Varonis Systems (VRNS) 10-K 12 Feb 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 08, 2019	Jun. 30, 2018
Document Information [Line Items]
Entity Registrant Name	VARONIS SYSTEMS INC
Entity Central Index Key	1,361,113
Trading Symbol	vrns
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		29,580,605
Entity Public Float			$ 2,150
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Emerging Growth Company	false
Entity Small Business	false
Amendment Flag	false
Entity Shell Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 48,707	$ 56,689
Marketable securities	39,770	39,731
Short-term deposits	70,438	40,137
Trade receivables (net of allowance for doubtful accounts of $483 and $433 at December 31, 2018 and December 31, 2017, respectively)	83,223	75,596
Prepaid expenses and other current assets	16,952	14,346
Total current assets	259,090	226,499
Long-term assets:
Other assets	8,565	7,243
Property and equipment, net	17,323	11,896
Total long-term assets	25,888	19,139
Total assets	284,978	245,638
Current liabilities:
Trade payables	2,620	635
Accrued expenses and other short term liabilities	55,991	42,453
Deferred revenues	87,729	73,493
Total current liabilities	146,340	116,581
Long-term liabilities:
Deferred revenues	6,487	6,608
Other liabilities	6,781	7,807
Total long-term liabilities	13,268	14,415
Stockholders’ equity:
Common stock of $0.001 par value - Authorized: 200,000,000 shares at December 31, 2018 and 2017; Issued and outstanding: 29,576,880 shares at December 31, 2018 and 28,146,162 shares at December 31, 2017	30	28
Accumulated other comprehensive income (loss)	(3,633)	136
Additional paid-in capital	266,941	223,868
Accumulated deficit	(137,968)	(109,390)
Total stockholders’ equity	125,370	114,642
Total liabilities and stockholders’ equity	$ 284,978	$ 245,638

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 483	$ 433
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	29,576,880	28,146,162
Common stock, shares, outstanding	29,576,880	28,146,162

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenue	$ 270,288	$ 215,390	$ 165,863
Cost of revenues	27,683	20,714	15,737
Gross profit	242,605	194,676	150,126
Operating costs and expenses:
Research and development	69,971	47,369	36,660
Sales and marketing	168,309	133,925	105,639
General and administrative	33,460	26,801	19,822
Total operating expenses	271,740	208,095	162,121
Operating loss	(29,135)	(13,419)	(11,995)
Financial income (expenses), net	970	2,362	(885)
Loss before income taxes	(28,165)	(11,057)	(12,880)
Income taxes	(413)	(2,787)	(1,313)
Net loss	$ (28,578)	$ (13,844)	$ (14,193)
Net loss per share of common stock, basic and diluted	$ (0.984737072521992)	$ (0.5)	$ (0.54)
Weighted average number of shares used in computing net loss per share of common stock, basic and diluted	29,020,645	27,467,440	26,406,312
License
Revenues:
Revenue	$ 147,613	$ 120,341	$ 93,243
Maintenance
Revenues:
Revenue	$ 122,675	$ 95,049	$ 72,620

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	$ (28,578)	$ (13,844)	$ (14,193)
Other comprehensive income (loss):
Unrealized income (loss) on marketable securities, net of tax	48	(27)	0
Gains on marketable securities reclassified into earnings, net of tax	(27)	0	0
Total	21	(27)	0
Unrealized income (loss) on short-term investments, net of tax	(7,531)	3,291	184
Losses (gains) on derivative instruments reclassified into earnings, net of tax	3,741	(2,649)	(332)
Total	(3,790)	642	(148)
Total other comprehensive income (loss)	(3,769)	615	(148)
Comprehensive loss	$ (32,347)	$ (13,229)	$ (14,341)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive	Accumulated deficit
Effect of adoption of ASU | Accounting Standards Update 2014-09	$ 9,697				$ 9,697
Balance (in shares) at Dec. 31, 2015		26,069
Balance at Dec. 31, 2015	83,587	$ 26	$ 172,326	$ (331)	(88,434)
Stock-based compensation expense	12,938		12,938
Common stock issued under employee stock plans, net (in shares)		753
Common stock issued under employee stock plans, net	4,072	$ 1	4,071
Unrealized gain (loss) on derivative instruments	(148)			(148)
Unrealized gains and losses on available for sale securities	0
Net loss	(14,193)				(14,193)
Net loss | Accounting Standards Update 2014-09	(14,193)
Balance (in shares) at Dec. 31, 2016		26,822
Balance at Dec. 31, 2016	95,953	$ 27	189,335	(479)	(92,930)
Effect of adoption of ASU | Accounting Standards Update 2016-09	0		2,616		(2,616)
Stock-based compensation expense	19,835		19,835
Common stock issued under employee stock plans, net (in shares)		1,324
Common stock issued under employee stock plans, net	12,083	$ 1	12,082
Unrealized gain (loss) on derivative instruments	642			642
Unrealized gains and losses on available for sale securities	(27)			(27)
Net loss	(13,844)				(13,844)
Net loss | Accounting Standards Update 2014-09	(13,844)
Balance (in shares) at Dec. 31, 2017		28,146
Balance at Dec. 31, 2017	114,642	$ 28	223,868	136	(109,390)
Stock-based compensation expense	34,961		34,961
Common stock issued under employee stock plans, net (in shares)		1,431
Common stock issued under employee stock plans, net	8,114	$ 2	8,112
Unrealized gain (loss) on derivative instruments	(3,790)			(3,790)
Unrealized gains and losses on available for sale securities	21			21
Net loss	(28,578)				(28,578)
Balance (in shares) at Dec. 31, 2018		29,577
Balance at Dec. 31, 2018	$ 125,370	$ 30	$ 266,941	$ (3,633)	$ (137,968)

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	$ (28,578)	$ (13,844)	$ (14,193)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation	4,156	3,328	2,180
Stock-based compensation	34,961	19,835	12,938
Amortization of deferred commissions	13,185	12,591	9,525
Capital gain from disposal of fixed assets	(27)	(20)	(2)
Prepaid expenses and other current assets
Deferred commissions	(7,627)	(21,735)	(6,425)
Other long term assets	(1,932)	(3,317)	(1,028)
Deferred commissions	(15,308)	(14,742)	(11,817)
Other long term assets	(270)	0	0
Trade payables	1,985	(653)	(1,324)
Accrued expenses and other short term liabilities	9,910	14,453	5,302
Deferred revenues	14,115	20,860	11,860
Other long term liabilities	(1,025)	(405)	331
Net cash provided by operating activities	23,545	16,351	7,347
Cash flows from investing activities:
Decrease (increase) in short-term deposits	(30,280)	25,329	(8,390)
Increase in marketable securities	(39)	(39,731)	0
Increase in long-term deposits	(313)	(305)	(111)
Proceeds from sale of property and equipment	27	20	2
Purchase of property and equipment	(9,583)	(5,314)	(3,825)
Net cash used in investing activities	(40,188)	(20,001)	(12,324)
Cash flows from financing activities:
Proceeds from employee stock plans, net	8,114	12,083	4,072
Net cash provided by financing activities	8,114	12,083	4,072
Increase (decrease) in cash, cash equivalents and restricted cash	(8,529)	8,433	(905)
Cash, cash equivalents and restricted cash at beginning of period	57,236	48,803	49,708
Cash, cash equivalents and restricted cash at end of period	48,707	57,236	48,803
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 710	$ 469	$ 246

