Imperva 10-K 27 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Feb. 15, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	IMPV
Entity Registrant Name	IMPERVA INC
Entity Central Index Key	1,364,962
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		33,395,393
Entity Public Float			$ 1,390

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 107,343	$ 168,252
Short-term investments	153,749	96,555
Restricted cash	68	79
Accounts receivable, net of allowance of $1,784 and $ 1,438 as of December 31, 2016 and 2015, respectively	62,571	61,051
Inventory	590	815
Prepaid expenses and other current assets	7,922	7,965
Total current assets	332,243	334,717
Property and equipment, net	21,496	12,164
Goodwill	37,448	34,972
Acquired intangible assets, net	8,393	7,991
Severance pay fund	5,070	4,530
Restricted cash	1,884	1,665
Deferred tax assets	1,220	588
Other assets	1,065	1,042
TOTAL ASSETS	408,819	397,669
CURRENT LIABILITIES:
Accounts payable	5,529	6,870
Accrued compensation and benefits	20,840	20,259
Accrued and other current liabilities	7,683	14,283
Deferred revenue	104,042	79,132
Total current liabilities	138,094	120,544
Other liabilities	6,637	4,515
Deferred revenue	26,429	27,525
Accrued severance pay	5,696	4,884
TOTAL LIABILITIES	176,856	157,468
Commitments and Contingencies (Note 11)
STOCKHOLDERS' EQUITY:
Preferred stock, $0.0001 par value - 5,000,000 shares authorized, no shares issued and outstanding as of December 31, 2016 and 2015, respectively	0	0
Common stock, $0.0001 par value - 145,000,000 shares authorized, 33,088,990 and 31,837,144 shares issued and outstanding as of December 31, 2016 and 2015, respectively	3	3
Additional paid-in capital	510,257	448,069
Accumulated deficit	(276,819)	(206,540)
Accumulated other comprehensive loss	(1,478)	(1,331)
TOTAL STOCKHOLDERS' EQUITY	231,963	240,201
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 408,819	$ 397,669

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,784	$ 1,438
Preferred stock, par value, per share	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value, per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	33,088,990	31,837,144
Common stock, shares outstanding	33,088,990	31,837,144

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net revenue:
Products and license	$ 86,798	$ 107,563	$ 74,299
Services	177,657	126,735	89,711
Total net revenue	264,455	234,298	164,010
Cost of revenue:
Products and license	9,525	10,947	9,248
Services	44,307	36,633	27,335
Total cost of revenue	53,832	47,580	36,583
Gross profit	210,623	186,718	127,427
Operating expenses:
Research and development	62,402	53,376	43,052
Sales and marketing	156,465	136,292	106,382
General and administrative	51,260	43,440	34,499
Restructuring charges	8,118
Amortization of acquired intangible assets	1,408	1,408	1,269
Total operating expenses	279,653	234,516	185,202
Loss from operations	(69,030)	(47,798)	(57,775)
Other income (expense), net	(77)	(402)	(220)
Loss before provision for income taxes	(69,107)	(48,200)	(57,995)
Provision for income taxes	1,172	682	1,181
Net loss	(70,279)	(48,882)	(59,176)
Loss attributable to non - controlling interest	0		213
Net loss attributable to Imperva, Inc. stockholders	$ (70,279)	$ (48,882)	$ (58,963)
Net loss per share of common stock attributable to Imperva, Inc. stockholders, basic and diluted	$ (2.18)	$ (1.64)	$ (2.28)
Shares used in computing net loss per share of common stock, basic and diluted	32,284	29,849	25,806

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (70,279)	$ (48,882)	$ (59,176)
Other comprehensive loss (net of tax):
Net change in net unrealized loss on investments	(103)	(249)	(59)
Net change in unrealized gain (loss) on hedging instruments	(44)	407	(1,002)
Other comprehensive income (loss)	(147)	158	(1,061)
Comprehensive loss	(70,426)	(48,724)	(60,237)
Comprehensive loss attributable to non - controlling interest	0	0	213
Comprehensive loss attributable to Imperva, Inc. stockholders	$ (70,426)	$ (48,724)	$ (60,024)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-controlling Interest [Member]
Beginning balance at Dec. 31, 2013	$ 86,222	$ 2	$ 187,957	$ (98,695)	$ (428)	$ (2,614)
Beginning balance, shares at Dec. 31, 2013		25,206,498
Issuance of common stock related to acquisitions	24,163	$ 0	24,163
Issuance of common stock related to acquisitions, shares		738,479
Issuance of common stock, net of repurchases	7,371	$ 0	7,371	0	0	0
Issuance of common stock, net of repurchases, shares		672,832
Vesting of restricted stock	454	$ 0	454	0	0	0
Stock-based compensation	37,273	0	37,273	0	0	0
Issuance of common stock in connection with employee stock purchase plan	3,332	$ 0	3,332	0	0	0
Issuance of common stock in connection with employee stock purchase plan, shares		188,068
Income tax benefit from employee stock option exercises	385	$ 0	385	0	0	0
Shares withheld for tax withholding on vesting of restricted stock units	(2,074)	0	(2,074)
Pre-combination service relating to acquired Skyfence option plan	354	0	354	0	0	0
Purchase of additional ownership interest in Incapsula, Inc.	0	$ 0	(2,827)	0	0	2,827
Purchase of additional ownership interest in Incapsula, Inc. Shares		89,603
Components of other comprehensive income (loss), net of tax
Change in unrealized loss on investments	(59)	$ 0	0	0	(59)	0
Change in unrealized loss on derivatives	(1,002)	0	0	0	(1,002)	0
Net loss	(59,176)	0	0	(58,963)	0	(213)
Comprehensive loss	(60,237)
Ending balance at Dec. 31, 2014	97,243	$ 2	256,388	(157,658)	(1,489)	0
Ending balance, shares at Dec. 31, 2014		26,895,480
Proceeds from follow-on public offering, net of offering costs	127,741	$ 1	127,740	0	0	0
Proceeds from follow-on public offering, net of offering costs, shares		3,450,000
Issuance of common stock, net of repurchases	18,724	$ 0	18,724	0	0	0
Issuance of common stock, net of repurchases, shares		670,844
Vesting of restricted stock	767	$ 0	767	0	0	0
Vesting of restricted stock, shares		706,121
Stock-based compensation	50,964	$ 0	50,964	0	0	0
Issuance of common stock in connection with employee stock purchase plan	4,785	$ 0	4,785	0	0	0
Issuance of common stock in connection with employee stock purchase plan, shares		114,699
Income tax benefit from employee stock option exercises	165	$ 0	165	0	0	0
Shares withheld for tax withholding on vesting of restricted stock units	(11,464)	0	(11,464)
Components of other comprehensive income (loss), net of tax
Change in unrealized loss on investments	(249)	0	0	0	(249)	0
Change in unrealized loss on derivatives	407	0	0	0	407	0
Net loss	(48,882)	0	0	(48,882)	0	0
Comprehensive loss	(48,724)	0	0
Ending balance at Dec. 31, 2015	240,201	$ 3	448,069	(206,540)	(1,331)	0
Ending balance, shares at Dec. 31, 2015		31,837,144
Issuance of common stock related to acquisitions	0	$ 0	0	0	0	0
Issuance of common stock related to acquisitions, shares		206,499
Issuance of common stock, net of repurchases	5,402		5,402
Issuance of common stock, net of repurchases, shares		843,724
Stock-based compensation	59,750	$ 0	59,750	0	0	0
Issuance of common stock in connection with employee stock purchase plan	5,831		5,831	0	0	0
Issuance of common stock in connection with employee stock purchase plan, shares		201,623
Income tax benefit from employee stock option exercises	36	$ 0	36	0	0	0
Shares withheld for tax withholding on vesting of restricted stock units	(8,831)	0	(8,831)	0	0	0
Components of other comprehensive income (loss), net of tax
Change in unrealized loss on investments	(103)	0	0	0	(103)	0
Change in unrealized loss on derivatives	(44)	0	0	0	(44)
Net loss	(70,279)	0	0	(70,279)	0	0
Comprehensive loss	(70,426)	0	0	0		0
Ending balance at Dec. 31, 2016	$ 231,963	$ 3	$ 510,257	$ (276,819)	$ (1,478)	$ 0
Ending balance, shares at Dec. 31, 2016		33,088,990

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (70,279)	$ (48,882)	$ (59,176)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	7,488	4,551	3,578
Stock-based compensation	62,875	50,964	37,273
Amortization of acquired intangibles	1,408	1,408	1,269
Amortization of premiums/accretion of discounts on short-term investments	238	496	416
Loss on disposal of equipment	267	0	0
Excess tax benefits from share-based compensation	(36)	(165)	(385)
Other	125	0	0
Changes in operating assets and liabilities:
Accounts receivable, net	(1,520)	(13,605)	(3,000)
Inventory	(16)	(1,056)	253
Prepaid expenses and other assets	383	(4,220)	409
Accounts payable	(1,398)	977	1,150
Accrued compensation and benefits	(2,543)	4,510	2,630
Accrued and other liabilities	2,178	3,242	1,847
Severance pay, net	272	16	93
Deferred revenue	23,684	25,482	18,123
Deferred tax assets	(632)	149	(354)
Net cash provided by operating activities	22,494	23,867	4,126
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of short-term investments	(129,989)	(89,626)	(33,267)
Proceeds from sales/maturities of short-term investments	72,453	33,948	29,821
Acquisitions, net of cash acquired	(3,914)	0	(12,083)
Net purchases of property and equipment	(16,789)	(8,080)	(5,621)
Change in restricted cash	(208)	(17)	(441)
Net cash used in investing activities	(78,447)	(63,775)	(21,591)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from follow-on public offering, net of offering costs	0	127,853	0
Settlement of holdback liability	(7,157)	0	0
Proceeds from issuance of common stock, net of repurchases	11,233	23,524	10,546
Shares withheld for tax withholding on vesting of restricted stock units	(8,831)	(11,464)	(2,074)
Offering costs relating to follow-on public offering	(112)	0	0
Excess tax benefits from share-based compensation	36	165	385
Net cash (used in) provided by financing activities	(4,831)	140,078	8,857
Effect of exchange rate changes on cash and cash equivalents	(125)	(14)	0
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(60,909)	100,156	(8,608)
CASH AND CASH EQUIVALENTS - Beginning of period	168,252	68,096	76,704
CASH AND CASH EQUIVALENTS - End of period	107,343	168,252	68,096
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes	1,480	652	287
NONCASH INVESTING AND FINANCING ACTIVITIES:
Common stock issued related to acquisitions of businesses	0	0	24,163
Property and equipment incurred but not yet paid	574	517	820
Vesting of restricted and early exercised stock options	$ 0	$ 767	$ 454

The Company and Summary of Sign

The Company and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
The Company and Summary of Significant Accounting Policies	1. The Company and Summary of Significant Accounting Policies Business Imperva, Inc. (together with its subsidiaries, the “Company”) was incorporated in April 2002 in Delaware. The Company is headquartered in Redwood Shores, California and has subsidiaries located throughout the world including Israel, Asia and Europe. The Company is engaged in the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications, whether in the cloud or on premises. On February 23, 2017, we completed the sale of our Skyfence cloud access security broker business to Forcepoint LLC for $40 million subject to potential working capital and other adjustments. See Note 18 for further discussion of the sale of the Skyfence business. Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s consolidated financial position, results of operations and cash flows for the periods presented. The consolidated financial statements include the accounts of Imperva Inc., and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Non-controlling Interest On March 20, 2014, the Company acquired the remaining interest it did not previously own in its majority-owned subsidiary, Incapsula, Inc. (“Incapsula”) (Refer to Note 2). The Company separately presented the non-controlling interest on its Consolidated Balance Sheets in Total Stockholders’ Equity, Consolidated Statements of Operations, Consolidated Statements of Comprehensive Loss and Consolidated Statements of Stockholders’ Equity for periods prior to such date. The Company had recorded a non - controlling interest in these consolidated financial statements for the 19% ownership interest of the minority owners of Incapsula as of December 31, 2013. Changes to the ownership interest in Incapsula held by the minority owners were accounted for as equity transactions in the consolidated statements of stockholders’ equity as the Company obtained control of Incapsula on November 5, 2009. Segment Information Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company has one operating segment, which is the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications, whether in the cloud or on premises. Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Such management estimates include the fair value of accounts receivable, inventory, intangible assets and goodwill, useful lives of intangible assets and property and equipment, and assumptions used in the calculation of revenue, income taxes and stock-based compensation, among others. These estimates and assumptions are based on management’s best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Concentration of Supply Risk The Company relies on a single third party to manufacture its hardware appliances, and purchases its hardware appliances through such third party’s value-added resellers. Quality or performance failures of the Company’s products or changes in the Company’s suppliers’ financial or business condition could disrupt the Company’s ability to supply quality products to its customers and thereby have a material adverse effect on its business and consolidated financial statements. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash, cash equivalents, short-term investments, restricted cash and derivative financial instruments. The Company’s cash, cash equivalents, short-term investments and restricted cash are invested in high-quality instruments with banks and financial institutions located in the United States and Israel. Such deposits may be in excess of insured limits provided on such deposits. The Company uses derivative financial instruments to manage exposures to foreign currency risks. The Company’s derivatives expose it to credit risk to the extent that the counterparty may be unable to meet the terms of the agreement. The Company seeks to mitigate such risk by limiting its counterparties to those with high or investment-grade credit ratings. The Company does not require collateral under these agreements and has not historically experienced any losses due to credit risk or lack of performance by counterparties. Derivative Financial Instruments The Company uses forward foreign currency exchange contracts to reduce its exposure to foreign currency rate changes for operating expenses that are forecasted to be incurred in currencies other than U.S. dollars. The Company records all of its derivative instruments at their gross fair value on the consolidated balance sheets. The Company classifies its cash flows from derivative financial instruments as operating activities. The accounting for changes in the fair value of a derivative instrument depends on whether the instrument has been designated and qualifies as a cash flow hedge for accounting purposes. For forward foreign currency exchange contracts that are designated and qualify as cash flow hedges, the effective portion of the gain or loss resulting from changes in the fair value of the derivative instruments is accounted for in accumulated other comprehensive income (loss) (“AOCI”) in the consolidated statements of stockholders’ equity and reclassified into operating expenses in the consolidated statements of operations in the period or periods during which the hedged transaction affects earnings. As of December 31, 2016, the Company estimated that $0.6 million of net derivative loss included in accumulated other comprehensive income (loss) will be reclassified into earnings within the next 12 months. The ineffective portion of the gain or loss resulting from the change in fair value is recognized in other income (expense), net in the consolidated statements of operations. Cash, Cash Equivalents and Short-Term Investments 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 investments. Investments are available to be used in current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents and short-term investments are classified as available-for-sale and are, therefore, recorded at fair value on the consolidated balance sheets, with any unrealized gains and losses reported in the consolidated statements of stockholders’ equity as a component of accumulated other comprehensive income (loss) 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 other income (expense), net in the consolidated statements of operations. Restricted Cash The Company has restricted cash pledged as collateral representing a security deposit required for facility leases. As of December 31, 2016 and 2015, the Company has classified $1.9 million and $1.7 million, respectively, of security deposit as non-current assets relating to its facility lease arrangements. Inventory Inventory consists of finished goods hardware appliances and related component parts and is stated at the lower of cost or market value where the cost is determined as the lower of an average cost basis or last invoice. Inventory that is obsolete or in excess of forecasted demand is written down to its estimated realizable value. Inventory write-downs, once established, are not reversed as they establish a new cost basis for the inventory. For the years ended December 31, 2016, 2015 and 2014, the amount of inventory write-downs incurred by the Company were insignificant. Business Combination The Company accounts for its business acquisitions in accordance with Accounting Standards Codification (ASC) No. 805, Business Combinations. The total purchase price allocated to the tangible assets acquired is assigned based on the fair values as of the date of the acquisition. The identifiable intangible assets are subject to amortization on a straight-line basis as this best approximates the benefit period related to these assets Property and Equipment Property and equipment, including leasehold improvements, are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, generally two to seven years. Leasehold improvements are amortized using the straight-line method over the shorter of the remaining lease term or the estimated useful lives of the assets. Upon the retirement or disposition of property and equipment, the related costs and accumulated depreciation is removed and any related gain or loss is recorded in the consolidated statements of operations. Repairs and maintenance that do not extend the life or improve an asset are expensed in the periods incurred. Goodwill and Acquired Intangibles Goodwill is not amortized and is reviewed at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The Company operates its business in one operating segment and one reporting unit, which is the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications whether in the cloud or on premises. In reviewing goodwill, the Company bypasses the qualitative assessment and proceeds directly to performing the quantitative two step impairment test to test the reporting unit’s goodwill for impairment. The first step of the impairment test involves comparing the fair value of the reporting unit to its net book value, including goodwill and is used as a screening process for identifying a potential goodwill impairment loss. If the net book value exceeds its fair value, then the Company would perform the second step of the goodwill impairment test to determine the amount of the impairment loss. The impairment loss would be calculated by comparing the implied fair value of goodwill of the Company to its net book value. In calculating the implied fair value of the Company’s goodwill, the fair value of the Company would be allocated to all of the other assets and liabilities based on their fair values. The excess of the fair value of the Company over the amount assigned to its other assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds its implied fair value. The Company completes its annual impairment test during the fourth quarter of each fiscal year. There was no impairment of goodwill recorded for the fiscal year ended December 31, 2016. Intangible assets consist of purchased technology, customer relationships, trade names and domain names which are amortized over the period of estimated benefit using the straight-line method, as the consumption pattern of the asset is not apparent, and estimated useful lives ranging from seven to ten years as of December 31, 2016. No significant residual value is estimated for intangible assets. Impairment of Long-Lived Assets The Company evaluates its long-lived assets, which consist of property and equipment and acquired intangible assets, for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Impairment exists if the carrying amounts of such assets exceed the estimates of future net undiscounted cash flows expected to be generated by such assets. Should impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s estimated fair value. As of December 31, 2016 and 2015, the Company has not written down any of its long-lived assets as a result of impairment. Revenue Recognition The Company derives revenue from two sources: (i) products and license revenue, which includes hardware and perpetual software license revenue and (ii) services revenue, which includes maintenance and support, professional services, training and subscription arrangements. Substantially all of product and license sales have been sold in combination with maintenance and support services. Revenue is recognized when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery or performance has occurred; the sales price is fixed or determinable; and collection is reasonably assured. The Company defines each of the four criteria above as follows: • Persuasive evidence of an arrangement exists: Evidence of an arrangement consists of a purchase order or acknowledgment issued pursuant to the terms and conditions of a direct customer end user or distributor or value-added reseller (VAR) agreement and, in limited cases with both distributor/VAR and an end user agreement and/or purchase order • Delivery or performance has occurred: The Company uses shipping and related documents, or written evidence of customer acceptance, when applicable, to verify delivery or performance. The Company recognizes product revenue upon transfer of title and risk of loss, which primarily is upon shipment to value-added resellers, distributors or end users. In most instances, the Company does not have significant obligations for future performance, such as customer acceptance provisions, rights of return or pricing credits, associated with the Company’s sales. In instances where final acceptance of the product or service is specified by the customer, revenue is deferred until all acceptance criteria have been met. • The sales price is fixed or determinable: The Company assesses whether the sales price is fixed or determinable based on payment terms and whether the sales price is subject to refund or adjustment. Standard payment terms to customers range from 30 to 90 days. In the event payment terms are provided that differ from the Company’s standard business practices, the fees are deemed to not be fixed or determinable and revenue is recognized when the payments become due, provided the remaining criteria for revenue recognition have been met. • Collection is reasonably assured: The Company assesses probability of collection on a customer-by-customer basis. The Company’s customers are subjected to a credit review process that evaluates their financial condition and ability to pay for products and services. If the Company concludes that collection is not reasonably assured based upon an initial review, the Company does not recognize revenue until payment is received. Maintenance and support and subscription revenue includes arrangements for software maintenance and technical support for the Company’s products and subscription services revenue primarily related to the Company’s cloud-based services. The terms of the Company’s subscription service arrangements do not provide customers the right to take possession of the related software. Maintenance and support is offered under renewable, fee-based contracts, which include technical support, hardware repair and replacement parts, bug fixes, patches and unspecified upgrades on a when-and-if-available basis. Maintenance and support and subscription revenue is initially deferred and recognized ratably over the life of the contract, with the related expenses recognized as incurred. Maintenance and support and subscription contracts usually have a term of one to three years. Unearned maintenance and support and subscription revenue is included in deferred revenue. Professional service revenue primarily consists of the fees the Company earns related to installation and consulting services. The Company recognizes revenue from professional services upon delivery or completion of performance. Professional service arrangements are typically short term in nature and are largely completed within 90 days from the start of service. Training services are recognized upon delivery of the training. Multiple Element Arrangements Most of the Company’s products are hardware appliances containing software components that function together to provide the essential functionality of the product. Therefore, the Company’s hardware appliances are considered non-software deliverables and are not subject to industry-specific software revenue recognition guidance. The Company’s product revenue also includes revenue from the sale of stand-alone software products. Stand-alone software may operate on the Company’s hardware appliance, but is not considered essential to the functionality of the hardware and is, therefore, subject to the industry-specific software revenue recognition guidance. Additionally, the Company provides unspecified software upgrades for our products, on a when-and-if available basis, and hardware replacements through maintenance and support contracts. These support arrangements when sold on a stand-alone basis are subject to the industry-specific software revenue recognition guidance. Under the software revenue recognition guidance, the Company uses the residual method to recognize revenue when a product agreement includes one or more elements to be delivered at a future date and Vendor Specific Objective Evidence (“VSOE”) of the fair value of all undelivered elements exists. In the majority of the Company’s contracts, the only element that remains undelivered at the time of delivery of the product is maintenance and support services and subscriptions. Under the residual method, the VSOE of fair value of the undelivered elements is deferred and the remaining portion of the contract fee is recognized as product revenue. If evidence of the VSOE of fair value of one or more undelivered elements does not exist, all revenue is generally deferred and recognized when delivery of those elements occurs or when fair value can be established. For certain arrangements with multiple deliverables, the Company allocates the arrangement fee to the non-software element based upon the relative selling price of such element and, if software and software-related elements (e.g., maintenance and support for the software element) are also included in the arrangement, the Company allocates the arrangement fee to each of those software and software-related elements as a group. After such allocations are made, the amount of the arrangement fee allocated to the software and software-related elements is accounted for using the residual method. When applying the relative selling price method, the Company determines the selling price for each element using VSOE of selling price, if it exists, or if not, Third-Party Evidence (“TPE”) of selling price, if it exists. If neither VSOE nor TPE of selling price exist for an element, the Company uses its Best Estimate of Selling Price (“BESP”) for that element. The revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for that element. The Company limits the amount of revenue recognized for delivered elements to the amount that is not contingent on the future delivery of products or services, or subject to the Company’s future performance obligation. VSOE of fair value for elements of an arrangement is based upon the normal pricing and discounting practices for those services when sold separately. In determining VSOE, the Company requires that a substantial majority of the selling prices for a service fall within a reasonably narrow pricing range, evidenced by a substantial majority of such historical stand-alone transactions falling within a reasonably narrow range. In addition, the Company considers major service groups and geographies in determining VSOE. The Company is not able to determine TPE for its products or services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy differs from that of its peers and its offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, the Company is unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. When the Company is unable to establish the selling price of its non-software deliverables using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. The Company determines BESP for the purposes of allocating the arrangement by reviewing external and internal market factors including, but not limited to, pricing practices including discounting, the geographies in which the Company offers its products and services, the type of customer (i.e., distributor, value added reseller or direct end user) and competition. Additionally, the Company considers historical transactions, including transactions whereby the deliverable was sold on a stand-alone basis. The determination of BESP is made through consultation with and approval by the Company’s management. Selling prices are analyzed on a quarterly basis to identify if the Company has experienced significant changes in its selling prices. For its non-software deliverables the Company allocates the arrangement consideration based on the relative selling price of the deliverables. For its hardware appliances the Company uses BESP as its selling price. For its maintenance and support services, subscriptions and professional services and training, the Company primarily uses VSOE as the selling price and when the Company is unable to establish a selling price using VSOE, it uses BESP. Deferred Revenue Deferred revenue represents amounts invoiced to customers for which the related revenue has not been recognized because one or more of the revenue recognition criteria have not been met. The current portion of the deferred revenues represents the amount that is expected to be recognized as revenue within one year of the consolidated balance sheet date. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at invoiced amounts, net of allowances for doubtful accounts if applicable, and do not bear interest. The Company generally does not require collateral from its customers; however, in certain circumstances, may require letters of credit, other collateral, additional guarantees or advance payments. The allowance for doubtful accounts is based on the Company’s assessment of the collectability of its customer accounts. The Company regularly reviews its accounts receivable that remain outstanding past their applicable payment terms and establishes allowance and potential write-offs by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customers’ ability to pay. Concentration of Revenue and Accounts Receivable Significant customers are those which represent 10% or more of the Company’s total revenue or gross accounts receivable balance at each respective balance sheet date. For the year ended December 31, 2016 and 2015, we had one customer that represented 13% and 18% of our total revenue, respectively. For the year ended December 31, 2014, the Company did not have any customers that represented 10% or more of the Company’s total revenue. The same customer represented 18% and 21% of gross accounts receivable as of December 31, 2016 and 2015 respectively. Shipping and Handling Costs Costs related to shipping and handling are included in cost of revenue. Research and Development Costs Research and development costs, including direct and allocated expenses, are expensed as incurred. Software Development Costs The costs to develop software for sale have not been capitalized as the Company believes that the technological feasibility of the related software is not established until substantially all product development is complete. Warranty Costs The Company generally provides a 60-day warranty on hardware appliance products and software from the date of shipment to customers. To date, cost to repair or replace items sold to customers has been insignificant. Advertising Costs The Company expenses advertising costs as incurred. Advertising expense is included within sales and marketing expense in the consolidated statements of operations. For the years ended December 31, 2016, 2015 and 2014, advertising expenses were not material. Retirement Savings Plan The Company maintains a defined contribution 401(k) retirement savings plan for its U.S. employees. Each participant in the 401(k) retirement savings plan may elect to contribute a percentage of his or her annual compensation up to a specified maximum amount allowed under U.S. Internal Revenue Service regulations. There were no employer contributions to the 401(k) retirement savings plan for the years ended December 31, 2016, 2015 and 2014. Severance Pay Asset and Liability The Company has recorded a severance pay asset and liability on its consolidated balance sheets related to its employees located in Israel. The Company’s liability for severance pay is calculated pursuant to Israeli severance pay law based on the most recent salary for the employees multiplied by the number of years of employment, as of the respective balance sheet date. Employees are entitled to one month salary for each year of employment or a portion thereof. The Company’s liability at each respective balance sheet date for all of its Israeli employees is fully accrued in the accompanying consolidated financial statements and is mainly funded through monthly deposits to the employee’s pension and management insurance policies. The carrying value of these policies is recorded as a severance fund asset in the Company’s consolidated balance sheets. The deposited funds may be withdrawn only upon the fulfillment of the obligation pursuant to Israeli severance pay law. The carrying value of the deposited funds is based on the cash surrender value of these policies and includes profits accumulated through the respective balance sheet date. The Company recognized severance expense related to the Israeli severance pay law during the years ended December 31, 2016, 2015 and 2014 of $1.6 million, $1.3 million, and $1.4 million, respectively. Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification No. 740 (“ASC 740”), Accounting for Income Taxes. The Company uses the liability method for accounting for deferred income taxes, which requires recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements, but have not been reflected in its taxable income. Estimates and judgments occur in the calculation of certain tax liabilities and in the determination of the recoverability of certain deferred income tax assets, which arise from temporary differences and carryforwards. Deferred income tax assets and liabilities are measured using the currently enacted tax rates that apply to taxable income in effect for the years in which those tax assets and liabilities are expected to be realized or settled. The Company regularly assesses the likelihood that its deferred income tax assets will be realized from recoverable income taxes or recovered from future taxable income based on the realization criteria set forth in ASC 740. To the extent that the Company believes any amounts are more likely not to be realized, the Company records a valuation allowance to reduce the deferred income tax assets. In the event the Company determines that all or part of the net deferred tax assets are not realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period such determination is made. Similarly, if the Company subsequently realizes deferred income tax assets that were previously determined to be unrealizable, the respective valuation allowance would be reversed, resulting in an adjustment to earnings in the period such determination is made. In addition, the calculation of the Company’s tax liabilities involves addressing uncertainties in the application of complex tax regulations. The Company recognizes and measures potential liabilities based upon criteria set forth in ASC 740. Based upon these criteria, the Company estimates whether, and the extent to which, additional taxes will be due. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities may result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities is less than the amount ultimately assessed, a further charge to expense would result. Significant judgment is required in determining any valuation allowance recorded against deferred income tax assets. In assessing the need for a valuation allowance, the Company considers all available evidence, including past operating results, estimates of future taxable income, and the feasibility of tax planning strategies. In the event that the Company changes its determination as to the amount of deferred income tax assets that could be realized, it will adjust its valuation allowance with a corresponding effect to the provision for income taxes in the period in which such determination is made. Significant judgment is also required in evaluating the Company’s uncertain tax positions under ASC 740 and determining its provision for income taxes. Although the Company believes its reserves for uncertain tax positions are reasonable, no assurance can be given that the final tax outcome of these matters will not be different from that which is reflected in the Company’s historical income tax provisions and accruals. The Company adjusts these reserves in light of changing facts and circumstances, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different from the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made. The provision for income taxes includes the effect of reserves for uncertain tax positions and any changes to the reserves that are considered appropriate, as well as the related net interest and penalties, if applicable. Stock-Based Compensation Compensation costs related to employee stock option grants are based on the fair value of the options on the date of grant, net of estimated forfeitures. The Company determines the grant date fair value of the options using the Black-Scholes option-pricing model and the related stock-based compensation expense is generally recognized on a straight-line basis over the period in which an employee is required to provide service in exchange for the options, or the vesting period of the respective options. For performance based RSUs granted to employees which have multiple performance conditions and a market condition the Company used a Monte Carlo simulation model to determine the fair value of such awards. T

