement carrying amounts and their respective tax bases and (2) operating loss and tax credit carryforwards. Valuation allowances are provided when the expected realization of tax assets does not meet a more-likely-than-not criterion. Due to the Company’s lack of earnings history, the U.S. net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes tax benefits from uncertain tax positions if it is more likely than not that the tax position will be sustained upon examination by a taxing authority based on the technical merits of the position. The tax benefits recognized from such positions are measured based on the largest benefit that has a greater than 50% likelihood to be realized upon settlement. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in income tax expense in the accompanying consolidated statements of operations, when and if incurred. On December 22, 2017, the President of the United States signed the Tax Cuts and Jobs Act (the “Tax Act”) into law. The legislation significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a mandatory repatriation tax on earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. Staff Accounting Bulletin No. 118 (“SAB 118”) was issued to address the application of GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Act. In accordance with SAB 118, the measurement period is now closed and the Company has determined that provisional estimates of the impact recorded in the fourth quarter of 2017 in connection with the revaluation of deferred taxes and the transition tax on the mandatory deemed repatriation of foreign earnings is now final. No material adjustments from the provisional amounts were recorded in 2018.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The Company adopted Topic 606 effective January 1, 2018 using the full retrospective method, which required the Company to restate each prior reporting period presented. See Note 2 for the details of any impacts to previously reported results. In November 2016, the FASB issued ASU No. 2016-18 (Topic 230), Statement of Cash Flows: Restricted Cash . The new standard requires an entity to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows, and an entity will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. The standard is effective for annual and interim periods within those fiscal years, beginning after December 15, 2017, and should be applied retrospectively. The Company adopted this standard effective January 1, 2018 and as a result of adopting this standard, the Company no longer includes the changes in its restricted cash in net cash used in investing activities. The Company’s restricted cash primarily consists of letters of credit issued as security deposits required for facility leases. Recently Issued and Not Yet Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases (“ASU 2016-02”). The new standard requires lessees to recognize leases on their balance sheet as a right-of-use asset and a lease liability. The guidance also requires qualitative and quantitative disclosures to assess the amount, timing and uncertainty of cash flows arising from leases. The standard requires a modified retrospective transition approach and provides certain optional transitional relief. In July 2018, the FASB issued ASU No. 2018-10 (Topic 842), Codification Improvements to Topic 842, Leases (“ASU 2018-10”), and ASU No. 2018-11 (Topic 842), Targeted Improvements (“ASU 2018-11”) which provide a transition method to apply the new lease standards at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption . The Company will apply the transition method, whereby prior comparative periods will not be retrospectively presented. The new standard provides a number of optional practical expedients in transition. The Company plans to elect the following practical expedients and accounting policies: • Practical expedients not to reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs, • Practical expedient for lessees to combine lease and non-lease components, • Accounting policy to not record right-of-use assets and lease liabilities for a lease with an initial term of 12 months or less. The standard is effective for the Company in the first quarter of fiscal 2019. The Company is currently evaluating the lease portfolio, process, control and policy change requirements as part of the adoption. The Company expects the adoption of the new guidance to have a material impact on the total assets and liabilities reported on the Company’s consolidated balance sheets, and estimates an increase in long-term assets and total liabilities of approximately $15 million to $25 million as of January 1, 2019. The Company does not anticipate that the adoption of this standard will have a material impact on its consolidated statements of operations.

Revenue, Deferred Revenue and_2

Revenue, Deferred Revenue and Deferred Commissions (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The Company adjusted its consolidated financial statements from amounts previously reported due to the adoption of Topic 606. Selected consolidated balance sheet line items, which reflect the adoption of Topic 606, are as follows (in thousands): December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Assets Accounts receivable $ 65,428 $ (742 ) $ 64,686 Deferred commission - current $ — $ 10,957 $ 10,957 Prepaid expenses and other current assets $ 8,655 $ 558 $ 9,213 Deferred commission - non-current $ — $ 21,795 $ 21,795 Other assets $ 4,120 $ 488 $ 4,608 Liabilities and stockholders’ equity Deferred revenue - current $ 98,027 $ (18,396 ) $ 79,631 Deferred revenue - non-current $ 64,731 $ (9,503 ) $ 55,228 Accumulated deficit $ (497,376 ) $ 60,955 $ (436,421 ) Selected consolidated statement of operations line items, which reflect the adoption of Topic 606, are as follows (in thousands, except per share data): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Revenue: Product $ 121,413 $ 3,935 $ 125,348 Maintenance and professional services $ 99,458 $ (402 ) $ 99,056 Cost of revenue: Product $ 24,098 $ (257 ) $ 23,841 Operating expenses: Sales and marketing $ 151,093 $ (6,695 ) $ 144,398 Loss from operations $ (87,732 ) $ 10,485 $ (77,247 ) Net loss $ (91,205 ) $ 10,485 $ (80,720 ) Net loss attributable to common stockholders $ (104,015 ) $ 10,485 $ (93,530 ) Net loss per share attributable to common stockholders, basic and diluted $ (9.12 ) $ 0.92 $ (8.20 ) Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Revenue: Product $ 98,655 $ (661 ) $ 97,994 Maintenance and professional services $ 68,186 $ 1,366 $ 69,552 Cost of revenue: Product $ 21,678 $ 154 $ 21,832 Operating expenses: Sales and marketing $ 127,815 $ (8,744 ) $ 119,071 Loss from operations $ (71,444 ) $ 9,295 $ (62,149 ) Net loss $ (74,774 ) $ 9,295 $ (65,479 ) Net loss attributable to common stockholders $ (74,774 ) $ 9,295 $ (65,479 ) Net loss per share attributable to common stockholders, basic and diluted $ (13.33 ) $ 1.66 $ (11.67 ) The adoption of Topic 606 impacted certain line items in the cash flows from operating activities as follows (in thousands): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Cash flows from operating activities: Net loss $ (91,205 ) $ 10,485 $ (80,720 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Accounts receivable $ (20,734 ) $ 742 $ (19,992 ) Deferred commissions $ — $ (7,469 ) $ (7,469 ) Prepaid expenses and other current assets $ (63 ) $ (78 ) $ (141 ) Other assets $ (535 ) $ 595 $ 60 Deferred revenue $ 53,844 $ (4,275 ) $ 49,569 Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Cash flows from operating activities: Net loss $ (74,774 ) $ 9,295 $ (65,479 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Accounts receivable $ (15,469 ) $ 861 $ (14,608 ) Deferred commissions $ — $ (9,624 ) $ (9,624 ) Prepaid expenses and other current assets $ (5,032 ) $ 260 $ (4,772 ) Other assets $ (1,767 ) $ 775 $ (992 ) Deferred revenue $ 25,455 $ (1,567 ) $ 23,888
Schedule of Revenue by Geographic Area	Revenue by geographic area based on the billing address of the customer, which reflects the adoption of Topic 606, is as follows (in thousands): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 162,479 $ 2,661 $ 165,140 Other Americas 6,176 (54 ) 6,122 Total Americas 168,655 2,607 171,262 Europe, Middle East, and Africa 36,300 364 36,664 Asia Pacific and Japan 15,916 562 16,478 Total revenue $ 220,871 $ 3,533 $ 224,404 Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 133,615 $ (1,399 ) $ 132,216 Other Americas 4,949 1,017 5,966 Total Americas 138,564 (382 ) 138,182 Europe, Middle East, and Africa 18,918 463 19,381 Asia Pacific and Japan 9,359 624 9,983 Total revenue $ 166,841 $ 705 $ 167,546 Revenue by geographic area is attributed based on the billing address of the customer and is as follows (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Revenue: Americas United States $ 215,322 $ 165,140 $ 132,216 Other Americas 6,883 6,122 5,966 Total Americas 222,205 171,262 138,182 Europe, Middle East, and Africa (“EMEA”) 52,214 36,664 19,381 Asia Pacific and Japan (“APJ”) 23,232 16,478 9,983 Total revenue $ 297,651 $ 224,404 $ 167,546 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Contract with Customer, Liability	Significant changes in contract liabilities during the periods presented are as follows (in thousands): Contract Liabilities Balance as of December 31, 2016 $ 86,405 Additions 274,468 Gross revenue recognized (225,006 ) Balance as of December 31, 2017 135,867 Additions 327,650 Assumed in a business combination 6,297 Gross revenue recognized (297,783 ) Balance as of December 31, 2018 $ 172,031
Disaggregation of Revenue	The following table depicts the disaggregation of revenue according to revenue type and is consistent with how the Company evaluates its financial performance (in thousands): Year Ended December 31, Revenue: 2018 2017 2016 Software products $ 106,978 $ 49,405 $ 22,346 Hardware products 55,689 75,943 75,648 Support and maintenance 118,572 86,691 60,374 Professional services 16,412 12,365 9,178 Total revenue $ 297,651 $ 224,404 $ 167,546