General

General	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	GENERAL Varonis Systems, Inc. (“VSI” and together with its subsidiaries, collectively, the “Company”) was incorporated under the laws of the State of Delaware on November 3, 2004 and commenced operations on January 1, 2005 . VSI has nine wholly-owned subsidiaries: Varonis Systems Ltd. (“VSL”) incorporated under the laws of Israel on November 24, 2004 ; Varonis (UK) Limited (“VSUK”) incorporated under the laws of England on March 14, 2007; Varonis Systems (Deutschland) GmbH (“VSG”) incorporated under the laws of Germany on July 6, 2011; Varonis France SAS (“VSF”) incorporated under the laws of France on February 22, 2012; Varonis Systems Corp. (“VSC”) incorporated under the laws of British Columbia, Canada on February 19, 2013; Varonis Systems (Ireland) Limited (“VIRE”) incorporated under the laws of Ireland on November 11, 2016; and Varonis Systems (Australia) Pty Ltd (“VAUS”) incorporated under the laws of Victoria, Australia on February 28, 2017; Varonis Systems (Netherlands) B.V. ("VNL") incorporated under the laws of the Netherlands on March 13, 2018; and Varonis U.S. Public Sector LLC ("VPS") incorporated under the laws of the State of Delaware on May 14, 2018. The Company’s software products and services allow enterprises to manage, analyze and secure enterprise data. Varonis focuses on protecting enterprise data: sensitive files and emails; confidential customer, patient and employee data; financial records; strategic and product plans; and other intellectual property. Through its products DatAdvantage (including the Automation Engine), DatAlert (including Varonis Edge), DataPrivilege, Data Classification Engine (including GDPR Patterns and Data Classification Labels), Data Transport Engine and DatAnswers, the software platform allows enterprises to protect sensitive data from insider threats and cyberattacks, and realize the value of their enterprise data in ways that are not resource-intensive and easy to implement. VSI and VPS market and sell products and services mainly in the United States. VSUK, VSG, VSF, VSC, VIRE, VAUS and VNL resell the Company’s products and services mainly in the UK, Germany, France, Canada, Ireland, Australia and the Netherlands and Belgium, respectively. The Company primarily sells its products and services to a global network of distributors and Value Added Resellers (VARs), which sell the products to end user customers.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES The consolidated financial statements are prepared according to United States generally accepted accounting principles (“U.S. GAAP”), applied on a consistent basis, as follows: a. Use of Estimates: The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates, judgments and assumptions. The Company’s management believes that the estimates, judgments and assumptions used are reasonable based upon information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company’s management evaluates estimates, including those related to accounts receivable and sales allowances, fair values of stock-based awards, deferred taxes and income tax uncertainties, and contingent liabilities. Such estimates are based on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. b. Financial Statements in U.S. Dollars: Most of the revenues and costs of VSI are denominated in United States dollars (“dollars”). Some of the subsidiaries’ revenues and costs are primarily incurred in Euros, the Pound Sterling, Canadian dollars, Australian dollars and NIS; however, the Company’s management believes that the dollar is the primary currency of the economic environment in which VSI and each of its subsidiaries operate. Thus, the dollar is the Company’s functional and reporting currency. Accordingly, transactions denominated in currencies other than the functional currency are re-measured to the functional currency in accordance with ASC No. 830, “Foreign Currency Matters” at the exchange rate at the date of the transaction or the average exchange rate in the quarter. At the end of each reporting period, financial assets and liabilities are re-measured to the functional currency using exchange rates in effect at the balance sheet date. Non-financial assets and liabilities are re-measured at historical exchange rates. Gains and losses related to re-measurement are recorded as financial income (expense) in the consolidated statements of operations as appropriate. c. Principles of Consolidation: The consolidated financial statements include the accounts of VSI and its wholly-owned subsidiaries, VSL, VSUK, VSG, VSF, VSC, VIRE, VAUS, VNL and VPS. All intercompany transactions and balances have been eliminated upon consolidation. d. Cash, Cash Equivalents, Marketable Securities and Short-Term Deposits: The Company accounts for investments in marketable securities in accordance with ASC No. 320, “Investments—Debt and Equity Securities”. The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents consist of cash on hand, highly liquid investments in money market funds and various deposit accounts. The Company considers all high quality investments purchased with original maturities at the date of purchase greater than three months to be short-term deposits. Investments are available to be used for current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents, marketable securities and short-term deposits are classified as available for sale and are, therefore, recorded at fair value on the consolidated balance sheet, with any unrealized gains and losses reported in accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s consolidated balance sheets, until realized. The Company uses the specific identification method to compute gains and losses on the investments. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included as a component of financial income, net in the consolidated statement of operations. Cash, cash equivalents, marketable securities and short-term deposits consist of the following (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 2,594 $ — $ — $ 2,594 Total $ 2,594 $ — $ — $ 2,594 Marketable securities US Treasury securities $ 39,776 *) $ (6 ) $ 39,770 Total $ 39,776 *) $ (6 ) $ 39,770 Short-term deposits Term bank deposits $ 70,438 $ — $ — $ 70,438 Total $ 70,438 $ — $ — $ 70,438 *) Represents an amount lower than $1. As of December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 6,870 $ — $ — $ 6,870 Total $ 6,870 $ — $ — $ 6,870 Marketable securities US Treasury securities $ 39,758 *) $ (27 ) $ 39,731 Total $ 39,758 *) $ (27 ) $ 39,731 Short-term deposits Term bank deposits $ 40,137 $ — $ — $ 40,137 Total $ 40,137 $ — $ — $ 40,137 *) Represents an amount lower than $1. All the US Treasury securities in short-term deposits have a stated effective maturity of less than 12 months as of December 31, 2018 and 2017 . The gross unrealized loss related to these short-term deposits was due primarily to changes in interest rates. The Company reviews its short-term deposits on a regular basis to evaluate whether or not any security has experienced an other than temporary decline in fair value. The Company considers factors such as length of time and extent to which the market value has been less than the cost, the financial condition and near-term prospects of the issuer and its intent to sell, or whether it is more likely than not the Company will be required to sell the investment before recovery of the investment’s amortized cost basis. If the Company believes that an other than temporary decline exists in one of these securities, the Company writes down these investments to fair value. For debt securities, the portion of the write-down related to credit loss would be recorded to other income (expense), net in the Company’s consolidated statements of operations. Any portion not related to credit loss would be recorded to accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s condensed consolidated balance sheets. During the year ended December 31, 2018 and 2017, the Company did not consider any of its investments to be other-than-temporarily impaired. A short-term bank deposit is a deposit with a maturity of more than three months but less than one year. Deposits in U.S. dollars bore interest at rates ranging from 0.60% - 2.77% and 0.60% - 1.35% , per annum, as of December 31, 2018 and 2017 , respectively. There were no deposits in NIS as of December 31, 2018 , and, as of December 31, 2017 , the Company's deposits in NIS bore interest at a rate of 0.03% per annum. Short-term deposits are presented at cost which approximates market value due to their short maturities. e. Restricted Cash: Restricted cash is primarily invested in certificates of deposit and is used mostly as security for the Company’s lease commitments. The Company had no short-term restricted cash as of December 31, 2018 and 2017 . The Company had no long-term restricted cash as of December 31, 2018 and $547 in long-term restricted cash as of December 31, 2017 . f. Property and Equipment: Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets at the following annual rates: % Computer equipment 33 Office furniture and equipment 14 — 15 Leasehold improvements Over the shorter of the expected lease g. Impairment of Long-Lived Assets: The Company’s long-lived assets are reviewed for impairment in accordance with ASC No. 360 “Property, Plant and Equipment” whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. Recoverability of assets (or asset group) to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. During the years ended December 31, 2018 , 2017 and 2016 , no impairment losses have been recorded. h. Long-Term Lease Deposits: Long-term lease deposits include long-term deposits for offices. i. Revenue Recognition: The Company generates revenues in the form of software license fees and related maintenance and services fees. License fees include perpetual license fees and subscription license fees which provide customers with the same functionality and differ in the duration over which the customer benefits from the software. Maintenance and services primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements when and if they are available) and to a lesser extent professional services which focus on both operationalizing the software and training the Company’s customers to fully leverage the use of its products although the user can benefit from the software without the Company’s assistance. The Company sells its products worldwide directly to a network of distributors and VARs, and payment is typically due within 30 to 60 calendar days of the invoice date. The Company recognizes revenues in accordance with ASC No. 606, “Revenue from Contracts with Customers”. As such, the Company identifies a contract with a customer, identifies the performance obligations in the contract, determines the transaction price, allocates the transaction price to each performance obligation in the contract and recognizes revenues when (or as) the Company satisfies a performance obligation. Software license revenues are recognized at the point of time when the software license has been delivered and the benefit of the asset has transferred. The Company recognizes revenues from maintenance ratably over the term of the underlying maintenance contract term. The term of the maintenance contract is usually one year. Renewals of maintenance contracts create new performance obligations that are satisfied over the term with the revenues recognized ratably over the period. Revenues from professional services consist mostly of time and material services. The performance obligations are satisfied, and revenues are recognized, when the services are provided or once the service term has expired. The Company enters into contracts that can include combinations of products and services, which are generally capable of being distinct and accounted for as separate performance obligations. The license is distinct upon delivery as the customer can derive the economic benefit of the software without any professional services, updates or technical support. The Company allocates the transaction price to each performance obligation based on its relative standalone selling price out of the total consideration of the contract. For maintenance, the Company determines the standalone selling prices based on the price at which the Company separately sells a renewal contract. For professional services, the Company determines the standalone selling prices based on the price at which the Company separately sells those services. For software licenses, the Company uses the residual approach to determine the standalone selling prices due to the lack of history of selling software license on a standalone basis. Trade and other receivables are primarily comprised of trade receivables that are recorded at the invoice amount, net of an allowance for doubtful accounts. Deferred revenues represent mostly unrecognized fees billed or collected for maintenance and professional services. Deferred revenues are recognized as (or when) the Company performs under the contract. The amount of revenues recognized in the period that was included in the opening deferred revenues balance was $73,176 for the year ended December 31, 2018. The Company does not grant a right of return to its customers, except for one of its resellers. During the years ended December 31, 2018 , 2017 and 2016 , there were no returns from this reseller. For information regarding disaggregated revenues, please refer to Note 11 below. j. Contract Costs: The Company pays sales commissions to sales and marketing and certain management personnel based on their attainment of certain predetermined sales goals. Sales commissions earned by its employees are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions paid for initial contracts, which are not commensurate with sales commissions paid for renewal contracts, are capitalized and amortized over an expected period of benefit. Based on its technology, customer contracts and other factors, the Company has determined the expected period of benefit to be approximately four years. Sales commissions for renewal contracts are capitalized and then amortized on a straight line basis over the related contractual renewal period. Amortization expenses related to these costs are mostly included in sales and marketing expenses in the accompanying consolidated statements of operations. k. Cost of Revenues: Cost of revenues consists of the cost of maintenance and services, resulting from costs associated with support, and professional services. l. Accounting for Stock-Based Compensation: The Company accounts for stock-based compensation in accordance with ASC No. 718, “Compensation-Stock Compensation”. ASC No. 718 requires companies to estimate the fair value of equity-based payment awards on the date of grant using an OPM. The value of the portion of the award that is ultimately expected to vest is recognized as an expense over the requisite service periods in the Company’s consolidated statements of operations. The Company recognizes compensation expenses for the value of its awards granted based on the straight-line method over the requisite service period of each of the awards. The Company applies ASC 718 and ASC 505-50, “Equity-Based Payments to Non-Employees” with respect to options issued to non-employee consultants. Accordingly, the Company uses option valuation models to measure the fair value of the options at the measurement date as defined in ASC 505-50. The Company selected the Black-Scholes-Merton option pricing model as the most appropriate fair value method for its stock options awards, whereas the fair value of restricted stock units is based on the market value of the underlying shares at the date of grant. The fair value of options granted to employees and non-employee directors is estimated at the date of grant using the following weighted average assumptions: For the years ended December 31, 2018 and 2017 , there were no stock options granted. For the year ended December 31, 2016, dividend yield was 0% , expected volatility was 62.1% , risk-free interest was 1.42% and expected life was 6.25 . The Company used its historical volatility in accordance with ASC 718. The computation of volatility uses historical volatility derived from the Company’s exchange traded shares. Expected term of options granted is calculated based on the simplified method, in accordance with SAB 110, (i.e., as the average between the vesting period and the contractual term of the options). The risk free interest rate assumption is the implied yield currently available on United States treasury zero-coupon issues with a remaining term equal to the expected life of the Company’s options. The dividend yield assumption is based on the Company’s historical experience and expectation of no future dividend payouts and may be subject to substantial change in the future. The Company has historically not paid cash dividends and has no foreseeable plans to pay cash dividends in the future. The non-cash compensation expenses related to employees and consultants for the years ended December 31, 2018 , 2017 and 2016 amounted to $34,961 , $19,835 and $12,938 , respectively. Effective as of January 1, 2017, the Company adopted Accounting Standards Update 2016-09, “Compensation—Stock Compensation (Topic 718)” (“ASU 2016-09”) on a modified, retrospective basis. ASU 2016-09 permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation: to estimate the total number of awards for which the requisite service period will not be rendered or to account for forfeitures as they occur. Upon adoption of ASU 2016-09, the Company elected to change its accounting policy to account for forfeitures as they occur. The change was applied on a modified, retrospective basis with a cumulative-effect adjustment to retained earnings of $2,616 (which increased the accumulated deficit) as of January 1, 2017. ASU 2016-09 also eliminates the requirement that excess tax benefits be realized as a reduction in current taxes payable before the associated tax benefit can be recognized as an increase in paid in capital. Approximately $7,131 of federal net operating losses and $718 of state net operating losses, neither of which was included in the deferred tax assets recognized in the statement of financial position as of December 31, 2017 , have been attributed to tax deduction for stock-based compensation in excess of the related book expense. Under ASU 2016-09, these previously unrecognized deferred tax assets will be recognized on a modified, retrospective basis as of the start of the year in which the ASU 2016-09 is adopted; in this case as of January 1, 2017. The U.S. federal and state net operating losses and credits that were recognized as of January 1, 2017 have been offset by a valuation allowance. Additionally, ASU 2016-09 addresses the presentation of excess tax benefits and employee taxes paid on the statement of cash flows. The Company is now required to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. The Company adopted this change prospectively. m. Research and Development Costs: Research and development costs are charged to the statement of operations as incurred. ASC No. 985-20, “Software-Costs of Software to Be Sold, Leased, or Marketed,” requires capitalization of certain software development costs subsequent to the establishment of technological feasibility. Based on the Company’s product development process, technological feasibility is established upon the completion of a working model. The Company does not incur material costs between the completion of the working model and the point at which the product is ready for general release. Therefore, research and development costs are charged to the statement of operations as incurred. n. Income Taxes: The Company accounts for income taxes in accordance with ASC No. 740, using the liability method whereby deferred tax assets and liability account balances are determined based on the differences between financial reporting and the tax basis for assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, if necessary, to reduce deferred tax assets to the amounts that are more likely-than-not to be realized. ASC 740 contains a two-step approach to recognizing and measuring a liability for uncertain tax positions. The first step is to evaluate the tax position taken or expected to be taken in a tax return by determining if the weight of available evidence indicates that it is more likely than not that, on an evaluation of the technical merits, the tax position will be sustained on audit, including resolution of any related appeals or litigation processes. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon ultimate settlement. The Company accrues interest and penalties related to unrecognized tax provisions in its taxes on income. o. Derivative Instruments: The Company’s primary objective for holding derivative instruments is to reduce its exposure to foreign currency rate changes. The Company reduces its exposure by entering into forward foreign exchange contracts with respect to operating expenses that are forecast to be incurred in currencies other than the U.S. dollar. A majority of the Company’s revenues and operating expenditures are transacted in U.S. dollars. However, certain operating expenditures are incurred in or exposed to other currencies, primarily the NIS. The Company has established forecasted transaction currency risk management programs to protect against fluctuations in fair value and the volatility of future cash flows caused by changes in exchange rates. The Company’s currency risk management program includes forward foreign exchange contracts designated as cash flow hedges. These forward foreign exchange contracts generally mature within 12 months. The Company does not enter into derivative financial instruments for trading purposes. In addition, the Company enters into forward contracts to hedge a portion of its monetary items in the balance sheet, such as trade receivables and payables, denominated in Pound Sterling and Euro for short term periods (the “Fair Value Hedging Program”). The purpose of the Fair Value Hedging Program is to protect the fair value of the monetary assets from foreign exchange rate fluctuations. Gains and losses from derivatives related to the Fair Value Hedging Program are not designated as hedging instruments. Derivative instruments measured at fair value and their classification on the consolidated balance sheets are presented in the following table (in thousands): Liabilities as of Assets as of December 31, 2018 December 31, 2017 Notional Amount Fair Value Notional Amount Fair Value Foreign Exchange Forward Contract Derivatives in cash flow hedging relationships—included in other current assets and accrued expenses and other short term liabilities $ 75,153 $ (3,628 ) $ 1,746 $ 163 Foreign exchange forward contract derivatives for monetary items included in accrued expenses and other short term liabilities $ 29,162 $ (18 ) $ — $ — For the years ended December 31, 2018 and 2017 , the consolidated statements of operations reflect a loss of approximately $3,741 and a gain of $2,649 , respectively, related to the effective portion of foreign currency forward contracts. Any ineffective portion of the cash flow hedges is recognized in financial income (expenses), net in the consolidated statement of operations. No material ineffective hedges were recognized in financial income (expenses), net for the years ended December 31, 2018 and 2017 . For the year ended December 31, 2018 , the consolidated statements of operations reflect a gain of approximately $98 in financial income (expenses), net, related to the Fair Value Hedging Program. The Company did not enter into any transactions related to the Fair Value Hedging Program for year ended December 31, 2017 . p. Concentrations of Credit Risks: Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, marketable securities, short-term deposits and trade receivables. The Company’s cash, cash equivalents, marketable securities and short-term deposits are invested in major banks mainly in the United States but also in the United Kingdom, France, Germany, Israel, Canada, Ireland, Australia and the Netherlands. Such deposits in the United States may be in excess of insured limits and are not insured in other jurisdictions. The Company maintains cash and cash equivalents with diverse financial institutions and monitors the amount of credit exposure to each financial institution. The Company’s trade receivables are geographically diversified and derived primarily from sales to a network of distributors and VARs mainly in the United States and Europe. Concentration of credit risk with respect to trade receivables is limited by credit limits, ongoing credit evaluation and account monitoring procedures. The Company performs ongoing credit evaluations of its channel partners and establishes an allowance for doubtful accounts based upon a specific review of all significant outstanding invoices. The Company writes off receivables when they are deemed uncollectible and having exhausted all collection efforts. q. Retirement and Severance Pay: VSI makes available to its employees a retirement plan (the “U.S. Plan”) that qualifies as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code of 1986, as amended (“the Code”). Participants in the U.S. Plan may elect to defer a portion of their pre-tax earnings, up to the Internal Revenue Service annual contribution limit. VSI matches 100% of each participant’s contributions up to a maximum of 3% of the participant’s total pay and 50% of each participant’s contributions on contributions between 3% and 5% of the participant’s total pay. Each participant may contribute up to 80% of total remuneration up to the Internal Revenue Service’s annual contribution limit. Contributions to the U.S. Plan are recorded during the year contributed as an expense in the consolidated statements of income. Pursuant to Israel’s Severance Pay Law, Israeli employees are entitled to severance pay equal to one month’s salary for each year of employment, or a portion thereof. The employees of the Israeli subsidiary elected to be included under section 14 of the Severance Pay Law, 1963 (“section 14”). According to this section, these employees are entitled only to monthly deposits, at a rate of 8.33% of their monthly salary, made in their name with insurance companies. Payments in accordance with section 14 release the Company from any future severance payments (under the above Israeli Severance Pay Law) in respect of those employees; therefore, related assets and liabilities are not presented in the balance sheet. The Company’s liability for severance pay for the employees of its French subsidiary is calculated pursuant to French law, according to which French employees are entitled to an indemnity (a statutory redundancy). The law provides for the payment of severance payment to any employee working for the French subsidiary for at least a year. VSUK makes available to certain eligible employees a pension plan whereby participants in the plan may elect to defer a portion of their earnings. VSUK matches 100% of each participant’s contributions up to a maximum of 3% of the participant’s net pay. VIRE makes available to its employees a pension plan whereby participants in the plan may elect to defer a portion of their earnings. VIRE matches 100% of each participant’s contributions up to a maximum of 3% and 50% of the participant's contributions on contributions between 3% and 5% of the participant’s net pay. Total expenses related to retirement and severance pay amounted to $6,765 , $4,801 and $3,775 for the years ended December 31, 2018 , 2017 and 2016 , respectively. The amount of severance payable included in other liabilities as of December 31, 2018 and 2017 is $2,391 and $1,781 , respectively. r. Fair Value of Financial Instruments: Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: • Level 1: Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2: Observable inputs that reflect quoted prices for identical assets or 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: Unobservable inputs reflecting our own assumptions incorporated in valuation techniques used to determine fair value. These assumptions are required to be consistent with market participant assumptions that are reasonably available. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The carrying amounts of cash and cash equivalents, marketable securities, trade receivables, short-term deposits and trade payables approximate their fair value due to the short-term maturity of such instruments. s. Basic and Diluted Net Loss Per Share: Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including stock options, to the extent dilutive. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential shares of common stock outstanding would have been anti-dilutive. There were 3,173,188 and 3,505,729 potentially dilutive shares from the conversion of outstanding restricted stock units and stock options that were not included in the calculation of diluted net loss per share as of December 31, 2018 and 2017 , respectively. t. Contingent Liabilities: The Company accounts for its contingent liabilities in accordance with ASC No. 450 “Contingencies”. A provision is recorded when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. With respect to legal matters, provisions are reviewed and adjusted to reflect the impact of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. As of December 31, 2018 and 2017 , the Company was not a party to any litigation that could have a material adverse effect on the Company’s business, financial position, results of operations or cash flows. u. Basis of Presentation: Certain amounts in prior years' financial statements have been recast and reclassified to conform to the current year's presentation. v. Recently Adopted Accounting Pronouncements: In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers”, an updated standard on revenue recognition and issued subsequent amendments to the initial guidance in March 2016, April 2016, May 2016 and December 2016 within ASU 2016-08, 2016-10, 2016-12 and 2016-20, respectively. The new standards provide enhancements to the quality and consistency of how revenue is reported while also improving comparability in the financial statements of companies reporting using IFRS and US GAAP. The core principle of the new standard is for companies to recognize revenue to depict the transfer of goods or services to customers in amounts that reflect the consideration (that is, payment) to which the company expects to be entitled in exchange for those goods or services. The new standard results in enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively (for example, service revenue and contract modifications) and improves guidance for multiple-element arrangements. ASU 2014-09 was initially scheduled to be effective for annual and interim reporting periods beginning after December 15, 2016 and may be adopted either on a full retrospective or modified retrospective approach. However, on July 9, 2015, the FASB approved a one year deferral of the effective date of ASU 2014-09. The revised effective date is for annual reporting periods beginning after December 15, 2017 and interim periods thereafter, with an early adoption permitted as of the original effe

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2018
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Expenses and Other Current Assets	PREPAID EXPENSES AND OTHER CURRENT ASSETS December 31, 2018 2017 Deferred commission $ 8,055 $ 7,216 Prepaid expenses 6,857 6,044 Government institutions & other receivables 1,874 542 Foreign currency forward contracts derivatives — 163 Short-term deposits & other 166 381 $ 16,952 $ 14,346

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 December 31, 2018 2017 Cost: Computer equipment $ 12,848 $ 8,473 Office furniture and equipment 3,193 2,263 Leasehold improvements 12,814 9,163 28,855 19,899 Accumulated depreciation 11,532 8,003 Property and equipment, net $ 17,323 $ 11,896 Depreciation expenses for the years ended December 31, 2018 , 2017 and 2016 were $4,156 , $3,328 and $2,180 , respectively.