Incapsula

Incapsula	12 Months Ended
	Dec. 31, 2016
Noncontrolling Interest [Abstract]
Incapsula	2. Incapsula On November 5, 2009, the Company entered into a license agreement for Incapsula to use certain developed technology of the Company. In lieu of any other fee or royalty under the license agreement, Incapsula issued to the Company 5,000,000 shares of its Series A Convertible Preferred Stock representing a 58% ownership interest at the date of issuance. The transaction was accounted for as a business combination. In March 2010, the Company entered into a Series A and Series A-1 Purchase Agreement whereby Incapsula issued 6,666,666 shares of its Series A Convertible Preferred Stock to the Company in exchange for cash consideration of $3.0 million. As a result of this transaction, the Company increased its ownership interest in Incapsula to 76% at the date of issuance. The purchase of the additional ownership interest in Incapsula was treated as an equity transaction. In July 2011, the Company purchased 4,375,000 shares of Incapsula’s Series A-1 Preferred Stock for $3.5 million thereby increasing its ownership interest to 82%. In January 2012, the Company purchased the remaining 4,375,000 shares of Incapsula’s Series A-1 Preferred Stock for $3.5 million thereby increasing its ownership interest in Incapsula to 85%. Under the terms of the agreements between the Company and Incapsula, the Company had the right, but not the obligation, to purchase the remaining ownership interest in Incapsula commencing on November 5, 2013 and ending on November 5, 2018 (the “Purchase Right”). In March 2014, the Company acquired the remaining outstanding capital stock in exchange for approximately 124,088 shares of Company common stock with an aggregate fair value of $7.7 million, of which 34,420 shares were subject to a one-year holdback and were issued in 2015. As of the date of the acquisition, the remaining non-controlling interest on the Company’s balance sheet of $2.8 million was reclassified to additional paid-in capital given the Company’s complete ownership of Incapsula.

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisition	3. Acquisition On December 15, 2016, the Company acquired certain assets and liabilities of Camouflage Software Inc. (“Camouflage”), a private company based in Newfoundland, Canada. Camouflage is a provider of data management, security and data masking solutions. The Company acquired Camouflage for cash consideration of $4.5 million. Approximately $0.6 million of the consideration is a holdback payment commitment due 24 months from the date the acquisition closes. Imperva acquired certain tangible assets and also assumed liabilities of Camouflage. Substantially all of the consideration was allocated to goodwill and intangible assets, such as developed technology, customer relationships and trade name. The acquisition was accounted for in accordance with Accounting Standards Codification (ASC) No. 805, Business Combinations, While management uses its best estimates and assumptions as part of the purchase price allocation process to value assets acquired and liabilities assumed at the business combination date, its estimates and assumptions are subject to refinement. As a result, during the preliminary purchase price allocation period, which may be up to one year from the business combination date, the Company may record adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill. The Company records adjustments to assets acquired or liabilities assumed subsequent to the purchase price allocation period in its operating results in the period in which the adjustments were determined. The purchase consideration allocated to the tangible assets acquired is assigned based on the fair values as of the date of the acquisition. The Company believes that these identified intangible assets will have no residual value after their estimated economic useful lives. The identifiable intangible assets are subject to amortization on a straight-line basis over a seven-year estimated useful life as this best approximates the benefit period related to these assets. The excess of the purchase consideration over the identified tangible and intangible assets, less liabilities assumed, is recorded as goodwill and primarily reflects the value of the synergies expected to be generated from combining the Company’s and the acquired entities’ technology and operations. The following table summarizes the preliminary allocation of the consideration to the fair value of the tangible and intangible assets acquired and liabilities assumed as of the acquisition date based on information available at the business combination date (in thousands): Acquired Technology $ 1,050 Customer relationships 480 Trade name and other 280 Goodwill 2,476 Total intangible assets acquired 4,286 Other acquired tangible assets 363 Liability assumed (130 ) Fair value of assets acquired $ 4,519 The total purchase consideration was allocated using the information available at the business combination date. Goodwill recorded in connection with the acquisition is deductible for U.S. income tax purposes. The Company expensed the related acquisition costs, consisting primarily of legal costs in the amount of $0.1 million in general and administrative expenses. The Company’s management believes that the goodwill represents the synergies expected from combining the acquired technology and operations with those of Imperva. The results of operations related to the Camouflage assets and liabilities have been included in the Company’s consolidated statements of operations from the acquisition date. Pro forma results of operations have not been presented because the acquisition was not material to the Company’s results of operations.

Cash, Cash Equivalents, and Sho

Cash, Cash Equivalents, and Short-Term Investments	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Short-Term Investments	4. Cash, Cash Equivalents and Short-Term Investments Cash, cash equivalents and short-term investments consist of the following (in thousands): As of December 31, 2016 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents: Cash $ 63,642 $ — $ — $ 63,642 Commercial paper 6,995 — 2 6,993 Money market funds 36,708 — — 36,708 Total $ 107,345 $ — $ 2 $ 107,343 Short-term investments: Commercial paper $ 14,245 $ — $ 8 $ 14,237 Corporate debt obligations 110,062 — 347 109,715 US government agencies 18,998 2 50 18,950 Bank deposits 10,846 1 — 10,847 Total $ 154,151 $ 3 $ 405 $ 153,749 As of December 31, 2015 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents: Cash $ 57,906 $ — $ — $ 57,906 Bank deposits 10,253 — — 10,253 Commercial paper 13,896 — 3 13,893 Money market funds 86,200 — — 86,200 Total $ 168,255 $ — $ 3 $ 168,252 Short-term investments: Corporate debt obligations $ 86,590 $ 2 $ 300 86,292 Bank deposits 10,263 — — 10,263 Total $ 96,853 $ 2 $ 300 $ 96,555 The following table sets forth the cost and estimated fair value of short-term investments based on stated effective maturities as of December 31, 2016 (in thousands): As of December 31, 2016 Estimated Amortized Fair Cost Value Short-term investments: Due in 2017 $ 84,406 $ 84,315 Due in 2018 69,745 69,434 Total $ 154,151 $ 153,749 The Company reviews its short-term investments 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 the 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 condensed 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 years ended December 31, 2016 and 2015, the Company did not consider any of its investments to be other-than-temporarily impaired. The following tables show the short-term investments in an unrealized loss position and the related gross unrealized losses and fair value and length of time that the short-term investments have been in a continuous unrealized loss position (in thousands): As of December 31, 2016 Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 14,237 $ 8 $ 14,237 $ 8 Corporate debt obligations 78,821 323 29,689 24 108,510 347 US government agencies 11,451 46 3,496 4 14,947 50 $ 104,509 $ 377 $ 33,185 $ 28 $ 137,694 $ 405 As of December 31, 2015 Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt obligations $ 73,673 $ 286 $ 10,609 $ 14 $ 84,282 $ 300 $ 73,673 $ 286 $ 10,609 $ 14 $ 84,282 $ 300

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments The Company evaluates assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period. The following table sets forth the Company’s assets and liabilities that were measured at fair value as of December 31, 2016 and 2015, by level within the fair value hierarchy (in thousands): As of December 31, 2016 Level I Level II Level III Fair Financial Assets: Cash equivalents: Commercial paper — 6,993 — 6,993 Money market funds 36,708 — — 36,708 Short-term investments: Commercial paper — 14,237 — 14,237 Corporate debt obligations — 109,715 — 109,715 US government agencies — 18,950 — 18,950 Bank deposits — 10,847 — 10,847 Total financial assets $ 36,708 $ 160,742 $ — $ 197,450 Financial Liability: Accrued and other current liabilities - Forward foreign exchange contracts $ — $ 639 $ — $ 639 As of December 31, 2015 Level I Level II Level III Fair Value Financial Assets: Cash equivalents: Bank deposits $ — $ 10,253 $ — $ 10,253 Commercial paper — 13,893 — 13,893 Money market funds 86,200 — — 86,200 Short-term investments: Corporate debt obligations — 86,292 — 86,292 Bank deposits — 10,263 — 10,263 Total financial assets $ 86,200 $ 120,701 $ — $ 206,901 Financial Liability: Accrued and other current liabilities - Forward foreign exchange contracts $ — $ 595 $ — $ 595 In addition to the amounts disclosed in the above table, the fair value of the Company’s Israeli severance pay assets, which were comprised of Level II assets, was $5.1 million and $4.5 million as of December 31, 2016 and 2015, respectively. The Company’s cash equivalents and short-term investments are classified within Level 1 or Level 2 of the fair value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The types of instruments valued based on quoted market prices in active markets include mutual funds and money market securities. Such instruments are generally classified within Level 1 of the fair value hierarchy. The types of instruments valued based on quoted prices in less active markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability, include U.S. agency securities, investment-grade corporate bonds, term deposits and commercial paper. Such instruments are generally classified within Level 2 of the fair value hierarchy. There were no transfers between Level 1, Level 2 and Level 3 during the years ended December 31, 2016 and 2015.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2016
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments	6. 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 U.S. dollars. Substantially all of the Company’s revenue and capital purchasing activities and a majority of its operating expenditures are transacted in U.S. dollars. However, certain operating expenditures are incurred in or exposed to other currencies, primarily the Israeli shekel, the British Pound and the Euro. 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. Derivative instruments measured at fair value and their classification on the consolidated balance sheets are presented in the following tables (in thousands): Liability as of December 31, 2016 2015 Notional Amount Fair Value Notional Amount Fair Value Foreign exchange forward contract derivatives in cash flow hedging relationships - included in accrued and other current liabilities $ 60,756 $ 639 $ 47,231 $ 595 Gains (losses) on derivative instruments accounted for as hedges and their classification on the consolidated statement of operations, are presented in the following tables (in thousands): Years ended December 31, 2016 2015 2014 Foreign Exchange Forward Contract Derivatives in cash flow hedging relationships: Gains recognized in OCI (a) $ 1,775 $ 834 $ 191 Losses recognized in OCI (a) $ (1,909 ) $ (1,399 ) $ (1,846 ) Gains recognized from accumulated OCI into net loss (b) $ 257 $ — $ 55 Losses recognized from accumulated OCI into net loss (b) $ (347 ) $ (972 ) $ (708 ) (a) Net change in the fair value of the effective portion classified in other comprehensive income (loss) (“OCI”). (b) Effective portion of cash flow hedges reclassified from accumulated other income (loss), into net loss, of which $(8), $(107) and $(72) were recognized within cost of sales for the years ended December 31, 2016, 2015 and 2014, respectively, and $(82), $(865), and $(581) were recognized within operating expenses for the year ended December 31, 2016, 2015 and 2014, respectively. All amounts are reflected with the respective consolidated statement of operations.

