Proofpoint (PFPT) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2018	Jul. 20, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	PFPT
Entity Registrant Name	PROOFPOINT INC.
Entity Central Index Key (CIK)	1,212,458
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		51,272,010

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 114,225	$ 286,072
Short-term investments	19,832	45,526
Accounts receivable, net	140,644	107,696
Inventory	400	730
Deferred product costs	1,727	1,541
Deferred commissions	29,711	26,249
Prepaid expenses and other current assets	22,349	18,669
Total current assets	328,888	486,483
Property and equipment, net	75,941	73,617
Long-term deferred product costs	326	259
Goodwill	460,592	297,704
Intangible assets, net	158,355	95,602
Long-term deferred commissions	53,712	51,954
Other assets	6,088	12,813
Total assets	1,083,902	1,018,432
Current liabilities:
Accounts payable	17,229	12,271
Accrued liabilities	62,404	65,503
Capital lease obligations	35	34
Deferred rent	799	586
Deferred revenue	426,090	364,521
Total current liabilities	506,557	442,915
Convertible senior notes	204,011	197,858
Long-term capital lease obligations	38	55
Long-term deferred rent	3,950	4,102
Other long-term liabilities	7,162	11,069
Long-term deferred revenue	65,147	63,318
Total liabilities	786,865	719,317
Commitments and contingencies (Note 6)
Stockholders’ equity:
Convertible preferred stock, $0.0001 par value; 5,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.0001 par value; 200,000 shares authorized; 51,189 and 50,325 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	5	5
Additional paid-in capital	835,156	787,572
Accumulated other comprehensive loss	(1)	(9)
Accumulated deficit	(538,123)	(488,453)
Total stockholders’ equity	297,037	299,115
Total liabilities and stockholders’ equity	$ 1,083,902	$ 1,018,432

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Number of shares of common stock reserved for future issuance
Common Stock, Shares Authorized	200,000,000	200,000,000
Common stock issued (in shares)	51,189,000	50,325,000
Common stock outstanding (in shares)	51,189,000	50,325,000
Par value of common stock (USD per share)	$ 0.0001	$ 0.0001

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Total revenue		$ 171,875	$ 122,441	$ 334,336	$ 238,076
Cost of revenue:
Total cost of revenue	[1],[2]	50,772	34,493	97,829	66,869
Gross profit		121,103	87,948	236,507	171,207
Operating expense:(1)(2)
Research and development		47,527	32,306	91,259	61,912
Sales and marketing		84,911	60,126	162,808	116,046
General and administrative		19,029	12,348	36,554	22,835
Total operating expense		151,467	104,780	290,621	200,793
Operating loss		(30,364)	(16,832)	(54,114)	(29,586)
Interest expense		(3,187)	(5,848)	(6,008)	(11,814)
Other (expense) income, net		(633)	184	(290)	55
Loss before income taxes		(34,184)	(22,496)	(60,412)	(41,345)
(Provision for) benefit from income taxes		(114)	(999)	13,958	(2,433)
Net loss		$ (34,298)	$ (23,495)	$ (46,454)	$ (43,778)
Net loss per share, basic and diluted		$ (0.67)	$ (0.54)	$ (0.92)	$ (1)
Weighted average shares outstanding, basic and diluted		50,935	43,890	50,721	43,562
Subscription
Revenue:
Total revenue		$ 169,019	$ 118,703	$ 327,806	$ 231,794
Cost of revenue:
Total cost of revenue	[1],[2]	45,618	30,363	87,816	58,684
Hardware and Service
Revenue:
Total revenue		2,856	3,738	6,530	6,282
Cost of revenue:
Total cost of revenue	[1],[2]	$ 5,154	$ 4,130	$ 10,013	$ 8,185
[1]	(1) Includes stock-based compensation expense as follows: Cost of subscription revenue $3,448 $2,863 $6,899 $5,239 Cost of hardware and services revenue $571 $469 $1,162 $908 Research and development $9,986 $7,744 $20,021 $14,794 Sales and marketing $12,382 $8,230 $23,884 $16,127 General and administrative $7,410 $5,198 $12,903 $9,810
[2]	(2) Includes intangible amortization expense as follows: Cost of subscription revenue $7,244 $3,189 $13,020 $6,377 Research and development $15 $15 $30 $30 Sales and marketing $3,982 $949 $6,397 $1,916