Accrued Expenses and Other Shor

Accrued Expenses and Other Short Term Liabilities	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses And Other Short Term Liabilities	ACCRUED EXPENSES AND OTHER SHORT TERM LIABILITIES December 31, 2018 2017 Employees $ 20,111 $ 17,748 Accrued expenses 12,725 9,507 Government authorities and other 18,196 14,006 Foreign exchange forward contract derivatives 3,646 — Other short term liabilities 1,313 1,192 $ 55,991 $ 42,453

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	COMMITMENTS AND CONTINGENT LIABILITIES a. Liens: The Company has several liens granted to financial institutions mainly to secure various operating lease agreements in connection with its office space. b. Lease Commitments: The Company rents its facilities in all locations under operating leases with lease periods expiring from 2019-2030. The lease agreements of VSL include extension options. VSL leases cars for its employees under operating lease agreements expiring at various dates from 2019-2021. Aggregate minimum rental commitments under non-cancelable leases as of December 31, 2018 for the upcoming years were as follows: Payments Due By Period 2019 $ 7,174 2020 9,086 2021 8,865 2022 8,876 2023 8,690 Thereafter 37,507 $ 80,198 Total rent expenses for the years ended December 31, 2018 , 2017 and 2016 were $6,570 , $4,075 and $3,258 , respectively. For leases that contain predetermined fixed escalations of the minimum rent, the Company recognizes the related rent expense on a straight-line basis from the date of possession of the property to the end of the initial lease term. The Company records any differences between the straight-line rent amounts and amounts payable under the leases as part of deferred rent, in accrued liabilities or long-term liabilities, as appropriate. Cash or lease incentives received upon entering into certain leases (“tenant allowances”) are recognized on a straight-line basis as a reduction to rent from the date of possession of the property through the end of the initial lease term. The Company records the unamortized portion of tenant allowances as a part of deferred rent, in current liabilities or other long-term liabilities, as appropriate. As of December 31, 2018 and 2017 , deferred rent included $1,313 and $941 , respectively, in current liabilities in the Company’s consolidated balance sheets, and deferred rent included $4,236 and $4,780 , respectively, in long-term liabilities in the Company’s consolidated balance sheets. On March 31, 2014, the Company entered into a promissory note and related security documents with Bank Leumi USA, which the Company has extended a number of times. The Company may borrow up to $7,000 against certain of its accounts receivable outstanding amount, based on several conditions, at an annual interest rate of the Wall Street Journal Prime Rate plus 0.05% , provided that the annual interest rate applicable to advances will not be lower than 4.10% . As of December 31, 2018 , that rate amounted to 5.55% . This promissory note enables the Company, among other things, to engage in foreign currency hedging transactions with Bank Leumi USA to manage exposure to foreign currency risk without restricted cash requirements. The Company may borrow under the promissory note until November 15, 2020 at which time the principal sum of each such loan, together with accrued and unpaid interest payable, will become due and payable. As of December 31, 2018 , the Company had no balance outstanding under the promissory note. As part of the transaction, the Company granted the lender a security interest in its personal property, excluding intellectual property and other intangible assets. The promissory note also contains customary events of default.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following table sets forth the Company’s liabilities that were measured at fair value as of December 31, 2018 and 2017 by level within the fair value hierarchy (in thousands): As of December 31, 2018 As of December 31, 2017 Level I Level II Level III Fair Value Level I Level II Level III Fair Value Financial assets: Cash equivalents: Money market funds 2,594 — — 2,594 6,870 — — 6,870 Marketable securities: US Treasury securities 39,770 — — 39,770 39,731 — — 39,731 Other current assets: Forward foreign exchange contracts — — — — — 163 — 163 Financial liabilities: Forward foreign exchange contracts — (3,647 ) — (3,647 ) — — — — Total financial assets (liabilities) $ 42,364 $ (3,647 ) $ — $ 38,717 $ 46,601 $ 163 $ — $ 46,764

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY a. Composition of common stock capital: Authorized Issued and outstanding Number of shares December 31, December 31, 2018 2017 2018 2017 Stock of $0.001 par value: Common stock 200,000,000 200,000,000 29,576,880 28,146,162 b. Common stock rights: The Company’s Amended and Restated Certificate of Incorporation authorizes the Company to issue 200,000,000 shares of common stock, par value $0.001 per share. The common stock confers upon its holders the right to participate in the general meetings of the Company, to vote at such meetings (each share represents one vote), to elect board members and to participate in any distribution of dividends or any other distribution of the Company’s property, including the distribution of surplus assets upon liquidation. c. Stock option plans: On December 30, 2005, the Company’s board of directors adopted the Varonis Systems, Inc. 2005 Stock Plan (the “2005 Stock Plan”). As of December 31, 2013, the Company had reserved 4,713,319 shares of common stock available for issuance to employees, directors, officers and consultants of the Company and its subsidiaries. The options generally vest over four years. No awards were granted under the 2005 Stock Plan subsequent to December 31, 2013, and no further awards will be granted under the 2005 Stock Plan. On November 14, 2013, the Company’s board of directors adopted the Varonis Systems, Inc. 2013 Omnibus Equity Incentive Plan (the “2013 Plan”) which was subsequently approved by the Company’s stockholders. The Company initially reserved 1,904,633 shares of common stock for issuance under the 2013 Plan to employees, directors, officers and consultants of the Company and its subsidiaries. The number of shares of common stock available for issuance under the 2013 Plan was increased on January 1, 2016 and has been, and will be, increased on each January 1 thereafter by four percent ( 4% ) of the number of shares of common stock issued and outstanding on each December 31 immediately prior to the date of increase (rounded down to the nearest whole share), but the amount of each increase will be limited to the number of shares of common stock necessary to bring the total number of shares of Common Stock available for grant and issuance under the 2013 Plan to five percent ( 5% ) of the number of shares of common stock issued and outstanding on each December 31. On January 1, 2019, 2018, 2017 and 2016, the share reserve under the 2013 Plan was automatically increased by 1,183,075 , 1,125,846 , 1,072,870 and 1,042,766 shares, respectively. Awards granted under the 2013 Plan generally vest over four years. Any award that is forfeited or canceled before expiration becomes available for future grants under the 2013 Plan. A summary of employees’ stock options activities during the year ended December 31, 2018 is as follows: Year ended December 31, 2018 Number Weighted average exercise price Aggregate intrinsic value (in thousands) Weighted average remaining contractual life (years) Options outstanding at the beginning of the year 1,456,285 $ 16.172 $ 47,152 4.906 Granted — $ — Exercised (744,636 ) $ 14.469 Forfeited (1,981 ) $ 32.473 Options outstanding at the end of the period 709,668 $ 17.941 $ 24,810 4.513 Options exercisable at the end of the period 687,508 $ 17.856 $ 24,093 4.439 There were no options granted in 2018. The aggregate intrinsic value in the table above represents the total intrinsic value that would have been received by the option holders had all option holders exercised their options on the last date of the period. Total intrinsic value of options exercised for the years ended December 31, 2018 , 2017 and 2016 was $40,610 , $22,382 and $9,418 , respectively. As of December 31, 2018 and 2017 , there was $142 and $2,208 , respectively, of total unrecognized compensation cost related to non-vested share-based compensation arrangements granted under the 2005 Stock Plan and 2013 Plan. This cost is expected to be recognized over a period of approximately 0.712 and 0.887 years, respectively. The options outstanding as of December 31, 2018 have been separated into ranges of exercise price as follows: Range of exercise price Options outstanding as of December 31, 2018 Weighted average remaining contractual life (years) Weighted average exercise price Options exercisable as of December 31, 2018 Weighted average remaining contractual life (years) Weighted average exercise price of options exercisable $ 1.256 — 1.576 130,479 0.663 $ 1.282 130,479 0.663 $ 1.282 $ 6.230 — 8.800 12,356 3.007 $ 8.039 12,356 3.007 $ 8.039 $ 12.470 — 16.870 147,125 5.014 $ 14.030 132,541 4.781 $ 13.637 $ 19.510 — 21.660 220,211 5.599 $ 21.174 218,573 5.594 $ 21.185 $ 22.010 — 24.230 85,870 5.284 $ 22.364 85,870 5.284 $ 22.364 $29.880 66,349 6.145 $ 29.880 60,411 6.145 $ 29.880 $39.860 47,278 5.225 $ 39.860 47,278 5.225 $ 39.860 709,668 4.513 $ 17.941 687,508 4.439 $ 17.856 d. Options issued to consultants: The Company’s outstanding options granted to consultants for services as of December 31, 2018 were as follows: Issuance date Options for shares of common stock Exercise price per share Options exercisable Exercisable through (number) (number) February 2013 1,500 $ 12.470 1,500 February 2023 August 2013 4,000 $ 21.140 4,000 August 2023 March 2014 5,550 $ 39.860 5,550 March 2024 May 2014 3,700 $ 22.010 3,700 May 2024 November 2014 5,468 $ 21.660 5,468 November 2024 May 2015 1,137 $ 19.510 929 May 2025 February 2016 2,138 $ 16.870 1,408 February 2026 23,493 22,555 e. Restricted stock units: The following provides a summary of the restricted stock unit activity for the Company for the year ended December 31, 2018 : Number of Shares Underlying Outstanding Restricted Stock Units Weighted- Average Grant Date Fair Value Outstanding as of January 1, 2018 2,018,121 $ 27.32 Granted 1,255,824 $ 53.79 Vested (671,768 ) $ 28.54 Forfeited (162,150 ) $ 36.89 Unvested as of December 31, 2018 2,440,027 $ 40.00 f. 2015 Employee Stock Purchase Plan On May 5, 2015, the Company’s stockholders approved the Varonis Systems, Inc. 2015 Employee Stock Purchase Plan (the “ESPP”), which the Company’s board of directors had adopted on March 19, 2015. The ESPP became effective as of June 30, 2015. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, at not less than 85% of the fair market value of the Company’s common stock on the first day or last trading day in the offering period, subject to any plan limitations. The Company initially reserved 500,000 shares of common stock for issuance under the ESPP. The number of shares available for issuance under the ESPP was increased on January 1, 2016 and has been, and will be, increased each January 1 thereafter, by an amount equal to the lesser of (i) one percent ( 1% ) of the number of shares of common stock issued and outstanding on each December 31 immediately prior to the date of increase, except that the amount of each such increase will be limited to the number of shares of common stock necessary to bring the total number of shares of common stock available for issuance under the ESPP to two percent ( 2% ) of the number of shares of common stock issued and outstanding on each such December 31, or (ii) 400,000.00 shares of common stock. On January 1, 2019, 2018, 2017 and 2016, the share reserve under the ESPP was automatically increased by 177,358 , 188,813 , 158,695 and 21,383 shares, respectively. The ESPP will continue in effect until the earlier of (i) the date when no shares of common stock are available for issuance thereunder or (ii) June 30, 2025; unless terminated prior thereto by the Company’s board of directors or compensation committee, each of which has the right to terminate the ESPP at any time. g. Stock-based compensation expense for employees and consultants: The Company recognized non-cash stock-based compensation expense in the consolidated statements of operations as follows (in thousands): Year ended December 31, 2018 2017 2016 Cost of revenues $ 1,757 $ 1,078 $ 699 Research and development 9,645 5,209 3,052 Sales and marketing 16,081 8,542 6,104 General and administrative 7,478 5,006 3,083 Total $ 34,961 $ 19,835 $ 12,938 For the year ended December 31, 2018 , the Company recognized tax benefits on stock-based compensation expense, which are reflected in the provision for income taxes in the consolidated statements of operations, of $40 . The Company did not recognize any tax benefits on stock-based compensation expense in 2017 and 2016 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES a. Tax Reform: On December 22, 2017, the TCJA was signed into law. The TCJA makes broad and complex changes to the Code that impact the Company's provision for income taxes. The changes include, but are not limited to: • Decreasing the corporate income tax rate from 35% to 21% effective for tax years beginning after December 31, 2017 (“Rate Reduction”); • The Deemed Repatriation Transition Tax; and • Taxation of GILTI earned by foreign subsidiaries beginning after December 31, 2017. The GILTI tax imposes a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. Deemed Repatriation Transition Tax The Deemed Repatriation Transition Tax is a tax on previously untaxed accumulated and current earnings and profits (“E&P”) of certain of our foreign subsidiaries. To determine the amount of the Deemed Repatriation Transition Tax, the Company calculated the amount of post-1986 E&P of its foreign subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. Because the Company has a net cumulative deficit on the E&P of its foreign subsidiaries, it should not be subject to the Deemed Repatriation Transition Tax. 100% Dividend Received Deduction and Indefinite Reinvestment Assertion Effective for tax years beginning after December 31, 2017, the TCJA provides a 100% dividend received deduction, subject to a one-year holding period, to a U.S. corporate shareholder for the foreign source portion of dividends received from a “specified 10-percent owned foreign corporation.” Prior to the effectiveness of the TCJA, the Company did not recognize a deferred tax liability related to un-remitted foreign earnings because such earnings were expected to be reinvested indefinitely. Although the Company is not subject to the Deemed Repatriation Transition Tax, an actual repatriation from its non-U.S. subsidiaries could still be subject to additional foreign withholding taxes and U.S. state taxes. The Company’s intention is to continue reinvesting the earnings from its non-U.S. subsidiaries indefinitely. GILTI Tax The TCJA creates a new requirement that certain income (i.e., GILTI) earned by controlled foreign corporations (“CFCs”) must be included currently in the gross income of the CFCs’ U.S. shareholder. GILTI is the excess of the shareholder’s “net CFC tested income” over the net deemed tangible income return, which is currently defined as the excess of (1) 10 percent of the aggregate of the U.S. shareholder’s pro rata share of the qualified business asset investment of each CFC with respect to which it is a U.S. shareholder, over (2) the amount of certain interest expense taken into account in the determination of net CFC-tested income. For 2018, the Company is not subject to tax on account of GILTI as it has net CFC tested loss on an aggregated basis. Under U.S. GAAP, the Company is permitted to make an accounting policy election to either treat taxes due on future inclusions in U.S. taxable income related to GILTI as a component of current income tax expense when incurred or to factor such amounts into the Company’s measurement of its deferred tax expense. The Company has made an accounting policy election to treat GILTI as a component of current income tax expense. Accounting for the TCJA In March 2018, FASB issued Accounting Standards Update No. 2018-05, "Income Taxes Topic (740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118" ("ASU 2018-05") 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 TCJA. The Company completed the accounting treatment related to the tax effects of the TCJA. As a result: • The Company recognizes its accounting for changes in the US federal rate and deferred tax impact for the rate change to be complete. • The Company's analysis for the Deemed Repatriation Transition Tax has been filed with its December 31, 2017 tax return and the Company considered its accounting for this area of the TCJA to be complete as of such date and did not make any measurement-period adjustments related to it. • The Company accounted for the tax impact related to others areas of the TCJA and believe its analysis to be completed and consistent with the guidance in ASU 2018-05. In particular, the Company concluded that for 2018, it should not be subject to any tax on account of GILTI or base erosion and anti-abuse payments made by U.S. corporations to foreign related parties. Further, due to the NOL generated during 2018, the Company concluded that for 2018, it would not benefit from the reduced tax rate of 13.125% on its foreign derived intangible income. The Company recognizes that the IRS, the Financial Accounting Standards Board and the SEC are continuing to publish and finalize ongoing guidance with respect to the TCJA which may modify accounting interpretation for the TCJA, the Company will account for these impacts in the period in which any changes are enacted. b. The Company: The Company is taxed in accordance with U.S. tax laws. As of December 31, 2018 , the Company had net operating loss carry-forwards for federal, state and foreign income tax purposes of approximately $54,872 , $57,530 and $1,204 , respectively. If not utilized, these carryforwards will expire starting in 2028, 2020 and indefinitely for federal, state and foreign tax purposes, respectively. In addition, as of December 31, 2018 , the Company had federal research credit, retention credit, foreign tax credit and Ireland Employment credit carryforwards of approximately $1,412 , $24 , $190 and $78 , respectively. If not utilized, the federal tax carryforwards will begin to expire in 2033, 2032 and 2026, respectively. Ireland has no expiration on the employment credit. A U.S. corporation's ability to utilize its federal and state NOL and tax credit carryforwards to offset its taxable income or income is limited under Section 382 of the Code if the corporation undergoes an ownership change (within the meaning of Code Section 382). In general, an “ownership change” occurs whenever the percentage of the stock of a corporation owned by “5-percent shareholders” (within the meaning of Code Section 382) increases by more than 50 percentage points over the lowest percentage of the stock of such corporation owned by such “5-percent shareholders” at any time over the testing period. An ownership change under Code Section 382 would establish an annual limitation to the amount of NOL and tax credit carryforwards the Company could utilize to offset its taxable income or income tax in any single year. The Company performed a Section 382 analysis (the “Analysis”) which concluded that its ability to utilize its NOL and tax credit carryforwards is subject to an annual limitation as it underwent a section 382 ownership change during 2017. The Analysis further concluded that the Company's NOL carryforwards should be available for utilization by the Company before they expire, starting in 2028. As of December 31, 2017, the Company's U.S. federal NOL carryforwards was $22,907 . During 2018, the Company generated an additional $31,965 of NOLs which are not subject to the annual limitation described above. The TCJA also modified the rules regarding utilization of NOL and NOLs generated subsequent to the TCJA can only be used to offset 80% of taxable income with an indefinite carryforward period for unused carryforwards (i.e., they should not expire). Utilization of the federal and state net operating losses and credits may be subject to a substantial annual limitation due to an additional ownership change. The annual limitation may result in the expiration of net operating losses and credits before utilization and in the event we have a change of ownership, utilization of the carryforwards could be restricted. c. Loss before taxes on income is comprised as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Domestic $ (25,557 ) $ (19,239 ) $ (13,940 ) Foreign (2,608 ) 8,182 1,060 $ (28,165 ) $ (11,057 ) $ (12,880 ) d. Taxes on income (loss) are comprised as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Current: Domestic: Federal $ — $ (92 ) $ 92 State 169 191 109 Foreign 1,498 2,516 930 Total current income tax $ 1,667 $ 2,615 $ 1,131 Deferred: Foreign $ (1,254 ) $ 172 $ 182 Total deferred income tax $ (1,254 ) $ 172 $ 182 Income tax expense $ 413 $ 2,787 $ 1,313 e. Deferred income taxes: 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. The Company’s deferred tax assets are derived from its U.S. net operating loss carry forwards and other temporary differences. ASC 740 requires an assessment of both positive and negative evidence concerning the realizability of our deferred tax assets in each jurisdiction. After considering evidence such as current and cumulative financial reporting incomes, the expected sources of future taxable income and tax planning strategies, the Company's management concluded that a valuation allowance is required for US, state and Israel deferred tax assets. Future changes in these factors, including the Company's anticipated results, could have a significant impact on the realization of the deferred tax assets which would result in an increase or decrease to the valuation allowance and a corresponding charge to income tax expense. December 31, 2018 2017 (as adjusted) Deferred tax assets: Carry forward losses and credits $ 15,547 $ 7,407 Deferred revenues 13,995 14,226 Accrued payroll, commissions, vacation 1,912 2,685 Equity Compensation 5,737 908 Allowance for doubtful accounts 940 633 Accrued severance pay 297 238 Other 1,346 1,760 Deferred tax assets before valuation allowance 39,774 27,857 Valuation allowance (39,365 ) (27,702 ) Deferred tax assets $ 409 $ 155 Deferred tax liability: Accrued compensation and other accrued expense $ (272 ) $ (289 ) Deferred tax liability $ (272 ) $ (289 ) Net deferred tax asset (liability) $ 137 $ (134 ) The change in the valuation allowance was approximately an increase of $15,826 and a decrease of $8,623 during 2018 and 2017, which included the Company’s adoption of ASC 606. The adoption resulted in a decrease to deferred tax assets of $3,796 and a decrease to valuation allowance of $2,493 with an offsetting entry of $1,302 to retained earnings. As the Company adopted ASC 606 using the full retrospective method, the 2017 and 2016 valuation allowances above have been adjusted for ASC 606 adoption. In addition, the 2017 and 2016 tax disclosures have been updated to reflect the ASC 606 adoption. f. Reconciliation of the theoretical tax expenses: A reconciliation between the theoretical tax expense, assuming all income is taxed at the statutory tax rate applicable to income of the Company, and the actual tax expense (benefit) as reported in the consolidated statements of operations is as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Loss before taxes, as reported in the consolidated statements of operations $ (28,165 ) $ (11,057 ) $ (12,880 ) Statutory tax rate 21 % 34 % 34 % Theoretical tax benefits on the above amount at the US statutory tax rate $ (5,915 ) $ (3,759 ) $ (4,379 ) Income tax at rate other than the U.S. statutory tax rate 692 (1,047 ) (6 ) Tax advances and non-deductible expenses including equity based compensation expenses (7,623 ) 3,123 4,298 Operating losses and other temporary differences for which valuation allowance was provided 15,826 (8,623 ) 1,885 Research and Development Tax Credit — 1,126 (1,182 ) State tax (1,221 ) (601 ) (426 ) Impact of rate change — 10,920 (360 ) Change in tax reserve for uncertain tax positions (1,728 ) 1,576 1,209 Other individually immaterial income tax items 382 72 274 Actual tax expense $ 413 $ 2,787 $ 1,313 g. A reconciliation of the beginning and ending amounts of unrecognized tax benefits in the years ended December 31, 2018 and 2017 are as follows: Gross unrecognized tax benefits as of January 1, 2017 $ 2,106 Increase in tax position for current year 1,752 Increase in tax position for prior years 135 Decrease in tax position for prior years (311 ) Gross unrecognized tax benefits as of December 31, 2017 $ 3,682 Increase in tax position for current year 169 Increase in tax position for prior years 241 Decrease in tax position for prior years (720 ) Decrease for lapse of statute of limitations/ settlements (1,418 ) Gross unrecognized tax benefits as of December 31, 2018 $ 1,954 There was $1,954 of unrecognized income tax benefits that, if recognized, approximately $1,431 would impact the effective tax rate in the period in which each of the benefits is recognized. The Company includes interest and penalties related to unrecognized tax benefits within the provision for income taxes on the consolidated statements of operations. The total amount of penalties and interest is approximately $93 as of December 31, 2018 . h. Foreign taxation: 1. Israeli tax benefits under the Law for the Encouragement of Capital Investments, 1959 (the “Investment Law”): Conditions for entitlement to the benefits: The benefits available to a Beneficiary Enterprise relate only to taxable income attributable to the specific investment program and are conditioned upon terms stipulated in the Investment Law and the related regulations and the criteria set forth in the applicable certificate of approval (for a Beneficiary Enterprise). If VSL does not fulfill these conditions, in whole or in part, the benefits can be cancelled, and VSL may be required to refund the benefits, in an amount linked to the Israeli consumer price index plus interest. The Office of the Chief Scientist at Israel’s Ministry of Industry, Trade and Labor approved the Israeli subsidiary as an R&D-incentive enterprise for a foreign resident company in accordance with the Encouragement of Capital Investments (Consolidated Version) Law. If cash dividends are distributed out of tax exempt profits in a manner other than upon complete liquidation, VSL will then become liable for tax at the rate of 10% - 25% (depending on the level of foreign investments in VSL) in respect of the amount distributed. 2. Undistributed earnings of foreign subsidiaries: As of December 31, 2018 , the Company has accumulated undistributed earnings generated by its foreign subsidiaries of approximately $678 . Because approximately $285 of such earnings have previously been subject to the one-time transition tax on foreign earnings required by the TCJA, any additional taxes due with respect to such earnings or the excess of the amount for financial reporting over the tax basis of our foreign investments would generally be limited to foreign and state taxes. The Company plans to indefinitely reinvest any additional cash on hand outside of the previously taxed income and expects future U.S. cash generation to be sufficient to meet future U.S. cash needs. i. Tax assessments: The Company was audited by the Internal Revenue Service for tax year 2016. As of December 31, 2018, our federal returns for the years ended 2010 through the current period and most state returns for the years ended 2009 through the current period are still open to examination. In addition, all of the net operating losses and research and development credit carryforwards that may be used in future years are still subject to adjustment. The Company has final tax assessments for VSL in Israel through 2015, VSUK in UK through 2016 and VSF in France through 2015. VSG in Germany, VSC in Canada, VIRE in Ireland and VAUS in Australia do not have final tax assessments since their respective inceptions.