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Assets and Liabilities	The following table presents the fair value of the Company’s financial assets and liabilities according to the fair value hierarchy (in thousands): December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Financial Assets Cash and cash equivalents: Cash $ 46,017 $ — $ — $ 24,526 $ — $ — Money market accounts 20,878 — — 38,483 — — Total cash and cash equivalents 66,895 — — 63,009 — — Marketable securities: Commercial paper — 3,991 — — 40,610 — Corporate debt securities — 35,639 — — 58,948 — U.S. government securities — 8,002 — — 23,826 — Total marketable securities — 47,632 — — 123,384 — Restricted cash (current and non-current) 2,117 — — 4,348 — — Total financial assets $ 69,012 $ 47,632 $ — $ 67,357 $ 123,384 $ —

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Unrealized Losses and Fair Value of Available-for-Sale Securities	The following table summarizes the unrealized losses and fair value of the Company’s marketable securities as of December 31, 2018 and 2017 (in thousands): December 31, 2018 December 31, 2017 Amortized Cost Unrealized Losses Fair Value Amortized Cost Unrealized Losses Fair Value Marketable securities: Available-for-sale: Commercial paper $ 3,991 $ — $ 3,991 $ 40,610 $ — $ 40,610 Corporate debt securities 35,730 (90 ) 35,640 59,031 (83 ) 58,948 U.S. government securities 8,012 (11 ) 8,001 23,855 (29 ) 23,826 Total marketable securities $ 47,733 $ (101 ) $ 47,632 $ 123,496 $ (112 ) $ 123,384
Investments Classified by Contractual Maturity Date	The following table summarizes the amortized cost and fair value of the Company’s available-for-sale securities as of December 31, 2018 and 2017 , by the contractual maturity date (in thousands): December 31, 2018 December 31, 2017 Amortized Cost Fair Value Amortized Cost Fair Value Due within one year $ 47,733 $ 47,632 $ 83,419 $ 83,374 Due between one and five years — — 40,077 40,010 Total $ 47,733 $ 47,632 $ 123,496 $ 123,384
Schedule of Unrealized Loss on Marketable Securities	For individual marketable securities that were in an unrealized loss position as of December 31, 2018 and 2017 , the fair value and gross unrealized loss for these securities aggregated by investment category and length of time in an unrealized loss position are presented in the following tables (in thousands): December 31, 2018 Less Than 12 Months Greater Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate debt securities $ 4,020 $ (3 ) $ 31,620 $ (87 ) $ 35,640 $ (90 ) U.S. government securities — — 8,001 (11 ) 8,001 (11 ) Total $ 4,020 $ (3 ) $ 39,621 $ (98 ) $ 43,641 $ (101 ) December 31, 2017 Less Than 12 Months Greater Than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate debt securities $ 58,581 $ (83 ) $ — $ — $ 58,581 $ (83 ) U.S. government securities 23,771 (29 ) — — 23,771 (29 ) Total $ 82,352 $ (112 ) $ — $ — $ 82,352 $ (112 )

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2018 2017 Leasehold improvements $ 19,832 $ 18,631 Computer, equipment and software 14,591 9,835 Furniture and fixtures 4,361 3,577 Demonstration units 3,262 2,528 Total property and equipment 42,046 34,571 Less: accumulated depreciation (17,697 ) (11,311 ) Total property and equipment, net $ 24,349 $ 23,260

Acquisitions, Goodwill, and I_2

Acquisitions, Goodwill, and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Allocation of Purchase Price	The Purchase Consideration of $109.3 million was preliminary allocated as follows (in thousands): Amount Net tangible assets acquired $ 686 Intangible assets 19,500 Deferred tax liabilities, net (3,486 ) Goodwill 92,648 Total purchase price allocation $ 109,348
Schedule of Identifiable Intangible Assets	The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition (in thousands, except useful life): Intangible Assets Cost Weighted Average Useful Life (in years) Developed technology $ 13,300 7.0 Customer relationships 6,200 5.0 Total intangible assets acquired $ 19,500 6.4
Schedule of Goodwill	The changes in the carrying amount of goodwill during the year ended December 31, 2018 are as follows (in thousands): Amount Balance as of December 31, 2017 $ — Goodwill acquired 92,648 Foreign currency translation adjustments (166 ) Balance as of December 31, 2018 $ 92,482
Schedule of Finite-Lived Intangible Assets	Intangible assets subject to amortization realized from acquisitions as of December 31, 2018 are as follows (in thousands): Intangible Assets Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Developed technology $ 13,300 $ (280 ) $ (24 ) $ 12,996 Customer relationships 6,200 (183 ) (11 ) 6,006 $ 19,500 $ (463 ) $ (35 ) $ 19,002
Schedule of Expected Future Amortization Expense of Intangible Assets	The expected future annual amortization expense of intangible assets as of December 31, 2018 is presented below (in thousands): Year Ending December 31, Amount 2019 $ 3,122 2020 3,122 2021 3,122 2022 3,122 2023 and thereafter 6,514 Total $ 19,002

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	As of December 31, 2018 , the future minimum lease payments by fiscal year under non-cancelable leases are as follows (in thousands): Years Ending December 31, Operating 2019 $ 5,551 2020 4,188 2021 4,307 2022 4,435 2023 4,461 2024 and thereafter 11,933 Total $ 34,875

Debt Agreements (Tables)

Debt Agreements (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Carrying Value of Notes Payable	The following table presents the carrying value of the Company’s notes payable (in thousands): December 31, 2018 2017 Principal amount of notes payable $ 15,825 $ 23,325 Unamortized debt discount (246 ) (501 ) Net carrying amount of notes payable 15,579 22,824 Less current portion (7,331 ) (7,245 ) Non-current portion of notes payable $ 8,248 $ 15,579
Schedule of Maturities of Long-term Debt	As of December 31, 2018 , the future principal payments on the Company’s notes payable were as follows (in thousands): Years Ending December 31, Amount 2019 $ 7,500 2020 8,325 Total $ 15,825