Consolidated Balance Sheet Comp

Consolidated Balance Sheet Components	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Consolidated Balance Sheet Components	7. Consolidated Balance Sheet Components Allowance for Doubtful Accounts The allowance for doubtful accounts is comprised of the following activity (in thousands): Years Ended December 31, 2016 2015 2014 Allowance for doubtful accounts and sales returns reserve, beginning balance $ 1,438 $ 215 $ 410 Allowance for doubtful accounts, beginning balance $ 1,115 $ 215 $ 410 Charged to costs and expenses, net of recoveries 315 1,044 418 Deductions (write-offs) (477 ) (144 ) (613 ) Allowance for doubtful accounts, ending balance 953 1,115 215 Sales returns reserve, beginning balance 323 Charged to revenue 1,560 677 - Deductions (write-offs) (1,052 ) (354 ) - Sales returns reserve, ending balance 831 323 - Total allowance for doubtful accounts and sales returns reserve, ending balance $ 1,784 $ 1,438 $ 215 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): As of December 31, 2016 2015 Prepaid expenses 4,980 5,111 Prepaid income taxes 1,559 585 Interest receivable 758 467 Other 625 1,802 Total prepaid expenses and other current assets $ 7,922 $ 7,965 Property and Equipment, net Property and equipment, net consist of the following (in thousands): As of December 31, 2016 2015 Computers and related equipment $ 25,285 $ 15,953 Office furniture and equipment 3,228 1,632 Leasehold improvements 11,947 7,791 Total property and equipment 40,460 25,376 Less: accumulated depreciation and amortization (18,964 ) (13,212 ) Total property and equipment, net $ 21,496 $ 12,164 Depreciation and amortization expense totaled $7.5 million, $4.5 million and $3.6 million, for the years ended December 31, 2016, 2015 and 2014, respectively. Accrued Compensation and Benefits Accrued compensation and benefits consist of the following (in thousands): As of December 31, 2016 2015 Salary and related benefits $ 9,588 $ 7,215 Accrued vacation 4,178 3,774 Accrued incentive payments 5,942 9,270 Accrued restructuring 1,132 - Total accrued compensation and benefits $ 20,840 $ 20,259 Accrued and Other Current Liabilities Accrued and other current liabilities consist of the following (in thousands): As of December 31, 2016 2015 Accrued expenses $ 4,616 $ 4,633 Derivative liability 639 595 Income tax payable 435 323 Short-term deferred rent 461 283 Skyfence holdback liability - 7,556 Sales Taxes Payable 849 411 Other 683 482 Total accrued and other current liabilities $ 7,683 $ 14,283 Other Liabilities Other long-term liabilities consist of the following (in thousands): As of December 31, 2016 2015 Long-term deferred rent $ 2,111 $ 1,926 Deferred tax liability 1,265 1,145 Uncertain Tax Positions 2,446 1,236 Other 815 208 Total other liabilities $ 6,637 $ 4,515

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Acquired Intangible Assets	8. Goodwill and Acquired Intangible Assets In December 2016, the Company completed the acquisition of Camouflage Software Inc., which $2.5 million was allocated to goodwill and $1.8 million to acquired intangible assets. The Company did not have any goodwill impairments during 2016, 2015 or 2014. The changes in the carrying amount of goodwill for the years ended December 31, 2016 and 2015 were as follows (in thousands): Balance as of December 31, 2015 $ 34,972 Goodwill acquired 2,476 Balance as of December 31, 2016 $ 37,448 Acquired intangible assets subject to amortization as of December 31, 2016 and 2015 were as follows (in thousands): As of December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Book Value Acquired Technology $ 11,718 $ (4,085 ) $ 7,633 Customer relationships 480 - 480 Trade name and other 280 - 280 Total $ 12,478 $ (4,085 ) $ 8,393 As of December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Book Value Acquired Technology $ 10,668 $ (2,677 ) $ 7,991 Total $ 10,668 $ (2,677 ) $ 7,991 Amortization expense related to acquired intangible assets was $1.4 million for the year ended December 31, 2016. Acquired intangible assets are amortized over their estimated useful lives of 7 to 10 years. Acquired technology, customer relationships, and trade names and other have weighted-average useful lives from the date of purchase of 5.2 years, 7.0 years, and 7.0 years, respectively. As of December 31, 2016, the Company expects amortization expense in future periods to be as follows (in thousands): Acquired Fiscal Year Intangibles 2017 $ 1,666 2018 1,666 2019 1,666 2020 1,666 Thereafter 1,729 Total expected amortization expense $ 8,393

Other Income (Expense), net

Other Income (Expense), net	12 Months Ended
	Dec. 31, 2016
Other Income And Expenses [Abstract]
Other Income (Expense), net	9. Other Income (Expense), net Other income (expense), net is comprised of the following (in thousands): Years Ended December 31, 2016 2015 2014 Other Income: Interest income $ 1,369 $ 701 $ 163 Foreign currency forward contract gains, net 9 - - Foreign currency exchange gains, net 209 5 8 Total other income 1,587 706 171 Other Expense: Skyfence holdback liability accretion (6 ) (212 ) (186 ) Foreign currency exchange losses, net (708 ) (322 ) - Bank charges and Other expenses (950 ) (574 ) (205 ) Total other expense (1,664 ) (1,108 ) (391 ) Total other income (expense), net $ (77 ) $ (402 ) $ (220 )

Revolving Credit Facility

Revolving Credit Facility	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Revolving Credit Facility	10. Revolving Credit Facility In September 2010, the Company entered into a revolving credit facility with a financial institution. The agreement, provided for maximum borrowing capacity of up to $7.5 million. In November 2016, we terminated the credit facility. As of December 31, 2016 and 2015, there was no balance outstanding on the credit facility.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies (a) Operating Leases The Company rents its facilities under operating leases with lease periods expiring from 2017 through 2021. Future minimum payments under these facility operating leases are as follows as of December 31, 2016 (in thousands): Operating Leases Estimated Sublease Income Year Ending December 31: 2017 $ 7,598 $ 611 2018 8,054 399 2019 4,650 - 2020 4,243 - 2021 106 - Total $ 24,651 $ 1,010 Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. Rent expense for the years ended December 31, 2016, 2015 and 2014 was $6.1 million, $4.6 million, and $3.9 million, respectively. In connection with leases for office space, the Company received tenant improvement allowances of $0.7 million, $0.3 million and $0.6 million during the years ended December 31, 2016, 2012 and 2010, respectively. The Company has recorded the tenant improvement allowances as a leasehold improvement within property and equipment, net and as deferred rent within other liabilities on the consolidated balance sheets. The deferred rent liability is amortized to rent expense over the term of the lease on a straight-line basis. The leasehold improvements are being amortized to expense over the period from when the improvements were placed into service until the end of their useful life, which is the end of the respective lease term. In addition, certain of the Company’s operating lease agreements for office space also include rent holidays and scheduled rent escalations during the initial lease term. The Company has recorded the rent holidays as a deferred rent within other liabilities on the consolidated balance sheets. The Company recognizes the deferred rent liability and scheduled rent increase on a straight-line basis into rent expense over the lease term commencing on the date the Company takes possession of the lease space. As of December 31, 2016 and 2015 the Company has $1.9 million and $1.7 million, respectively, in restricted deposits to secure bank guarantees provided to the lessor. (b) Cancelable Lease Agreement The Company leases motor vehicles under a cancelable operating lease agreement. The Company has an option to cancel the lease agreement, which may result in penalties in a maximum amount of $0.1 million as of December 31, 2016. Motor vehicle lease expenses for the years ended December 31, 2016, 2015 and 2014 were $2.7 million, $2.4 million and $2.6 million, respectively. (c) Purchase Commitments As of both December 31, 2016 and 2015, the Company had purchase commitments of $3.8 million and $5.8 million, respectively, to purchase inventory, trial units, and research and development equipment from its vendors. The purchase commitments result from the Company’s contractual obligation to order or build inventory in advance of anticipated sales. According to the Company’s agreements with its vendors, the Company committed to purchase inventory within six months from the date the inventory arrived at the vendor’s warehouse. (d) Litigation From time to time, the Company may be subject to other legal proceedings and claims in the ordinary course of business. On April 11, 2014, a purported shareholder class action lawsuit was filed in the United States District Court for the Northern District of California against the Company and certain of its current and former officers. On August 7, 2014, the Court entered an order appointing lead plaintiff and counsel for the purported class. The lead plaintiff filed an amended complaint on October 10, 2014. The lawsuit named the Company and certain of its current and former officers and purported to bring suit on behalf of those investors who purchased the Company’s publicly traded securities between May 2, 2013 and April 9, 2014. The plaintiff alleged that defendants made false and misleading statements about the Company’s operations and business and financial results and purported to assert claims for violations of the federal securities laws. The amended complaint sought unspecified compensatory damages, interest thereon, costs incurred in the action and equitable/injunctive or other relief. On January 6, 2015, defendants filed a motion to dismiss the amended complaint. On September 17, 2015, the Court granted defendants’ motion to dismiss with leave to amend. The lead plaintiff filed an amended complaint on January 13, 2016, again naming the same current and former officers, alleging false and misleading statements about the Company’s operations and business and financial results, and seeking the same relief. On February 10, 2016, defendants filed a motion to dismiss the amended complaint. On May 16, 2016, the Court granted the motion in part and denied the motion in part. On September 7, 2016, defendants filed their operative answer to the amended complaint. On October 19, 2016, plaintiff filed a motion for class certification. In addition, the Company has received, and may in the future continue to receive, claims from third parties asserting, among other things, infringement of their intellectual property rights. Future litigation may be necessary to defend the Company, its channel partners and its customers by determining the scope, enforceability and validity of third-party proprietary rights or to establish its proprietary rights. In the opinion of management, liabilities associated with these claims, while possible, are not probable at this time, and therefore the Company has not recorded any accrual for them as of December 31, 2016 and 2015. Further, any possible range of loss cannot be reasonably estimated at this time. The ultimate outcome of any litigation is uncertain and, regardless of outcome, litigation can have an adverse impact on the Company because of defense costs, potential negative publicity, diversion of management resources and other factors. Accordingly, there can be no assurance that existing or future legal proceedings arising in the ordinary course of business or otherwise will not have a material adverse effect on the Company’s business, consolidated financial position, results of operations or cash flows. (e) Indemnification Under the indemnification provisions of its standard sales contracts, the Company agrees to defend its channel partners and end customers against third-party claims asserting infringement of certain intellectual property rights, which may include patents, copyrights, trademarks, or trade secrets, and to pay judgments and settlements entered on such claims. The Company’s exposure under these indemnifications provisions is generally limited to the total amount paid under the agreement. However, certain agreements included indemnification provisions that could potentially expose the Company to losses in excess of the amount received under the agreement. To date, there have been no claims under such indemnification provisions. Accordingly, the Company has not recorded a liability on its consolidated balance sheets for these indemnification provisions. In addition to the foregoing, the Company maintains director and officer insurance, which may cover certain liabilities arising from its obligation to indemnify its directors and officers.

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Capital Stock	12. Capital Stock Common Stock Reserved for Issuance The Company had reserved shares of common stock, on an as if converted basis, for issuance as follows: As of December 31, 2016 2015 Issuance in connection with outstanding stock options 1,570,765 1,949,089 Issuance in connection with restricted stock units outstanding 1,994,790 1,898,025 Reserved for future stock option and restricted stock unit grants 2,464,181 1,726,346 Reserved for future issuance under the employee stock purchase plan 1,161,396 1,049,524 7,191,132 6,622,984 Preferred Stock Our board of directors is authorized, subject to any limitations prescribed by law, without stockholder approval, to issue from time to time up to an aggregate of 5,000,000 shares of preferred stock, in one or more series, each series to have such rights and preferences, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences as the Company’s board of directors determines. The rights of the holders of common stock will be subject to, and may be adversely affected by, the rights of holders of any preferred stock that may be issued in the future. The Company currently has no shares of preferred stock outstanding and the Company has no present plans to issue any shares of preferred stock. Stock Plans (a) 2003 Stock Plan During 2003, the Board of Directors adopted the 2003 Stock Plan (the “2003 Plan”), which allows for the granting of both incentive stock options and non-qualified stock options and the direct award or sale of shares of the Company’s common stock (including restricted common stock) to officers, employees, directors, consultants and other key persons. In connection with the Company’s initial public offering, which was completed in November 2011, the Board of Directors determined not to grant any further awards under the 2003 Plan upon completion of the public offering. The 2011 Stock Option and Incentive Plan (the “2011 Plan”) replaced the 2003 Plan in November 2011. Under the 2003 Plan, incentive stock options could have been granted to employees with exercise prices of no less than the fair value of the common stock on the grant date, and non-qualified options could have been granted to employees, directors, or consultants at exercise prices of no less than 85% of the fair value of the common stock on the grant date, as determined by the Board of Directors. If, at the time the Company granted an option, the optionee directly or by attribution owned stock possessing more than 10% of the total combined voting power of all classes of stock of the Company, the option price had to have been at least 110% of the fair value. Options granted under the 2003 Plan generally expire no later than ten years from the date of grant and, in general, vest four years from the date of grant. (b) 2011 Stock Option and Incentive Plan In September 2011, the Board of Directors adopted the 2011 Stock Option and Incentive Plan (the “2011 Plan”) which was subsequently approved by the Company’s stockholders. The 2011 Plan replaced the 2003 Plan and the Company no longer grants awards under the 2003 Plan. The Company initially reserved 1,000,000 shares of common stock for issuance under the 2011 Plan. In addition, 955,568 reserved but unissued shares under the 2003 Stock Plan were added to the number of shares reserved for issuance under the 2011 Plan. The 2011 Plan also provided that the number of shares reserved and available for issuance under the plan would automatically increase each January 1, beginning in 2012 and ending in 2015, by 4% of the outstanding number of shares of common stock on the immediately preceding December 31. The last automatic increase occurred on January 1, 2015. In May 2016, the Company’s stockholders approved of an increase to the share reserve under the 2011 Stock Plan and Incentive Plan by 1,300,000 shares. The 2011 Plan permits the granting of incentive stock options, non-qualified stock options, restricted stock units (RSUs), stock appreciation rights, restricted shares of common stock and performance share awards. The exercise price of stock options may not be less than 100% of the fair market value of the common stock on the date of grant. Options granted pursuant to the 2011 Plan generally expire no later than ten years from the date of grant. The Company also grants RSUs, which generally vest over either a four-year period with 25% vesting at the end of one year and the remainder vesting quarterly thereafter or they completely vest at the end of a three-year period. Additionally, the Company grants performance-based RSUs to its executives on an annual basis. (c) 2011 Employee Stock Purchase Plan In September 2011, the Board of Directors adopted the 2011 Employee Stock Purchase Plan (the “ESPP”) which was subsequently approved by the Company’s stockholders. The ESPP took effect on the effective date of the registration statement for the Company’s IPO. The ESPP permits eligible employees to acquire shares of the Company’s common stock by accumulating funds through periodic payroll deductions of up to 15% of base salary. Each offering period may run for no more than 24 months and consist of no more than five purchase periods. The purchase price for shares of the Company’s common stock purchased under the ESPP will be 85% of the lesser of the fair market value of the Company’s common stock on the first day of the offering period or the last trading day of the applicable purchase period within that offering period. The Company has initially reserved a total of 500,000 shares of common stock for future issuance under the ESPP. The number of shares reserved for issuance under the ESPP will increase automatically on January 1 of each of the first eight years commencing in 2012 by the number of shares equal to 1% of the Company’s total outstanding shares as of the immediately preceding December 31. The Board of Directors or compensation committee may reduce the amount of the increase in any particular year. No more than 20,000,000 shares of common stock may be issued under the ESPP and no other shares may be added to the ESPP without the approval of the Company’s stockholders. On January 1, 2016, the share reserve under the 2011 Employee Stock Purchase Plan was automatically increased by 318,371 shares. (d) Inducement Stock Option Plans and Agreement and Inducement Restricted Stock Unit Plans and Agreement In August 2014 and August 2015, the Compensation Committee of the Board of Directors adopted Inducement Stock Option Plan and Agreement (the “Inducement Option Plan”) and Inducement Restricted Stock Unit Plan and Agreement (the “Inducement RSU Plan”), in each case created as employment inducement awards. In accordance with the terms of the Inducement Option Plans, the Company issued options to purchase up to 290,000 shares of the Company’s common stock at an exercise price equal to the fair market value of a share of the Company’s common stock on the dates of grant of the options. The options, which have a ten-year term, vest at the rate of 25% of the shares on each of the first anniversary of the vesting commencement date with an additional 6.25% of the shares subject to the option vesting each quarter thereafter so long as the participant has not been terminated. In accordance with the terms of the Inducement RSU Plans, the Company issued RSUs representing a total of 290,000 shares of the Company’s common stock. The RSUs, which expire following settlement, vest at the rate of 25% of the shares on each of the first anniversary of the vesting commencement date with an additional 6.25% of the shares subject to the RSU vesting each quarter thereafter so long as the participant has not been terminated. (e) 2015 Equity Inducement Plan In October 2015, the Board of Directors adopted the 2015 Equity Inducement Plan, a non-stockholder approved plan that provides for the granting of stock options and RSUs as employment inducement awards and in connection with acquisitions, subject to compliance with applicable securities laws and stock exchange requirements for such plans. The Company has reserved 100,000 shares of common stock for issuance under the 2015 Equity Inducement Plan. No awards have been made under the 2015 Equity Inducement Plan and the entire reserve remains available for grant. Under the terms of the 2015 Equity Inducement Plan, the exercise price of stock options may not be less than 100% of the fair market value of common stock on the date of grant and generally expire no later than ten years from the date of grant. (f) Incapsula 2010 Share Incentive Plan In March 2010, Incapsula’s board of directors adopted the Incapsula 2010 Share Incentive Plan (the “Incapsula Plan”), pursuant to which Incapsula was able to grant to its employees and service providers options to purchase shares of its common stock, restricted shares, or RSUs. As of November 2013, the total number of shares of common stock that could have been granted under the Incapsula Plan was not to exceed 10,263,211 shares in the aggregate, subject to certain adjustments. In November 2013, the board of directors of Incapsula approved the grant of RSUs for 7,095,461 shares of Incapsula’s common stock (“Incapsula RSUs”). As part of the Incapsula acquisition, the Incapsula RSUs were assumed and replaced by performance-based RSUs for Company Common Stock to be issued to continuing employees of Incapsula. The Incapsula RSUs were earned upon Incapsula’s achievement of revenue targets for Incapsula and Incapsula-related products and services for fiscal year 2014 and were converted into approximately 198,825 shares of Company Common Stock at the same exchange ratio applicable to the shares of Incapsula common stock acquired in the acquisition. In addition to performance conditions, the awards were dependent on the market price of Imperva’s common stock during February 2014, which was deemed a market condition under ASC 718. The outstanding options and RSUs under the Incapsula 2010 Stock Incentive Plan were assumed as part of the Incapsula acquisition and are equivalent to 247,184 shares of Company common stock on an as-converted basis. The Company does not intend to grant any additional shares under the Incapsula 2010 Stock Incentive Plan. (g) Option Activity The following table summarizes option activity under the Plans and related information: Options Outstanding Weighted- Average Remaining Number of Shares Weighted Average Exercis e Contractual Term (in years) Aggregate Intrinsic Value (i n Outstanding - December 31, 2013 1,675,506 $ 23.78 8.01 $ 40,813 Granted 1,256,559 $ 41.39 Options assumed in acquisitions 72,607 $ 13.30 Exercised or released (496,297 ) $ 14.85 Cancelled or forfeited (264,012 ) $ 35.85 Outstanding - December 31, 2014 2,244,363 $ 33.83 8.27 $ 38,457 Granted 696,971 $ 49.20 Exercised or released (636,424 ) $ 29.44 Cancelled or forfeited (355,821 ) $ 42.00 Balances - December 31, 2015 1,949,089 $ 39.27 8.09 $ 47,480 Granted 48,260 $ 53.59 Exercised or released (184,737 ) $ 29.24 Cancelled or forfeited (241,847 ) $ 47.35 Balances - December 31, 2016 1,570,765 $ 39.64 6.90 $ 9,226 Vested and expected to vest - December 31, 2016 1,463,772 $ 39.03 6.82 $ 9,061 Exercisable - December 31, 2016 967,186 $ 36.66 6.31 $ 7,339 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the closing stock price of $38.40 of the Company’s common stock on December 31, 2016 Additional information regarding the Company’s stock options outstanding and exercisable as of December 31, 2016 is summarized below: Options Outstanding Options Exercisable Exercise Prices Number of Stock Options Outstanding Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price per Share Shares Subject to Stock Options Weighted Average Exercise Price per Share $0.02 to $10.70 134,548 4.02 $ 7.01 130,579 $ 7.22 $10.71 to $29.10 168,845 6.66 $ 25.73 121,118 $ 25.37 $29.11 to $32.54 236,906 7.51 $ 29.40 116,285 $ 29.53 $32.55 to $34.55 149,082 5.09 $ 33.78 133,559 $ 33.76 $34.56 to $54.48 464,660 7.68 $ 43.41 240,153 $ 43.04 $54.49 to $61.50 248,776 7.21 $ 55.16 149,677 $ 54.92 $61.51 to $69.19 143,729 7.42 $ 65.04 68,611 $ 64.52 $69.20 to $77.00 24,219 8.50 $ 71.73 7,204 $ 71.74 1,570,765 6.90 $ 39.64 967,186 $ 36.66 (h) RSU Activity A summary of RSU activity for the year ended December 31, 2016, is as follows: Number of Restricted Stock Units Outstanding Weighted- Average Grant Date Fair Value Unvested - December 31, 2014 2,279,081 $ 39.07 Granted 911,734 $ 53.02 Granted, performance RSUs 249,220 $ 42.58 Released (898,205 ) $ 34.97 Cancelled or expired (643,805 ) $ 35.09 Unvested - December 31, 2015 1,898,025 $ 49.53 Granted 1,160,062 $ 47.42 Granted, performance RSUs 273,900 $ 51.55 Released (884,349 ) $ 43.04 Cancelled or forfeited (452,848 ) $ 49.86 Unvested - December 31, 2016 1,994,790 $ 51.42 (i) Stock-Based Compensation Expense The Company recognized stock-based compensation expense under the 2011 Stock Option and Incentive Plan, 2003 Stock Plan, Inducement Plans, 2011 Employee Stock Purchase Plan, and the Incapsula 2010 Share Incentive Plan in the consolidated statements of operations as follows (in thousands): Years Ended December 31, 2016 2015 2014 Cost of revenue $ 4,664 $ 3,862 $ 2,058 Research and development 14,711 13,831 8,799 Sales and marketing 20,510 16,717 13,558 General and administrative 17,131 16,554 12,858 Restructuring charges 5,859 - - Total stock-based compensation expense $ 62,875 $ 50,964 $ 37,273 Included in the total above is $3.1 million related to a liability award which is expected to settle in 2017 (j) Determining the Fair Value of RSUs, Performance RSUs, Stock Options, and ESPP The fair value of RSUs is determined using the closing price of the Company’s stock on the date of grant. Compensation is recognized on a straight-line basis over the requisite service period of each grant adjusted for estimated forfeitures. The fair value of RSUs granted to employees which have multiple performance conditions is determined by the Company using a Monte Carlo simulation model. The key inputs used were the Company’s stock price on the date of grant, the expected volatility, the risk free interest rate and a revenue forecast. The Company updates the estimated expense, net of forfeitures, at the end of each reporting period. The expense is recognized on an accelerated basis over the requisite service period, which is generally the vesting period of the respective awards. The fair value of each stock option and ESPP grant to employees was determined by the Company and its board of directors using the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine. Expected Term — The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. For option grants that are considered to be “plain vanilla,” the Company used the simplified method to determine the expected term as provided by the Securities and Exchange Commission. The simplified method is calculated as the average of the time-to-vesting and the contractual life of the options. For option grants that are not considered “plain vanilla”, the expected term is derived from historical data on employee exercises and post-vesting employment termination behavior taking into account the contractual life of the award. For ESPP grants, the expected term is based on the length of the offering period, which is six months. Expected Volatility —The expected volatility was based on our historical volatilities. The volatility is over a period equal to the expected terms of the stock option grants and the offering period for employee stock purchase plan. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero coupon U.S. Treasury notes with maturities approximately equal to the grant’s expected term. Expected Dividend — The Company has never paid dividends and does not expect to pay dividends. Forfeiture Rate —The Company estimates its forfeiture rate based on an analysis of its actual forfeitures and will continue to evaluate the adequacy of the forfeiture rate based on actual forfeiture experience, analysis of employee turnover behavior, and other factors. The impact from a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual number of future forfeitures differs from that estimated by the Company, the Company may be required to record adjustments to stock-based compensation expense in future periods. A summary of the weighted-average assumptions is as follows: Years Ended December 31 2016 2015 2014 Stock option grants: Dividend rate 0 % 0 % 0 % Risk-free interest rate 1.4 % 1.8 % 1.8 % Expected term (in years) 6.0 6.1 6.1 Expected volatility 58 % 49 % 46 % ESPP grants: Dividend rate 0 % 0 % 0 % Risk-free interest rate 0.5 % 0.4 % 0.1 % Expected term (in years) 0.5 0.5 0.5 Expected volatility 58 % 65 % 45 % The weighted-average grant date fair value of the Company’s stock options granted during the years ended December 31, 2016, 2015 and 2014 was $29.23, $23.75, and $19.36 per share, respectively. The aggregate grant date fair value of the Company’s stock options granted to employees during the years ended December 31, 2016, 2015 and 2014 was $1.4 million, $16.6 million, and $24.3 million, respectively. The aggregate grant date fair value of the Company’s stock options vested during the years ended December 31, 2016, 2015, and 2014 was $11.9 million, $11.7 million, and $7.2 million, respectively. The fair value of the Company’s RSUs vested during the year ended December 31, 2016, 2015 and 2014 was $38.1 million, $31.4 million and $8.3 million, respectively. The aggregate intrinsic value of options exercised under the Plans was $2.5 million, $21.6 million, and $14.7 million for the years ended December 31, 2016, 2015 and 2014, respectively. The aggregate intrinsic value of options exercised is calculated as the difference between the fair market value of the Company’s common stock on the date of the exercise and the exercise price of each option. As of December 31, 2016, total compensation cost related to unvested stock-based awards granted to employees under the Plans, but not yet recognized, was $69.5 million, net of estimated forfeitures. As of December 31, 2016, this cost will be amortized to expense over a weighted-average remaining period of 2.5 years, and will be adjusted for subsequent changes in estimated forfeitures. Future option grants will increase the amount of compensation expense to be recorded in these periods. Net cash proceeds from the exercise of stock options and the issuance of common stock in connection with the employee stock purchase plan were $2.4 million, $12.1 million, and $8.5 million for the years ended December 31, 2016, 2015 and 2014, respectively. There was no capitalized stock-based compensation cost during the years ended December 31, 2016, 2015 and 2014. Recognized stock-based compensation tax benefits during the year ended December 31, 2016, 2015 and 2014 was $0.1 million $0.2 million and $0.4 million, respectively. (k) Common Stock Subject to Repurchase In connection with the acquisition of Skyfence in the first quarter of 2014, the Company issued 532,262 shares of the Company’s common stock with a fair value per share of $59.08 which are subject to forfeiture based upon time-based vesting and continuing employment over the term of the corresponding four-year service period. 421,365 and 236,537 shares were fully vested as of December 31, 2016 and 2015 respectively. (l) Follow-On Public Offering In March 2015, the Company completed a follow-on public offering whereby the Company sold 3,450,000 shares of common stock at a price of $39.00 per share, for aggregate net proceeds of $127.9 million, after deducting underwriting discounts, commissions and other offering costs of approximately $6.7 million.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	13. Accumulated Other Comprehensive Income (Loss) The changes in the balances of accumulated other comprehensive income (loss) by component are as follows (in thousands): Years ended December 31, 2016 2015 2014 Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Balance at January 1 $ (1,021 ) $ (310 ) $ (1,331 ) $ (1,428 ) $ (61 ) $ (1,489 ) $ (426 ) $ (2 ) $ (428 ) Other comprehensive income (loss) before reclassifications (134 ) (103 ) (237 ) (565 ) (249 ) (814 ) (1,655 ) (59 ) (1,714 ) Amounts reclassified to net loss 90 — 90 972 — 972 653 — 653 Change in other comprehensive income (loss) (44 ) (103 ) (147 ) 407 (249 ) 158 (1,002 ) (59 ) (1,061 ) Balance at December 31 $ (1,065 ) $ (413 ) $ (1,478 ) $ (1,021 ) $ (310 ) $ (1,331 ) $ (1,428 ) $ (61 ) $ (1,489 ) The following is a summary of reclassifications out of accumulated other comprehensive income (loss) for the years 2016, 2015, and 2014 (in thousands): Year ended December 31, 2016 2015 2014 Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Unrealized gains (losses) on cash flow hedges: Current period unrealized gain (loss) $ (134 ) - $ (134 ) $ (565 ) $ — $ (565 ) $ (1,655 ) $ — $ (1,655 ) Reclassification adjustments 1 90 - 90 972 — 972 653 — $ 653 Unrealized gains (losses) on cash flow hedges, net (44 ) - (44 ) 407 - 407 (1,002 ) — (1,002 ) Unrealized gains (losses) on investments: Current period unrealized gain (loss) $ (103 ) - (103 ) $ (249 ) - (249 ) (59 ) — (59 ) Reclassification adjustments 2 — - — — - — — — - Unrealized gains (losses) on investments: (103 ) — (103 ) (249 ) — (249 ) (59 ) — (59 ) Other comprehensive income (loss) $ (147 ) $ — $ (147 ) $ 158 $ — $ 158 $ (1,061 ) $ — $ (1,061 ) 1 Refer to Note 6 for the affected line items in the consolidated statement of operations 2 Amount included in other income (expense), net, in the consolidated statement of operations