Financial Expenses, Net

Financial Expenses, Net	12 Months Ended
	Dec. 31, 2018
FInancial Expenses, Net [Abstract]
Financial Expenses, Net	FINANCIAL EXPENSES, NET Year ended December 31, 2018 2017 2016 Financial income: Interest on bank deposits, net $ 1,741 $ 747 $ 520 Foreign currency transactions gains, net — 1,773 — Other — 27 — 1,741 2,547 520 Financial expenses: Bank charges 195 185 149 Foreign currency transactions losses, net 574 — 1,224 Other 2 — 32 (771 ) (185 ) (1,405 ) $ 970 $ 2,362 $ (885 )

Geographic Information and Majo

Geographic Information and Major Customer and Product Data	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Geographic Information and Major Customer and Product Data	GEOGRAPHIC INFORMATION AND MAJOR CUSTOMER AND PRODUCT DATA Summary information about geographic areas: ASC 280, “Segment Reporting,” establishes standards for reporting information about operating segments. Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company manages its business on the basis of one reportable segment, and derives revenues from licensing of software, sale of professional services, maintenance and technical support (see Note 1 above for a brief description of the Company’s business). The following is a summary of revenues within geographic areas: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Revenues based on customer’s location: North America $ 167,361 $ 139,720 $ 106,069 EMEA (*) 93,816 68,998 53,170 Rest of the World 9,111 6,672 6,624 Total revenues $ 270,288 $ 215,390 $ 165,863 (*) Sales to customers in France accounted for $31,532 , $22,658 and $17,103 for the years ended December 31, 2018 , 2017 and 2016 , respectively. During the years ended December 31, 2018 , 2017 and 2016 , there were no sales to a single customer exceeding 10% of the Company’s revenues. December 31, 2018 2017 Long-lived assets by geographic region: United States $ 7,612 $ 7,072 Israel 7,834 2,944 France 1,243 1,426 Other 634 454 $ 17,323 $ 11,896