Common Stock and Stockholders_2

Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Common Stock Reserved	As of December 31, 2018 , common stock reserved, on an as-if converted basis for issuance are as follows: December 31, 2018 Reserved for future issuance under equity award plans 3,905,796 Common stock options outstanding 6,012,830 Restricted stock units outstanding 5,709,472 Common stock warrants outstanding 74 Total common stock reserved for issuance 15,628,172
Schedule of Option Activity under the Plan	The following table summarizes option activity under the Plan and related information (in thousands, except per share and contractual life amounts): Options Outstanding Number Weighted- Weighted- Aggregate Balance—December 31, 2016 9,588 $ 10.13 8.0 $ 61,865 Options granted 549 $ 20.05 Options forfeited (517 ) $ 14.58 Options exercised (306 ) $ 5.32 Balance—December 31, 2017 9,314 $ 10.63 7.2 $ 198,012 Options granted 44 $ 30.81 Options exercised (2,979 ) $ 8.13 Options forfeited (366 ) $ 16.59 Balance—December 31, 2018 6,013 $ 11.65 6.4 $ 86,624 Options vested and exercisable—December 31, 2018 4,525 $ 10.26 6.1 $ 71,237
Schedule of RSU Activity under the Plan	The following table summarizes RSU activity under the Plan and related information (in thousands, except per share and contractual life amounts): RSUs Outstanding Number Weighted- Weighted- Aggregate Balance—December 31, 2016 1,899 $ 14.83 1.7 $ 30,720 RSUs granted 2,355 $ 25.20 RSUs forfeited (38 ) $ 20.44 Balance—December 31, 2017 4,216 $ 20.57 1.7 $ 134,448 RSUs granted 3,354 $ 30.94 RSUs released (1,607 ) $ 14.78 RSUs forfeited (254 ) $ 26.80 Balance—December 31, 2018 5,709 $ 28.01 1.8 $ 148,389
Schedule of Stock-based Compensation Expense for Employees and Non-Employees	Stock-based compensation expense for both employees and non-employees included in the accompanying consolidated statements of operations is as follows (in thousands): Year Ended December 31, 2018 2017 2016 Cost of revenue: Product $ 253 $ 103 $ 30 Maintenance and professional services 3,015 2,291 1,123 Research and development 10,161 6,213 2,311 Sales and marketing 24,999 14,451 8,084 General and administrative 15,069 19,538 5,286 Total $ 53,497 $ 42,596 $ 16,834
Schedule of Assumptions Used to Determine Grant Date Fair Value of Employee Stock Options	The assumptions used to determine the grant date fair value of employee stock options and ESPP purchase rights for the periods presented are as follows: Year Ended December 31, 2018 2017 2016 Employee Stock Options Fair value of common stock $29.92 – $30.97 $16.73 – $31.16 $15.78 – $21.56 Risk-free interest rate 2.4% – 2.8% 1.9% – 2.2% 1.2% – 2.1% Expected term (in years) 6.1 6.0 – 6.1 6.0 – 8.1 Volatility 48% 46% – 49% 47% – 51% Dividend yield —% —% —% Employee Stock Purchase Plan Fair value of common stock $24.65 – $31.00 $25.12 $— Risk-free interest rate 2.14% – 2.52% 1.4% —% Expected term (in years) 0.5 0.5 0 Volatility 30% – 43% 30% —% Dividend yield —% —% —%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of loss before provision for income taxes, domestic and foreign	The components of loss before provision for income taxes are as follows (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Domestic $ (85,252 ) $ (82,292 ) $ (66,810 ) Foreign 13,361 3,411 2,581 Total $ (71,891 ) $ (78,881 ) $ (64,229 ) * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of components of income tax expense	The provision for income taxes consists of the following (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Current Federal $ 1 $ 17 $ 4 State 56 50 66 Foreign 3,263 1,788 1,273 Total current 3,320 1,855 1,343 Deferred Foreign (375 ) (16 ) (93 ) Total deferred $ (375 ) $ (16 ) $ (93 ) Total $ 2,945 $ 1,839 $ 1,250 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of deferred tax assets and liabilities	Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): December 31, 2018 2017 *As Adjusted Deferred tax assets: Federal and state net operating losses $ 59,803 $ 43,410 Research/other credits 2,913 1,060 Non-deductible and accrued expenses 4,756 4,485 Deferred revenue 14,040 3,725 Property and equipment 506 — Stock-based compensation 10,323 9,507 Other 1,024 610 Gross deferred tax assets 93,365 62,797 Valuation allowance (83,376 ) (54,233 ) Net deferred tax assets 9,989 8,564 Deferred tax liabilities: Acquired intangible assets (4,117 ) — Property and equipment — (13 ) Deferred commission (8,691 ) (8,375 ) Others (116 ) — Net deferred tax liabilities (12,924 ) (8,388 ) Total $ (2,935 ) $ 176 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of effective income tax rate reconciliation	Reconciliation of the statutory federal income tax to the Company’s effective tax (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Tax at federal statutory rate $ (15,097 ) $ (30,385 ) $ (21,838 ) State, net of federal benefit 61 60 61 Stock-based compensation (6,215 ) 4,097 3,225 Non-deductible warrant expenses — 272 (365 ) Tax Reform federal rate change — 36,460 — Change in valuation allowance 23,929 (10,512 ) 19,225 Other 267 1,847 942 Total $ 2,945 $ 1,839 $ 1,250 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the gross unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2018 2017 2016 Unrecognized tax benefits at the beginning of the period $ 1,727 $ 1,050 $ 254 Additions for tax positions taken in prior years 104 248 185 Additions for tax positions taken in current year 195 845 611 Reductions for tax positions taken in prior years (759 ) — — Settlements with taxing authorities — (416 ) — Unrecognized tax benefits at the end of the period $ 1,267 $ 1,727 $ 1,050

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Share	The following table presents the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share amounts): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Net loss $ (74,836 ) $ (80,720 ) $ (65,479 ) Deemed dividend on the conversion of Series G redeemable convertible preferred stock — 12,810 — Net loss attributable to common stockholders $ (74,836 ) $ (93,530 ) $ (65,479 ) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 40,980 11,405 5,609 Net loss per share attributable to common stockholders, basic and diluted $ (1.83 ) $ (8.20 ) $ (11.67 ) * Adjusted to include the impact of ASC 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of Securities Excluded from Computation of Diluted Net Loss Per Share	The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because their inclusion would reduce the net loss per share (in thousands). Year Ended December 31, 2018 2017 2016 Options to purchase common stock 6,013 9,314 9,588 Unvested early exercised common shares 47 146 330 Unvested restricted stock units 5,709 4,216 1,899 Shares estimated under ESPP 233 221 — Warrants to purchase common stock — 83 233 Redeemable convertible preferred stock — — 24,788 Warrants to purchase redeemable convertible preferred stock — — 293

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue by Geographic Area	Revenue by geographic area based on the billing address of the customer, which reflects the adoption of Topic 606, is as follows (in thousands): Year ended December 31, 2017 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 162,479 $ 2,661 $ 165,140 Other Americas 6,176 (54 ) 6,122 Total Americas 168,655 2,607 171,262 Europe, Middle East, and Africa 36,300 364 36,664 Asia Pacific and Japan 15,916 562 16,478 Total revenue $ 220,871 $ 3,533 $ 224,404 Year ended December 31, 2016 As Previously Reported Impact of Adoption As Adjusted Revenue: Americas United States $ 133,615 $ (1,399 ) $ 132,216 Other Americas 4,949 1,017 5,966 Total Americas 138,564 (382 ) 138,182 Europe, Middle East, and Africa 18,918 463 19,381 Asia Pacific and Japan 9,359 624 9,983 Total revenue $ 166,841 $ 705 $ 167,546 Revenue by geographic area is attributed based on the billing address of the customer and is as follows (in thousands): Year Ended December 31, 2018 2017 *As Adjusted 2016 *As Adjusted Revenue: Americas United States $ 215,322 $ 165,140 $ 132,216 Other Americas 6,883 6,122 5,966 Total Americas 222,205 171,262 138,182 Europe, Middle East, and Africa (“EMEA”) 52,214 36,664 19,381 Asia Pacific and Japan (“APJ”) 23,232 16,478 9,983 Total revenue $ 297,651 $ 224,404 $ 167,546 * Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard.
Schedule of Long-lived Assets by Geographical Area	Long-lived assets, net by geographic area are attributed based on legal entity structure and are as follows (in thousands): December 31, 2018 2017 Long-lived assets, net: United States $ 18,570 $ 18,989 Israel 5,057 3,453 Other 722 818 Total long-lived assets, net $ 24,349 $ 23,260

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	The following tables set forth selected unaudited quarterly consolidated statements of operations data for each of the eight quarters in the period ended December 31, 2018 . The information for each of these quarters has been prepared on the same basis as the audited annual consolidated financial statements included elsewhere in this report and, in the opinion of management, includes all adjustments, which consist only of normal recurring adjustments, necessary for the fair presentation of the results of operations for these periods in accordance with GAAP. This data should be read in conjunction with our audited consolidated financial statements and related notes included elsewhere in this report. These quarterly operating results are not necessarily indicative of our operating results for a full year or any future period. Three Months Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 December 31, 2017 (1) September 30, 2017 June 30, 2017 March 31, 2017 (In thousands, except per share amounts) Revenue: Product $ 47,482 $ 51,082 $ 34,323 $ 29,780 $ 34,994 $ 43,204 $ 26,842 $ 20,308 Maintenance and professional services 37,250 34,546 33,271 29,917 27,913 26,136 23,139 21,868 Total revenue 84,732 85,628 67,594 59,697 62,907 69,340 49,981 42,176 Cost of revenue: Product (2) 6,852 8,947 4,919 7,136 6,964 7,240 5,545 4,092 Maintenance and professional services (2) 10,634 10,250 9,794 9,350 9,109 8,688 8,543 8,431 Total cost of revenue 17,486 19,197 14,713 16,486 16,073 15,928 14,088 12,523 Total gross profit 67,246 66,431 52,881 43,211 46,834 53,412 35,893 29,653 Operating expenses: Research and development (2) 17,161 15,062 14,803 14,687 14,801 10,985 10,702 10,947 Sales and marketing (2) 50,464 46,098 45,039 42,279 41,769 34,028 33,556 35,045 General and administrative (2) 16,849 13,880 13,260 13,732 23,941 9,148 8,902 9,215 Total operating expenses 84,474 75,040 73,102 70,698 80,511 54,161 53,160 55,207 Loss from operations (17,228 ) (8,609 ) (20,221 ) (27,487 ) (33,677 ) (749 ) (17,267 ) (25,554 ) Interest expense (237 ) (208 ) (225 ) (243 ) (270 ) (290 ) (318 ) (345 ) Other income (expense), net 527 865 513 662 382 160 (82 ) (144 ) Revaluation of warrant liabilities — — — — (385 ) — 50 (392 ) Loss before income taxes (16,938 ) (7,952 ) (19,933 ) (27,068 ) (33,950 ) (879 ) (17,617 ) (26,435 ) Income tax provision 1,010 334 473 1,128 618 412 174 635 Net loss $ (17,948 ) $ (8,286 ) $ (20,406 ) $ (28,196 ) $ (34,568 ) $ (1,291 ) $ (17,791 ) $ (27,070 ) Deemed dividend on the conversion of Series G redeemable convertible preferred stock — — — — 12,810 — — — Net loss attributable to common stockholders $ (17,948 ) $ (8,286 ) $ (20,406 ) $ (28,196 ) $ (47,378 ) $ (1,291 ) $ (17,791 ) $ (27,070 ) Net loss per share attributable to common stockholders, basic and diluted $ (0.42 ) $ (0.20 ) $ (0.50 ) $ (0.74 ) $ (1.73 ) $ (0.21 ) $ (2.95 ) $ (4.57 ) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 43,016 42,064 40,457 38,313 27,349 6,140 6,031 5,924 _____________________ (1) Adjusted to include the impact of Topic 606. Refer to Note 2 for more details on the impact of the adoption of this standard. (2) Includes stock-based compensation expense as follows: Three Months Ended December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31, (In thousands) Cost of revenue: Product $ 79 $ 67 $ 54 $ 53 $ 43 $ 19 $ 20 $ 21 Maintenance and professional services 804 715 723 773 1,361 286 319 325 Research and development 2,688 2,613 2,513 2,347 4,170 630 613 800 Sales and marketing 6,804 6,165 5,850 6,180 9,583 1,602 1,609 1,657 General and administrative 3,578 3,458 3,796 4,237 15,379 1,372 1,372 1,415 Total $ 13,953 $ 13,018 $ 12,936 $ 13,590 $ 30,536 $ 3,909 $ 3,933 $ 4,218