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes The Company’s geographical breakdown of its loss before provision for income taxes is as follows (in thousands): Years Ended December 31, 2016 2015 2014 Domestic $ (72,139 ) $ (50,892 ) $ (55,330 ) Foreign 3,032 2,692 (2,665 ) Loss before provision for taxes $ (69,107 ) $ (48,200 ) $ (57,995 ) The components of the provision for income taxes are as follows (in thousands): Years Ended December 31, 2016 2015 2014 Current Federal $ — $ — $ — State 62 34 66 Foreign 1,654 857 1,523 Total current provision 1,716 891 1,589 Deferred Federal 130 63 109 State 6 (1 ) 6 Foreign (680 ) (271 ) (523 ) Total deferred provision (544 ) (209 ) (408 ) Total $ 1,172 $ 682 $ 1,181 Reconciliation of the provision for income taxes at the statutory rate to the Company’s provision for income tax is as follows (in thousands): Years Ended December 31, 2016 2015 2014 Tax benefit at federal statutory tax rate $ (23,496 ) $ (16,388 ) $ (19,718 ) Tax benefit at state statutory tax rate (1,008 ) (499 ) (1,169 ) Foreign tax rate differential 57 (826 ) (526 ) Unbenefitted loss of consolidated investment - - 2,366 Change in valuation allowance 17,701 9,738 12,407 Meals and entertainment 222 44 34 Stock compensation 7,857 8,492 7,160 Nondeductible expenses and other (161 ) 121 627 Provision for income taxes $ 1,172 $ 682 $ 1,181 Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2016 2015 Deferred tax assets: Reserves and accruals $ 2,817 $ 2,662 Deferred revenue 10,379 8,724 Stock-based compensation 7,361 4,772 Net operating loss carryforwards 47,452 37,793 Loss on OCI 370 374 Other 67 32 Gross deferred tax assets 68,446 54,357 Valuation allowance (68,227 ) (53,468 ) Total deferred tax assets 219 889 Deferred tax liabilities: Stock-based compensation (21 ) (21 ) Depreciation and amortization (243 ) (1,425 ) Total deferred tax liabilities (264 ) (1,446 ) Net deferred tax liability $ (45 ) $ (557 ) Recognition of deferred tax assets is appropriate when realization of these assets is more likely than not. Based upon the weight of available evidence, which includes the Company’s historical operating performance and the recorded cumulative net losses in all prior fiscal periods, the Company has provided a full valuation allowance against its U.S. deferred tax assets and Imperva Israel net operating loss generated. The Company’s valuation allowance increased by $14.8 million, $13.0 million, and $7.8 million in the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, the Company had U.S. federal and state net operating loss carryforwards of approximately $180.4 million and $85.2 million, respectively. The U.S. federal net operating loss carryforwards will expire at various dates beginning in 2022 through 2036 if not utilized. Most state net operating loss carryforwards will expire at various dates beginning in 2017 through 2036. The Company uses the “with-and-without” approach to determine the recognition and measurement of excess tax benefits. Accordingly, the Company has elected to recognize excess income tax benefits from stock option exercises in additional paid in capital only if an incremental income tax benefit would be realized after considering all other tax attributes presently available to the Company. As of December 31, 2016, the amount of such excess tax benefits from stock options included in deferred tax assets for federal and state net operating losses were $49.9 million and $29.5 million, respectively. In addition, the Company has elected to account for the indirect effects of stock-based awards on other tax attributes, such as the research and alternative minimum tax credits, through the statement of operations. Net operating loss carryforwards reflected above may be subject to limitations due to ownership changes as provided in the Internal Revenue Code and similar state provisions. The Company has not provided U.S. income tax on certain foreign earnings that are deemed to be indefinitely invested outside the U.S. For fiscal years 2016, 2015, and 2014 the amount of accumulated unremitted earnings from the Company’s foreign subsidiaries is approximately $9.7 million, $13.6 million and $12.9 million, respectively. Determination of the amount of unrecognized deferred U.S. income tax liability is not practical due to the complexities associated with the hypothetical calculation. As of December 31, 2016 and 2015, the Company had gross unrecognized tax benefits of approximately $2.3 million and $1.2 million, respectively, all of which would impact the effective tax rate if recognized. While it is often difficult to predict the final outcome of any particular uncertain tax position, the Company does not believe that the amount of unrecognized tax benefits will change significantly in the next twelve months. The Company recognizes interest accrued and penalties related to unrecognized tax benefits in its income tax provision. For the years ended December 31, 2016 and 2015, the Company accrued interest of $0.2 million and $0.1 million in income tax expense, respectively. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2016 2015 2014 Balance at January 1 $ 1,154 $ 672 $ 353 Additions based on tax positions taken during the current period 761 401 222 Reductions based on tax positions taken during the prior period (42 ) (50 ) (47 ) Additions based on tax positions taken during a prior period 409 131 144 Balance at December 31 $ 2,282 $ 1,154 $ 672 The Company’s material income tax jurisdictions are the United States (federal), California and Israel. As a result of net operating loss carryforwards, the Company is subject to audit for tax years 2004 and forward for federal purposes and 2006 and forward for California purposes. The Company’s tax years 2011 and forward are subject to audit in Israel. The Company’s 2011 and 2012 tax years are currently under examination by Israeli Tax Authorities. The Company does not expect a material impact on its consolidated financial statements as a result of this examination. There are tax years which remain subject to examination in various other jurisdictions that are not material to the Company’s financial statements. The Company's Israeli subsidiaries ("Israeli subsidiaries") research and development intercompany services activity ("R&D activity") have a "Beneficiary Enterprise" status for a separate investment program that was elected by the Israel subsidiaries starting 2012 under the Law for Encouragement of Capital Investments, 1959 (the "Investments Law), amended from time to time. The entitlement to the above benefits is conditional upon the Israeli subsidiaries fulfilling the conditions stipulated by the Investments Law and regulations published there under.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Information	15. Segment Information The Company operates its business in one operating segment, which is the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications whether in the cloud or on premises. Operating segments are defined as components of an enterprise that engage in business activities for which separate financial information is available and evaluated by the chief operating decision maker in deciding how to allocate resources and assessing performance. The chief operating decision maker is the Company’s Chief Executive Officer. The Company’s services revenue was comprised of the following (in thousands): Years Ended December 31, 2016 2015 2014 Maintenance and support $ 80,007 $ 66,380 $ 54,795 Professional services and training 13,693 14,084 11,414 Subscriptions 83,957 46,271 23,502 Total net services revenue $ 177,657 $ 126,735 $ 89,711 The Company’s revenue by geographic region, based on the customer’s location, is summarized as follows (in thousands): Years Ended December 31, 2016 2015 2014 United States $ 143,607 $ 141,225 $ 87,155 EMEA 50,838 47,429 39,579 APAC 48,391 30,180 27,798 Other 21,619 15,464 9,478 Total net revenue $ 264,455 $ 234,298 $ 164,010 The following table presents long-lived assets by location (in thousands): As of December 31, 2016 2015 2014 United States $ 20,525 $ 9,913 $ 6,761 Israel 9,344 10,224 10,221 Other 20 18 35 Total long-lived assets $ 29,889 $ 20,155 $ 17,017

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2016
Restructuring Charges [Abstract]
Restructuring Charges	16. Restructuring Charges In November 2016, we implemented a restructuring plan and cost reduction initiatives to reduce expenses, streamline the organization, and reallocate resources to align more closely with future business needs. The restructuring charge during the year ended December 31, 2016 of $8.1 million includes a non-cash charge of $5.8 million related to stock-based compensation and $2.3 million of cash charges related to involuntary employee termination benefits. Of the $2.3 million of cash charges, $1.2 million was paid in 2016 and $1.1 million of the restructuring charges will be paid in the first quarter of 2017, and was recorded as a current liability within accrued compensation and benefits on the consolidated balance sheet as of December 31, 2016. The restructuring activity was substantially complete during the year ended December 31, 2016 and we do not expect material costs associated with the activity in future periods.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss per Share	17. Net Loss per Share The following table sets forth the computation of the Company’s basic and diluted net loss per share of common stock (in thousands, except per share amounts): Years Ended December 31, 2016 2015 2014 Net loss attributable to Imperva, Inc. stockholders $ (70,279 ) $ (48,882 ) $ (58,963 ) Shares used in computing net loss per share of common stock, basic and diluted 32,284 29,849 25,806 Net loss per share of common stock, basic and diluted $ (2.18 ) $ (1.64 ) $ (2.28 ) The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have been antidilutive: Years Ended December 31, 2016 2015 2014 Stock options to purchase common stock 1,570,765 1,949,089 2,244,363 Restricted stock units for common stock 1,994,790 1,898,025 2,279,081 Restricted shares of common stock subject to repurchase - - 217,621 Restricted stock issued in connection with Skyfence acquisition 110,897 118,961 355,499

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Event	18. Subsequent Event On February 8, 2017, the Company and its wholly-owned subsidiary, Skyfence Networks Ltd., entered into an Asset Purchase Agreement with Forcepoint LLC, to sell the assets used in the Skyfence cloud access security broker business for total purchase price of approximately $40 million in cash, subject to potential working capital and other adjustments as are set forth in the Asset Purchase Agreement. The sale was completed on February 23, 2017. We are in the process of finalizing the impact of the transaction on our financial statements, including evaluating the resulting gain that will be recognized, based on all the terms of the agreement. The following table presents our best estimate of the aggregate carrying amounts of the major classes of assets and liabilities related to the Skyfence business to be disposed of as of December 31, 2016: (dollars Assets Accounts receivables $ 463 Prepaid and other current assets 15 Property and equipment, net 234 Goodwill 1,179 Acquired intangible assets, net 4,668 Total assets $ 6,559 Liabilities: Accounts payable $ 163 Accrued and other current liabilities 76 Deferred revenue 1,334 Total liabilities $ 1,573