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Use of Estimates	a. Use of Estimates: The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates, judgments and assumptions. The Company’s management believes that the estimates, judgments and assumptions used are reasonable based upon information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company’s management evaluates estimates, including those related to accounts receivable and sales allowances, fair values of stock-based awards, deferred taxes and income tax uncertainties, and contingent liabilities. Such estimates are based on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities.
Financial Statements U.S. Dollars	b. Financial Statements in U.S. Dollars: Most of the revenues and costs of VSI are denominated in United States dollars (“dollars”). Some of the subsidiaries’ revenues and costs are primarily incurred in Euros, the Pound Sterling, Canadian dollars, Australian dollars and NIS; however, the Company’s management believes that the dollar is the primary currency of the economic environment in which VSI and each of its subsidiaries operate. Thus, the dollar is the Company’s functional and reporting currency. Accordingly, transactions denominated in currencies other than the functional currency are re-measured to the functional currency in accordance with ASC No. 830, “Foreign Currency Matters” at the exchange rate at the date of the transaction or the average exchange rate in the quarter. At the end of each reporting period, financial assets and liabilities are re-measured to the functional currency using exchange rates in effect at the balance sheet date. Non-financial assets and liabilities are re-measured at historical exchange rates. Gains and losses related to re-measurement are recorded as financial income (expense) in the consolidated statements of operations as appropriate.
Principles of Consolidation	c. Principles of Consolidation: The consolidated financial statements include the accounts of VSI and its wholly-owned subsidiaries, VSL, VSUK, VSG, VSF, VSC, VIRE, VAUS, VNL and VPS. All intercompany transactions and balances have been eliminated upon consolidation.
Cash, Cash Equivalents, Marketable Securities and Short-Term Deposits	d. Cash, Cash Equivalents, Marketable Securities and Short-Term Deposits: The Company accounts for investments in marketable securities in accordance with ASC No. 320, “Investments—Debt and Equity Securities”. The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents consist of cash on hand, highly liquid investments in money market funds and various deposit accounts. The Company considers all high quality investments purchased with original maturities at the date of purchase greater than three months to be short-term deposits. Investments are available to be used for current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents, marketable securities and short-term deposits are classified as available for sale and are, therefore, recorded at fair value on the consolidated balance sheet, with any unrealized gains and losses reported in accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s consolidated balance sheets, until realized. The Company uses the specific identification method to compute gains and losses on the investments. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included as a component of financial income, net in the consolidated statement of operations. Cash, cash equivalents, marketable securities and short-term deposits consist of the following (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 2,594 $ — $ — $ 2,594 Total $ 2,594 $ — $ — $ 2,594 Marketable securities US Treasury securities $ 39,776 *) $ (6 ) $ 39,770 Total $ 39,776 *) $ (6 ) $ 39,770 Short-term deposits Term bank deposits $ 70,438 $ — $ — $ 70,438 Total $ 70,438 $ — $ — $ 70,438 *) Represents an amount lower than $1. As of December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 6,870 $ — $ — $ 6,870 Total $ 6,870 $ — $ — $ 6,870 Marketable securities US Treasury securities $ 39,758 *) $ (27 ) $ 39,731 Total $ 39,758 *) $ (27 ) $ 39,731 Short-term deposits Term bank deposits $ 40,137 $ — $ — $ 40,137 Total $ 40,137 $ — $ — $ 40,137 *) Represents an amount lower than $1. All the US Treasury securities in short-term deposits have a stated effective maturity of less than 12 months as of December 31, 2018 and 2017 . The gross unrealized loss related to these short-term deposits was due primarily to changes in interest rates. The Company reviews its short-term deposits on a regular basis to evaluate whether or not any security has experienced an other than temporary decline in fair value. The Company considers factors such as length of time and extent to which the market value has been less than the cost, the financial condition and near-term prospects of the issuer and its intent to sell, or whether it is more likely than not the Company will be required to sell the investment before recovery of the investment’s amortized cost basis. If the Company believes that an other than temporary decline exists in one of these securities, the Company writes down these investments to fair value. For debt securities, the portion of the write-down related to credit loss would be recorded to other income (expense), net in the Company’s consolidated statements of operations. Any portion not related to credit loss would be recorded to accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s condensed consolidated balance sheets. During the year ended December 31, 2018 and 2017, the Company did not consider any of its investments to be other-than-temporarily impaired. A short-term bank deposit is a deposit with a maturity of more than three months but less than one year. Deposits in U.S. dollars bore interest at rates ranging from 0.60% - 2.77% and 0.60% - 1.35% , per annum, as of December 31, 2018 and 2017 , respectively. There were no deposits in NIS as of December 31, 2018 , and, as of December 31, 2017 , the Company's deposits in NIS bore interest at a rate of 0.03% per annum. Short-term deposits are presented at cost which approximates market value due to their short maturities.
Restricted Cash	e. Restricted Cash: Restricted cash is primarily invested in certificates of deposit and is used mostly as security for the Company’s lease commitments.
Property and Equipment	f. Property and Equipment: Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets at the following annual rates: % Computer equipment 33 Office furniture and equipment 14 — 15 Leasehold improvements Over the shorter of the expected lease
Impairment of Long-Lived Assets	g. Impairment of Long-Lived Assets: The Company’s long-lived assets are reviewed for impairment in accordance with ASC No. 360 “Property, Plant and Equipment” whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. Recoverability of assets (or asset group) to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. During the years ended December 31, 2018 , 2017 and 2016 , no impairment losses have been recorded.
Long-Term Lease Deposits	h. Long-Term Lease Deposits: Long-term lease deposits include long-term deposits for offices.
Revenue Recognition	i. Revenue Recognition: The Company generates revenues in the form of software license fees and related maintenance and services fees. License fees include perpetual license fees and subscription license fees which provide customers with the same functionality and differ in the duration over which the customer benefits from the software. Maintenance and services primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements when and if they are available) and to a lesser extent professional services which focus on both operationalizing the software and training the Company’s customers to fully leverage the use of its products although the user can benefit from the software without the Company’s assistance. The Company sells its products worldwide directly to a network of distributors and VARs, and payment is typically due within 30 to 60 calendar days of the invoice date. The Company recognizes revenues in accordance with ASC No. 606, “Revenue from Contracts with Customers”. As such, the Company identifies a contract with a customer, identifies the performance obligations in the contract, determines the transaction price, allocates the transaction price to each performance obligation in the contract and recognizes revenues when (or as) the Company satisfies a performance obligation. Software license revenues are recognized at the point of time when the software license has been delivered and the benefit of the asset has transferred. The Company recognizes revenues from maintenance ratably over the term of the underlying maintenance contract term. The term of the maintenance contract is usually one year. Renewals of maintenance contracts create new performance obligations that are satisfied over the term with the revenues recognized ratably over the period. Revenues from professional services consist mostly of time and material services. The performance obligations are satisfied, and revenues are recognized, when the services are provided or once the service term has expired. The Company enters into contracts that can include combinations of products and services, which are generally capable of being distinct and accounted for as separate performance obligations. The license is distinct upon delivery as the customer can derive the economic benefit of the software without any professional services, updates or technical support. The Company allocates the transaction price to each performance obligation based on its relative standalone selling price out of the total consideration of the contract. For maintenance, the Company determines the standalone selling prices based on the price at which the Company separately sells a renewal contract. For professional services, the Company determines the standalone selling prices based on the price at which the Company separately sells those services. For software licenses, the Company uses the residual approach to determine the standalone selling prices due to the lack of history of selling software license on a standalone basis. Trade and other receivables are primarily comprised of trade receivables that are recorded at the invoice amount, net of an allowance for doubtful accounts. Deferred revenues represent mostly unrecognized fees billed or collected for maintenance and professional services. Deferred revenues are recognized as (or when) the Company performs under the contract. The amount of revenues recognized in the period that was included in the opening deferred revenues balance was $73,176 for the year ended December 31, 2018. The Company does not grant a right of return to its customers, except for one of its resellers. During the years ended December 31, 2018 , 2017 and 2016 , there were no returns from this reseller. For information regarding disaggregated revenues, please refer to Note 11 below. j. Contract Costs: The Company pays sales commissions to sales and marketing and certain management personnel based on their attainment of certain predetermined sales goals. Sales commissions earned by its employees are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions paid for initial contracts, which are not commensurate with sales commissions paid for renewal contracts, are capitalized and amortized over an expected period of benefit. Based on its technology, customer contracts and other factors, the Company has determined the expected period of benefit to be approximately four years. Sales commissions for renewal contracts are capitalized and then amortized on a straight line basis over the related contractual renewal period. Amortization expenses related to these costs are mostly included in sales and marketing expenses in the accompanying consolidated statements of operations.
Cost of Revenues	k. Cost of Revenues: Cost of revenues consists of the cost of maintenance and services, resulting from costs associated with support, and professional services.
Accounting for Stock-Based Compensation	l. Accounting for Stock-Based Compensation: The Company accounts for stock-based compensation in accordance with ASC No. 718, “Compensation-Stock Compensation”. ASC No. 718 requires companies to estimate the fair value of equity-based payment awards on the date of grant using an OPM. The value of the portion of the award that is ultimately expected to vest is recognized as an expense over the requisite service periods in the Company’s consolidated statements of operations. The Company recognizes compensation expenses for the value of its awards granted based on the straight-line method over the requisite service period of each of the awards. The Company applies ASC 718 and ASC 505-50, “Equity-Based Payments to Non-Employees” with respect to options issued to non-employee consultants. Accordingly, the Company uses option valuation models to measure the fair value of the options at the measurement date as defined in ASC 505-50. The Company selected the Black-Scholes-Merton option pricing model as the most appropriate fair value method for its stock options awards, whereas the fair value of restricted stock units is based on the market value of the underlying shares at the date of grant. The fair value of options granted to employees and non-employee directors is estimated at the date of grant using the following weighted average assumptions: For the years ended December 31, 2018 and 2017 , there were no stock options granted. For the year ended December 31, 2016, dividend yield was 0% , expected volatility was 62.1% , risk-free interest was 1.42% and expected life was 6.25 . The Company used its historical volatility in accordance with ASC 718. The computation of volatility uses historical volatility derived from the Company’s exchange traded shares. Expected term of options granted is calculated based on the simplified method, in accordance with SAB 110, (i.e., as the average between the vesting period and the contractual term of the options). The risk free interest rate assumption is the implied yield currently available on United States treasury zero-coupon issues with a remaining term equal to the expected life of the Company’s options. The dividend yield assumption is based on the Company’s historical experience and expectation of no future dividend payouts and may be subject to substantial change in the future. The Company has historically not paid cash dividends and has no foreseeable plans to pay cash dividends in the future. The non-cash compensation expenses related to employees and consultants for the years ended December 31, 2018 , 2017 and 2016 amounted to $34,961 , $19,835 and $12,938 , respectively. Effective as of January 1, 2017, the Company adopted Accounting Standards Update 2016-09, “Compensation—Stock Compensation (Topic 718)” (“ASU 2016-09”) on a modified, retrospective basis. ASU 2016-09 permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation: to estimate the total number of awards for which the requisite service period will not be rendered or to account for forfeitures as they occur. Upon adoption of ASU 2016-09, the Company elected to change its accounting policy to account for forfeitures as they occur. The change was applied on a modified, retrospective basis with a cumulative-effect adjustment to retained earnings of $2,616 (which increased the accumulated deficit) as of January 1, 2017. ASU 2016-09 also eliminates the requirement that excess tax benefits be realized as a reduction in current taxes payable before the associated tax benefit can be recognized as an increase in paid in capital. Approximately $7,131 of federal net operating losses and $718 of state net operating losses, neither of which was included in the deferred tax assets recognized in the statement of financial position as of December 31, 2017 , have been attributed to tax deduction for stock-based compensation in excess of the related book expense. Under ASU 2016-09, these previously unrecognized deferred tax assets will be recognized on a modified, retrospective basis as of the start of the year in which the ASU 2016-09 is adopted; in this case as of January 1, 2017. The U.S. federal and state net operating losses and credits that were recognized as of January 1, 2017 have been offset by a valuation allowance. Additionally, ASU 2016-09 addresses the presentation of excess tax benefits and employee taxes paid on the statement of cash flows. The Company is now required to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. The Company adopted this change prospectively.
Research and Development Costs	m. Research and Development Costs: Research and development costs are charged to the statement of operations as incurred. ASC No. 985-20, “Software-Costs of Software to Be Sold, Leased, or Marketed,” requires capitalization of certain software development costs subsequent to the establishment of technological feasibility. Based on the Company’s product development process, technological feasibility is established upon the completion of a working model. The Company does not incur material costs between the completion of the working model and the point at which the product is ready for general release. Therefore, research and development costs are charged to the statement of operations as incurred.
Income Taxes	n. Income Taxes: The Company accounts for income taxes in accordance with ASC No. 740, using the liability method whereby deferred tax assets and liability account balances are determined based on the differences between financial reporting and the tax basis for assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, if necessary, to reduce deferred tax assets to the amounts that are more likely-than-not to be realized. ASC 740 contains a two-step approach to recognizing and measuring a liability for uncertain tax positions. The first step is to evaluate the tax position taken or expected to be taken in a tax return by determining if the weight of available evidence indicates that it is more likely than not that, on an evaluation of the technical merits, the tax position will be sustained on audit, including resolution of any related appeals or litigation processes. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon ultimate settlement. The Company accrues interest and penalties related to unrecognized tax provisions in its taxes on income.
Derivative Instruments	o. Derivative Instruments: The Company’s primary objective for holding derivative instruments is to reduce its exposure to foreign currency rate changes. The Company reduces its exposure by entering into forward foreign exchange contracts with respect to operating expenses that are forecast to be incurred in currencies other than the U.S. dollar. A majority of the Company’s revenues and operating expenditures are transacted in U.S. dollars. However, certain operating expenditures are incurred in or exposed to other currencies, primarily the NIS. The Company has established forecasted transaction currency risk management programs to protect against fluctuations in fair value and the volatility of future cash flows caused by changes in exchange rates. The Company’s currency risk management program includes forward foreign exchange contracts designated as cash flow hedges. These forward foreign exchange contracts generally mature within 12 months. The Company does not enter into derivative financial instruments for trading purposes. In addition, the Company enters into forward contracts to hedge a portion of its monetary items in the balance sheet, such as trade receivables and payables, denominated in Pound Sterling and Euro for short term periods (the “Fair Value Hedging Program”). The purpose of the Fair Value Hedging Program is to protect the fair value of the monetary assets from foreign exchange rate fluctuations. Gains and losses from derivatives related to the Fair Value Hedging Program are not designated as hedging instruments. Derivative instruments measured at fair value and their classification on the consolidated balance sheets are presented in the following table (in thousands): Liabilities as of Assets as of December 31, 2018 December 31, 2017 Notional Amount Fair Value Notional Amount Fair Value Foreign Exchange Forward Contract Derivatives in cash flow hedging relationships—included in other current assets and accrued expenses and other short term liabilities $ 75,153 $ (3,628 ) $ 1,746 $ 163 Foreign exchange forward contract derivatives for monetary items included in accrued expenses and other short term liabilities $ 29,162 $ (18 ) $ — $ — For the years ended December 31, 2018 and 2017 , the consolidated statements of operations reflect a loss of approximately $3,741 and a gain of $2,649 , respectively, related to the effective portion of foreign currency forward contracts. Any ineffective portion of the cash flow hedges is recognized in financial income (expenses), net in the consolidated statement of operations. No material ineffective hedges were recognized in financial income (expenses), net for the years ended December 31, 2018 and 2017 . For the year ended December 31, 2018 , the consolidated statements of operations reflect a gain of approximately $98 in financial income (expenses), net, related to the Fair Value Hedging Program. The Company did not enter into any transactions related to the Fair Value Hedging Program for year ended December 31, 2017 .
Concentrations of Credit Risks	p. Concentrations of Credit Risks: Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, marketable securities, short-term deposits and trade receivables. The Company’s cash, cash equivalents, marketable securities and short-term deposits are invested in major banks mainly in the United States but also in the United Kingdom, France, Germany, Israel, Canada, Ireland, Australia and the Netherlands. Such deposits in the United States may be in excess of insured limits and are not insured in other jurisdictions. The Company maintains cash and cash equivalents with diverse financial institutions and monitors the amount of credit exposure to each financial institution. The Company’s trade receivables are geographically diversified and derived primarily from sales to a network of distributors and VARs mainly in the United States and Europe. Concentration of credit risk with respect to trade receivables is limited by credit limits, ongoing credit evaluation and account monitoring procedures. The Company performs ongoing credit evaluations of its channel partners and establishes an allowance for doubtful accounts based upon a specific review of all significant outstanding invoices. The Company writes off receivables when they are deemed uncollectible and having exhausted all collection efforts.
Retirement and Severance Pay	q. Retirement and Severance Pay: VSI makes available to its employees a retirement plan (the “U.S. Plan”) that qualifies as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code of 1986, as amended (“the Code”). Participants in the U.S. Plan may elect to defer a portion of their pre-tax earnings, up to the Internal Revenue Service annual contribution limit. VSI matches 100% of each participant’s contributions up to a maximum of 3% of the participant’s total pay and 50% of each participant’s contributions on contributions between 3% and 5% of the participant’s total pay. Each participant may contribute up to 80% of total remuneration up to the Internal Revenue Service’s annual contribution limit. Contributions to the U.S. Plan are recorded during the year contributed as an expense in the consolidated statements of income. Pursuant to Israel’s Severance Pay Law, Israeli employees are entitled to severance pay equal to one month’s salary for each year of employment, or a portion thereof. The employees of the Israeli subsidiary elected to be included under section 14 of the Severance Pay Law, 1963 (“section 14”). According to this section, these employees are entitled only to monthly deposits, at a rate of 8.33% of their monthly salary, made in their name with insurance companies. Payments in accordance with section 14 release the Company from any future severance payments (under the above Israeli Severance Pay Law) in respect of those employees; therefore, related assets and liabilities are not presented in the balance sheet. The Company’s liability for severance pay for the employees of its French subsidiary is calculated pursuant to French law, according to which French employees are entitled to an indemnity (a statutory redundancy). The law provides for the payment of severance payment to any employee working for the French subsidiary for at least a year. VSUK makes available to certain eligible employees a pension plan whereby participants in the plan may elect to defer a portion of their earnings. VSUK matches 100% of each participant’s contributions up to a maximum of 3% of the participant’s net pay. VIRE makes available to its employees a pension plan whereby participants in the plan may elect to defer a portion of their earnings. VIRE matches 100% of each participant’s contributions up to a maximum of 3% and 50% of the participant's contributions on contributions between 3% and 5% of the participant’s net pay. Total expenses related to retirement and severance pay amounted to $6,765 , $4,801 and $3,775 for the years ended December 31, 2018 , 2017 and 2016 , respectively. The amount of severance payable included in other liabilities as of December 31, 2018 and 2017 is $2,391 and $1,781 , respectively.
Fair Value of Financial Instruments	r. Fair Value of Financial Instruments: Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: • Level 1: Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2: Observable inputs that reflect quoted prices for identical assets or 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: Unobservable inputs reflecting our own assumptions incorporated in valuation techniques used to determine fair value. These assumptions are required to be consistent with market participant assumptions that are reasonably available. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The carrying amounts of cash and cash equivalents, marketable securities, trade receivables, short-term deposits and trade payables approximate their fair value due to the short-term maturity of such instruments.
Basic and Diluted Net Loss Per Share	s. Basic and Diluted Net Loss Per Share: Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including stock options, to the extent dilutive. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential shares of common stock outstanding would have been anti-dilutive. There were 3,173,188 and 3,505,729 potentially dilutive shares from the conversion of outstanding restricted stock units and stock options that were not included in the calculation of diluted net loss per share as of December 31, 2018 and 2017 , respectively.
Contingent Liabilities	t. Contingent Liabilities: The Company accounts for its contingent liabilities in accordance with ASC No. 450 “Contingencies”. A provision is recorded when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. With respect to legal matters, provisions are reviewed and adjusted to reflect the impact of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. As of December 31, 2018 and 2017 , the Company was not a party to any litigation that could have a material adverse effect on the Company’s business, financial position, results of operations or cash flows.
Basis of Presentation	u. Basis of Presentation: Certain amounts in prior years' financial statements have been recast and reclassified to conform to the current year's presentation.
Recently Issued Accounting Pronouncements	w. Recently Issued Accounting Pronouncements Not Yet Adopted: In January 2016, the FASB issued ASU 2016-13, “Financial Instruments – Credit Losses on Financial Instruments”, which requires that expected credit losses relating to financial assets measured on an amortized cost basis and available for sale debt securities be recorded through an allowance for credit losses. ASU 2016-13 limits the amount of credit losses to be recognized for available for sale debt securities to the amount by which carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. The new standard will be effective for interim and annual periods beginning after January 1, 2020, and early adoption is permitted. The Company is currently evaluating whether to early adopt this standard and the potential effect on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, “Leases”, on the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for in a manner similar to the accounting under existing guidance for operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. ASC 842 supersedes the previous leases standard, ASC 840, "Leases". The guidance is effective for the interim and annual periods beginning on or after December 15, 2018, and the Company has adopted the standard on January 1, 2019. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. The standard provides a number of optional practical expedients in transition. The Company is electing the ‘package of practical expedients’, which permits it not to reassess under the new standard its prior conclusions about lease identification, lease classification and initial direct costs. To adopt this new standard, the Company has implemented changes to its existing systems and processes in conjunction with a review of existing vendor agreements. The Company expects adoption of the standard to have a material impact on its consolidated balance sheets which will result in the recognition of ROU assets and lease liabilities of approximately $60,000 to $70,000 at January 1, 2019. The most significant impact from recognition of ROU assets and lease liabilities relates to its office space. However, the Company does not anticipate that the adoption of this standard will have a material impact on the operating expenses in its consolidated statements of operations since the expense recognition under this new standard will be similar to current practice. The Company's financial income (expenses), net will be impacted by the revaluation of the lease liabilities in non-USD denominated currencies. In June 2018, the FASB issued ASU No. 2018-07, “Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting.” These amendments expand the scope of Topic 718, Compensation - Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. This ASU supersedes Subtopic 505-50, Equity - Equity-Based Payments to Non-Employees. The guidance is effective for the interim and annual periods beginning after December 15, 2018. The Company expects to adopt this standard effective January 1, 2019 and does not expect it to have a material effect on its consolidated financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Cash, Cash Equivalents and Investments	As of December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 6,870 $ — $ — $ 6,870 Total $ 6,870 $ — $ — $ 6,870 Marketable securities US Treasury securities $ 39,758 *) $ (27 ) $ 39,731 Total $ 39,758 *) $ (27 ) $ 39,731 Short-term deposits Term bank deposits $ 40,137 $ — $ — $ 40,137 Total $ 40,137 $ — $ — $ 40,137 The Company considers all high quality investments purchased with original maturities at the date of purchase greater than three months to be short-term deposits. Investments are available to be used for current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents, marketable securities and short-term deposits are classified as available for sale and are, therefore, recorded at fair value on the consolidated balance sheet, with any unrealized gains and losses reported in accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s consolidated balance sheets, until realized. The Company uses the specific identification method to compute gains and losses on the investments. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included as a component of financial income, net in the consolidated statement of operations. Cash, cash equivalents, marketable securities and short-term deposits consist of the following (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Fair Value Cash and cash equivalents Money market funds $ 2,594 $ — $ — $ 2,594 Total $ 2,594 $ — $ — $ 2,594 Marketable securities US Treasury securities $ 39,776 *) $ (6 ) $ 39,770 Total $ 39,776 *) $ (6 ) $ 39,770 Short-term deposits Term bank deposits $ 70,438 $ — $ — $ 70,438 Total $ 70,438 $ — $ — $ 70,438 *) Represents an amount lower than $1.
Property, Plant and Equipment Estimated Useful Life	Depreciation is calculated using the straight-line method over the estimated useful lives of the assets at the following annual rates: % Computer equipment 33 Office furniture and equipment 14 — 15 Leasehold improvements Over the shorter of the expected lease
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Derivative instruments measured at fair value and their classification on the consolidated balance sheets are presented in the following table (in thousands): Liabilities as of Assets as of December 31, 2018 December 31, 2017 Notional Amount Fair Value Notional Amount Fair Value Foreign Exchange Forward Contract Derivatives in cash flow hedging relationships—included in other current assets and accrued expenses and other short term liabilities $ 75,153 $ (3,628 ) $ 1,746 $ 163 Foreign exchange forward contract derivatives for monetary items included in accrued expenses and other short term liabilities $ 29,162 $ (18 ) $ — $ —
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	elect recast financial statement information, which reflects the effect of the adoption of this standard, is set forth below. Year ended As Reported Adjustments Recast for Adoption Revenues: License revenues $ 123,610 $ (3,269 ) $ 120,341 Maintenance and service revenues 93,754 1,295 95,049 Total revenues 217,364 (1,974 ) 215,390 Cost of revenues 20,873 (159 ) 20,714 Gross profit 196,491 (1,815 ) 194,676 Operating costs and expenses: Research and development 47,369 — 47,369 Sales and marketing 135,896 (1,971 ) 133,925 General and administrative 26,823 (22 ) 26,801 Total operating expenses 210,088 (1,993 ) 208,095 Operating loss (13,597 ) 178 (13,419 ) Financial income, net 2,362 — 2,362 Loss before income taxes (11,235 ) 178 (11,057 ) Income taxes (2,459 ) (328 ) (2,787 ) Net loss $ (13,694 ) $ (150 ) $ (13,844 ) Year ended As Reported Adjustments Recast for Adoption Revenues: License revenues $ 92,873 $ 370 $ 93,243 Maintenance and service revenues 71,583 1,037 72,620 Total revenues 164,456 1,407 165,863 Cost of revenues 15,843 (106 ) 15,737 Gross profit 148,613 1,513 150,126 Operating costs and expenses: Research and development 36,660 — 36,660 Sales and marketing 107,825 (2,186 ) 105,639 General and administrative 19,822 — 19,822 Total operating expenses 164,307 (2,186 ) 162,121 Operating loss (15,694 ) 3,699 (11,995 ) Financial expenses, net (885 ) — (885 ) Loss before income taxes (16,579 ) 3,699 (12,880 ) Income taxes (1,131 ) (182 ) (1,313 ) Net loss $ (17,710 ) $ 3,517 $ (14,193 ) December 31, 2017 As Reported Adjustments As Adjusted Assets Current assets: Prepaid expenses and other current assets $ 7,130 $ 7,216 $ 14,346 Long-term assets: Other assets $ 973 $ 6,270 $ 7,243 Liabilities and stockholders’ equity Current liabilities: Deferred revenues $ 73,891 $ (398 ) $ 73,493 Long-term liabilities: Deferred revenues $ 7,034 $ (426 ) $ 6,608 Other liabilities $ 6,561 $ 1,246 $ 7,807 Stockholders’ equity: Accumulated deficit $ (122,454 ) $ 13,064 $ (109,390 ) Statement of Cash Flows As Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (13,694 ) $ (150 ) $ (13,844 ) Amortization of deferred commissions $ — $ 12,591 $ 12,591 Deferred commissions $ — $ (14,742 ) $ (14,742 ) Deferred revenues $ 18,885 $ 1,975 $ 20,860 Other long term liabilities $ (731 ) $ 326 $ (405 ) Net cash provided by operating activities $ 16,351 $ — $ 16,351 Statement of Cash Flows As Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (17,710 ) $ 3,517 $ (14,193 ) Amortization of deferred commissions $ — $ 9,525 $ 9,525 Deferred commissions $ — $ (11,817 ) $ (11,817 ) Deferred revenues $ 13,269 $ (1,409 ) $ 11,860 Other long term liabilities $ 147 $ 184 $ 331 Net cash provided by operating activities $ 7,347 $ — $ 7,347
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash and cash equivalents, and long term restricted cash reported within the consolidated balance sheets that sum to the total of such amounts in the consolidated statements of cash flows: December 31, 2018 December 31, 2017 December 31, 2016 Cash and cash equivalents $ 48,707 $ 56,689 $ 48,315 Long term restricted cash included in other assets — 547 488 Cash, cash equivalents and long term restricted cash shown in the consolidated statement of cash flows $ 48,707 $ 57,236 $ 48,803