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Intangible amortization expense	$ 11,241	$ 4,153	$ 19,447	$ 8,323
Cost of subscription revenue
Stock-based compensation expense	3,448	2,863	6,899	5,239
Intangible amortization expense	7,244	3,189	13,020	6,377
Cost of hardware and services revenue
Stock-based compensation expense	571	469	1,162	908
Research and development
Stock-based compensation expense	9,986	7,744	20,021	14,794
Intangible amortization expense	15	15	30	30
Sales and marketing
Stock-based compensation expense	12,382	8,230	23,884	16,127
Intangible amortization expense	3,982	949	6,397	1,916
General and administrative
Stock-based compensation expense	$ 7,410	$ 5,198	$ 12,903	$ 9,810

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (34,298)	$ (23,495)	$ (46,454)	$ (43,778)
Other comprehensive income, net of tax:
Unrealized gain on short-term investments, net	1	0	8	4
Comprehensive loss	$ (34,297)	$ (23,495)	$ (46,446)	$ (43,774)

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (46,454)	$ (43,778)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	34,878	19,147
Stock-based compensation	64,869	46,878
Change in fair value of contingent consideration	(79)	(1,730)
Amortization of debt issuance costs and accretion of debt discount	6,153	10,888
Amortization of deferred commissions	16,708	13,275
Deferred income taxes	(14,896)	(1,974)
Other	820	139
Changes in assets and liabilities:
Accounts receivable	(23,025)	(2,746)
Inventory	330	101
Deferred product costs	(253)	359
Deferred commissions	(21,929)	(17,623)
Prepaid expenses	(2,614)	(1,686)
Other current assets	1,657	260
Long-term assets	350	(3,710)
Accounts payable	4,210	(1,374)
Accrued liabilities	(4,498)	4,565
Deferred rent	61	824
Deferred revenue	48,698	45,140
Net cash provided by operating activities	64,986	66,955
Cash flows from investing activities
Proceeds from maturities of short-term investments	37,432	56,081
Proceeds from sales for short-term investments	11,931	0
Purchase of short-term investments	(23,694)	(41,360)
Purchase of property and equipment	(16,611)	(22,867)
Receipt from escrow account	555	4,620
Acquisition of business, net of cash acquired	(223,786)	0
Net cash used in investing activities	(214,173)	(3,526)
Cash flows from financing activities
Proceeds from issuance of common stock	13,001	13,218
Withholding taxes related to restricted stock net share settlement	(34,640)	(25,122)
Repayments of equipment loans and capital lease obligations	(16)	(16)
Contingent consideration payment	(555)	(4,620)
Net cash used in financing activities	(22,210)	(16,540)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(213)	575
Net (decrease) increase in cash, cash equivalents and restricted cash	(171,610)	47,464
Cash, cash equivalents and restricted cash
Beginning of period	286,660	345,537
End of period	115,050	393,001
Supplemental disclosure of noncash investing and financing information
Unpaid purchases of property and equipment and asset retirement obligations	3,850	6,275
Liability awards converted to equity	8,870	8,307
Reconciliation of cash, cash equivalents and restricted cash as shown in the consolidated statement of cash flows
Cash and cash equivalents	114,225	392,886
Restricted cash included in prepaid expenses and other current assets	337	83
Restricted cash included in other non-current assets	488	32
End of period	$ 115,050	$ 393,001