The Company and Summary of Si26

The Company and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Business	Business Imperva, Inc. (together with its subsidiaries, the “Company”) was incorporated in April 2002 in Delaware. The Company is headquartered in Redwood Shores, California and has subsidiaries located throughout the world including Israel, Asia and Europe. The Company is engaged in the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications, whether in the cloud or on premises. On February 23, 2017, we completed the sale of our Skyfence cloud access security broker business to Forcepoint LLC for $40 million subject to potential working capital and other adjustments. See Note 18 for further discussion of the sale of the Skyfence business.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s consolidated financial position, results of operations and cash flows for the periods presented. The consolidated financial statements include the accounts of Imperva Inc., and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Non - controlling Interest	Non-controlling Interest On March 20, 2014, the Company acquired the remaining interest it did not previously own in its majority-owned subsidiary, Incapsula, Inc. (“Incapsula”) (Refer to Note 2). The Company separately presented the non-controlling interest on its Consolidated Balance Sheets in Total Stockholders’ Equity, Consolidated Statements of Operations, Consolidated Statements of Comprehensive Loss and Consolidated Statements of Stockholders’ Equity for periods prior to such date. The Company had recorded a non - controlling interest in these consolidated financial statements for the 19% ownership interest of the minority owners of Incapsula as of December 31, 2013. Changes to the ownership interest in Incapsula held by the minority owners were accounted for as equity transactions in the consolidated statements of stockholders’ equity as the Company obtained control of Incapsula on November 5, 2009.
Segment Information	Segment Information Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company has one operating segment, which is the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications, whether in the cloud or on premises.
Use of Estimates	Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Such management estimates include the fair value of accounts receivable, inventory, intangible assets and goodwill, useful lives of intangible assets and property and equipment, and assumptions used in the calculation of revenue, income taxes and stock-based compensation, among others. These estimates and assumptions are based on management’s best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates.
Concentration of Supply Risk	Concentration of Supply Risk The Company relies on a single third party to manufacture its hardware appliances, and purchases its hardware appliances through such third party’s value-added resellers. Quality or performance failures of the Company’s products or changes in the Company’s suppliers’ financial or business condition could disrupt the Company’s ability to supply quality products to its customers and thereby have a material adverse effect on its business and consolidated financial statements.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash, cash equivalents, short-term investments, restricted cash and derivative financial instruments. The Company’s cash, cash equivalents, short-term investments and restricted cash are invested in high-quality instruments with banks and financial institutions located in the United States and Israel. Such deposits may be in excess of insured limits provided on such deposits. The Company uses derivative financial instruments to manage exposures to foreign currency risks. The Company’s derivatives expose it to credit risk to the extent that the counterparty may be unable to meet the terms of the agreement. The Company seeks to mitigate such risk by limiting its counterparties to those with high or investment-grade credit ratings. The Company does not require collateral under these agreements and has not historically experienced any losses due to credit risk or lack of performance by counterparties.
Derivative Financial Instruments	Derivative Financial Instruments The Company uses forward foreign currency exchange contracts to reduce its exposure to foreign currency rate changes for operating expenses that are forecasted to be incurred in currencies other than U.S. dollars. The Company records all of its derivative instruments at their gross fair value on the consolidated balance sheets. The Company classifies its cash flows from derivative financial instruments as operating activities. The accounting for changes in the fair value of a derivative instrument depends on whether the instrument has been designated and qualifies as a cash flow hedge for accounting purposes. For forward foreign currency exchange contracts that are designated and qualify as cash flow hedges, the effective portion of the gain or loss resulting from changes in the fair value of the derivative instruments is accounted for in accumulated other comprehensive income (loss) (“AOCI”) in the consolidated statements of stockholders’ equity and reclassified into operating expenses in the consolidated statements of operations in the period or periods during which the hedged transaction affects earnings. As of December 31, 2016, the Company estimated that $0.6 million of net derivative loss included in accumulated other comprehensive income (loss) will be reclassified into earnings within the next 12 months. The ineffective portion of the gain or loss resulting from the change in fair value is recognized in other income (expense), net in the consolidated statements of operations.
Cash, Cash Equivalents and Short-Term Investments	Cash, Cash Equivalents and Short-Term Investments 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 investments. Investments are available to be used in current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents and short-term investments are classified as available-for-sale and are, therefore, recorded at fair value on the consolidated balance sheets, with any unrealized gains and losses reported in the consolidated statements of stockholders’ equity as a component of accumulated other comprehensive income (loss) 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 other income (expense), net in the consolidated statements of operations.
Restricted Cash	Restricted Cash The Company has restricted cash pledged as collateral representing a security deposit required for facility leases. As of December 31, 2016 and 2015, the Company has classified $1.9 million and $1.7 million, respectively, of security deposit as non-current assets relating to its facility lease arrangements.
Inventory	Inventory Inventory consists of finished goods hardware appliances and related component parts and is stated at the lower of cost or market value where the cost is determined as the lower of an average cost basis or last invoice. Inventory that is obsolete or in excess of forecasted demand is written down to its estimated realizable value. Inventory write-downs, once established, are not reversed as they establish a new cost basis for the inventory. For the years ended December 31, 2016, 2015 and 2014, the amount of inventory write-downs incurred by the Company were insignificant.
Business Combination	Business Combination The Company accounts for its business acquisitions in accordance with Accounting Standards Codification (ASC) No. 805, Business Combinations. The total purchase price allocated to the tangible assets acquired is assigned based on the fair values as of the date of the acquisition. The identifiable intangible assets are subject to amortization on a straight-line basis as this best approximates the benefit period related to these assets
Property and Equipment	Property and Equipment Property and equipment, including leasehold improvements, are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, generally two to seven years. Leasehold improvements are amortized using the straight-line method over the shorter of the remaining lease term or the estimated useful lives of the assets. Upon the retirement or disposition of property and equipment, the related costs and accumulated depreciation is removed and any related gain or loss is recorded in the consolidated statements of operations. Repairs and maintenance that do not extend the life or improve an asset are expensed in the periods incurred.
Goodwill and Acquired Intangibles	Goodwill and Acquired Intangibles Goodwill is not amortized and is reviewed at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The Company operates its business in one operating segment and one reporting unit, which is the development, marketing, sales, service and support of cyber-security solutions that protect business-critical data and applications whether in the cloud or on premises. In reviewing goodwill, the Company bypasses the qualitative assessment and proceeds directly to performing the quantitative two step impairment test to test the reporting unit’s goodwill for impairment. The first step of the impairment test involves comparing the fair value of the reporting unit to its net book value, including goodwill and is used as a screening process for identifying a potential goodwill impairment loss. If the net book value exceeds its fair value, then the Company would perform the second step of the goodwill impairment test to determine the amount of the impairment loss. The impairment loss would be calculated by comparing the implied fair value of goodwill of the Company to its net book value. In calculating the implied fair value of the Company’s goodwill, the fair value of the Company would be allocated to all of the other assets and liabilities based on their fair values. The excess of the fair value of the Company over the amount assigned to its other assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds its implied fair value. The Company completes its annual impairment test during the fourth quarter of each fiscal year. There was no impairment of goodwill recorded for the fiscal year ended December 31, 2016. Intangible assets consist of purchased technology, customer relationships, trade names and domain names which are amortized over the period of estimated benefit using the straight-line method, as the consumption pattern of the asset is not apparent, and estimated useful lives ranging from seven to ten years as of December 31, 2016. No significant residual value is estimated for intangible assets.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company evaluates its long-lived assets, which consist of property and equipment and acquired intangible assets, for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Impairment exists if the carrying amounts of such assets exceed the estimates of future net undiscounted cash flows expected to be generated by such assets. Should impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s estimated fair value. As of December 31, 2016 and 2015, the Company has not written down any of its long-lived assets as a result of impairment.
Revenue Recognition	Revenue Recognition The Company derives revenue from two sources: (i) products and license revenue, which includes hardware and perpetual software license revenue and (ii) services revenue, which includes maintenance and support, professional services, training and subscription arrangements. Substantially all of product and license sales have been sold in combination with maintenance and support services. Revenue is recognized when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery or performance has occurred; the sales price is fixed or determinable; and collection is reasonably assured. The Company defines each of the four criteria above as follows: • Persuasive evidence of an arrangement exists: Evidence of an arrangement consists of a purchase order or acknowledgment issued pursuant to the terms and conditions of a direct customer end user or distributor or value-added reseller (VAR) agreement and, in limited cases with both distributor/VAR and an end user agreement and/or purchase order • Delivery or performance has occurred: The Company uses shipping and related documents, or written evidence of customer acceptance, when applicable, to verify delivery or performance. The Company recognizes product revenue upon transfer of title and risk of loss, which primarily is upon shipment to value-added resellers, distributors or end users. In most instances, the Company does not have significant obligations for future performance, such as customer acceptance provisions, rights of return or pricing credits, associated with the Company’s sales. In instances where final acceptance of the product or service is specified by the customer, revenue is deferred until all acceptance criteria have been met. • The sales price is fixed or determinable: The Company assesses whether the sales price is fixed or determinable based on payment terms and whether the sales price is subject to refund or adjustment. Standard payment terms to customers range from 30 to 90 days. In the event payment terms are provided that differ from the Company’s standard business practices, the fees are deemed to not be fixed or determinable and revenue is recognized when the payments become due, provided the remaining criteria for revenue recognition have been met. • Collection is reasonably assured: The Company assesses probability of collection on a customer-by-customer basis. The Company’s customers are subjected to a credit review process that evaluates their financial condition and ability to pay for products and services. If the Company concludes that collection is not reasonably assured based upon an initial review, the Company does not recognize revenue until payment is received. Maintenance and support and subscription revenue includes arrangements for software maintenance and technical support for the Company’s products and subscription services revenue primarily related to the Company’s cloud-based services. The terms of the Company’s subscription service arrangements do not provide customers the right to take possession of the related software. Maintenance and support is offered under renewable, fee-based contracts, which include technical support, hardware repair and replacement parts, bug fixes, patches and unspecified upgrades on a when-and-if-available basis. Maintenance and support and subscription revenue is initially deferred and recognized ratably over the life of the contract, with the related expenses recognized as incurred. Maintenance and support and subscription contracts usually have a term of one to three years. Unearned maintenance and support and subscription revenue is included in deferred revenue. Professional service revenue primarily consists of the fees the Company earns related to installation and consulting services. The Company recognizes revenue from professional services upon delivery or completion of performance. Professional service arrangements are typically short term in nature and are largely completed within 90 days from the start of service. Training services are recognized upon delivery of the training. Multiple Element Arrangements Most of the Company’s products are hardware appliances containing software components that function together to provide the essential functionality of the product. Therefore, the Company’s hardware appliances are considered non-software deliverables and are not subject to industry-specific software revenue recognition guidance. The Company’s product revenue also includes revenue from the sale of stand-alone software products. Stand-alone software may operate on the Company’s hardware appliance, but is not considered essential to the functionality of the hardware and is, therefore, subject to the industry-specific software revenue recognition guidance. Additionally, the Company provides unspecified software upgrades for our products, on a when-and-if available basis, and hardware replacements through maintenance and support contracts. These support arrangements when sold on a stand-alone basis are subject to the industry-specific software revenue recognition guidance. Under the software revenue recognition guidance, the Company uses the residual method to recognize revenue when a product agreement includes one or more elements to be delivered at a future date and Vendor Specific Objective Evidence (“VSOE”) of the fair value of all undelivered elements exists. In the majority of the Company’s contracts, the only element that remains undelivered at the time of delivery of the product is maintenance and support services and subscriptions. Under the residual method, the VSOE of fair value of the undelivered elements is deferred and the remaining portion of the contract fee is recognized as product revenue. If evidence of the VSOE of fair value of one or more undelivered elements does not exist, all revenue is generally deferred and recognized when delivery of those elements occurs or when fair value can be established. For certain arrangements with multiple deliverables, the Company allocates the arrangement fee to the non-software element based upon the relative selling price of such element and, if software and software-related elements (e.g., maintenance and support for the software element) are also included in the arrangement, the Company allocates the arrangement fee to each of those software and software-related elements as a group. After such allocations are made, the amount of the arrangement fee allocated to the software and software-related elements is accounted for using the residual method. When applying the relative selling price method, the Company determines the selling price for each element using VSOE of selling price, if it exists, or if not, Third-Party Evidence (“TPE”) of selling price, if it exists. If neither VSOE nor TPE of selling price exist for an element, the Company uses its Best Estimate of Selling Price (“BESP”) for that element. The revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for that element. The Company limits the amount of revenue recognized for delivered elements to the amount that is not contingent on the future delivery of products or services, or subject to the Company’s future performance obligation. VSOE of fair value for elements of an arrangement is based upon the normal pricing and discounting practices for those services when sold separately. In determining VSOE, the Company requires that a substantial majority of the selling prices for a service fall within a reasonably narrow pricing range, evidenced by a substantial majority of such historical stand-alone transactions falling within a reasonably narrow range. In addition, the Company considers major service groups and geographies in determining VSOE. The Company is not able to determine TPE for its products or services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy differs from that of its peers and its offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, the Company is unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. When the Company is unable to establish the selling price of its non-software deliverables using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. The Company determines BESP for the purposes of allocating the arrangement by reviewing external and internal market factors including, but not limited to, pricing practices including discounting, the geographies in which the Company offers its products and services, the type of customer (i.e., distributor, value added reseller or direct end user) and competition. Additionally, the Company considers historical transactions, including transactions whereby the deliverable was sold on a stand-alone basis. The determination of BESP is made through consultation with and approval by the Company’s management. Selling prices are analyzed on a quarterly basis to identify if the Company has experienced significant changes in its selling prices. For its non-software deliverables the Company allocates the arrangement consideration based on the relative selling price of the deliverables. For its hardware appliances the Company uses BESP as its selling price. For its maintenance and support services, subscriptions and professional services and training, the Company primarily uses VSOE as the selling price and when the Company is unable to establish a selling price using VSOE, it uses BESP.
Deferred Revenue	Deferred Revenue Deferred revenue represents amounts invoiced to customers for which the related revenue has not been recognized because one or more of the revenue recognition criteria have not been met. The current portion of the deferred revenues represents the amount that is expected to be recognized as revenue within one year of the consolidated balance sheet date.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recorded at invoiced amounts, net of allowances for doubtful accounts if applicable, and do not bear interest. The Company generally does not require collateral from its customers; however, in certain circumstances, may require letters of credit, other collateral, additional guarantees or advance payments. The allowance for doubtful accounts is based on the Company’s assessment of the collectability of its customer accounts. The Company regularly reviews its accounts receivable that remain outstanding past their applicable payment terms and establishes allowance and potential write-offs by considering certain factors such as historical experience, industry data, credit quality, age of balances and current economic conditions that may affect a customers’ ability to pay.
Concentration of Revenue and Accounts Receivable	Concentration of Revenue and Accounts Receivable Significant customers are those which represent 10% or more of the Company’s total revenue or gross accounts receivable balance at each respective balance sheet date. For the year ended December 31, 2016 and 2015, we had one customer that represented 13% and 18% of our total revenue, respectively. For the year ended December 31, 2014, the Company did not have any customers that represented 10% or more of the Company’s total revenue. The same customer represented 18% and 21% of gross accounts receivable as of December 31, 2016 and 2015 respectively.
Shipping and Handling Costs	Shipping and Handling Costs Costs related to shipping and handling are included in cost of revenue.
Research and Development Costs	Research and Development Costs Research and development costs, including direct and allocated expenses, are expensed as incurred.
Software Development Costs	Software Development Costs The costs to develop software for sale have not been capitalized as the Company believes that the technological feasibility of the related software is not established until substantially all product development is complete.
Warranty Costs	Warranty Costs The Company generally provides a 60-day warranty on hardware appliance products and software from the date of shipment to customers. To date, cost to repair or replace items sold to customers has been insignificant.
Advertising Costs	Advertising Costs The Company expenses advertising costs as incurred. Advertising expense is included within sales and marketing expense in the consolidated statements of operations. For the years ended December 31, 2016, 2015 and 2014, advertising expenses were not material.
Retirement Savings Plan	Retirement Savings Plan The Company maintains a defined contribution 401(k) retirement savings plan for its U.S. employees. Each participant in the 401(k) retirement savings plan may elect to contribute a percentage of his or her annual compensation up to a specified maximum amount allowed under U.S. Internal Revenue Service regulations. There were no employer contributions to the 401(k) retirement savings plan for the years ended December 31, 2016, 2015 and 2014.
Severance Pay Asset and Liability	Severance Pay Asset and Liability The Company has recorded a severance pay asset and liability on its consolidated balance sheets related to its employees located in Israel. The Company’s liability for severance pay is calculated pursuant to Israeli severance pay law based on the most recent salary for the employees multiplied by the number of years of employment, as of the respective balance sheet date. Employees are entitled to one month salary for each year of employment or a portion thereof. The Company’s liability at each respective balance sheet date for all of its Israeli employees is fully accrued in the accompanying consolidated financial statements and is mainly funded through monthly deposits to the employee’s pension and management insurance policies. The carrying value of these policies is recorded as a severance fund asset in the Company’s consolidated balance sheets. The deposited funds may be withdrawn only upon the fulfillment of the obligation pursuant to Israeli severance pay law. The carrying value of the deposited funds is based on the cash surrender value of these policies and includes profits accumulated through the respective balance sheet date. The Company recognized severance expense related to the Israeli severance pay law during the years ended December 31, 2016, 2015 and 2014 of $1.6 million, $1.3 million, and $1.4 million, respectively.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification No. 740 (“ASC 740”), Accounting for Income Taxes. The Company uses the liability method for accounting for deferred income taxes, which requires recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements, but have not been reflected in its taxable income. Estimates and judgments occur in the calculation of certain tax liabilities and in the determination of the recoverability of certain deferred income tax assets, which arise from temporary differences and carryforwards. Deferred income tax assets and liabilities are measured using the currently enacted tax rates that apply to taxable income in effect for the years in which those tax assets and liabilities are expected to be realized or settled. The Company regularly assesses the likelihood that its deferred income tax assets will be realized from recoverable income taxes or recovered from future taxable income based on the realization criteria set forth in ASC 740. To the extent that the Company believes any amounts are more likely not to be realized, the Company records a valuation allowance to reduce the deferred income tax assets. In the event the Company determines that all or part of the net deferred tax assets are not realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period such determination is made. Similarly, if the Company subsequently realizes deferred income tax assets that were previously determined to be unrealizable, the respective valuation allowance would be reversed, resulting in an adjustment to earnings in the period such determination is made. In addition, the calculation of the Company’s tax liabilities involves addressing uncertainties in the application of complex tax regulations. The Company recognizes and measures potential liabilities based upon criteria set forth in ASC 740. Based upon these criteria, the Company estimates whether, and the extent to which, additional taxes will be due. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities may result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities is less than the amount ultimately assessed, a further charge to expense would result. Significant judgment is required in determining any valuation allowance recorded against deferred income tax assets. In assessing the need for a valuation allowance, the Company considers all available evidence, including past operating results, estimates of future taxable income, and the feasibility of tax planning strategies. In the event that the Company changes its determination as to the amount of deferred income tax assets that could be realized, it will adjust its valuation allowance with a corresponding effect to the provision for income taxes in the period in which such determination is made. Significant judgment is also required in evaluating the Company’s uncertain tax positions under ASC 740 and determining its provision for income taxes. Although the Company believes its reserves for uncertain tax positions are reasonable, no assurance can be given that the final tax outcome of these matters will not be different from that which is reflected in the Company’s historical income tax provisions and accruals. The Company adjusts these reserves in light of changing facts and circumstances, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different from the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made. The provision for income taxes includes the effect of reserves for uncertain tax positions and any changes to the reserves that are considered appropriate, as well as the related net interest and penalties, if applicable.
Stock-Based Compensation	Stock-Based Compensation Compensation costs related to employee stock option grants are based on the fair value of the options on the date of grant, net of estimated forfeitures. The Company determines the grant date fair value of the options using the Black-Scholes option-pricing model and the related stock-based compensation expense is generally recognized on a straight-line basis over the period in which an employee is required to provide service in exchange for the options, or the vesting period of the respective options. For performance based RSUs granted to employees which have multiple performance conditions and a market condition the Company used a Monte Carlo simulation model to determine the fair value of such awards. The key inputs used were the Company’s stock price on the date of grant, the expected volatility, the risk free interest rate and revenues achieved. The Company updates the estimated expense, net of forfeitures, at the end of each reporting period. The expense is recognized on an accelerated basis over the requisite service period, which is generally the vesting period of the respective awards. For performance based RSUs granted to employees which only have performance conditions, we recognized expense based on our best estimate of number of awards which are expected to vest upon achievement of performance conditions. We revisit this estimate periodically.
Foreign Currency	Foreign Currency The functional currency of the Company’s foreign subsidiaries is the U.S. dollar. Transactions denominated in currencies other than the functional currency are remeasured to the functional currency at the average exchange rate in effect during the period. At the end of each reporting period, monetary assets and liabilities are re-measured to the functional currency using exchange rates in effect at the balance sheet date. Non-monetary assets and liabilities are re-measured at historical exchange rates. Gains and losses related to remeasurement are recorded in other income (expense) in the consolidated statements of operations.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company measures and reports its cash equivalents, short-term investments, derivative instruments, and the Israeli severance pay fund assets at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level I—Unadjusted quoted prices in active markets for identical assets or liabilities; Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s financial instruments consist of Level I and Level II assets. Level I securities include highly liquid money market funds and mutual funds. Level II instruments include deposits maintained with financial institutions and derivative instruments.
Net Loss per Share of Common Stock	Net Loss per Share of Common Stock The Company’s basic net loss per share of common stock is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. The weighted-average number of shares of common stock used to calculate the Company’s basic net loss per share of common stock excludes those shares subject to repurchase as these shares are not deemed to be issued for accounting purposes until they vest. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, stock options to purchase common stock, common stock subject to repurchase, and warrants to purchase common stock are considered to be common stock equivalents. Basic and diluted net loss per share of common stock was the same for each period presented as the inclusion of all potential common shares outstanding was anti-dilutive.
Reclassifications	Reclassifications From time to time the Company reclassifies certain prior period balances to conform to the current year presentation. Starting first quarter 2015, we present tax withholdings on vesting of restricted stock units separately from proceeds from issuance of common stock in connection with employee stock purchase plan, in the Consolidated Statements of Stockholders’ Equity and Consolidated Statements of Cash Flows. The change was made to better reflect nature of the transactions, and prior period balances were reclassified accordingly. These reclassifications have no material impact on previously reported total assets, total liabilities, stockholders’ equity, results of operations or cash flows.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The new standard provides a screen to determine when a set of activities and assets, or “set,” is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If the screen is not met, the amendments in this Update: (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. The amendments provide a framework to assist entities in evaluating whether both an input and a substantive process are present. The framework includes two sets of criteria to consider that depend on whether a set has outputs. Although outputs are not required for a set to be a business, outputs generally, are a key element of a business; therefore, the Board has developed more stringent criteria for sets without outputs. Lastly, the amendments in this Update narrow the definition of the term output so that the term is consistent with how outputs are described in Topic 606. The standard will be effective for the Company beginning January 1, 2018, with early application permitted. The standard will require adoption on a prospective basis. The Company is evaluating the impact of adopting this new accounting guidance on its consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The standard will be effective for the Company beginning January 1, 2018, with early application permitted. The standard will require adoption on a retrospective basis. The new accounting pronouncements will not have a significant impact on the Company’s consolidated financial statements. In August 2016, FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The new standard will make eight targeted changes to how cash receipts and cash payments are presented and classified in the statement of cash flows. The standard will be effective for the Company beginning January 1, 2018, with early application permitted. The standard will require adoption on a retrospective basis unless it is impracticable to apply, in which case we would be required to apply the amendments prospectively as of the earliest date practicable. The Company is evaluating the impact of adopting this new accounting guidance on its consolidated financial statements. In June 2016, the FASB Issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The new standard requires financial assets measured at amortized cost be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. The standard will be effective for the Company beginning January 1, 2020, with early application permitted. The Company is evaluating the impact of adopting this new accounting guidance on its consolidated financial statements. In March 2016, the FASB Issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The updated guidance changes how companies account for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company will adopt the updated guidance on January 1, 2017 and will recognize excess tax benefits or deficiencies in net income, as well as the related cash flows in operating activities, on a prospective basis. The earnings impact of the adoption will depend on the excess tax benefits or deficiencies realized on vesting or settlement of awards resulting from the difference between the market value of awards at vesting or settlement and the grant date fair value. As required in the updated guidance, the Company will present cash flows related to employee withholding taxes as operating activities as opposed to financing activities, on a retrospective basis. The Company is in the process of evaluating the other potential effects this guidance will have on its consolidated financial statements. In February 2016, the FASB issued Accounting Standards Update No. 2016-02 regarding ASC Topic 842 "Leases." The amendments in this guidance require balance sheet recognition of lease assets and lease liabilities by lessees for leases classified as operating leases, with an optional policy election to not recognize lease assets and lease liabilities for leases with a term of 12 months or less. The amendments also require new disclosures, including qualitative and quantitative requirements, providing additional information about the amounts recorded in the financial statements. The standard will be effective for the Company beginning January 1, 2019. The amendments require a modified retrospective approach with optional practical expedients. The Company is evaluating the impact of adopting this new accounting guidance on its consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This guidance relates accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. This guidance will be effective for the Company beginning January 1, 2018, early adoption is permitted only for certain provisions. Adoption of the guidance is retrospective with a cumulative adjustment to retained earnings or accumulated deficit as of the adoption date. The Company is evaluating the impact of adopting this new accounting standard on its consolidated financial statements. In May 2014, the FASB issued ASU 2014-09—Revenue (Topic 606): Revenue from Contracts with Customers. The standard will replace most existing U.S. GAAP guidance on this topic. The standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. The standard defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation, among others. The standard also provides guidance on the recognition of costs related to obtaining customer contracts. The standard will be effective for the Company beginning January 1, 2018 using either of two methods: (1) retrospective application of the standard to each prior reporting period presented with the option to elect certain practical expedients as defined within the standard, or (2) retrospective application of the standard with the cumulative effect of initially applying the standard recognized at the date of initial application and providing certain additional disclosures as defined per the standard. Adoption as of the original effective date of January 1, 2017 is permitted. The Company is considering adopting the standard under the full retrospective method effective January 1, 2018; however, a final decision regarding the adoption method has not been finalized at this time. The Company’s ability to adopt using the full retrospective method is dependent on several factors such as the significance of the impact of the new standard on the Company’s financial results, system readiness, and the completion of the review and analysis of information necessary to restate prior-period financial statements. The Company is in the initial stages of its evaluation of the impact of the new standard on its accounting policies, processes, and system requirements. The Company has assigned internal resources in addition to the engagement of a third party service provider to assist in the evaluation. Furthermore, the Company has made and will continue to make investments in systems to enable timely and accurate reporting under the new standard. As part of its preliminary evaluation, the Company has considered the impact of the standard’s requirements with respect to capitalization and amortization of incremental costs of obtaining a contract, primarily sales commissions. Under the Company’s current accounting policy, contract origination costs are expensed as incurred. The new standard requires the capitalization of all incremental costs that the Company incurs to obtain a contract with a customer that it would not have incurred if the contract had not been obtained, provided the Company expects to recover the costs. While the Company continues to assess the potential impacts of the new standard, the Company does not know or cannot reasonably estimate quantitative information related to the impact of the new standard on the financial statements at this time.