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Prepaid Expense and Other Assets, Current [Abstract]
Schedule of prepaid expenses and other current assets	December 31, 2018 2017 Deferred commission $ 8,055 $ 7,216 Prepaid expenses 6,857 6,044 Government institutions & other receivables 1,874 542 Foreign currency forward contracts derivatives — 163 Short-term deposits & other 166 381 $ 16,952 $ 14,346

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	December 31, 2018 2017 Cost: Computer equipment $ 12,848 $ 8,473 Office furniture and equipment 3,193 2,263 Leasehold improvements 12,814 9,163 28,855 19,899 Accumulated depreciation 11,532 8,003 Property and equipment, net $ 17,323 $ 11,896

Accrued Expenses and Other Sh_2

Accrued Expenses and Other Short Term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of Accounts Expense and Other Liabilities	December 31, 2018 2017 Employees $ 20,111 $ 17,748 Accrued expenses 12,725 9,507 Government authorities and other 18,196 14,006 Foreign exchange forward contract derivatives 3,646 — Other short term liabilities 1,313 1,192 $ 55,991 $ 42,453

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Aggregate minimum rental commitments under non-cancelable leases as of December 31, 2018 for the upcoming years were as follows: Payments Due By Period 2019 $ 7,174 2020 9,086 2021 8,865 2022 8,876 2023 8,690 Thereafter 37,507 $ 80,198

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table sets forth the Company’s liabilities that were measured at fair value as of December 31, 2018 and 2017 by level within the fair value hierarchy (in thousands): As of December 31, 2018 As of December 31, 2017 Level I Level II Level III Fair Value Level I Level II Level III Fair Value Financial assets: Cash equivalents: Money market funds 2,594 — — 2,594 6,870 — — 6,870 Marketable securities: US Treasury securities 39,770 — — 39,770 39,731 — — 39,731 Other current assets: Forward foreign exchange contracts — — — — — 163 — 163 Financial liabilities: Forward foreign exchange contracts — (3,647 ) — (3,647 ) — — — — Total financial assets (liabilities) $ 42,364 $ (3,647 ) $ — $ 38,717 $ 46,601 $ 163 $ — $ 46,764

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Schedule of Stock by Class	Authorized Issued and outstanding Number of shares December 31, December 31, 2018 2017 2018 2017 Stock of $0.001 par value: Common stock 200,000,000 200,000,000 29,576,880 28,146,162
Share-based Compensation, Stock Options, Activity	A summary of employees’ stock options activities during the year ended December 31, 2018 is as follows: Year ended December 31, 2018 Number Weighted average exercise price Aggregate intrinsic value (in thousands) Weighted average remaining contractual life (years) Options outstanding at the beginning of the year 1,456,285 $ 16.172 $ 47,152 4.906 Granted — $ — Exercised (744,636 ) $ 14.469 Forfeited (1,981 ) $ 32.473 Options outstanding at the end of the period 709,668 $ 17.941 $ 24,810 4.513 Options exercisable at the end of the period 687,508 $ 17.856 $ 24,093 4.439
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	The options outstanding as of December 31, 2018 have been separated into ranges of exercise price as follows: Range of exercise price Options outstanding as of December 31, 2018 Weighted average remaining contractual life (years) Weighted average exercise price Options exercisable as of December 31, 2018 Weighted average remaining contractual life (years) Weighted average exercise price of options exercisable $ 1.256 — 1.576 130,479 0.663 $ 1.282 130,479 0.663 $ 1.282 $ 6.230 — 8.800 12,356 3.007 $ 8.039 12,356 3.007 $ 8.039 $ 12.470 — 16.870 147,125 5.014 $ 14.030 132,541 4.781 $ 13.637 $ 19.510 — 21.660 220,211 5.599 $ 21.174 218,573 5.594 $ 21.185 $ 22.010 — 24.230 85,870 5.284 $ 22.364 85,870 5.284 $ 22.364 $29.880 66,349 6.145 $ 29.880 60,411 6.145 $ 29.880 $39.860 47,278 5.225 $ 39.860 47,278 5.225 $ 39.860 709,668 4.513 $ 17.941 687,508 4.439 $ 17.856
Schedule of Stockholders' Equity Note, Warrants or Rights	The Company’s outstanding options granted to consultants for services as of December 31, 2018 were as follows: Issuance date Options for shares of common stock Exercise price per share Options exercisable Exercisable through (number) (number) February 2013 1,500 $ 12.470 1,500 February 2023 August 2013 4,000 $ 21.140 4,000 August 2023 March 2014 5,550 $ 39.860 5,550 March 2024 May 2014 3,700 $ 22.010 3,700 May 2024 November 2014 5,468 $ 21.660 5,468 November 2024 May 2015 1,137 $ 19.510 929 May 2025 February 2016 2,138 $ 16.870 1,408 February 2026 23,493 22,555
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	The following provides a summary of the restricted stock unit activity for the Company for the year ended December 31, 2018 : Number of Shares Underlying Outstanding Restricted Stock Units Weighted- Average Grant Date Fair Value Outstanding as of January 1, 2018 2,018,121 $ 27.32 Granted 1,255,824 $ 53.79 Vested (671,768 ) $ 28.54 Forfeited (162,150 ) $ 36.89 Unvested as of December 31, 2018 2,440,027 $ 40.00
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	The Company recognized non-cash stock-based compensation expense in the consolidated statements of operations as follows (in thousands): Year ended December 31, 2018 2017 2016 Cost of revenues $ 1,757 $ 1,078 $ 699 Research and development 9,645 5,209 3,052 Sales and marketing 16,081 8,542 6,104 General and administrative 7,478 5,006 3,083 Total $ 34,961 $ 19,835 $ 12,938

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	c. Loss before taxes on income is comprised as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Domestic $ (25,557 ) $ (19,239 ) $ (13,940 ) Foreign (2,608 ) 8,182 1,060 $ (28,165 ) $ (11,057 ) $ (12,880 )
Schedule of Components of Income Tax Expense (Benefit)	d. Taxes on income (loss) are comprised as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Current: Domestic: Federal $ — $ (92 ) $ 92 State 169 191 109 Foreign 1,498 2,516 930 Total current income tax $ 1,667 $ 2,615 $ 1,131 Deferred: Foreign $ (1,254 ) $ 172 $ 182 Total deferred income tax $ (1,254 ) $ 172 $ 182 Income tax expense $ 413 $ 2,787 $ 1,313
Schedule of Deferred Tax Assets and Liabilities	December 31, 2018 2017 (as adjusted) Deferred tax assets: Carry forward losses and credits $ 15,547 $ 7,407 Deferred revenues 13,995 14,226 Accrued payroll, commissions, vacation 1,912 2,685 Equity Compensation 5,737 908 Allowance for doubtful accounts 940 633 Accrued severance pay 297 238 Other 1,346 1,760 Deferred tax assets before valuation allowance 39,774 27,857 Valuation allowance (39,365 ) (27,702 ) Deferred tax assets $ 409 $ 155 Deferred tax liability: Accrued compensation and other accrued expense $ (272 ) $ (289 ) Deferred tax liability $ (272 ) $ (289 ) Net deferred tax asset (liability) $ 137 $ (134 )
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation between the theoretical tax expense, assuming all income is taxed at the statutory tax rate applicable to income of the Company, and the actual tax expense (benefit) as reported in the consolidated statements of operations is as follows: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Loss before taxes, as reported in the consolidated statements of operations $ (28,165 ) $ (11,057 ) $ (12,880 ) Statutory tax rate 21 % 34 % 34 % Theoretical tax benefits on the above amount at the US statutory tax rate $ (5,915 ) $ (3,759 ) $ (4,379 ) Income tax at rate other than the U.S. statutory tax rate 692 (1,047 ) (6 ) Tax advances and non-deductible expenses including equity based compensation expenses (7,623 ) 3,123 4,298 Operating losses and other temporary differences for which valuation allowance was provided 15,826 (8,623 ) 1,885 Research and Development Tax Credit — 1,126 (1,182 ) State tax (1,221 ) (601 ) (426 ) Impact of rate change — 10,920 (360 ) Change in tax reserve for uncertain tax positions (1,728 ) 1,576 1,209 Other individually immaterial income tax items 382 72 274 Actual tax expense $ 413 $ 2,787 $ 1,313
Schedule of Unrecognized Tax Benefits Roll Forward	g. A reconciliation of the beginning and ending amounts of unrecognized tax benefits in the years ended December 31, 2018 and 2017 are as follows: Gross unrecognized tax benefits as of January 1, 2017 $ 2,106 Increase in tax position for current year 1,752 Increase in tax position for prior years 135 Decrease in tax position for prior years (311 ) Gross unrecognized tax benefits as of December 31, 2017 $ 3,682 Increase in tax position for current year 169 Increase in tax position for prior years 241 Decrease in tax position for prior years (720 ) Decrease for lapse of statute of limitations/ settlements (1,418 ) Gross unrecognized tax benefits as of December 31, 2018 $ 1,954

Financial Expenses, Net (Tables

Financial Expenses, Net (Tables)	12 Months Ended
	Dec. 31, 2018
FInancial Expenses, Net [Abstract]
Schedule Of Nonoperating Income, by Component	Year ended December 31, 2018 2017 2016 Financial income: Interest on bank deposits, net $ 1,741 $ 747 $ 520 Foreign currency transactions gains, net — 1,773 — Other — 27 — 1,741 2,547 520 Financial expenses: Bank charges 195 185 149 Foreign currency transactions losses, net 574 — 1,224 Other 2 — 32 (771 ) (185 ) (1,405 ) $ 970 $ 2,362 $ (885 )