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies - Company Background (Details)	12 Months Ended
	Dec. 31, 2018product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products	2

Description of Business and S_4

Description of Business and Summary of Significant Accounting Policies - Initial Public Offering and Follow-On Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 31, 2017	Mar. 31, 2018	Oct. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsidiary, Sale of Stock [Line Items]
IPO price per share (in dollars per share)		$ 29
Offering costs				$ 1,542	$ 4,245	$ 7
Options exercised (shares)		425,436		2,979,000	306,000
IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in IPO (in shares)	6,072,000
IPO price per share (in dollars per share)	$ 22		$ 22
Consideration received from IPO	$ 124,200
Offering costs	$ 4,500
Follow-on offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in IPO (in shares)		500,000
Consideration received from IPO		$ 16,400
Offering costs		1,200
Underwriters discounts and commissions		700
Proceeds from exercise of stock options		$ 2,600
Follow-on offering - shares from existing shareholders
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in IPO (in shares)		4,572,650
Common stock
Subsidiary, Sale of Stock [Line Items]
Shares converted into common stock (in shares)			25,370,616		24,845,000
Options exercised (shares)				4,616,000	306,000	644,000

Description of Business and S_5

Description of Business and Summary of Significant Accounting Policies - Reverse Stock Split (Details)	Oct. 16, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reverse stock split conversion ratio	0.5

Description of Business and S_6

Description of Business and Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2018business_activitysegment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of business activities | business_activity	1
Number of segments | segment	1

Description of Business and S_7

Description of Business and Summary of Significant Accounting Policies - Concentrations (Details) - manufacturer	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Number of contract manufacturers	1
Customer Concentration Risk | Accounts Receivable | Customer One
Concentration Risk [Line Items]
Concentration risk percentage	17.00%	33.00%
Customer Concentration Risk | Accounts Receivable | Customer Two
Concentration Risk [Line Items]
Concentration risk percentage	15.00%	17.00%
Customer Concentration Risk | Accounts Receivable | Customer Three
Concentration Risk [Line Items]
Concentration risk percentage	11.00%
Customer Concentration Risk | Accounts Receivable | Customer Four
Concentration Risk [Line Items]
Concentration risk percentage	11.00%
Customer Concentration Risk | Revenue | Customer One
Concentration Risk [Line Items]
Concentration risk percentage	22.00%	31.00%	24.00%
Customer Concentration Risk | Revenue | Customer Two
Concentration Risk [Line Items]
Concentration risk percentage	18.00%	22.00%	16.00%
Customer Concentration Risk | Revenue | Customer Three
Concentration Risk [Line Items]
Concentration risk percentage	13.00%	16.00%	14.00%

Description of Business and S_8

Description of Business and Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restricted cash - current	$ 851	$ 202	$ 201
Restricted cash - non current	$ 1,266	$ 4,146	$ 4,011

Description of Business and S_9

Description of Business and Summary of Significant Accounting Policies - Property and Equipment and Product Warranty (Details)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Standard product warranty period	90 days
Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Extended product warranty period	1 year
Maximum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Extended product warranty period	5 years
Demonstration units
Property, Plant and Equipment [Line Items]
Useful life	3 years

Description of Business and _10

Description of Business and Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - Accounting Standards Update 2018-11 - Forecast $ in Millions	Jan. 01, 2019USD ($)
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	$ 15
Operating lease, liability	15
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	25
Operating lease, liability	$ 25

Revenue, Deferred Revenue and_3

Revenue, Deferred Revenue and Deferred Commissions - Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Accounts receivable	$ 79,255	$ 64,686
Deferred commissions - current	12,543	10,957
Prepaid expenses and other current assets	13,353	9,213
Deferred commissions - non-current	22,831	21,795
Other assets	7,369	4,608
Liabilities and stockholders’ equity
Deferred revenue - current	101,900	79,631
Deferred revenue - non-current	69,618	55,228
Accumulated deficit	$ (511,257)	(436,421)
As Previously Reported
Assets
Accounts receivable		65,428
Deferred commissions - current		0
Prepaid expenses and other current assets		8,655
Deferred commissions - non-current		0
Other assets		4,120
Liabilities and stockholders’ equity
Deferred revenue - current		98,027
Deferred revenue - non-current		64,731
Accumulated deficit		(497,376)
Impact of Adoption | Accounting Standards Update 2014-09
Assets
Accounts receivable		(742)
Deferred commissions - current		10,957
Prepaid expenses and other current assets		558
Deferred commissions - non-current		21,795
Other assets		488
Liabilities and stockholders’ equity
Deferred revenue - current		(18,396)
Deferred revenue - non-current		(9,503)
Accumulated deficit		$ 60,955

Revenue, Deferred Revenue and_4

Revenue, Deferred Revenue and Deferred Commissions - Condensed Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Cost of revenue:
Cost of revenue	17,486	19,197	14,713	16,486	16,073	15,928	14,088	12,523	67,882	58,612	48,403
Operating expenses:
Sales and marketing	50,464	46,098	45,039	42,279	41,769	34,028	33,556	35,045	183,880	144,398	119,071
Loss from operations	(17,228)	(8,609)	(20,221)	(27,487)	(33,677)	(749)	(17,267)	(25,554)	(73,545)	(77,247)	(62,149)
Net loss	(17,948)	(8,286)	(20,406)	(28,196)	(34,568)	(1,291)	(17,791)	(27,070)	(74,836)	(80,720)	(65,479)
Net loss attributable to common stockholders	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (47,378)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (93,530)	$ (65,479)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.42)	$ (0.20)	$ (0.50)	$ (0.74)	$ (1.73)	$ (0.21)	$ (2.95)	$ (4.57)	$ (1.83)	$ (8.20)	$ (11.67)
As Previously Reported
Revenue:
Revenue										$ 220,871	$ 166,841
Operating expenses:
Sales and marketing										151,093	127,815
Loss from operations										(87,732)	(71,444)
Net loss										(91,205)	(74,774)
Net loss attributable to common stockholders										$ (104,015)	$ (74,774)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)										$ (9.12)	$ (13.33)
Impact of Adoption | Accounting Standards Update 2014-09
Revenue:
Revenue										$ 3,533	$ 705
Operating expenses:
Sales and marketing										(6,695)	(8,744)
Loss from operations										10,485	9,295
Net loss										10,485	9,295
Net loss attributable to common stockholders										$ 10,485	$ 9,295
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)										$ 0.92	$ 1.66
Product
Revenue:
Revenue	$ 47,482	$ 51,082	$ 34,323	$ 29,780	$ 34,994	$ 43,204	$ 26,842	$ 20,308	$ 162,667	$ 125,348	$ 97,994
Cost of revenue:
Cost of revenue	6,852	8,947	4,919	7,136	6,964	7,240	5,545	4,092	27,854	23,841	21,832
Product | As Previously Reported
Revenue:
Revenue										121,413	98,655
Cost of revenue:
Cost of revenue										24,098	21,678
Product | Impact of Adoption | Accounting Standards Update 2014-09
Revenue:
Revenue										3,935	(661)
Cost of revenue:
Cost of revenue										(257)	154
Maintenance and professional services
Revenue:
Revenue	37,250	34,546	33,271	29,917	27,913	26,136	23,139	21,868	134,984	99,056	69,552
Cost of revenue:
Cost of revenue	$ 10,634	$ 10,250	$ 9,794	$ 9,350	$ 9,109	$ 8,688	$ 8,543	$ 8,431	$ 40,028	34,771	26,571
Maintenance and professional services | As Previously Reported
Revenue:
Revenue										99,458	68,186
Maintenance and professional services | Impact of Adoption | Accounting Standards Update 2014-09
Revenue:
Revenue										$ (402)	$ 1,366