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2016
Camouflage Software, Inc [Member]
Summary of Allocation of Consideration to Fair Value of Tangible and Intangible Assets Acquired and Liabilities Assumed	The following table summarizes the preliminary allocation of the consideration to the fair value of the tangible and intangible assets acquired and liabilities assumed as of the acquisition date based on information available at the business combination date (in thousands): Acquired Technology $ 1,050 Customer relationships 480 Trade name and other 280 Goodwill 2,476 Total intangible assets acquired 4,286 Other acquired tangible assets 363 Liability assumed (130 ) Fair value of assets acquired $ 4,519

Cash, Cash Equivalents, and S28

Cash, Cash Equivalents, and Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Summary of Cash, Cash Equivalents and Short-Term Investments	Cash, cash equivalents and short-term investments consist of the following (in thousands): As of December 31, 2016 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents: Cash $ 63,642 $ — $ — $ 63,642 Commercial paper 6,995 — 2 6,993 Money market funds 36,708 — — 36,708 Total $ 107,345 $ — $ 2 $ 107,343 Short-term investments: Commercial paper $ 14,245 $ — $ 8 $ 14,237 Corporate debt obligations 110,062 — 347 109,715 US government agencies 18,998 2 50 18,950 Bank deposits 10,846 1 — 10,847 Total $ 154,151 $ 3 $ 405 $ 153,749 As of December 31, 2015 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Cash and cash equivalents: Cash $ 57,906 $ — $ — $ 57,906 Bank deposits 10,253 — — 10,253 Commercial paper 13,896 — 3 13,893 Money market funds 86,200 — — 86,200 Total $ 168,255 $ — $ 3 $ 168,252 Short-term investments: Corporate debt obligations $ 86,590 $ 2 $ 300 86,292 Bank deposits 10,263 — — 10,263 Total $ 96,853 $ 2 $ 300 $ 96,555
Summary of Cost and Estimated Fair Value of Short-Term Investments	The following table sets forth the cost and estimated fair value of short-term investments based on stated effective maturities as of December 31, 2016 (in thousands): As of December 31, 2016 Estimated Amortized Fair Cost Value Short-term investments: Due in 2017 $ 84,406 $ 84,315 Due in 2018 69,745 69,434 Total $ 154,151 $ 153,749
Schedule of Short-Term Investments at Fair Value and Length of Continuous Unrealized Loss Position	The following tables show the short-term investments in an unrealized loss position and the related gross unrealized losses and fair value and length of time that the short-term investments have been in a continuous unrealized loss position (in thousands): As of December 31, 2016 Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 14,237 $ 8 $ 14,237 $ 8 Corporate debt obligations 78,821 323 29,689 24 108,510 347 US government agencies 11,451 46 3,496 4 14,947 50 $ 104,509 $ 377 $ 33,185 $ 28 $ 137,694 $ 405 As of December 31, 2015 Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt obligations $ 73,673 $ 286 $ 10,609 $ 14 $ 84,282 $ 300 $ 73,673 $ 286 $ 10,609 $ 14 $ 84,282 $ 300

Fair Value of Financial Instr29

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis	The following table sets forth the Company’s assets and liabilities that were measured at fair value as of December 31, 2016 and 2015, by level within the fair value hierarchy (in thousands): As of December 31, 2016 Level I Level II Level III Fair Financial Assets: Cash equivalents: Commercial paper — 6,993 — 6,993 Money market funds 36,708 — — 36,708 Short-term investments: Commercial paper — 14,237 — 14,237 Corporate debt obligations — 109,715 — 109,715 US government agencies — 18,950 — 18,950 Bank deposits — 10,847 — 10,847 Total financial assets $ 36,708 $ 160,742 $ — $ 197,450 Financial Liability: Accrued and other current liabilities - Forward foreign exchange contracts $ — $ 639 $ — $ 639 As of December 31, 2015 Level I Level II Level III Fair Value Financial Assets: Cash equivalents: Bank deposits $ — $ 10,253 $ — $ 10,253 Commercial paper — 13,893 — 13,893 Money market funds 86,200 — — 86,200 Short-term investments: Corporate debt obligations — 86,292 — 86,292 Bank deposits — 10,263 — 10,263 Total financial assets $ 86,200 $ 120,701 $ — $ 206,901 Financial Liability: Accrued and other current liabilities - Forward foreign exchange contracts $ — $ 595 $ — $ 595

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments Measured at Fair Value and Classification on Consolidated Balance Sheets	Derivative instruments measured at fair value and their classification on the consolidated balance sheets are presented in the following tables (in thousands): Liability as of December 31, 2016 2015 Notional Amount Fair Value Notional Amount Fair Value Foreign exchange forward contract derivatives in cash flow hedging relationships - included in accrued and other current liabilities $ 60,756 $ 639 $ 47,231 $ 595
Gains (Losses) on Derivative Instruments and Classification on Consolidated Statement of Operations	Gains (losses) on derivative instruments accounted for as hedges and their classification on the consolidated statement of operations, are presented in the following tables (in thousands): Years ended December 31, 2016 2015 2014 Foreign Exchange Forward Contract Derivatives in cash flow hedging relationships: Gains recognized in OCI (a) $ 1,775 $ 834 $ 191 Losses recognized in OCI (a) $ (1,909 ) $ (1,399 ) $ (1,846 ) Gains recognized from accumulated OCI into net loss (b) $ 257 $ — $ 55 Losses recognized from accumulated OCI into net loss (b) $ (347 ) $ (972 ) $ (708 ) (a) Net change in the fair value of the effective portion classified in other comprehensive income (loss) (“OCI”). (b) Effective portion of cash flow hedges reclassified from accumulated other income (loss), into net loss, of which $(8), $(107) and $(72) were recognized within cost of sales for the years ended December 31, 2016, 2015 and 2014, respectively, and $(82), $(865), and $(581) were recognized within operating expenses for the year ended December 31, 2016, 2015 and 2014, respectively. All amounts are reflected with the respective consolidated statement of operations.

Consolidated Balance Sheet Co31

Consolidated Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Allowance for Doubtful Accounts	The allowance for doubtful accounts is comprised of the following activity (in thousands): Years Ended December 31, 2016 2015 2014 Allowance for doubtful accounts and sales returns reserve, beginning balance $ 1,438 $ 215 $ 410 Allowance for doubtful accounts, beginning balance $ 1,115 $ 215 $ 410 Charged to costs and expenses, net of recoveries 315 1,044 418 Deductions (write-offs) (477 ) (144 ) (613 ) Allowance for doubtful accounts, ending balance 953 1,115 215 Sales returns reserve, beginning balance 323 Charged to revenue 1,560 677 - Deductions (write-offs) (1,052 ) (354 ) - Sales returns reserve, ending balance 831 323 - Total allowance for doubtful accounts and sales returns reserve, ending balance $ 1,784 $ 1,438 $ 215
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): As of December 31, 2016 2015 Prepaid expenses 4,980 5,111 Prepaid income taxes 1,559 585 Interest receivable 758 467 Other 625 1,802 Total prepaid expenses and other current assets $ 7,922 $ 7,965
Property and Equipment, Net	Property and equipment, net consist of the following (in thousands): As of December 31, 2016 2015 Computers and related equipment $ 25,285 $ 15,953 Office furniture and equipment 3,228 1,632 Leasehold improvements 11,947 7,791 Total property and equipment 40,460 25,376 Less: accumulated depreciation and amortization (18,964 ) (13,212 ) Total property and equipment, net $ 21,496 $ 12,164
Accrued Compensation and Benefits	Accrued compensation and benefits consist of the following (in thousands): As of December 31, 2016 2015 Salary and related benefits $ 9,588 $ 7,215 Accrued vacation 4,178 3,774 Accrued incentive payments 5,942 9,270 Accrued restructuring 1,132 - Total accrued compensation and benefits $ 20,840 $ 20,259
Accrued and Other Current Liabilities	Accrued and other current liabilities consist of the following (in thousands): As of December 31, 2016 2015 Accrued expenses $ 4,616 $ 4,633 Derivative liability 639 595 Income tax payable 435 323 Short-term deferred rent 461 283 Skyfence holdback liability - 7,556 Sales Taxes Payable 849 411 Other 683 482 Total accrued and other current liabilities $ 7,683 $ 14,283
Other Long-term Liabilities	Other long-term liabilities consist of the following (in thousands): As of December 31, 2016 2015 Long-term deferred rent $ 2,111 $ 1,926 Deferred tax liability 1,265 1,145 Uncertain Tax Positions 2,446 1,236 Other 815 208 Total other liabilities $ 6,637 $ 4,515

Goodwill and Acquired Intangi32

Goodwill and Acquired Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Changes in the Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the years ended December 31, 2016 and 2015 were as follows (in thousands): Balance as of December 31, 2015 $ 34,972 Goodwill acquired 2,476 Balance as of December 31, 2016 $ 37,448
Summary of Acquired Intangible Assets Subject to Amortization	Acquired intangible assets subject to amortization as of December 31, 2016 and 2015 were as follows (in thousands): As of December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Book Value Acquired Technology $ 11,718 $ (4,085 ) $ 7,633 Customer relationships 480 - 480 Trade name and other 280 - 280 Total $ 12,478 $ (4,085 ) $ 8,393 As of December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Book Value Acquired Technology $ 10,668 $ (2,677 ) $ 7,991 Total $ 10,668 $ (2,677 ) $ 7,991
Schedule of Expected Amortization Expense in Future Periods	As of December 31, 2016, the Company expects amortization expense in future periods to be as follows (in thousands): Acquired Fiscal Year Intangibles 2017 $ 1,666 2018 1,666 2019 1,666 2020 1,666 Thereafter 1,729 Total expected amortization expense $ 8,393

Other Income (Expense), net (Ta

Other Income (Expense), net (Tables)	12 Months Ended
	Dec. 31, 2016
Other Income And Expenses [Abstract]
Schedule of Other Income (Expense), Net	Other income (expense), net is comprised of the following (in thousands): Years Ended December 31, 2016 2015 2014 Other Income: Interest income $ 1,369 $ 701 $ 163 Foreign currency forward contract gains, net 9 - - Foreign currency exchange gains, net 209 5 8 Total other income 1,587 706 171 Other Expense: Skyfence holdback liability accretion (6 ) (212 ) (186 ) Foreign currency exchange losses, net (708 ) (322 ) - Bank charges and Other expenses (950 ) (574 ) (205 ) Total other expense (1,664 ) (1,108 ) (391 ) Total other income (expense), net $ (77 ) $ (402 ) $ (220 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Payments Under Operating Leases	Future minimum payments under these facility operating leases are as follows as of December 31, 2016 (in thousands): Operating Leases Estimated Sublease Income Year Ending December 31: 2017 $ 7,598 $ 611 2018 8,054 399 2019 4,650 - 2020 4,243 - 2021 106 - Total $ 24,651 $ 1,010

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Reserved Shares of Common Stock	The Company had reserved shares of common stock, on an as if converted basis, for issuance as follows: As of December 31, 2016 2015 Issuance in connection with outstanding stock options 1,570,765 1,949,089 Issuance in connection with restricted stock units outstanding 1,994,790 1,898,025 Reserved for future stock option and restricted stock unit grants 2,464,181 1,726,346 Reserved for future issuance under the employee stock purchase plan 1,161,396 1,049,524 7,191,132 6,622,984
Summary of Option Activity under Plans and Related Information	The following table summarizes option activity under the Plans and related information: Options Outstanding Weighted- Average Remaining Number of Shares Weighted Average Exercis e Contractual Term (in years) Aggregate Intrinsic Value (i n Outstanding - December 31, 2013 1,675,506 $ 23.78 8.01 $ 40,813 Granted 1,256,559 $ 41.39 Options assumed in acquisitions 72,607 $ 13.30 Exercised or released (496,297 ) $ 14.85 Cancelled or forfeited (264,012 ) $ 35.85 Outstanding - December 31, 2014 2,244,363 $ 33.83 8.27 $ 38,457 Granted 696,971 $ 49.20 Exercised or released (636,424 ) $ 29.44 Cancelled or forfeited (355,821 ) $ 42.00 Balances - December 31, 2015 1,949,089 $ 39.27 8.09 $ 47,480 Granted 48,260 $ 53.59 Exercised or released (184,737 ) $ 29.24 Cancelled or forfeited (241,847 ) $ 47.35 Balances - December 31, 2016 1,570,765 $ 39.64 6.90 $ 9,226 Vested and expected to vest - December 31, 2016 1,463,772 $ 39.03 6.82 $ 9,061 Exercisable - December 31, 2016 967,186 $ 36.66 6.31 $ 7,339 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the closing stock price of $38.40 of the Company’s common stock on December 31, 2016
Additional Information Regarding Company's Stock Options Outstanding and Exercisable	Additional information regarding the Company’s stock options outstanding and exercisable as of December 31, 2016 is summarized below: Options Outstanding Options Exercisable Exercise Prices Number of Stock Options Outstanding Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price per Share Shares Subject to Stock Options Weighted Average Exercise Price per Share $0.02 to $10.70 134,548 4.02 $ 7.01 130,579 $ 7.22 $10.71 to $29.10 168,845 6.66 $ 25.73 121,118 $ 25.37 $29.11 to $32.54 236,906 7.51 $ 29.40 116,285 $ 29.53 $32.55 to $34.55 149,082 5.09 $ 33.78 133,559 $ 33.76 $34.56 to $54.48 464,660 7.68 $ 43.41 240,153 $ 43.04 $54.49 to $61.50 248,776 7.21 $ 55.16 149,677 $ 54.92 $61.51 to $69.19 143,729 7.42 $ 65.04 68,611 $ 64.52 $69.20 to $77.00 24,219 8.50 $ 71.73 7,204 $ 71.74 1,570,765 6.90 $ 39.64 967,186 $ 36.66
Summary of RSU Activity Outstanding and Weighted Average Grant Date Fair Value	A summary of RSU activity for the year ended December 31, 2016, is as follows: Number of Restricted Stock Units Outstanding Weighted- Average Grant Date Fair Value Unvested - December 31, 2014 2,279,081 $ 39.07 Granted 911,734 $ 53.02 Granted, performance RSUs 249,220 $ 42.58 Released (898,205 ) $ 34.97 Cancelled or expired (643,805 ) $ 35.09 Unvested - December 31, 2015 1,898,025 $ 49.53 Granted 1,160,062 $ 47.42 Granted, performance RSUs 273,900 $ 51.55 Released (884,349 ) $ 43.04 Cancelled or forfeited (452,848 ) $ 49.86 Unvested - December 31, 2016 1,994,790 $ 51.42
Stock-Based Compensation Expense	The Company recognized stock-based compensation expense under the 2011 Stock Option and Incentive Plan, 2003 Stock Plan, Inducement Plans, 2011 Employee Stock Purchase Plan, and the Incapsula 2010 Share Incentive Plan in the consolidated statements of operations as follows (in thousands): Years Ended December 31, 2016 2015 2014 Cost of revenue $ 4,664 $ 3,862 $ 2,058 Research and development 14,711 13,831 8,799 Sales and marketing 20,510 16,717 13,558 General and administrative 17,131 16,554 12,858 Restructuring charges 5,859 - - Total stock-based compensation expense $ 62,875 $ 50,964 $ 37,273
Weighted Average Assumptions for Fair Value of Stock Options Grants and ESPP Grants	A summary of the weighted-average assumptions is as follows: Years Ended December 31 2016 2015 2014 Stock option grants: Dividend rate 0 % 0 % 0 % Risk-free interest rate 1.4 % 1.8 % 1.8 % Expected term (in years) 6.0 6.1 6.1 Expected volatility 58 % 49 % 46 % ESPP grants: Dividend rate 0 % 0 % 0 % Risk-free interest rate 0.5 % 0.4 % 0.1 % Expected term (in years) 0.5 0.5 0.5 Expected volatility 58 % 65 % 45 %

Accumulated Other Comprehensi36

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Changes in Balances of Accumulated Other Comprehensive Income (Loss)	The changes in the balances of accumulated other comprehensive income (loss) by component are as follows (in thousands): Years ended December 31, 2016 2015 2014 Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Unrealized gain (loss) on cash flow hedges Unrealized gain (loss) on investments Total Balance at January 1 $ (1,021 ) $ (310 ) $ (1,331 ) $ (1,428 ) $ (61 ) $ (1,489 ) $ (426 ) $ (2 ) $ (428 ) Other comprehensive income (loss) before reclassifications (134 ) (103 ) (237 ) (565 ) (249 ) (814 ) (1,655 ) (59 ) (1,714 ) Amounts reclassified to net loss 90 — 90 972 — 972 653 — 653 Change in other comprehensive income (loss) (44 ) (103 ) (147 ) 407 (249 ) 158 (1,002 ) (59 ) (1,061 ) Balance at December 31 $ (1,065 ) $ (413 ) $ (1,478 ) $ (1,021 ) $ (310 ) $ (1,331 ) $ (1,428 ) $ (61 ) $ (1,489 )
Summary of Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	The following is a summary of reclassifications out of accumulated other comprehensive income (loss) for the years 2016, 2015, and 2014 (in thousands): Year ended December 31, 2016 2015 2014 Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Pre-Tax Amount Tax Expense (Benefit) After-Tax Amount Unrealized gains (losses) on cash flow hedges: Current period unrealized gain (loss) $ (134 ) - $ (134 ) $ (565 ) $ — $ (565 ) $ (1,655 ) $ — $ (1,655 ) Reclassification adjustments 1 90 - 90 972 — 972 653 — $ 653 Unrealized gains (losses) on cash flow hedges, net (44 ) - (44 ) 407 - 407 (1,002 ) — (1,002 ) Unrealized gains (losses) on investments: Current period unrealized gain (loss) $ (103 ) - (103 ) $ (249 ) - (249 ) (59 ) — (59 ) Reclassification adjustments 2 — - — — - — — — - Unrealized gains (losses) on investments: (103 ) — (103 ) (249 ) — (249 ) (59 ) — (59 ) Other comprehensive income (loss) $ (147 ) $ — $ (147 ) $ 158 $ — $ 158 $ (1,061 ) $ — $ (1,061 ) 1 Refer to Note 6 for the affected line items in the consolidated statement of operations 2 Amount included in other income (expense), net, in the consolidated statement of operations

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Loss Before Provision for Income Taxes	The Company’s geographical breakdown of its loss before provision for income taxes is as follows (in thousands): Years Ended December 31, 2016 2015 2014 Domestic $ (72,139 ) $ (50,892 ) $ (55,330 ) Foreign 3,032 2,692 (2,665 ) Loss before provision for taxes $ (69,107 ) $ (48,200 ) $ (57,995 )
Provision for Income Taxes	The components of the provision for income taxes are as follows (in thousands): Years Ended December 31, 2016 2015 2014 Current Federal $ — $ — $ — State 62 34 66 Foreign 1,654 857 1,523 Total current provision 1,716 891 1,589 Deferred Federal 130 63 109 State 6 (1 ) 6 Foreign (680 ) (271 ) (523 ) Total deferred provision (544 ) (209 ) (408 ) Total $ 1,172 $ 682 $ 1,181
Reconciliation of Provision for Income Taxes at Statutory Rate	Reconciliation of the provision for income taxes at the statutory rate to the Company’s provision for income tax is as follows (in thousands): Years Ended December 31, 2016 2015 2014 Tax benefit at federal statutory tax rate $ (23,496 ) $ (16,388 ) $ (19,718 ) Tax benefit at state statutory tax rate (1,008 ) (499 ) (1,169 ) Foreign tax rate differential 57 (826 ) (526 ) Unbenefitted loss of consolidated investment - - 2,366 Change in valuation allowance 17,701 9,738 12,407 Meals and entertainment 222 44 34 Stock compensation 7,857 8,492 7,160 Nondeductible expenses and other (161 ) 121 627 Provision for income taxes $ 1,172 $ 682 $ 1,181
Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2016 2015 Deferred tax assets: Reserves and accruals $ 2,817 $ 2,662 Deferred revenue 10,379 8,724 Stock-based compensation 7,361 4,772 Net operating loss carryforwards 47,452 37,793 Loss on OCI 370 374 Other 67 32 Gross deferred tax assets 68,446 54,357 Valuation allowance (68,227 ) (53,468 ) Total deferred tax assets 219 889 Deferred tax liabilities: Stock-based compensation (21 ) (21 ) Depreciation and amortization (243 ) (1,425 ) Total deferred tax liabilities (264 ) (1,446 ) Net deferred tax liability $ (45 ) $ (557 )
Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2016 2015 2014 Balance at January 1 $ 1,154 $ 672 $ 353 Additions based on tax positions taken during the current period 761 401 222 Reductions based on tax positions taken during the prior period (42 ) (50 ) (47 ) Additions based on tax positions taken during a prior period 409 131 144 Balance at December 31 $ 2,282 $ 1,154 $ 672

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Company's Services Revenue	The Company’s services revenue was comprised of the following (in thousands): Years Ended December 31, 2016 2015 2014 Maintenance and support $ 80,007 $ 66,380 $ 54,795 Professional services and training 13,693 14,084 11,414 Subscriptions 83,957 46,271 23,502 Total net services revenue $ 177,657 $ 126,735 $ 89,711
Company's Revenue by Geographic Region, Based on Customer's Location	The Company’s revenue by geographic region, based on the customer’s location, is summarized as follows (in thousands): Years Ended December 31, 2016 2015 2014 United States $ 143,607 $ 141,225 $ 87,155 EMEA 50,838 47,429 39,579 APAC 48,391 30,180 27,798 Other 21,619 15,464 9,478 Total net revenue $ 264,455 $ 234,298 $ 164,010
Long-Lived Assets by Location	The following table presents long-lived assets by location (in thousands): As of December 31, 2016 2015 2014 United States $ 20,525 $ 9,913 $ 6,761 Israel 9,344 10,224 10,221 Other 20 18 35 Total long-lived assets $ 29,889 $ 20,155 $ 17,017