Geographic Information and Ma_2

Geographic Information and Major Customer and Product Data (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Revenue from External Customers by Geographic Areas	The following is a summary of revenues within geographic areas: Year ended December 31, 2018 2017 2016 (as adjusted) (as adjusted) Revenues based on customer’s location: North America $ 167,361 $ 139,720 $ 106,069 EMEA (*) 93,816 68,998 53,170 Rest of the World 9,111 6,672 6,624 Total revenues $ 270,288 $ 215,390 $ 165,863 (*) Sales to customers in France accounted for $31,532 , $22,658 and $17,103 for the years ended December 31, 2018 , 2017 and 2016 , respectively.
Long-lived Assets by Geographic Areas	December 31, 2018 2017 Long-lived assets by geographic region: United States $ 7,612 $ 7,072 Israel 7,834 2,944 France 1,243 1,426 Other 634 454 $ 17,323 $ 11,896

General (Details Textual)

General (Details Textual)	12 Months Ended
	Dec. 31, 2018subsidiary
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operations Commenced Date	Jan. 1, 2005
Subsidiary or Equity Method Investee, Number	9
Entity Incorporation, Date of Incorporation	Nov. 24, 2004

Significant Accounting Polici_4

Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2017	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Short term restricted cash	$ 0	$ 0
Long term restricted cash included in other assets	0	547,000	$ 488,000
Asset impairment charges	0	0	0
Deferred revenue, revenue recognized	73,176,000
Sales returns	$ 0	0	$ 0
Granted (in shares)	0
Dividend yield			0.00%
Expected volatility rate			62.10%
Risk free interest rate			1.42%
Expected life			6 years 3 months
Stock-based compensation	$ 34,961,000	19,835,000	$ 12,938,000
Gain on derivative	98,000
Severance and retirement costs	$ 6,765,000	$ 4,801,000	3,775,000
Antidilutive securities excluded from computation of earnings per share, shares	3,173,188	3,505,729
Revenues	$ 270,288,000	$ 215,390,000	165,863,000
Deferred revenues	87,729,000	73,493,000
Deferred revenues	6,487,000	6,608,000
Deferred tax liabilities		134,000
Accumulated deficit	(137,968,000)	(109,390,000)
Other Noncurrent Liabilities
Significant Accounting Policies [Line Items]
Restructuring reserve	$ 2,391,000	1,781,000
Foreign Plan | VSUK Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, maximum annual contributions per employee, percent	8.33%
United Kingdom | VSUK Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Defined contribution plan, employer matching contribution, percent of base pay	3.00%
Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Defined contribution, plan employer matching contribution, percent of participants contribution	50.00%
Foreign Exchange Contract
Significant Accounting Policies [Line Items]
Derivative, gain on derivative, net	$ 3,741,000	2,649,000
Derivative instruments, gain (loss) recognized in income, ineffective portion and amount excluded from effectiveness testing, net	0	0
Accounting Standards Update 2016-09
Significant Accounting Policies [Line Items]
Effect of adoption of ASU			0
Deferred tax assets, operating loss carryforwards, domestic		7,131,000
Deferred tax assets, operating loss carryforwards, state and local		718,000
Accumulated deficit				$ 1,302,000
Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Effect of adoption of ASU					$ (9,697,000)
Deferred revenues		73,493,000
Deferred revenues		6,608,000
Accumulated deficit		(109,390,000)
Accounting Standards Update 2014-09 | Restatement Adjustments | Year Ended December 31, 2017
Significant Accounting Policies [Line Items]
Revenues	1,974,000
Accounting Standards Update 2014-09 | Restatement Adjustments | Year Ended December 31, 2016
Significant Accounting Policies [Line Items]
Revenues		$ 1,407,000
Accounting Standards Update 2014-09 | Restatement Adjustments | As of January 1, 2016
Significant Accounting Policies [Line Items]
Deferred commission	13,486,000
Deferred revenues	398,000
Deferred revenues	426,000
Deferred tax liabilities	1,246,000
Accumulated deficit	$ 9,697,000
Accumulated deficit | Accounting Standards Update 2016-09
Significant Accounting Policies [Line Items]
Effect of adoption of ASU			$ 2,616,000
Accumulated deficit | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Effect of adoption of ASU					$ (9,697,000)
Israel, New Shekels
Significant Accounting Policies [Line Items]
Investment interest rate		0.03%
Minimum | Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution, plan employer matching contribution, percent of participants contribution	3.00%
Defined contribution plan, employer matching contribution, percent of base pay	3.00%
Minimum | Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, contributions, percentage of participants base pay	3.00%
Minimum | Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease, liability	$ 60,000,000
Operating lease, right-of-use asset	$ 60,000,000
Minimum | United States of America, Dollars
Significant Accounting Policies [Line Items]
Investment interest rate	0.60%	0.60%
Maximum | Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution, plan employer matching contribution, percent of participants contribution	50.00%
Defined contribution plan, employer matching contribution, percent of base pay	5.00%
Maximum | Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of base pay	3.00%
Defined contribution plan, contributions, percentage of participants base pay	5.00%
Participant matching contribution percentage of base remuneration	80.00%
Maximum | Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease, liability	$ 70,000,000
Operating lease, right-of-use asset	$ 70,000,000
Maximum | United States of America, Dollars
Significant Accounting Policies [Line Items]
Investment interest rate	2.77%	1.35%
Short-term Deposits | US Treasury Securities | Maximum
Significant Accounting Policies [Line Items]
Short term investment maturity period	1 year	1 year

Significant Accounting Polici_5

Significant Accounting Policies - Cash, Cash Equivalents and Short-term Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents
Significant Accounting Policies [Line Items]
Amortized Cost	$ 2,594	$ 6,870
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair value	2,594	6,870
Cash and Cash Equivalents | Money Market Funds
Significant Accounting Policies [Line Items]
Amortized Cost	2,594	6,870
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair value	2,594	6,870
Marketable Securities
Significant Accounting Policies [Line Items]
Amortized Cost	39,776
Gross Unrealized Loss	(6)
Fair value	39,770
Marketable Securities | US Treasury Securities
Significant Accounting Policies [Line Items]
Amortized Cost	39,776	39,758
Gross Unrealized Loss	(6)	(27)
Fair value	39,770	39,731
Short-term Deposits
Significant Accounting Policies [Line Items]
Amortized Cost	70,438	40,137
Gross Unrealized Loss	0	0
Fair value	70,438	40,137
Short-term Deposits | Term Bank Deposits
Significant Accounting Policies [Line Items]
Amortized Cost	70,438	40,137
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair value	$ 70,438	$ 40,137

Significant Accounting Polici_6

Significant Accounting Policies - Property and Equipment, Schedule of Depreciation Annual Rates and Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2018
Computer Equipment
Significant Accounting Policies [Line Items]
Depreciation rate	3300.00%
Office Furniture and Equipment | Minimum
Significant Accounting Policies [Line Items]
Depreciation rate	1400.00%
Office Furniture and Equipment | Maximum
Significant Accounting Policies [Line Items]
Depreciation rate	1500.00%
Leasehold Improvements
Significant Accounting Policies [Line Items]
Leasehold improvements	Over the shorter of the expected lease term or estimated useful life

Significant Accounting Polici_7

Significant Accounting Policies - Derivative Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amount	$ 75,153	$ 1,746
Derivative asset, fair value		163
Derivative liabilities, fair value	(3,628)
Other Current Assets
Derivative [Line Items]
Notional amount	29,162	0
Derivative asset, fair value		$ 0
Derivative liabilities, fair value	$ (18)

Significant Accounting Polici_8

Significant Accounting Policies - Recast Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Revenue	$ 270,288	$ 215,390	$ 165,863
Cost of revenues	27,683	20,714	15,737
Gross profit	242,605	194,676	150,126
Research and development	69,971	47,369	36,660
Sales and marketing	168,309	133,925	105,639
General and administrative	33,460	26,801	19,822
Total operating expenses	271,740	208,095	162,121
Operating loss	(29,135)	(13,419)	(11,995)
Financial expenses, net	970	2,362	(885)
Loss before income taxes	(28,165)	(11,057)	(12,880)
Income taxes	(413)	(2,787)	(1,313)
Net loss	(28,578)	(13,844)	(14,193)
Current assets:
Prepaid expenses and other current assets	16,952	14,346
Current liabilities:
Deferred revenues	87,729	73,493
Long-term liabilities:
Deferred revenues	6,487	6,608
Other liabilities	6,781	7,807
Stockholders’ equity:
Accumulated deficit	(137,968)	(109,390)
Cash flows from operating activities:
Amortization of deferred commissions	13,185	12,591	9,525
Deferred commissions	(15,308)	(14,742)	(11,817)
Deferred revenues	14,115	20,860	11,860
Other long term liabilities	(1,025)	(405)	331
Net cash provided by operating activities	23,545	16,351	7,347
Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		215,390	165,863
Cost of revenues		20,714	15,737
Gross profit		194,676	150,126
Research and development		47,369	36,660
Sales and marketing		133,925	105,639
General and administrative		26,801	19,822
Total operating expenses		208,095	162,121
Operating loss		(13,419)	(11,995)
Financial expenses, net		2,362	(885)
Loss before income taxes		(11,057)	(12,880)
Income taxes		2,787	(1,313)
Net loss		(13,844)	(14,193)
Current assets:
Prepaid expenses and other current assets		14,346
Long-term assets:
Other assets		7,243
Current liabilities:
Deferred revenues		73,493
Long-term liabilities:
Deferred revenues		6,608
Other liabilities		7,807
Stockholders’ equity:
Accumulated deficit		(109,390)
Cash flows from operating activities:
Amortization of deferred commissions		12,591	9,525
Deferred commissions		(14,742)	(11,817)
Deferred revenues		20,860	11,860
Other long term liabilities		(405)	331
Net cash provided by operating activities		16,351	7,347
Previously Reported | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		217,364	164,456
Cost of revenues		20,873	15,843
Gross profit		196,491	148,613
Research and development		47,369	36,660
Sales and marketing		135,896	107,825
General and administrative		26,823	19,822
Total operating expenses		210,088	164,307
Operating loss		(13,597)	(15,694)
Financial expenses, net		2,362	(885)
Loss before income taxes		(11,235)	(16,579)
Income taxes		2,459	(1,131)
Net loss		(13,694)	(17,710)
Current assets:
Prepaid expenses and other current assets		7,130
Long-term assets:
Other assets		973
Current liabilities:
Deferred revenues		73,891
Long-term liabilities:
Deferred revenues		7,034
Other liabilities		6,561
Stockholders’ equity:
Accumulated deficit		(122,454)
Cash flows from operating activities:
Amortization of deferred commissions		0	0
Deferred commissions		0	0
Deferred revenues		18,885	13,269
Other long term liabilities		(731)	147
Net cash provided by operating activities		16,351	7,347
Adjustments | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		(1,974)	1,407
Cost of revenues		(159)	(106)
Gross profit		(1,815)	1,513
Research and development		0	0
Sales and marketing		(1,971)	(2,186)
General and administrative		(22)	0
Total operating expenses		(1,993)	(2,186)
Operating loss		178	3,699
Financial expenses, net		0	0
Loss before income taxes		178	3,699
Income taxes		328	(182)
Net loss		(150)	3,517
Current assets:
Prepaid expenses and other current assets		7,216
Long-term assets:
Other assets		6,270
Current liabilities:
Deferred revenues		(398)
Long-term liabilities:
Deferred revenues		(426)
Other liabilities		1,246
Stockholders’ equity:
Accumulated deficit		13,064
Cash flows from operating activities:
Amortization of deferred commissions		12,591	9,525
Deferred commissions		(14,742)	(11,817)
Deferred revenues		1,975	(1,409)
Other long term liabilities		326	184
Net cash provided by operating activities		0	0
License
Significant Accounting Policies [Line Items]
Revenue	147,613	120,341	93,243
License | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		120,341	93,243
License | Previously Reported | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		123,610	92,873
License | Adjustments | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		(3,269)	370
Maintenance
Significant Accounting Policies [Line Items]
Revenue	$ 122,675	95,049	72,620
Maintenance | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		95,049	72,620
Maintenance | Previously Reported | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		93,754	71,583
Maintenance | Adjustments | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Revenue		$ 1,295	$ 1,037

Significant Accounting Polici_9

Significant Accounting Policies - Cash and Cash Equivalents, and Long Term Restricted Cash (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 48,707,000	$ 56,689,000	$ 48,315,000
Long term restricted cash included in other assets	0	547,000	488,000
Cash, cash equivalents and long term restricted cash shown in the consolidated statement of cash flows	$ 48,707,000	$ 57,236,000	$ 48,803,000	$ 49,708,000

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule Of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expense and Other Assets, Current [Abstract]
Deferred commission	$ 8,055	$ 7,216
Prepaid expenses	6,857	6,044
Government institutions & other receivables	1,874	542
Foreign currency forward contracts derivatives	0	163
Short-term deposits & other	166	381
Total	$ 16,952	$ 14,346

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 28,855	$ 19,899
Accumulated depreciation	11,532	8,003
Property and equipment, net	17,323	11,896
Computer Equipment
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	12,848	8,473
Office Furniture and Equipment
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	3,193	2,263
Leasehold Improvements
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 12,814	$ 9,163

Property and Equipment, Net (De

Property and Equipment, Net (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation	$ 4,156	$ 3,328	$ 2,180

Accrued Expenses and Other Sh_3

Accrued Expenses and Other Short Term Liabilities - Schedule of Accrued Expenses and Other Short Term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities and Other Liabilities [Abstract]
Employees	$ 20,111	$ 17,748
Accrued expenses	12,725	9,507
Government authorities and other	18,196	14,006
Foreign exchange forward contract derivatives	3,646	0
Other short term liabilities	1,313	1,192
Total	$ 55,991	$ 42,453

Commitments and Contingent Li_3

Commitments and Contingent Liabilities (Details Textual) - USD ($)	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Operating leases, rent expense		$ 7,000	$ 4,000	$ 3,000
Deferred rent credit, current		1,000	1,000
Deferred rent credit, noncurrent		$ 4,000	$ 5,000
Promissory Note
Other Commitments [Line Items]
Maximum borrowing capacity	$ 7,000,000
Basis spread on variable rate	0.05%
Interest rate at period end		5.55%
Long-term line of credit		$ 0
Promissory Note | Minimum
Other Commitments [Line Items]
Debt instrument, interest rate, effective percentage	4.10%

Commitments and Contingent Li_4

Commitments and Contingent Liabilities - Aggregate Minimum Rental Commitments Under Non-cancelable Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 7,174
2,020	9,086
2,021	8,865
2,022	8,876
2,023	8,690
Thereafter	37,507
Total	$ 80,198

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets (liabilities)	$ 38,717	$ 46,764
Foreign Exchange Forward
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	163
Derivative liabilities	3,647	0
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	2,594	6,870
US Treasury Securities Included in Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	39,770	39,731
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets (liabilities)	42,364	46,601
Fair Value, Inputs, Level 1 | Foreign Exchange Forward
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	2,594	6,870
Fair Value, Inputs, Level 1 | US Treasury Securities Included in Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	39,770	39,731
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets (liabilities)	(3,647)	163
Fair Value, Inputs, Level 2 | Foreign Exchange Forward
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	163
Derivative liabilities	3,647	0
Fair Value, Inputs, Level 2 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	0	0
Fair Value, Inputs, Level 2 | US Treasury Securities Included in Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	0	0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets (liabilities)	0	0
Fair Value, Inputs, Level 3 | Foreign Exchange Forward
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Fair Value, Inputs, Level 3 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	0	0
Fair Value, Inputs, Level 3 | US Treasury Securities Included in Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	$ 0	$ 0