Revenue, Deferred Revenue and_5

Revenue, Deferred Revenue and Deferred Commissions - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Total Americas
Disaggregation of Revenue [Line Items]
Revenue									222,205	171,262	138,182
United States
Disaggregation of Revenue [Line Items]
Revenue									215,322	165,140	132,216
Other Americas
Disaggregation of Revenue [Line Items]
Revenue									6,883	6,122	5,966
Europe, Middle East, and Africa (“EMEA”)
Disaggregation of Revenue [Line Items]
Revenue									52,214	36,664	19,381
Asia Pacific and Japan (“APJ”)
Disaggregation of Revenue [Line Items]
Revenue									$ 23,232	16,478	9,983
As Previously Reported
Disaggregation of Revenue [Line Items]
Revenue										220,871	166,841
As Previously Reported | Total Americas
Disaggregation of Revenue [Line Items]
Revenue										168,655	138,564
As Previously Reported | United States
Disaggregation of Revenue [Line Items]
Revenue										162,479	133,615
As Previously Reported | Other Americas
Disaggregation of Revenue [Line Items]
Revenue										6,176	4,949
As Previously Reported | Europe, Middle East, and Africa (“EMEA”)
Disaggregation of Revenue [Line Items]
Revenue										36,300	18,918
As Previously Reported | Asia Pacific and Japan (“APJ”)
Disaggregation of Revenue [Line Items]
Revenue										15,916	9,359
Impact of Adoption | Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Revenue										3,533	705
Impact of Adoption | Accounting Standards Update 2014-09 | Total Americas
Disaggregation of Revenue [Line Items]
Revenue										2,607	(382)
Impact of Adoption | Accounting Standards Update 2014-09 | United States
Disaggregation of Revenue [Line Items]
Revenue										2,661	(1,399)
Impact of Adoption | Accounting Standards Update 2014-09 | Other Americas
Disaggregation of Revenue [Line Items]
Revenue										(54)	1,017
Impact of Adoption | Accounting Standards Update 2014-09 | Europe, Middle East, and Africa (“EMEA”)
Disaggregation of Revenue [Line Items]
Revenue										364	463
Impact of Adoption | Accounting Standards Update 2014-09 | Asia Pacific and Japan (“APJ”)
Disaggregation of Revenue [Line Items]
Revenue										$ 562	$ 624

Revenue, Deferred Revenue and_6

Revenue, Deferred Revenue and Deferred Commissions - Cash Flows from Operating Activities (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net loss	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (34,568)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (80,720)	$ (65,479)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Accounts receivable									(10,899)	(19,992)	(14,608)
Deferred commissions									(2,621)	(7,469)	(9,624)
Prepaid expenses and other current assets									(3,084)	(141)	(4,772)
Other assets									(3,543)	60	(992)
Deferred revenue									$ 30,366	49,569	23,888
As Previously Reported
Cash flows from operating activities
Net loss										(91,205)	(74,774)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Accounts receivable										(20,734)	(15,469)
Deferred commissions										0	0
Prepaid expenses and other current assets										(63)	(5,032)
Other assets										(535)	(1,767)
Deferred revenue										53,844	25,455
Impact of Adoption | Accounting Standards Update 2014-09
Cash flows from operating activities
Net loss										10,485	9,295
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Accounts receivable										742	861
Deferred commissions										(7,469)	(9,624)
Prepaid expenses and other current assets										(78)	260
Other assets										595	775
Deferred revenue										$ (4,275)	$ (1,567)

Revenue, Deferred Revenue and_7

Revenue, Deferred Revenue and Deferred Commissions - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)product	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Number of products | product	2
Capitalized contract cost, amortization period	5 years
Capitalized contract cost	$ 35,900,000	$ 33,800,000
Capitalized contract cost, amortization	14,900,000	11,400,000	$ 11,400,000
Capitalized contract cost, impairment loss	0	0	$ 0
Contract with customer, asset	0
Deferred revenue, revenue recognized that was previously deferred	$ 80,000,000	$ 52,400,000
Support and maintenance
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, performance obligation, description of timing	term of one or three years, but can be up to five years
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment term period	30 days
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment term period	90 days

Revenue, Deferred Revenue and_8

Revenue, Deferred Revenue and Deferred Commissions - Significant Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change In Contract With Customer, Liability [Roll Forward]
Beginning balance	$ 135,867	$ 86,405
Additions	327,650	274,468
Assumed in a business combination	6,297
Gross revenue recognized	(297,783)	(225,006)
Ending balance	$ 172,031	$ 135,867

Revenue, Deferred Revenue and_9

Revenue, Deferred Revenue and Deferred Commissions - Performance Obligations (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation	$ 177.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	60.00%
Performance obligation expected to be satisfied, expected timing	1 year

Revenue, Deferred Revenue an_10

Revenue, Deferred Revenue and Deferred Commissions - Disaggregation of Revenue According to Revenue Type (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Software products
Disaggregation of Revenue [Line Items]
Revenue									106,978	49,405	22,346
Hardware products
Disaggregation of Revenue [Line Items]
Revenue									55,689	75,943	75,648
Support and maintenance
Disaggregation of Revenue [Line Items]
Revenue									118,572	86,691	60,374
Professional services
Disaggregation of Revenue [Line Items]
Revenue									$ 16,412	$ 12,365	$ 9,178

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial Assets
Marketable securities	$ 47,632	$ 123,384
Commercial paper
Financial Assets
Marketable securities	3,991	40,610
Corporate debt securities
Financial Assets
Marketable securities	35,640	58,948
U.S. government securities
Financial Assets
Marketable securities	8,001	23,826
Recurring | Level 1
Financial Assets
Cash and cash equivalents	66,895	63,009
Restricted cash (current and non-current)	2,117	4,348
Total financial assets	69,012	67,357
Recurring | Level 1 | Debt Securities
Financial Assets
Marketable securities	0	0
Recurring | Level 1 | Commercial paper
Financial Assets
Marketable securities	0	0
Recurring | Level 1 | Corporate debt securities
Financial Assets
Marketable securities	0	0
Recurring | Level 1 | U.S. government securities
Financial Assets
Marketable securities	0	0
Recurring | Level 1 | Cash
Financial Assets
Cash and cash equivalents	46,017	24,526
Recurring | Level 1 | Money market accounts
Financial Assets
Cash and cash equivalents	20,878	38,483
Recurring | Level 2
Financial Assets
Cash and cash equivalents	0	0
Restricted cash (current and non-current)	0	0
Total financial assets	47,632	123,384
Recurring | Level 2 | Debt Securities
Financial Assets
Marketable securities	47,632	123,384
Recurring | Level 2 | Commercial paper
Financial Assets
Marketable securities	3,991	40,610
Recurring | Level 2 | Corporate debt securities
Financial Assets
Marketable securities	35,639	58,948
Recurring | Level 2 | U.S. government securities
Financial Assets
Marketable securities	8,002	23,826
Recurring | Level 2 | Cash
Financial Assets
Cash and cash equivalents	0	0
Recurring | Level 2 | Money market accounts
Financial Assets
Cash and cash equivalents	0	0
Recurring | Level 3
Financial Assets
Cash and cash equivalents	0	0
Restricted cash (current and non-current)	0	0
Total financial assets	0	0
Recurring | Level 3 | Debt Securities
Financial Assets
Marketable securities	0	0
Recurring | Level 3 | Commercial paper
Financial Assets
Marketable securities	0	0
Recurring | Level 3 | Corporate debt securities
Financial Assets
Marketable securities	0	0
Recurring | Level 3 | U.S. government securities
Financial Assets
Marketable securities	0	0
Recurring | Level 3 | Cash
Financial Assets
Cash and cash equivalents	0	0
Recurring | Level 3 | Money market accounts
Financial Assets
Cash and cash equivalents	$ 0	$ 0