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Computation of Company's Basic and Diluted Net Loss Per Share of Common Stock	The following table sets forth the computation of the Company’s basic and diluted net loss per share of common stock (in thousands, except per share amounts): Years Ended December 31, 2016 2015 2014 Net loss attributable to Imperva, Inc. stockholders $ (70,279 ) $ (48,882 ) $ (58,963 ) Shares used in computing net loss per share of common stock, basic and diluted 32,284 29,849 25,806 Net loss per share of common stock, basic and diluted $ (2.18 ) $ (1.64 ) $ (2.28 )
Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share of Common Stock	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have been antidilutive: Years Ended December 31, 2016 2015 2014 Stock options to purchase common stock 1,570,765 1,949,089 2,244,363 Restricted stock units for common stock 1,994,790 1,898,025 2,279,081 Restricted shares of common stock subject to repurchase - - 217,621 Restricted stock issued in connection with Skyfence acquisition 110,897 118,961 355,499

Subsequent Event (Tables)

Subsequent Event (Tables)	12 Months Ended
	Dec. 31, 2016
Skyfence Networks Ltd. [Member]
Subsequent Event [Line Items]
Summarized Estimate of Aggregate Carrying Amounts of the Major Classes of Assets and Liabilities Related to Disposed Business	The following table presents our best estimate of the aggregate carrying amounts of the major classes of assets and liabilities related to the Skyfence business to be disposed of as of December 31, 2016: (dollars Assets Accounts receivables $ 463 Prepaid and other current assets 15 Property and equipment, net 234 Goodwill 1,179 Acquired intangible assets, net 4,668 Total assets $ 6,559 Liabilities: Accounts payable $ 163 Accrued and other current liabilities 76 Deferred revenue 1,334 Total liabilities $ 1,573

The Company and Summary of Si41

The Company and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)SegmentPartyCustomer	Dec. 31, 2015USD ($)Customer	Dec. 31, 2014USD ($)Customer	Feb. 23, 2017USD ($)	Dec. 31, 2013
Revenue, Major Customer [Line Items]
Non - controlling interest of minority owners					19.00%
Number of operating segments | Segment	1
Number of third party | Party	1
Net derivative loss included in AOCI to be reclassified into earnings	$ 600,000
Security deposit as non-current assets	1,884,000	$ 1,665,000
Impairment of goodwill	$ 0
Estimated useful life	7 years
Weighted average useful lives of acquired technology intangible assets	5 years 6 months
Period to complete Professional service arrangements	90 days
Warranty period	60 days
Employer contributions to the 401(k) retirement savings plan	$ 0	0	$ 0
Salary in calculation for severance pay by severance pay law	1 month
Severance expense for employees in Israel	$ 1,600,000	$ 1,300,000	$ 1,400,000
Credit Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Number of customers representing 18% or more of gross accounts receivable | Customer	1
Number of customers representing 21% or more of gross accounts receivable | Customer		1
Revenue [Member] | Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Minimum percentage of revenue or gross accounts receivable balance required to be significant customers	13.00%	18.00%
Number of customers representing 10% or more of revenue | Customer	1	1	0
Accounts Receivable | Credit Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Minimum percentage of revenue or gross accounts receivable balance required to be significant customers	18.00%	21.00%
Minimum [Member]
Revenue, Major Customer [Line Items]
Estimated useful lives	2 years
Estimated useful life	7 years
Standard payment terms to customers range	30 days
Term of maintenance and support and subscription contracts	1 year
Maximum [Member]
Revenue, Major Customer [Line Items]
Estimated useful lives	7 years
Estimated useful life	10 years
Standard payment terms to customers range	90 days
Term of maintenance and support and subscription contracts	3 years
Subsequent Event [Member] | Skyfence Cloud Access Security Broker Business [Member]
Revenue, Major Customer [Line Items]
Business disposal consideration				$ 40,000,000

Incapsula - Additional Informat

Incapsula - Additional Information (Detail) - USD ($) $ in Thousands	Nov. 05, 2009	Mar. 31, 2014	Jan. 31, 2012	Jul. 31, 2011	Mar. 31, 2010	Dec. 31, 2015	Dec. 31, 2014
Subsidiary or Equity Method Investee [Line Items]
Non-controlling interest reclassified to additional paid-in capital		$ 2,800					$ 0
Incapsula Acquisition [Member]
Subsidiary or Equity Method Investee [Line Items]
Amount paid for remaining outstanding capital stock		$ 7,700
Business acquisition, shares issued		124,088				34,420
Series A Convertible Preferred Stock [Member] | Incapsula [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments, shares	5,000,000				6,666,666
Ownership interest	58.00%				76.00%
Cash consideration					$ 3,000
Series A-1 Preferred Stock [Member] | Incapsula [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments, shares			4,375,000	4,375,000
Ownership interest			85.00%	82.00%
Cash consideration			$ 3,500	$ 3,500

Acquisition - Additional Inform

Acquisition - Additional Information (Detail) - USD ($)	Dec. 15, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Business acquisition purchase price, cash paid		$ 3,914,000	$ 0	$ 12,083,000
Residual value of intangible assets		$ 0
Estimated useful life		7 years
Camouflage Software, Inc [Member]
Business Acquisition [Line Items]
Business acquisition purchase price, cash paid	$ 4,500,000
Holdback payment commitment period	24 months
Holdback liability	$ 600,000
Related acquisition costs	$ 100,000

Acquisition - Summary of Alloca

Acquisition - Summary of Allocation of Consideration to Fair Value of Tangible and Intangible Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 15, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 37,448	$ 34,972
Camouflage Software, Inc [Member]
Business Acquisition [Line Items]
Goodwill	$ 2,476
Total intangible assets acquired	4,286
Other acquired tangible assets	363
Liability assumed	(130)
Fair value of assets acquired	4,519
Camouflage Software, Inc [Member] | Acquired Technology [Member]
Business Acquisition [Line Items]
Intangible assets acquired other than goodwill	1,050
Camouflage Software, Inc [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets acquired other than goodwill	480
Camouflage Software, Inc [Member] | Trade Name and Other [Member]
Business Acquisition [Line Items]
Intangible assets acquired other than goodwill	$ 280

Cash, Cash Equivalents, and S45

Cash, Cash Equivalents, and Short-Term Investments - Summary of Cash, Cash Equivalents and Short-Term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	$ 107,345	$ 168,255
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	2	3
Cash and cash equivalents, Fair Value	107,343	168,252
Short-term investments, Amortized Cost	154,151	96,853
Short-term investments, Gross Unrealized Gains	3	2
Short-term investments, Gross Unrealized Losses	405	300
Short-term investments, Estimated Fair Value	153,749	96,555
Cash [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	63,642	57,906
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents, Fair Value	63,642	57,906
Commercial Paper [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	6,995	13,896
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	2	3
Cash and cash equivalents, Fair Value	6,993	13,893
Short-term investments, Amortized Cost	14,245
Short-term investments, Gross Unrealized Gains	0
Short-term investments, Gross Unrealized Losses	8
Short-term investments, Estimated Fair Value	14,237
Money Market Funds [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	36,708	86,200
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents, Fair Value	36,708	86,200
Corporate Debt Obligations [Member]
Schedule of Investments [Line Items]
Short-term investments, Amortized Cost	110,062	86,590
Short-term investments, Gross Unrealized Gains	0	2
Short-term investments, Gross Unrealized Losses	347	300
Short-term investments, Estimated Fair Value	109,715	86,292
Bank Deposits [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost		10,253
Cash and cash equivalents, Gross Unrealized Gains		0
Cash and cash equivalents, Gross Unrealized Losses		0
Cash and cash equivalents, Fair Value		10,253
Short-term investments, Amortized Cost	10,846	10,263
Short-term investments, Gross Unrealized Gains	1	0
Short-term investments, Gross Unrealized Losses	0	0
Short-term investments, Estimated Fair Value	10,847	$ 10,263
US Government Agencies [Member]
Schedule of Investments [Line Items]
Short-term investments, Amortized Cost	18,998
Short-term investments, Gross Unrealized Gains	2
Short-term investments, Gross Unrealized Losses	50
Short-term investments, Estimated Fair Value	$ 18,950

Cash, Cash Equivalents, and S46

Cash, Cash Equivalents, and Short-Term Investments - Summary of Cost and Estimated Fair Value of Short-Term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Short Term Investments [Abstract]
Amortized Cost of short-term investments, Due in 2017	$ 84,406
Amortized Cost of short-term investments, Due in 2018	69,745
Short-term investments, Amortized Cost	154,151	$ 96,853
Estimated fair value of short-term investments, Due in 2017	84,315
Estimated fair value of short-term investments, Due in 2018	69,434
Short-term investments, Estimated Fair Value	$ 153,749	$ 96,555

Cash, Cash Equivalents, and S47

Cash, Cash Equivalents, and Short-Term Investments - Schedule of Short-Term Investments at Fair Value and Length of Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 104,509	$ 73,673
Less than 12 Months, Unrealized Losses	377	286
12 Months or Greater, Fair Value	33,185	10,609
12 Months or Greater, Unrealized Losses	28	14
Total, Fair Value	137,694	84,282
Total, Unrealized Losses	405	300
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	14,237
Less than 12 Months, Unrealized Losses	8
Total, Fair Value	14,237
Total, Unrealized Losses	8
Corporate Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	78,821	73,673
Less than 12 Months, Unrealized Losses	323	286
12 Months or Greater, Fair Value	29,689	10,609
12 Months or Greater, Unrealized Losses	24	14
Total, Fair Value	108,510	84,282
Total, Unrealized Losses	347	$ 300
US Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	11,451
Less than 12 Months, Unrealized Losses	46
12 Months or Greater, Fair Value	3,496
12 Months or Greater, Unrealized Losses	4
Total, Fair Value	14,947
Total, Unrealized Losses	$ 50

Fair Value of Financial Instr48

Fair Value of Financial Instruments - Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 107,343	$ 168,252
Short-term investments	153,749	96,555
Bank Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		10,253
Short-term investments	10,847	10,263
Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	6,993	13,893
Short-term investments	14,237
Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	36,708	86,200
Corporate Debt Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	109,715	86,292
US Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	18,950
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	197,450	206,901
Fair Value, Measurements, Recurring [Member] | Bank Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		10,253
Short-term investments	10,847	10,263
Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	6,993	13,893
Short-term investments	14,237
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	36,708	86,200
Fair Value, Measurements, Recurring [Member] | Corporate Debt Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	109,715	86,292
Fair Value, Measurements, Recurring [Member] | US Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	18,950
Fair Value, Measurements, Recurring [Member] | Level I [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	36,708	86,200
Fair Value, Measurements, Recurring [Member] | Level I [Member] | Bank Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Fair Value, Measurements, Recurring [Member] | Level I [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0
Fair Value, Measurements, Recurring [Member] | Level I [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	36,708	86,200
Fair Value, Measurements, Recurring [Member] | Level I [Member] | Corporate Debt Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	0	0
Fair Value, Measurements, Recurring [Member] | Level I [Member] | US Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	0
Fair Value, Measurements, Recurring [Member] | Level II [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	160,742	120,701
Fair Value, Measurements, Recurring [Member] | Level II [Member] | Bank Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		10,253
Short-term investments	10,847	10,263
Fair Value, Measurements, Recurring [Member] | Level II [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	6,993	13,893
Short-term investments	14,237
Fair Value, Measurements, Recurring [Member] | Level II [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Level II [Member] | Corporate Debt Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	109,715	86,292
Fair Value, Measurements, Recurring [Member] | Level II [Member] | US Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	18,950
Fair Value, Measurements, Recurring [Member] | Level III [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	0	0
Fair Value, Measurements, Recurring [Member] | Level III [Member] | Bank Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Fair Value, Measurements, Recurring [Member] | Level III [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0
Fair Value, Measurements, Recurring [Member] | Level III [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Level III [Member] | Corporate Debt Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	0	0
Fair Value, Measurements, Recurring [Member] | Level III [Member] | US Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	0
Forward Foreign Exchange Contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued and Other Current Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued and other current liabilities - Forward foreign exchange contracts	639	595
Forward Foreign Exchange Contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued and Other Current Liabilities [Member] | Level I [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued and other current liabilities - Forward foreign exchange contracts	0	0
Forward Foreign Exchange Contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued and Other Current Liabilities [Member] | Level II [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued and other current liabilities - Forward foreign exchange contracts	639	595
Forward Foreign Exchange Contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued and Other Current Liabilities [Member] | Level III [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued and other current liabilities - Forward foreign exchange contracts	$ 0	$ 0

Fair Value of Financial Instr49

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value transfers between level 1 to level 2	$ 0	$ 0
Fair value transfers between level 2 to level 1	0	0
Fair value transfers into level 3	0	0
Fair value transfers out of level 3	0	0
Level II [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Severance pay assets	$ 5,100,000	$ 4,500,000

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016
Forward Foreign Exchange Contracts [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative contracts maturity	12 months

Derivative Instruments - Deriva

Derivative Instruments - Derivative Instruments Measured at Fair Value and Classification on Consolidated Balance Sheets (Detail) - Forward Foreign Exchange Contracts [Member] - Accrued and Other Current Liabilities [Member] - Designated As Hedging Instrument [Member] - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Notional Amount	$ 60,756,000	$ 47,231,000
Derivative Fair Value	$ 639,000	$ 595,000

Derivative Instruments - Gains

Derivative Instruments - Gains (Losses) on Derivative Instruments and Classification on Consolidated Statement of Operations (Detail) - Designated As Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gains recognized in OCI	$ 1,775	$ 834	$ 191
Losses recognized in OCI	(1,909)	(1,399)	(1,846)
Gains recognized from accumulated OCI into net loss	257	0	55
Losses recognized from accumulated OCI into net loss	$ (347)	$ (972)	$ (708)

Derivative Instruments - Gain53

Derivative Instruments - Gains (Losses) on Derivative Instruments and Classification on Consolidated Statement of Operations (Parenthetical) (Detail) - Designated As Hedging Instrument [Member] - Unrealized Gain (Loss) on Cash Flow Hedges [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cost of revenues [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge Gain (loss) reclassified	$ (8)	$ (107)	$ (72)
Operating Expenses [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge Gain (loss) reclassified	$ (82)	$ (865)	$ (581)

Consolidated Balance Sheet Co54

Consolidated Balance Sheet Components - Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts and sales returns reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts, beginning balance	$ 1,438	$ 215	$ 410
Allowance for doubtful accounts, ending balance	1,784	1,438	215
Allowance for doubtful accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts, beginning balance	1,115	215	410
Charged to costs and expenses, net of recoveries	315	1,044	418
Deductions (write-offs)	(477)	(144)	(613)
Allowance for doubtful accounts, ending balance	953	1,115	215
Sales returns reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts, beginning balance	323	0
Charged to revenue	1,560	677	0
Deductions (write-offs)	(1,052)	(354)	0
Allowance for doubtful accounts, ending balance	$ 831	$ 323	$ 0

Consolidated Balance Sheet Co55

Consolidated Balance Sheet Components - Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 4,980	$ 5,111
Prepaid income taxes	1,559	585
Interest receivable	758	467
Other	625	1,802
Total prepaid expenses and other current assets	$ 7,922	$ 7,965

Consolidated Balance Sheet Co56

Consolidated Balance Sheet Components - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 40,460	$ 25,376
Less: accumulated depreciation and amortization	(18,964)	(13,212)
Total property and equipment, net	21,496	12,164
Computers and related equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	25,285	15,953
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	3,228	1,632
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 11,947	$ 7,791

Consolidated Balance Sheet Co57

Consolidated Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 7,488	$ 4,551	$ 3,578

Consolidated Balance Sheet Co58

Consolidated Balance Sheet Components - Accrued Compensation and Benefits (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Employee Related Liabilities Current [Abstract]
Salary and related benefits	$ 9,588	$ 7,215
Accrued vacation	4,178	3,774
Accrued incentive payments	5,942	9,270
Accrued restructuring	1,132	0
Total accrued compensation and benefits	$ 20,840	$ 20,259

Consolidated Balance Sheet Co59

Consolidated Balance Sheet Components - Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities And Other Liabilities [Abstract]
Accrued expenses	$ 4,616	$ 4,633
Derivative liability	639	595
Income tax payable	435	323
Short-term deferred rent	461	283
Skyfence holdback liability	0	7,556
Sales Taxes Payable	849	411
Other	683	482
Total accrued and other current liabilities	$ 7,683	$ 14,283

Consolidated Balance Sheet Co60

Consolidated Balance Sheet Components - Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other Liabilities Noncurrent [Abstract]
Long-term deferred rent	$ 2,111	$ 1,926
Deferred tax liability	1,265	1,145
Uncertain Tax Positions	2,446	1,236
Other	815	208
Total other liabilities	$ 6,637	$ 4,515

Goodwill and Acquired Intangi61

Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Goodwill acquired	$ 2,476,000
Intangible assets acquired	12,478,000	$ 10,668,000
Impairment of goodwill	0
Amortization of acquired intangibles	$ 1,408,000	1,408,000	$ 1,269,000
Estimated useful life	7 years
Weighted average useful lives of acquired technology intangible assets	5 years 6 months
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life	7 years
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life	10 years
Acquired Technology [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 11,718,000	10,668,000
Weighted average useful lives of acquired technology intangible assets	5 years 2 months 12 days
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 480,000
Weighted average useful lives of acquired technology intangible assets	7 years
Trade Name and Other [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 280,000
Weighted average useful lives of acquired technology intangible assets	7 years
Camouflage Software, Inc [Member]
Finite Lived Intangible Assets [Line Items]
Goodwill acquired	$ 2,500,000
Intangible assets acquired	1,800,000
Impairment of goodwill	$ 0	$ 0	$ 0

Changes in the Carrying Amount

Changes in the Carrying Amount of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Balance as of December 31, 2015	$ 34,972
Goodwill acquired	2,476
Balance as of December 31, 2016	$ 37,448

Goodwill and Acquired Intangi63

Goodwill and Acquired Intangible Assets - Summary of Acquired Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 12,478	$ 10,668
Accumulated Amortization	(4,085)	(2,677)
Net Book Value	8,393	7,991
Acquired Technology [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	11,718	10,668
Accumulated Amortization	(4,085)	(2,677)
Net Book Value	7,633	$ 7,991
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	480
Net Book Value	480
Trade Name and Other [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	280
Net Book Value	$ 280

Goodwill and Acquired Intangi64

Goodwill and Acquired Intangible Assets - Schedule of Expected Amortization Expense in Future Periods (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
2,017	$ 1,666
2,018	1,666
2,019	1,666
2,020	1,666
Thereafter	1,729
Net Book Value	$ 8,393	$ 7,991

Other Income (Expense), Net - S

Other Income (Expense), Net - Schedule of Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income:
Interest income	$ 1,369	$ 701	$ 163
Foreign currency forward contract gains, net	9	0	0
Foreign currency exchange gains, net	209	5	8
Total other income	1,587	706	171
Other Expense:
Skyfence holdback liability accretion	(6)	(212)	(186)
Foreign currency exchange losses, net	(708)	(322)	0
Bank charges and Other expenses	(950)	(574)	(205)
Total other expense	(1,664)	(1,108)	(391)
Total other income (expense), net	$ (77)	$ (402)	$ (220)

Revolving Credit Facility - Add

Revolving Credit Facility - Additional Information (Detail) - Revolving Credit Facility [Member] - London Interbank Offered Rate (LIBOR) [Member] - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2010
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 7,500,000
Outstanding credit facility	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Payments Under Operating Leases and Minimum Rentals to be Received Under Non-Cancellable Subleases (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Operating Leases
2,017	$ 7,598
2,018	8,054
2,019	4,650
2,020	4,243
2,021	106
Total	24,651
Estimated Sublease Income
2,017	611
2,018	399
2,019	0
2,020	0
2,021	0
Total	$ 1,010

Commitments and Contingencies68

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2010
Loss Contingencies [Line Items]
Rent expense	$ 6,100,000	$ 4,600,000	$ 3,900,000
Tenant improvement allowances	700,000			$ 300,000	$ 600,000
Restricted cash	1,884,000	1,665,000
Purchase commitments	$ 3,800,000	5,800,000
Period of purchase commitment of inventory from specified date	6 months
Loss contingency accrual	$ 0	0
Cancelable Lease Agreement [Member]
Loss Contingencies [Line Items]
Motor vehicle lease expenses	$ 2,700,000	$ 2,400,000	$ 2,600,000
Minimum [Member]
Loss Contingencies [Line Items]
Operating lease expiration year	2,017
Maximum [Member]
Loss Contingencies [Line Items]
Operating lease expiration year	2,021
Maximum [Member] | Cancelable Lease Agreement [Member]
Loss Contingencies [Line Items]
Penalties	$ 100,000

Capital Stock - Reserved Shares

Capital Stock - Reserved Shares of Common Stock (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Issuance in connection with outstanding stock options	1,570,765	1,949,089	2,244,363	1,675,506
Issuance in connection with restricted stock units outstanding	1,994,790	1,898,025	2,279,081
Reserved for future stock option and restricted stock unit grants	2,464,181	1,726,346
Reserved for future issuance under the employee stock purchase plan	1,161,396	1,049,524
Total	7,191,132	6,622,984