Stockholders' Equity - Composit

Stockholders' Equity - Composition of Common Stock (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	29,576,880	28,146,162

Stockholders' Equity (Details T

Stockholders' Equity (Details Textual)	Jan. 01, 2019shares	Jan. 01, 2018shares	Jan. 01, 2017shares	Jan. 01, 2016shares	Jun. 30, 2015shares	Nov. 14, 2013shares	Dec. 31, 2018USD ($)vote$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2013shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized							200,000,000	200,000,000
Common stock, par value | $ / shares							$ 0.001	$ 0.001	$ 0.001
Common stock, number of voting rights | vote							1
Capital shares reserved for future issuance, annual increase, maximum		1,125,846	1,072,870	1,042,766
Exercises in period, intrinsic value | $							$ 40,610,000	$ 22,382,000	$ 9,418,000
Compensation cost not yet recognized | $							$ 142,000	$ 2,208,000
Compensation cost not yet recognized, period for recognition							8 months 17 days	10 months 20 days
Granted (in shares)							0
Stock-based compensation expense recognized | $							$ 40,000	$ 0	$ 0
The 2005 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance										4,713,319
Vesting period							4 years
The 2013 Omnibus Equity Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance						1,904,633
Percentage of outstanding stock reserved for grant						4.00%
Percentage of outstanding stock maximum						5.00%
2015 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized					500,000
Maximum employee subscription rate					15.00%
Purchase price of common stock, percent					85.00%
Percent of shares increase, employee stock purchase plan					1.00%
Common stock availability threshold, employee stock purchase plan					2.00%
Shares increase threshold, employee stock purchase plan					400,000
Number of additional shares authorized		188,813	158,695	21,383
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capital shares reserved for future issuance, annual increase, maximum	1,183,075
Subsequent Event | 2015 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized	177,358

Stockholders' Equity - Compos_2

Stockholders' Equity - Composition of Common Stock (Details) (Footnote) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Common stock, shares, outstanding	29,576,880	28,146,162	26,821,762
Common stock, par value	$ 0.001	$ 0.001	$ 0.001

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at the beginning of the year (in shares)	1,456,285
Granted (in shares)	0
Exercised (in shares)	(744,636)
Forfeited (in shares)	(1,981)
Options outstanding at the end of the period (in shares)	709,668	1,456,285
Options exercisable at the end of the year (in shares)	687,508
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding at the beginning of the year, weighted average exercise price (in dollars per share)	$ 16.172
Granted, weighted average exercise price (in dollars per share)	0
Exercised, weighted average exercise price (in dollars per share)	14.469
Forfeited, weighted average exercise price (in dollars per share)	32.473
Options outstanding at the end of the period, weighted average exercise price (in dollars per share)	17.941	$ 16.172
Options exercisable at the end of the year, weighted average exercise price (in dollars per share)	$ 17.856
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding at the beginning of the year, aggregate intrinsic value	$ 24,810	$ 47,152
Options exercisable at the end of the year, aggregate intrinsic value	$ 24,093
Options outstanding at the beginning of the year, weighted average remaining contractual life (Year)	4 years 6 months 5 days	4 years 10 months 27 days
Options exercisable at the end of the year, weighted average remaining contractual life (Year)	4 years 5 months 8 days

Stockholders' Equity - Options

Stockholders' Equity - Options Outstanding Separated Into Range of Exercise Price (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Class of Stock [Line Items]
Exercise price range, number of outstanding options | shares	709,668,000
Exercise price range, outstanding options, weighted average remaining contractual term	4 years 6 months 5 days
Exercise price range, outstanding options, weighted average exercise price	$ 17.941
Exercise price range, number of exercisable options | shares	687,508,000
Exercise price range, exercisable options, weighted average remaining contractual term	4 years 5 months 8 days
Exercise price range, exercisable options, weighted average exercise price	$ 17.856
Range One
Class of Stock [Line Items]
Exercise price range, upper range limit	1.576
Exercise price range, lower range limit	$ 1.256
Exercise price range, number of outstanding options | shares	130,479,000
Exercise price range, outstanding options, weighted average remaining contractual term	7 months 29 days
Exercise price range, outstanding options, weighted average exercise price	$ 1.282
Exercise price range, number of exercisable options | shares	130,479,000
Exercise price range, exercisable options, weighted average remaining contractual term	7 months 29 days
Exercise price range, exercisable options, weighted average exercise price	$ 1.282
Range Two
Class of Stock [Line Items]
Exercise price range, upper range limit	8.800
Exercise price range, lower range limit	$ 6.230
Exercise price range, number of outstanding options | shares	12,356,000
Exercise price range, outstanding options, weighted average remaining contractual term	3 years 3 days
Exercise price range, outstanding options, weighted average exercise price	$ 8.039
Exercise price range, number of exercisable options | shares	12,356,000
Exercise price range, exercisable options, weighted average remaining contractual term	3 years 3 days
Exercise price range, exercisable options, weighted average exercise price	$ 8.039
Range Three
Class of Stock [Line Items]
Exercise price range, upper range limit	16.870
Exercise price range, lower range limit	$ 12.470
Exercise price range, number of outstanding options | shares	147,125,000
Exercise price range, outstanding options, weighted average remaining contractual term	5 years 5 days
Exercise price range, outstanding options, weighted average exercise price	$ 14.030
Exercise price range, number of exercisable options | shares	132,541,000
Exercise price range, exercisable options, weighted average remaining contractual term	4 years 9 months 11 days
Exercise price range, exercisable options, weighted average exercise price	$ 13.637
Range Four
Class of Stock [Line Items]
Exercise price range, upper range limit	21.660
Exercise price range, lower range limit	$ 19.510
Exercise price range, number of outstanding options | shares	220,211,000
Exercise price range, outstanding options, weighted average remaining contractual term	5 years 7 months 6 days
Exercise price range, outstanding options, weighted average exercise price	$ 21.174
Exercise price range, number of exercisable options | shares	218,573,000
Exercise price range, exercisable options, weighted average remaining contractual term	5 years 7 months 4 days
Exercise price range, exercisable options, weighted average exercise price	$ 21.185
Range Five
Class of Stock [Line Items]
Exercise price range, upper range limit	24.230
Exercise price range, lower range limit	$ 22.010
Exercise price range, number of outstanding options | shares	85,870,000
Exercise price range, outstanding options, weighted average remaining contractual term	5 years 3 months 12 days
Exercise price range, outstanding options, weighted average exercise price	$ 22.364
Exercise price range, number of exercisable options | shares	85,870,000
Exercise price range, exercisable options, weighted average remaining contractual term	5 years 3 months 12 days
Exercise price range, exercisable options, weighted average exercise price	$ 22.364
Range Six
Class of Stock [Line Items]
Exercise price range, number of outstanding options | shares	66,349,000
Exercise price range, outstanding options, weighted average remaining contractual term	6 years 1 month 23 days
Exercise price range, outstanding options, weighted average exercise price	$ 29.880
Exercise price range, number of exercisable options | shares	60,411,000
Exercise price range, exercisable options, weighted average remaining contractual term	6 years 1 month 23 days
Exercise price range, exercisable options, weighted average exercise price	$ 29.880
Range Seven
Class of Stock [Line Items]
Exercise price range, number of outstanding options | shares	47,278,000
Exercise price range, outstanding options, weighted average remaining contractual term	5 years 2 months 21 days
Exercise price range, outstanding options, weighted average exercise price	$ 39.860
Exercise price range, number of exercisable options | shares	47,278,000
Exercise price range, exercisable options, weighted average remaining contractual term	5 years 2 months 21 days
Exercise price range, exercisable options, weighted average exercise price	$ 39.860

Stockholders' Equity - Outstand

Stockholders' Equity - Outstanding Options Granted to Consultants for Sales and Pre-marketing Services (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Options exercisable at the end of the year (in shares)	687,508
Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	23,493
Options exercisable at the end of the year (in shares)	22,555
February 2013 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	1,500
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 12.470
Options exercisable at the end of the year (in shares)	1,500
Exercisable through	44,958
August 2013 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	4,000
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 21.140
Options exercisable at the end of the year (in shares)	4,000
Exercisable through	45,139
March 2014 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	5,550
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 39.860
Options exercisable at the end of the year (in shares)	5,550
Exercisable through	45,352
May 2014 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	3,700
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 22.010
Options exercisable at the end of the year (in shares)	3,700
Exercisable through	45,413
November 2014 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	5,468
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 21.660
Options exercisable at the end of the year (in shares)	5,468
Exercisable through	45,597
May 2015 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	1,137
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 19.510
Options exercisable at the end of the year (in shares)	929
Exercisable through	45,778
February 2016 | Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options for shares of common stock (in shares)	2,138
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 16.870
Options exercisable at the end of the year (in shares)	1,408
Exercisable through	46,054

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance, restricted stock units (in shares) | shares	2,018,121
Granted, restricted stock units (in shares) | shares	1,255,824
Vested, restricted stock units (in shares) | shares	(671,768)
Forfeited, restricted stock units (in shares) | shares	(162,150)
Balance, restricted stock units (in shares) | shares	2,440,027
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Balance, weighted average grant date fair value on restricted stock units (in dollars per share) | $ / shares	$ 27.32
Granted, weighted average grant date fair value on restricted stock units (in dollars per share) | $ / shares	53.79
Vested, weighted average grant date fair value on restricted stock units (in dollars per share) | $ / shares	28.54
Forfeited, weighted average grant date fair value on restricted stock units (in dollars per share) | $ / shares	36.89
Balance, weighted average grant date fair value on restricted stock units (in dollars per share) | $ / shares	$ 40

Stockholders' Equity - Non-cash

Stockholders' Equity - Non-cash Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 34,961	$ 19,835	$ 12,938
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,757	1,078	699
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	9,645	5,209	3,052
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	16,081	8,542	6,104
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 7,478	$ 5,006	$ 3,083

Income Taxes (Details Textual)

Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Effective income tax rate, foreign dertived intangible income, percent	13.125%
Valuation allowance, deferred tax asset, increase (decrease), amount	$ 15,826,000	$ 8,623,000
Deferred tax assets	137,000
Deferred tax assets, valuation allowance	39,365,000	27,702,000
Accumulated deficit	(137,968,000)	(109,390,000)
Unrecognized tax benefits	1,954,000	3,682,000		$ 2,106,000
Unrecognized tax benefits that would impact effective tax rate	1,431,000
Unrecognized tax benefits, income tax penalties and interest expense	93,000
Undistributed earnings of foreign subsidiaries	678,000
Undistributed earnings of foreign subsidiaries subject to transition tax	285
Accounting Standards Update 2016-09
Tax Credit Carryforward [Line Items]
Deferred tax assets			$ 3,796,000
Deferred tax assets, valuation allowance			2,493,000
Accumulated deficit			$ 1,302,000
Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	54,872,000
Domestic Tax Authority | Accounting Standards Update 2018-02
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	31,965,000	$ 22,907,000
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	57,530,000
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 1,204,000
Israel Tax Authority | Foreign Tax Authority | VSL | Minimum
Tax Credit Carryforward [Line Items]
Tax rate for amount of dividends distributed, other than complete liquidation	10.00%
Israel Tax Authority | Foreign Tax Authority | VSL | Maximum
Tax Credit Carryforward [Line Items]
Tax rate for amount of dividends distributed, other than complete liquidation	25.00%
Research Tax Credit Carryforward | Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	$ 1,412,000
Retention | Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	24,000
Foreign Tax Credit | Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	190,000
Ireland Employment | Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	$ 78,000

Income Taxes - Schedule of Prof

Income Taxes - Schedule of Profit (Loss) Before Taxes on Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (25,557)	$ (19,239)	$ (13,940)
Foreign	(2,608)	8,182	1,060
Loss before income taxes	$ (28,165)	$ (11,057)	$ (12,880)

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Taxes on Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 0	$ (92)	$ 92
State	169	191	109
Foreign	1,498	2,516	930
Total current income tax	1,667	2,615	1,131
Deferred:
Foreign	(1,254)	172	182
Total deferred income tax	(1,254)	172	182
Income tax expense	$ 413	$ 2,787	$ 1,313

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Carry forward losses and credits	$ 15,547	$ 7,407
Deferred revenues	13,995	14,226
Accrued payroll, commissions, vacation	1,912	2,685
Equity Compensation	5,737	908
Allowance for doubtful accounts	940	633
Accrued severance pay	297	238
Other	1,346	1,760
Deferred tax assets before valuation allowance	39,774	27,857
Valuation allowance	(39,365)	(27,702)
Deferred tax assets	409	155
Deferred tax liability:
Accrued compensation and other accrued expense	(272)	(289)
Deferred tax liability	(272)	(289)
Net deferred tax asset (liability)	$ 137
Net deferred tax asset (liability)		$ (134)

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Theoretical Tax Expense and Actual Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Loss before taxes, as reported in the consolidated statements of operations	$ (28,165)	$ (11,057)	$ (12,880)
Statutory tax rate	21.00%	34.00%	34.00%
Theoretical tax benefits on the above amount at the US statutory tax rate	$ (5,915)	$ (3,759)	$ (4,379)
Income tax at rate other than the U.S. statutory tax rate	692	(1,047)	(6)
Tax advances and non-deductible expenses including equity based compensation expenses	(7,623)	3,123	4,298
Operating losses and other temporary differences for which valuation allowance was provided	15,826	(8,623)	1,885
Research and Development Tax Credit	0	1,126	(1,182)
State tax	(1,221)	(601)	(426)
Impact of rate change	0	10,920	(360)
Change in tax reserve for uncertain tax positions	1,728	(1,576)	(1,209)
Other individually immaterial income tax items	382	72	274
Income tax expense	$ 413	$ 2,787	$ 1,313

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits	$ 3,682	$ 2,106
Increase in tax position for current year	169	1,752
Increase in tax position for prior years	241	135
Decrease in tax position for prior years	(720)	(311)
Decrease for lapse of statute of limitations/ settlements	(1,418)
Gross unrecognized tax benefits	$ 1,954	$ 3,682

Financial Expenses, Net - Summa

Financial Expenses, Net - Summary of Financial Income and Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
FInancial Expenses, Net [Abstract]
Interest on bank deposits, net	$ 1,741	$ 747	$ 520
Foreign currency transactions gains, net	0	1,773	0
Other	0	27	0
Financial Income	1,741	2,547	520
Bank charges	195	185	149
Foreign currency transactions losses, net	574	0	1,224
Other	2	0	32
Financial expenses	(771)	(185)	(1,405)
Total	$ 970	$ 2,362	$ (885)

Geographic Information and Ma_3

Geographic Information and Major Customer and Product Data (Details Textual)	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Revenues	$ 270,288,000	$ 215,390,000	$ 165,863,000
Sales	0	0	0
France
Segment Reporting Information [Line Items]
Revenues	$ 31,532,000	$ 22,658,000	$ 17,103,000

Geographic Information and Ma_4

Geographic Information and Major Customer and Product Data - Revenues Within Geographical Areas (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues		$ 270,288	$ 215,390	$ 165,863
North America
Segment Reporting Information [Line Items]
Revenues		167,361	139,720	106,069
EMEA
Segment Reporting Information [Line Items]
Revenues	[1]	93,816	68,998	53,170
Rest of World
Segment Reporting Information [Line Items]
Revenues		$ 9,111	$ 6,672	$ 6,624
[1]	Sales to customers in France accounted for $31,532, $22,658 and $17,103 for the years ended December 31, 2018, 2017 and 2016, respectively.

Geographic Information and Ma_5

Geographic Information and Major Customer and Product Data - Long-lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Long-lived assets	$ 17,323	$ 11,896
United States
Segment Reporting Information [Line Items]
Long-lived assets	7,612	7,072
Israel
Segment Reporting Information [Line Items]
Long-lived assets	7,834	2,944
France
Segment Reporting Information [Line Items]
Long-lived assets	1,243	1,426
Other
Segment Reporting Information [Line Items]
Long-lived assets	$ 634	$ 454