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 47,733	$ 123,496
Unrealized Losses	(101)	(112)
Fair Value	47,632	123,384
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,991	40,610
Unrealized Losses	0	0
Fair Value	3,991	40,610
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	35,730	59,031
Unrealized Losses	(90)	(83)
Fair Value	35,640	58,948
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,012	23,855
Unrealized Losses	(11)	(29)
Fair Value	$ 8,001	$ 23,826

Marketable Securities - Maturit

Marketable Securities - Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due within one year	$ 47,733	$ 83,419
Due between one and five years	0	40,077
Amortized Cost	47,733	123,496
Fair Value
Due within one year	47,632	83,374
Due between one and five years	0	40,010
Total	$ 47,632	$ 123,384

Marketable Securities - Narrati

Marketable Securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)security	Dec. 31, 2017USD ($)security
Investments, Debt and Equity Securities [Abstract]
Marketable securities in unrealized loss positions | security	13	20
Other than temporary impairment | $	$ 0	$ 0

Marketable Securities - Continu

Marketable Securities - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value
Less Than 12 Months	$ 4,020	$ 82,352
Greater Than 12 Months	39,621	0
Total	43,641	82,352
Unrealized Loss
Less Than 12 Months	(3)	(112)
Greater Than 12 Months	(98)	0
Total	(101)	(112)
Corporate debt securities
Fair Value
Less Than 12 Months	4,020	58,581
Greater Than 12 Months	31,620	0
Total	35,640	58,581
Unrealized Loss
Less Than 12 Months	(3)	(83)
Greater Than 12 Months	(87)	0
Total	(90)	(83)
U.S. government securities
Fair Value
Less Than 12 Months	0	23,771
Greater Than 12 Months	8,001	0
Total	8,001	23,771
Unrealized Loss
Less Than 12 Months	0	(29)
Greater Than 12 Months	(11)	0
Total	$ (11)	$ (29)

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 42,046	$ 34,571
Less: accumulated depreciation	(17,697)	(11,311)
Total property and equipment, net	24,349	23,260
Depreciation expense	7,500	6,100	$ 3,600
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	19,832	18,631
Computer, equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	14,591	9,835
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	4,361	3,577
Demonstration units
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 3,262	$ 2,528

Acquisitions, Goodwill, and I_3

Acquisitions, Goodwill, and Intangible Assets - Narrative (Details) - USD ($)	Nov. 07, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Amortization of intangible assets		$ 500,000	$ 0	$ 0
Acquisition related costs		$ 2,700,000
SecurityMatters, B.V.
Business Acquisition [Line Items]
Percentage of voting interests acquired	100.00%
Business combination, consideration transferred	$ 109,300,000
Escrow deposit	6,200,000
Unvested restricted stock units | SecurityMatters, B.V.
Business Acquisition [Line Items]
RSUs issued in connection with acquisition	$ 5,900,000
Award vesting period	4 years
Future cash payments for unvested equity awards | SecurityMatters, B.V.
Business Acquisition [Line Items]
Unvested equity award cash amounts	$ 1,200,000

Acquisitions, Goodwill, and I_4

Acquisitions, Goodwill, and Intangible Assets - Allocation of Purchase Price (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Nov. 07, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 92,482		$ 0
SecurityMatters, B.V.
Business Acquisition [Line Items]
Net tangible assets acquired		$ 686
Intangible assets		19,500
Deferred tax liabilities, net		(3,486)
Goodwill		92,648
Total purchase price allocation		$ 109,348

Acquisitions, Goodwill, and I_5

Acquisitions, Goodwill, and Intangible Assets - Schedule of Identifiable Intangible Assets Acquired (Details) - SecurityMatters, B.V. $ in Thousands	Nov. 07, 2018USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	$ 19,500
Weighted Average Useful Life (in years)	6 years 4 months 24 days
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	$ 13,300
Weighted Average Useful Life (in years)	7 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	$ 6,200
Weighted Average Useful Life (in years)	5 years

Acquisitions, Goodwill, and I_6

Acquisitions, Goodwill, and Intangible Assets - Schedule of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 0
Goodwill acquired	92,648
Foreign currency translation adjustments	(166)
Goodwill, ending balance	$ 92,482

Acquisitions, Goodwill, and I_7

Acquisitions, Goodwill, and Intangible Assets - Intangible Assets Subject to Amortization (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Cost	$ 19,500
Accumulated Amortization	(463)
Foreign Currency Translation Adjustments	(35)
Net	19,002
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	13,300
Accumulated Amortization	(280)
Foreign Currency Translation Adjustments	(24)
Net	12,996
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	6,200
Accumulated Amortization	(183)
Foreign Currency Translation Adjustments	(11)
Net	$ 6,006

Acquisitions, Goodwill, and I_8

Acquisitions, Goodwill, and Intangible Assets - Expected Future Amortization Expense of Intangible Assets (Details) $ in Thousands	Dec. 31, 2018USD ($)
Business Combinations [Abstract]
2,019	$ 3,122
2,020	3,122
2,021	3,122
2,022	3,122
2023 and thereafter	6,514
Total	$ 19,002

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2015renewal_option	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Operating Leased Assets [Line Items]
Rent expense		$ 6.4	$ 5.6	$ 5.3
Purchase obligations		6.5
Contract manufacturer commitments
Operating Leased Assets [Line Items]
Contract manufacturer commitments		8
Corporate Office
Operating Leased Assets [Line Items]
Lease agreement	11 years
Number of operating leases | renewal_option	1
Lease renewal term	5 years
Lease rent free period	1 year
Incentive for tenant improvements		4.8
Corporate Office | Maximum
Operating Leased Assets [Line Items]
Incentive for tenant improvements		$ 4.8

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 5,551
2,020	4,188
2,021	4,307
2,022	4,435
2,023	4,461
2024 and thereafter	11,933
Total	$ 34,875

Debt Agreements - Narrative (De

Debt Agreements - Narrative (Details)	Dec. 22, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Amortization of debt discount (premium)		$ 300,000	$ 300,000	$ 700,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding revolving line of credit		$ 0	$ 0
Line of Credit | Amended Loan and Security Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Percentage of qualified accounts receivable	80.00%
Face amount	$ 30,000,000
Maximum credit available for borrowing	$ 40,000,000
Quick ratio required	1.25
Monthly installments of principal	$ 625,000
Stated interest rate	3.25%
Additional payment at maturity	$ 825,000

Debt Agreements - Carrying Valu

Debt Agreements - Carrying Value of Notes Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Less current portion	$ (7,331)	$ (7,245)
Non-current portion of notes payable	8,248	15,579
Notes Payable to Banks
Debt Instrument [Line Items]
Principal amount of notes payable	15,825	23,325
Unamortized debt discount	(246)	(501)
Net carrying amount of notes payable	15,579	22,824
Less current portion	(7,331)	(7,245)
Non-current portion of notes payable	$ 8,248	$ 15,579

Debt Agreements Debt Agreements

Debt Agreements Debt Agreements - Future Payments of Notes Payable (Details) - Notes Payable to Banks - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
2,019	$ 7,500
2,020	8,325
Total	$ 15,825	$ 23,325