Capital Stock - Additional Info

Capital Stock - Additional Information (Detail)	Jan. 01, 2015shares	Feb. 07, 2014$ / sharesshares	Oct. 31, 2015shares	Mar. 31, 2015USD ($)$ / sharesshares	Aug. 31, 2014shares	Nov. 30, 2013shares	Jan. 31, 2012	Sep. 30, 2011Periodshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized									5,000,000	5,000,000
Preferred stock, shares outstanding									0	0
Preferred stock, shares issued									0	0
Reserve of common stock for future issuance									7,191,132	6,622,984
Number of stock option outstanding, granted									48,260	696,971	1,256,559
Performance-based restricted stock units granted									1,160,062	911,734
Total stock-based compensation expense | $									$ 62,875,000	$ 50,964,000	$ 37,273,000
Weighted-average grant date fair value | $ / shares									$ 29.23	$ 23.75	$ 19.36
Aggregate grant date fair value, stock options granted | $									$ 1,400,000	$ 16,600,000	$ 24,300,000
Aggregate grant date fair value, stock options vested | $									11,900,000	11,700,000	7,200,000
Intrinsic value of options exercised | $									$ 2,500,000	21,600,000	14,700,000
Compensation cost related to unvested stock-based awards granted, but not yet recognized | $										69,500,000
Nonvested awards, compensation cost not yet recognized, period for recognition									2 years 6 months
Net cash proceeds from the exercise of stock options | $									$ 2,400,000	12,100,000	8,500,000
Capitalized stock-based compensation cost | $									0	0	0
Recognized stock-based compensation tax benefits | $									100,000	200,000	400,000
Aggregate net proceeds from sale of common stock, net of underwriting discounts, commissions and offering costs | $									11,233,000	23,524,000	10,546,000
Underwriting discounts, commissions and other offering expenses | $									$ 112,000	$ 0	0
Follow-On Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock, shares				3,450,000
Sale of common stock, price per share | $ / shares				$ 39
Aggregate net proceeds from sale of common stock, net of underwriting discounts, commissions and offering costs | $				$ 127,900,000
Underwriting discounts, commissions and other offering expenses | $				$ 6,700,000
Skyfence Networks Ltd. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested awards, compensation cost not yet recognized, period for recognition		4 years
Closing price of stock | $ / shares		$ 59.08
Common stock, shares vested									421,365	236,537
Restricted Stock Units for Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Restricted Stock Units Vested in Period | $									$ 38,100,000	$ 31,400,000	$ 8,300,000
Restricted Stock Units for Common Stock [Member] | Incapsula [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issuable, as-converted to common stock-basis											198,825
Restricted Stock Units And Outstanding Options [Member] | Incapsula [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issuable, as-converted to common stock-basis									247,184
Liability Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense | $									$ 3,100,000
Restricted Shares of Common Stock Subject to Repurchase [Member] | Skyfence Networks Ltd. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business acquisition purchase price, shares issued		532,262
2003 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance									955,568
2003 Stock Plan [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of fair value of common stock on grant date									85.00%
2003 Stock Plan [Member] | Maximum [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period									10 years
2003 Stock Plan [Member] | Minimum [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period									4 years
2011 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance								1,000,000
Increase percentage of common stock outstanding									4.00%
Increase in reserve share									1,300,000
2011 Stock Option and Incentive Plan [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of fair value of common stock on grant date									100.00%
Expiration period									10 years
2011 Stock Option and Incentive Plan [Member] | Restricted Stock Units for Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period									4 years
Description of vesting terms									The Company also grants RSUs, which generally vest over either a four-year period with 25% vesting at the end of one year and the remainder vesting quarterly thereafter or they completely vest at the end of a three-year period.
2011 Stock Option and Incentive Plan [Member] | Restricted Stock Units for Common Stock [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage at the end of period									25.00%
2011 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance								500,000
Increase percentage of common stock outstanding							1.00%
Increase in reserve share	318,371
Percentage in payroll of deduction base salary to acquire shares of common stock								15.00%
Offering period								24 months
Percentage of fair value of common stock on offering period								85.00%
Number of years, shares reserved for issuance increase							8 years
2011 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance								20,000,000
Number of purchase periods for offering | Period								5
Inducement Stock Option Plan And Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of vesting terms									In accordance with the terms of the Inducement Option Plans, the Company issued options to purchase up to 290,000 shares of the Company’s common stock at an exercise price equal to the fair market value of a share of the Company’s common stock on the dates of grant of the options. The options, which have a ten-year term, vest at the rate of 25% of the shares on each of the first anniversary of the vesting commencement date with an additional 6.25% of the shares subject to the option vesting each quarter thereafter so long as the participant has not been terminated.
Number of stock option outstanding, granted					290,000
Inducement Stock Option Plan And Agreement [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage at the end of period					25.00%
Inducement Stock Option Plan And Agreement [Member] | Quarterly Vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage at the end of period					6.25%
Inducement Restricted Stock Unit Plan and Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of vesting terms									In accordance with the terms of the Inducement RSU Plans, the Company issued RSUs representing a total of 290,000 shares of the Company’s common stock. The RSUs, which expire following settlement, vest at the rate of 25% of the shares on each of the first anniversary of the vesting commencement date with an additional 6.25% of the shares subject to the RSU vesting each quarter thereafter so long as the participant has not been terminated.
Shares available for grant					290,000
Inducement Restricted Stock Unit Plan and Agreement [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage at the end of period					25.00%
Inducement Restricted Stock Unit Plan and Agreement [Member] | Quarterly Vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage at the end of period					6.25%
2015 Equity Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance			100,000
2015 Equity Inducement Plan [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of fair value of common stock on grant date			100.00%
Expiration period			10 years
Incapsula 2010 Share Incentive Plan [Member] | Restricted Stock Units for Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based restricted stock units granted						7,095,461
Incapsula 2010 Share Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserve of common stock for future issuance						10,263,211
Greater 10% Ownership [Member] | 2003 Stock Plan [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of fair value of common stock on grant date									110.00%
Minimum percentage of combined voting power									10.00%

Capital Stock - Summary of Opti

Capital Stock - Summary of Option Activity under Plans and Related Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Stock Options Outstanding, Beginning balance	1,949,089	2,244,363	1,675,506
Number of Stock Options Outstanding, Granted	48,260	696,971	1,256,559
Number of Shares, Options assumed in acquisitions			72,607
Number of Stock Options Outstanding, Exercised or released	(184,737)	(636,424)	(496,297)
Number of Stock Options Outstanding, Cancelled or forfeited	(241,847)	(355,821)	(264,012)
Number of Stock Options Outstanding, Ending balance	1,570,765	1,949,089	2,244,363	1,675,506
Number of Shares, Vested and expected to vest	1,463,772
Number of Shares, Exercisable	967,186
Weighted Average Exercise Price of Stock Options Outstanding	$ 39.64	$ 39.27	$ 33.83	$ 23.78
Weighted Average Exercise Price, Granted	53.59	49.20	41.39
Weighted Average Exercise Price, Options assumed in acquisitions			13.30
Weighted Average Exercise Price, Exercised or released	29.24	29.44	14.85
Weighted Average Exercise Price, Cancelled or forfeited	47.35	$ 42	$ 35.85
Weighted-Average Exercise Price, Vested and expected to vest	39.03
Weighted Average Exercise Price, Exercisable	$ 36.66
Weighted-Average Remaining Contractual Term (in years)	6 years 10 months 24 days	8 years 1 month 2 days	8 years 3 months 7 days	8 years 4 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest	6 years 9 months 26 days
Weighted Average Remaining Contractual Term (in years), Exercisable	6 years 3 months 22 days
Aggregate Intrinsic Value	$ 9,226	$ 47,480	$ 38,457	$ 40,813
Aggregate Intrinsic Value, Vested and expected to vest	9,061
Aggregate Intrinsic Value, Exercisable	$ 7,339

Capital Stock - Summary of Op72

Capital Stock - Summary of Option Activity under Plans and Related Information (Parenthetical) (Detail)	Dec. 31, 2016$ / shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Closing stock price	$ 38.40

Capital Stock - Additional In73

Capital Stock - Additional Information Regarding Company's Stock Options Outstanding and Exercisable (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Stock Options Outstanding	1,570,765
Weighted Average Remaining Contractual Life (Years)	6 years 10 months 24 days
Weighted Average Exercise Price per Share	$ 39.64	$ 39.27	$ 33.83	$ 23.78
Shares Subject to Stock Options	967,186
Weighted Average Exercise Price per Share	$ 36.66
Exercise price range one [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	0.02
Company's stock options outstanding and exercisable, Upper Range	$ 10.70
Number of Stock Options Outstanding	134,548
Weighted Average Remaining Contractual Life (Years)	4 years 7 days
Weighted Average Exercise Price per Share	$ 7.01
Shares Subject to Stock Options	130,579
Weighted Average Exercise Price per Share	$ 7.22
Exercise price range two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	10.71
Company's stock options outstanding and exercisable, Upper Range	$ 29.10
Number of Stock Options Outstanding	168,845
Weighted Average Remaining Contractual Life (Years)	6 years 7 months 28 days
Weighted Average Exercise Price per Share	$ 25.73
Shares Subject to Stock Options	121,118
Weighted Average Exercise Price per Share	$ 25.37
Exercise price range three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	29.11
Company's stock options outstanding and exercisable, Upper Range	$ 32.54
Number of Stock Options Outstanding	236,906
Weighted Average Remaining Contractual Life (Years)	7 years 6 months 4 days
Weighted Average Exercise Price per Share	$ 29.40
Shares Subject to Stock Options	116,285
Weighted Average Exercise Price per Share	$ 29.53
Exercise price range four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	32.55
Company's stock options outstanding and exercisable, Upper Range	$ 34.55
Number of Stock Options Outstanding	149,082
Weighted Average Remaining Contractual Life (Years)	5 years 1 month 2 days
Weighted Average Exercise Price per Share	$ 33.78
Shares Subject to Stock Options	133,559
Weighted Average Exercise Price per Share	$ 33.76
Exercise price range five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	34.56
Company's stock options outstanding and exercisable, Upper Range	$ 54.48
Number of Stock Options Outstanding	464,660
Weighted Average Remaining Contractual Life (Years)	7 years 8 months 5 days
Weighted Average Exercise Price per Share	$ 43.41
Shares Subject to Stock Options	240,153
Weighted Average Exercise Price per Share	$ 43.04
Exercise price range six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	54.49
Company's stock options outstanding and exercisable, Upper Range	$ 61.50
Number of Stock Options Outstanding	248,776
Weighted Average Remaining Contractual Life (Years)	7 years 2 months 16 days
Weighted Average Exercise Price per Share	$ 55.16
Shares Subject to Stock Options	149,677
Weighted Average Exercise Price per Share	$ 54.92
Exercise price range seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	61.51
Company's stock options outstanding and exercisable, Upper Range	$ 69.19
Number of Stock Options Outstanding	143,729
Weighted Average Remaining Contractual Life (Years)	7 years 5 months 1 day
Weighted Average Exercise Price per Share	$ 65.04
Shares Subject to Stock Options	68,611
Weighted Average Exercise Price per Share	$ 64.52
Exercise price range eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Company's stock options outstanding and exercisable, Lower Range	69.20
Company's stock options outstanding and exercisable, Upper Range	$ 77
Number of Stock Options Outstanding	24,219
Weighted Average Remaining Contractual Life (Years)	8 years 6 months
Weighted Average Exercise Price per Share	$ 71.73
Shares Subject to Stock Options	7,204
Weighted Average Exercise Price per Share	$ 71.74

Capital Stock - Summary of RSU

Capital Stock - Summary of RSU Activity Outstanding and Weighted Average Grant Date Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Restricted Stock Units Outstanding, Unvested - Beginning Balance	1,898,025	2,279,081
Number of Restricted Stock Units Outstanding, Granted	1,160,062	911,734
Number of Restricted Stock Units Outstanding, Granted, performance RSUs	273,900	249,220
Number of Restricted Stock Units Outstanding, Released	(884,349)	(898,205)
Number of Restricted Stock Units Outstanding, Cancelled or forfeited	(452,848)	(643,805)
Number of Restricted Stock Units Outstanding, Unvested - Ending Balance	1,994,790	1,898,025
Weighted-Average Grant Date Fair Value, Unvested	$ 51.42	$ 49.53	$ 39.07
Weighted-Average Grant Date Fair Value, Granted	47.42	53.02
Weighted-Average Grant Date Fair Value, Granted, performance RSUs	51.55	42.58
Weighted-Average Grant Date Fair Value, Released	43.04	34.97
Weighted-Average Grant Date Fair Value, Cancelled or expired	$ 49.86	$ 35.09

Capital Stock - Stock-Based Com

Capital Stock - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 62,875	$ 50,964	$ 37,273
Cost of revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4,664	3,862	2,058
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	14,711	13,831	8,799
Sales and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	20,510	16,717	13,558
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	17,131	$ 16,554	$ 12,858
Restructuring Charges [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 5,859

Capital Stock - Weighted Averag

Capital Stock - Weighted Average Assumptions for Fair Value of Stock Options Grants and ESPP Grants (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend rate	0.00%	0.00%	0.00%
Risk-free interest rate	1.40%	1.80%	1.80%
Expected term (in years)	0 years	6 years 1 month 6 days	6 years 1 month 6 days
Expected volatility	58.00%	49.00%	46.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend rate	0.00%	0.00%	0.00%
Risk-free interest rate	0.50%	0.40%	0.10%
Expected term (in years)	0 years	6 months	6 months
Expected volatility	58.00%	65.00%	45.00%

Accumulated Other Comprehensi77

Accumulated Other Comprehensive Income (Loss) - Changes in Balances of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 240,201
Other comprehensive income (loss) before reclassifications	(237)	$ (814)	$ (1,714)
Amounts reclassified to net loss	90	972	653
Other comprehensive income (loss)	(147)	158	(1,061)
Ending balance	231,963	240,201
Unrealized Gain (Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,021)	(1,428)	(426)
Other comprehensive income (loss) before reclassifications	(134)	(565)	(1,655)
Amounts reclassified to net loss	90	972	653
Other comprehensive income (loss)	(44)	407	(1,002)
Ending balance	(1,065)	(1,021)	(1,428)
Unrealized Gain (Loss) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(310)	(61)	(2)
Other comprehensive income (loss) before reclassifications	(103)	(249)	(59)
Amounts reclassified to net loss	0	0	0
Other comprehensive income (loss)	(103)	(249)	(59)
Ending balance	(413)	(310)	(61)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,331)	(1,489)	(428)
Ending balance	$ (1,478)	$ (1,331)	$ (1,489)

Accumulated Other Comprehensi78

Accumulated Other Comprehensive Income (Loss) - Summary of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), Pre-Tax Amount	$ (147)	$ 158	$ (1,061)
Other comprehensive income (loss), Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss) before reclassification adjustments, After-Tax Amount	(237)	(814)	(1,714)
Other comprehensive income (loss), Reclassification adjustments, After-Tax Amount	90	972	653
Other comprehensive income (loss)	(147)	158	(1,061)
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassification adjustments, Pre-Tax Amount	(134)	(565)	(1,655)
Other comprehensive income (loss), Reclassification adjustments, Pre-Tax Amount	90	972	653
Other comprehensive income (loss), Pre-Tax Amount	(44)	407	(1,002)
Other comprehensive income (loss) before reclassification adjustments, Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss), Reclassification adjustments, Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss), Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss) before reclassification adjustments, After-Tax Amount	(134)	(565)	(1,655)
Other comprehensive income (loss), Reclassification adjustments, After-Tax Amount	90	972	653
Other comprehensive income (loss)	(44)	407	(1,002)
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassification adjustments, Pre-Tax Amount	(103)	(249)	(59)
Other comprehensive income (loss), Reclassification adjustments, Pre-Tax Amount	0	0	0
Other comprehensive income (loss), Pre-Tax Amount	(103)	(249)	(59)
Other comprehensive income (loss) before reclassification adjustments, Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss), Reclassification adjustments, Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss), Tax Expense (Benefit)	0	0	0
Other comprehensive income (loss) before reclassification adjustments, After-Tax Amount	(103)	(249)	(59)
Other comprehensive income (loss), Reclassification adjustments, After-Tax Amount	0	0	0
Other comprehensive income (loss)	$ (103)	$ (249)	$ (59)

Income Taxes - Loss Before Prov

Income Taxes - Loss Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ (72,139)	$ (50,892)	$ (55,330)
Foreign	3,032	2,692	(2,665)
Loss before provision for income taxes	$ (69,107)	$ (48,200)	$ (57,995)

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current
Federal	$ 0	$ 0	$ 0
State	62	34	66
Foreign	1,654	857	1,523
Total current provision	1,716	891	1,589
Deferred
Federal	130	63	109
State	6	(1)	6
Foreign	(680)	(271)	(523)
Total deferred provision	(544)	(209)	(408)
Provision for income taxes	$ 1,172	$ 682	$ 1,181

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Provision for Income Taxes at Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory tax rate	$ (23,496)	$ (16,388)	$ (19,718)
Tax benefit at state statutory tax rate	(1,008)	(499)	(1,169)
Foreign tax rate differential	57	(826)	(526)
Unbenefitted loss of consolidated investment	0	0	2,366
Change in valuation allowance	17,701	9,738	12,407
Meals and entertainment	222	44	34
Stock compensation	7,857	8,492	7,160
Nondeductible expenses and other	(161)	121	627
Provision for income taxes	$ 1,172	$ 682	$ 1,181

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Reserves and accruals	$ 2,817	$ 2,662
Deferred revenue	10,379	8,724
Stock-based compensation	7,361	4,772
Net operating loss carryforwards	47,452	37,793
Loss on OCI	370	374
Other	67	32
Gross deferred tax assets	68,446	54,357
Valuation allowance	(68,227)	(53,468)
Total deferred tax assets	219	889
Deferred tax liabilities:
Stock-based compensation	(21)	(21)
Depreciation and amortization	(243)	(1,425)
Total deferred tax liabilities	(264)	(1,446)
Net deferred tax liability	$ (45)	$ (557)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Expenses [Line Items]
Valuation allowance	$ 14,800	$ 13,000	$ 7,800
U.S. federal, net operating loss carryforwards	180,400
State net operating loss carryforwards	85,200
Excess tax benefits from stock options included in deferred tax assets for federal net operating losses	49,900
Excess tax benefits from stock options included in deferred tax assets for state net operating losses	29,500
Accumulated unremitted earnings	9,700	13,600	12,900
Unrecognized tax benefits	2,282	1,154	$ 672	$ 353
Accrued interest on income tax expense	$ 200	$ 100
Maximum [Member] | State [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2,036
Maximum [Member] | Federal [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2,036
Minimum [Member] | State [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2,017
Minimum [Member] | Federal [Member]
Income Tax Expenses [Line Items]
Expiration of net operating loss carryforwards	2,022

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Beginning Balance	$ 1,154	$ 672	$ 353
Additions based on tax positions taken during the current period	761	401	222
Reductions based on tax positions taken during the prior period	(42)	(50)	(47)
Additions based on tax positions taken during a prior period	409	131	144
Ending Balance	$ 2,282	$ 1,154	$ 672

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016Segment
Segment Reporting [Abstract]
Number of operating segments	1

Segment Information - Company's

Segment Information - Company's of Services Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue from External Customer [Line Items]
Total net services revenue	$ 177,657	$ 126,735	$ 89,711
Maintenance and Support [Member]
Revenue from External Customer [Line Items]
Total net services revenue	80,007	66,380	54,795
Professional Services and Training [Member]
Revenue from External Customer [Line Items]
Total net services revenue	13,693	14,084	11,414
Subscriptions [Member]
Revenue from External Customer [Line Items]
Total net services revenue	$ 83,957	$ 46,271	$ 23,502

Segment Information - Company87

Segment Information - Company's Revenue by Geographic Region, Based on Customer's Location (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	$ 264,455	$ 234,298	$ 164,010
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	143,607	141,225	87,155
EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	50,838	47,429	39,579
APAC [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	48,391	30,180	27,798
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	$ 21,619	$ 15,464	$ 9,478

Segment Information - Long-Live

Segment Information - Long-Lived Assets by Location (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 29,889	$ 20,155	$ 17,017
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	20,525	9,913	6,761
Israel [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	9,344	10,224	10,221
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 20	$ 18	$ 35

Restructuring Charges - Additio

Restructuring Charges - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring plan approval date by board of directors		2016-11
Restructuring charges		$ 8,118
Non-cash charges		5,800
Termination related costs, cash severance costs		2,300
Payments for restructuring charges		$ 1,200
Scenario, Forecast [Member]
Restructuring Cost And Reserve [Line Items]
Payments for restructuring charges	$ 1,100

Net Loss per Share - Computatio

Net Loss per Share - Computation of Company's Basic and Diluted Net Loss Per Share of Common Stock (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net loss attributable to Imperva, Inc. stockholders	$ (70,279)	$ (48,882)	$ (58,963)
Shares used in computing net loss per share of common stock, basic and diluted	32,284	29,849	25,806
Net loss per share of common stock, basic and diluted	$ (2.18)	$ (1.64)	$ (2.28)

Net Loss per Share - Antidiluti

Net Loss per Share - Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share of Common Stock (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	1,570,765	1,949,089	2,244,363
Restricted Stock Units for Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	1,994,790	1,898,025	2,279,081
Restricted Shares of Common Stock Subject to Repurchase [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	0	0	217,621
Restricted Stock Issued In Connection with Skyfence Acquisition [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	110,897	118,961	355,499

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) $ in Millions	Feb. 23, 2017USD ($)
Subsequent Event [Member] | Forcepoint LLC [Member]
Subsequent Event [Line Items]
Expected proceeds on sale of assets	$ 40

Subsequent Event - Summarized E

Subsequent Event - Summarized Estimate of Aggregate Carrying Amounts of the Major Classes of Assets and Liabilities Related to Disposed Business (Detail) - Skyfence Networks Ltd. [Member] $ in Thousands	Dec. 31, 2016USD ($)
Assets
Accounts receivables	$ 463
Prepaid and other current assets	15
Property and equipment, net	234
Goodwill	1,179
Acquired intangible assets, net	4,668
Total assets	6,559
Liabilities:
Accounts payable	163
Accrued and other current liabilities	76
Deferred revenue	1,334
Total liabilities	$ 1,573