Common Stock and Stockholders_3

Common Stock and Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands	Apr. 25, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Oct. 31, 2017USD ($)$ / sharesshares	Oct. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)employee$ / shares	Mar. 31, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued as stock dividend (in shares)				582,254
IPO price per share (in dollars per share) | $ / shares									$ 29
Fair value adjustment on conversion of warrants | $				$ 300
Conversion of preferred stock warrants to common stock warrants in connection with initial public offering | $				$ 4,200			$ 4,173
Fair value adjustment on exercise of warrants | $		$ 100
Common stock reserved for issuance (shares)						15,628,172
Number of shares available for grant (in shares)		3,700,000			3,700,000	3,900,000	3,700,000
Early exercises, compensation cost | $						$ 400	$ 1,200	$ 2,300
Common stock, shares outstanding including early exercises (shares)		38,266,450			38,266,450	43,450,819	38,266,450
Options grants in period, weighted average grant date fair value (in dollars per share) | $ / shares						$ 14.95	$ 9.79	$ 8.24
Aggregate intrinsic value of employee options exercised | $						$ 71,900	$ 4,400	$ 6,000
Unrecognized compensation cost related to unvested options | $						$ 11,500
Share price (in dollars per share) | $ / shares	$ 32.76
Number of employees with separation agreements | employee								3
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period						10 years
Straight-line basis weighted-average amortization period						1 year 4 months 24 days
Equity award plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (shares)						3,905,796
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (shares)						793,617
Number of shares available for grant (in shares)			800,000	800,000
Purchase price of common stock, percent of market price				85.00%
Annual increase to shares available for future issuance (in shares)			800,000	800,000
Percentage of common stock outstanding annual increase to shares available for issuance			1.00%	1.00%
Stock purchase offering period				6 months
Participants maximum percentage of annual salary			15.00%	15.00%
Shares purchased during period (in shares)						387,602
Weighted average price of shares purchased (in dollars per share) | $ / shares						$ 19.53
Proceeds from issuance of shares under ESPP | $						$ 7,600
Unrecognized compensation cost | $						$ 1,200
Straight-line basis weighted-average amortization period						4 months 24 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (shares)						5,709,472
Award vesting period						4 years
Unrecognized compensation cost | $						$ 124,300
Straight-line basis weighted-average amortization period						2 years 10 months 25 days
RSUs vested (shares)	892,996					1,607,000
Award requisite service period						181 days
Stock options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $			$ 21,200
Non-Executive Employee | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Adjustments related to tax withholding for share-based compensation | $	$ 1,800
Executive Officer | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares paid for tax withholding for share based compensation (in shares)	227,044
Adjustments related to tax withholding for share-based compensation | $	$ 7,400
CEO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock-based compensation cost over service period | $							$ 7,600
Incremental stock-based compensation expense | $					$ 6,500	$ 1,100
2000 Stock Option and Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent of market price						100.00%
Outstanding common stock ownership threshold, percentage						10.00%
Purchase price of common stock for executive officers that own more than 10%, percent of market price						110.00%
Option expiration period						10 years
2000 Stock Option and Incentive Plan | Stock options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						4 years
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized to be added to the Plan (shares)			12,500,000	12,500,000
Annual increase to shares available for future issuance (in shares)			3,800,000	3,800,000
Percentage of common stock outstanding annual increase to shares available for issuance			5.00%	5.00%
2017 Equity Incentive Plan | Equity award plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (shares)			3,800,000	3,800,000
Common stock warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued, price per share (in dollars per share) | $ / shares		$ 25.28			$ 25.28	$ 33.36	$ 25.28
Issuance of common stock upon exercise of common stock warrants (in shares)						66,661	111,147
Warrants to purchase common stock (in shares)		149,786			149,786	83,163	149,786
Common stock reserved for issuance (shares)						74
Redeemable convertible preferred stock warrant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued, price per share (in dollars per share) | $ / shares		$ 25.12			$ 25.12		$ 25.12
Issuance of common stock upon exercise of common stock warrants (in shares)							224,691
Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares converted into common stock (in shares)				25,370,616			24,845,000
Shares issued as stock dividend (in shares)							582,000
Issuance of common stock upon exercise of common stock warrants (in shares)						67,000	280,000
Stock issued for tax obligations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in IPO (in shares)	55,904
IPO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
IPO price per share (in dollars per share) | $ / shares			$ 22	$ 22
Number of shares issued in IPO (in shares)			6,072,000

Common Stock and Stockholders_4

Common Stock and Stockholders' Equity - Common Stock Reserved for Issuance (Details)	Dec. 31, 2018shares
Class of Stock [Line Items]
Common stock reserved for issuance (shares)	15,628,172
Equity award plans
Class of Stock [Line Items]
Common stock reserved for issuance (shares)	3,905,796
Stock options | Common stock
Class of Stock [Line Items]
Common stock reserved for issuance (shares)	6,012,830
Restricted stock units
Class of Stock [Line Items]
Common stock reserved for issuance (shares)	5,709,472
Common stock warrants
Class of Stock [Line Items]
Common stock reserved for issuance (shares)	74

Common Stock and Stockholders_5

Common Stock and Stockholders' Equity - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Balance beginning of the period (shares)		9,314,000	9,588,000
Options granted (shares)		44,000	549,000
Options forfeited (shares)		(366,000)	(517,000)
Options exercised (shares)	(425,436)	(2,979,000)	(306,000)
Balance end of the period (shares)		6,013,000	9,314,000	9,588,000
Weighted- Average Exercise Price
Balance beginning of the period (in dollars per share)		$ 10.63	$ 10.13
Options granted (in dollars per share)		30.81	20.05
Options forfeited (in dollars per share)		16.59	14.58
Options exercised (in dollars per share)		8.13	5.32
Balance end of the period (in dollars per share)		$ 11.65	$ 10.63	$ 10.13
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Options vested and exercisable at end of period (shares)		4,525,000
Options vested and exercisable at end of period (in dollars per share)		$ 10.26
Balance, Weighted-Average Remaining Contractual Life (Years)		6 years 4 months 24 days	7 years 2 months 12 days	8 years
Options vested and exercisable, Weighted Average-Remaining Contractual Life (Years)		6 years 1 month 6 days
Balance, Aggregate Intrinsic Value		$ 86,624	$ 198,012	$ 61,865
Options vested and exercisable at end of period, Aggregate Intrinsic Value		$ 71,237

Common Stock and Stockholders_6

Common Stock and Stockholders' Equity - RSU Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	Apr. 25, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Balance at beginning of period (shares)		4,216,000	1,899,000
RSUs granted (shares)		3,354,000	2,355,000
RSUs released (shares)	(892,996)	(1,607,000)
RSUs forfeited (shares)		(254,000)	(38,000)
Balance at end of period (shares)		5,709,000	4,216,000	1,899,000
Weighted- Average Grant Date Fair Value Per Share
Balance at beginning of period (in dollars per share)		$ 20.57	$ 14.83
RSUs granted (in dollars per share)		30.94	25.20
RSUs released (in dollars per share)		14.78
RSUs forfeited (in dollars per share)		26.80	20.44
Balance at end of period (in dollars per share)		$ 28.01	$ 20.57	$ 14.83
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures
Balance, Weighted-Average Remaining Contractual Live (Years)		1 year 9 months 18 days	1 year 8 months 12 days	1 year 8 months 12 days
Balance, Aggregate Intrinsic Value		$ 148,389	$ 134,448	$ 30,720

Common Stock and Stockholders_7

Common Stock and Stockholders' Equity - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 13,953	$ 13,018	$ 12,936	$ 13,590	$ 30,536	$ 3,909	$ 3,933	$ 4,218	$ 53,497	$ 42,596	$ 16,834
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,688	2,613	2,513	2,347	4,170	630	613	800	10,161	6,213	2,311
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	6,804	6,165	5,850	6,180	9,583	1,602	1,609	1,657	24,999	14,451	8,084
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3,578	3,458	3,796	4,237	15,379	1,372	1,372	1,415	15,069	19,538	5,286
Product | Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	79	67	54	53	43	19	20	21	253	103	30
Maintenance and professional services | Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 804	$ 715	$ 723	$ 773	$ 1,361	$ 286	$ 319	$ 325	$ 3,015	$ 2,291	$ 1,123

Common Stock and Stockholders_8

Common Stock and Stockholders' Equity - Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	2.40%	1.90%	1.20%
Risk-free interest rate, maximum	2.80%	2.20%	2.10%
Expected term (in years)	6 years 1 month 6 days
Volatility	48.00%
Volatility, minimum		46.00%	47.00%
Volatility, maximum		49.00%	51.00%
Dividend yield	0.00%	0.00%	0.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)		$ 25.12	$ 0
Risk-free interest rate		1.40%	0.00%
Expected term (in years)	6 months	6 months 7 days	0 years
Volatility		30.00%	0.00%
Volatility, minimum	30.00%
Volatility, maximum	43.00%
Dividend yield	0.00%	0.00%	0.00%
Minimum | Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years	6 years
Minimum | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)		$ 24.65
Risk-free interest rate	2.14%
Maximum | Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years 1 month 6 days	8 years 1 month 6 days
Maximum | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)		$ 31
Risk-free interest rate	2.52%
Common stock | Minimum | Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)	$ 29.92	16.73	$ 15.78
Common stock | Maximum | Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)	$ 30.97	$ 31.16	$ 21.56

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic									$ (85,252)	$ (82,292)	$ (66,810)
Foreign									13,361	3,411	2,581
Loss before income taxes	$ (16,938)	$ (7,952)	$ (19,933)	$ (27,068)	$ (33,950)	$ (879)	$ (17,617)	$ (26,435)	$ (71,891)	$ (78,881)	$ (64,229)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal									$ 1	$ 17	$ 4
State									56	50	66
Foreign									3,263	1,788	1,273
Total current									3,320	1,855	1,343
Deferred
Foreign									(375)	(16)	(93)
Total deferred									(375)	(16)	(93)
Total	$ 1,010	$ 334	$ 473	$ 1,128	$ 618	$ 412	$ 174	$ 635	$ 2,945	$ 1,839	$ 1,250

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Federal and state net operating losses	$ 59,803	$ 43,410
Research/other credits	2,913	1,060
Non-deductible and accrued expenses	4,756	4,485
Deferred revenue	14,040	3,725
Property and equipment	506	0
Stock-based compensation	10,323	9,507
Other	1,024	610
Gross deferred tax assets	93,365	62,797
Valuation allowance	(83,376)	(54,233)
Net deferred tax assets	9,989	8,564
Deferred tax liabilities:
Acquired intangible assets	(4,117)	0
Property and equipment	0	(13)
Property and equipment	(8,691)	(8,375)
Others	(116)	0
Net deferred tax liabilities	(12,924)	(8,388)
Total	$ (2,935)
Total		$ 176

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax at federal statutory rate									$ (15,097)	$ (30,385)	$ (21,838)
State, net of federal benefit									61	60	61
Stock-based compensation									(6,215)	4,097	3,225
Non-deductible warrant expenses									0	272	(365)
Tax Reform federal rate change									0	36,460	0
Change in valuation allowance									23,929	(10,512)	19,225
Other									267	1,847	942
Total	$ 1,010	$ 334	$ 473	$ 1,128	$ 618	$ 412	$ 174	$ 635	$ 2,945	$ 1,839	$ 1,250

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Tax reform federal rate change	$ 0	$ 36,460	$ 0
Provisional undistributed accumulated earnings of foreign subsidiary		6,900
Undistributed earnings of foreign subsidiaries		5,900
Increase (decrease) in valuation allowance	29,100	(900)
Operating loss carryforward written off due to limitation	2,800
Settlements with taxing authorities	0	416	$ 0
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	243,800
Research and development tax credit carryforward | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	1,800
California | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	29,300
California | Research and development tax credit carryforward | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	1,200
Other states excluding California | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	102,900
Texas | Research and development tax credit carryforward | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 100
Israel Tax Authority | Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Settlements with taxing authorities		400
Increase in income taxes payable		$ 400

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at the beginning of the period	$ 1,727	$ 1,050	$ 254
Additions for tax positions taken in prior years	104	248	185
Additions for tax positions taken in current year	195	845	611
Reductions for tax positions taken in prior years	(759)	0
Settlements with taxing authorities	0	(416)	0
Unrecognized tax benefits at the end of the period	$ 1,267	$ 1,727	$ 1,050

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net loss	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (34,568)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (80,720)	$ (65,479)
Deemed dividend on the conversion of Series G redeemable convertible preferred stock	0	0	0	0	12,810	0	0	0	0	12,810	0
Net loss attributable to common stockholders	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (47,378)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (93,530)	$ (65,479)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	43,016	42,064	40,457	38,313	27,349	6,140	6,031	5,924	40,980	11,405	5,609
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.42)	$ (0.20)	$ (0.50)	$ (0.74)	$ (1.73)	$ (0.21)	$ (2.95)	$ (4.57)	$ (1.83)	$ (8.20)	$ (11.67)

Net Loss Per Share - Securities

Net Loss Per Share - Securities Excluded from Diluted Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	6,013	9,314	9,588
Unvested early exercised common shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	47	146	330
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	5,709	4,216	1,899
Shares estimated under ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	233	221	0
Warrants to purchase | Common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	0	83	233
Warrants to purchase | Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	0	0	293
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of diluted net loss per share (shares)	0	0	24,788

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Estimated accrued severance benefits, noncurrent liability	$ 2,505,000	$ 2,617,000
Deposits in severance pay fund	$ 1,973,000	2,118,000
Company percent of match	50.00%
Employee percent contributed for company match	6.00%
Maximum matching dollar amount	$ 2,000
Matching contributions vesting percentage	100.00%
Company contributions to the 401(k)	$ 1,300,000	$ 1,100,000	$ 1,000,000

Segment Information - Narrative

Segment Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2018business_activitysegment
Segment Reporting [Abstract]
Number of business activities | business_activity	1
Single reportable segment	1
Single operating unit structure	1

Segment Information - Revenue (

Segment Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Total Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									222,205	171,262	138,182
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									215,322	165,140	132,216
Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									6,883	6,122	5,966
Europe, Middle East, and Africa (“EMEA”)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									52,214	36,664	19,381
Asia Pacific and Japan (“APJ”)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									$ 23,232	$ 16,478	$ 9,983

Segment Information - Long-live

Segment Information - Long-lived Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	$ 24,349	$ 23,260
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	18,570	18,989
Israel
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	5,057	3,453
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	$ 722	$ 818

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) - Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue	$ 84,732	$ 85,628	$ 67,594	$ 59,697	$ 62,907	$ 69,340	$ 49,981	$ 42,176	$ 297,651	$ 224,404	$ 167,546
Cost of revenue:
Cost of revenue	17,486	19,197	14,713	16,486	16,073	15,928	14,088	12,523	67,882	58,612	48,403
Total gross profit	67,246	66,431	52,881	43,211	46,834	53,412	35,893	29,653	229,769	165,792	119,143
Operating expenses:
Research and development	17,161	15,062	14,803	14,687	14,801	10,985	10,702	10,947	61,713	47,435	31,490
Sales and marketing	50,464	46,098	45,039	42,279	41,769	34,028	33,556	35,045	183,880	144,398	119,071
General and administrative	16,849	13,880	13,260	13,732	23,941	9,148	8,902	9,215	57,721	51,206	30,731
Total operating expenses	84,474	75,040	73,102	70,698	80,511	54,161	53,160	55,207	303,314	243,039	181,292
Loss from operations	(17,228)	(8,609)	(20,221)	(27,487)	(33,677)	(749)	(17,267)	(25,554)	(73,545)	(77,247)	(62,149)
Interest expense	(237)	(208)	(225)	(243)	(270)	(290)	(318)	(345)	(913)	(1,223)	(2,577)
Other income (expense), net	527	865	513	662	382	160	(82)	(144)	2,567	316	(607)
Revaluation of warrant liabilities	0	0	0	0	(385)	0	50	(392)	0	(727)	1,104
Loss before income taxes	(16,938)	(7,952)	(19,933)	(27,068)	(33,950)	(879)	(17,617)	(26,435)	(71,891)	(78,881)	(64,229)
Income tax provision	1,010	334	473	1,128	618	412	174	635	2,945	1,839	1,250
Net loss	(17,948)	(8,286)	(20,406)	(28,196)	(34,568)	(1,291)	(17,791)	(27,070)	(74,836)	(80,720)	(65,479)
Deemed dividend on the conversion of Series G redeemable convertible preferred stock	0	0	0	0	12,810	0	0	0	0	12,810	0
Net loss attributable to common stockholders	$ (17,948)	$ (8,286)	$ (20,406)	$ (28,196)	$ (47,378)	$ (1,291)	$ (17,791)	$ (27,070)	$ (74,836)	$ (93,530)	$ (65,479)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.42)	$ (0.20)	$ (0.50)	$ (0.74)	$ (1.73)	$ (0.21)	$ (2.95)	$ (4.57)	$ (1.83)	$ (8.20)	$ (11.67)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	43,016	42,064	40,457	38,313	27,349	6,140	6,031	5,924	40,980	11,405	5,609
Product
Revenue:
Revenue	$ 47,482	$ 51,082	$ 34,323	$ 29,780	$ 34,994	$ 43,204	$ 26,842	$ 20,308	$ 162,667	$ 125,348	$ 97,994
Cost of revenue:
Cost of revenue	6,852	8,947	4,919	7,136	6,964	7,240	5,545	4,092	27,854	23,841	21,832
Maintenance and professional services
Revenue:
Revenue	37,250	34,546	33,271	29,917	27,913	26,136	23,139	21,868	134,984	99,056	69,552
Cost of revenue:
Cost of revenue	$ 10,634	$ 10,250	$ 9,794	$ 9,350	$ 9,109	$ 8,688	$ 8,543	$ 8,431	$ 40,028	$ 34,771	$ 26,571

Selected Quarterly Financial _4

Selected Quarterly Financial Data (Unaudited) - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 13,953	$ 13,018	$ 12,936	$ 13,590	$ 30,536	$ 3,909	$ 3,933	$ 4,218	$ 53,497	$ 42,596	$ 16,834
Cost of revenue | Product
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	79	67	54	53	43	19	20	21	253	103	30
Cost of revenue | Maintenance and professional services
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	804	715	723	773	1,361	286	319	325	3,015	2,291	1,123
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,688	2,613	2,513	2,347	4,170	630	613	800	10,161	6,213	2,311
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	6,804	6,165	5,850	6,180	9,583	1,602	1,609	1,657	24,999	14,451	8,084
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,578	$ 3,458	$ 3,796	$ 4,237	$ 15,379	$ 1,372	$ 1,372	$ 1,415	$ 15,069	$ 19,538	$ 5,286