The Company and Summary of Sign

The Company and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
The Company and Summary of Significant Accounting Policies	1. The Company and Summary of Significant Accounting Policies The Company Proofpoint, Inc. (the “Company”) was incorporated in Delaware in June 2002 and is headquartered in California. Proofpoint, Inc. is a leading security-as-a-service provider that enables large and mid-sized organizations worldwide to defend, protect, archive and govern their most sensitive data. The Company’s security-and compliance platform is comprised of an integrated suite of threat protection, information protection, and brand protection solutions, including email protection, advanced threat protection, email authentication, data loss prevention, SaaS application protection, response orchestration and automation, digital risk, web browser isolation, email encryption, archiving, eDiscovery, supervision, secure communication, phishing simulation and security awareness computer-based training. Basis of Presentation and Consolidation These condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”), pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and note disclosures have been condensed or omitted pursuant to such rules and regulations. The accompanying Condensed Consolidated Balance Sheet as of December 31, 2017 is derived from audited financial statements as of that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. Certain prior period amounts have been adjusted due to the adoption of Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers: Topic 606 These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC. The Company’s significant accounting policies are described in Note 1 to those audited consolidated financial statements. See Note 2 “Revenue, Deferred Revenue and Deferred Contract Costs” for the summary of the new accounting policies under ASC 606. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates and such difference may be material to the financial statements. Goodwill and Intangible Assets Goodwill represents the excess of the purchase price of the acquired enterprise over the fair value of identifiable assets acquired and liabilities assumed. The Company performs an annual goodwill impairment test during the fourth quarter of a calendar year and more frequently if an event or circumstances indicates that impairment may have occurred. For the purposes of impairment testing, the Company has determined that it has one operating segment and one reporting unit. The Company performs a two-step impairment test of goodwill whereby the fair value of the reporting unit is compared to its carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets assigned to that unit, goodwill is not considered impaired and further testing is not required. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company must perform the second step of the impairment test in order to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of a reporting unit’s goodwill exceeds its implied fair value, then impairment loss equal to the difference is recorded. The identification and measurement of goodwill impairment involves the estimation of the fair value of the Company. The estimate of fair value of the Company, based on the best information available as of the date of the assessment, is subjective and requires judgment, including management assumptions about expected future revenue forecasts and discount rates, changes in the overall economy, trends in the stock price and other factors. No impairment indicators were identified by the Company as of June 30, 2018. Intangible assets consist of developed technology, customer relationships, non-compete arrangements, trademarks and patents and order backlog. The values assigned to intangibles are based on estimates and judgments regarding expectations for success and life cycle of solutions and technologies acquired. Intangible assets are amortized on a straight-line basis over their estimated lives, which approximate the pattern in which the economic benefits of the intangible assets are consumed, as follows (in years): Low High Patents 4 5 Developed technology 3 7 Customer relationships 2 8 Order backlog 1 3 Trade names and trademarks 1 5 Comprehensive Loss Comprehensive loss includes all changes in equity that are not the result of transactions with stockholders. The Company’s comprehensive loss consists of its net loss and changes in unrealized gains (losses) from its available-for-sale investments. The Company had no material reclassifications out of accumulated other comprehensive loss into net loss for the three and six months ended June 30, 2018 and 2017. Accounting Pronouncements Adopted in 2018 In May 2014, the FASB issued ASC 606 to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The standard contains a comprehensive new revenue recognition model that requires revenue to be recognized in a manner to depict the transfer of services or products to a customer at an amount that reflects the consideration expected to be received in exchange for those services or products. The FASB has issued several amendments to the standard, including clarifications on disclosure of prior-period and remaining performance obligations. The Company adopted ASC 606 effective January 1, 2018 using full retrospective transition method. Refer to Note 2 “Revenue, Deferred Revenue and Deferred Contract Costs” for more information. In October 2016, FASB issued ASU No. 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory In August 2016, FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ” ” Recent Accounting Pronouncements Not Yet Effective In January 2017, FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment In June 2016, FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842)

Revenue, Deferred Revenue and D

Revenue, Deferred Revenue and Deferred Contract Costs	6 Months Ended
	Jun. 30, 2018
Revenue From Contract With Customer [Abstract]
Revenue, Deferred Revenue and Deferred Contract Costs	2. Revenue, Deferred Revenue and Deferred Contract Costs Effective January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Under this method, the Company is presenting the consolidated financial statements as of December 31, 2017, and for the three and six months ended June 30, 2017, as if ASC 606 had been effective for those periods. The most significant impact of the standard related to i) the timing of revenue recognition for contracts related to certain on-premise offerings, in which the Company granted customers the right to deploy its subscription software on the customers’ own servers. For these contracts, the Company is required to recognize as revenue a significant portion of the contract price upon delivery of the software compared to the previous practice of recognizing the entire contract price ratably over a subscription period; and ii) the timing of revenue recognition in instances when all revenue recognition criteria were not met until after the start date of the subscription. Previously these amounts were recognized prospectively over the remaining contract term, while under ASC 606, the Company is required to recognize revenue on a cumulative catch-up basis for amounts earned up to the time all revenue recognition criteria have been met. In addition, iii) certain contract acquisition costs such as sales commissions are being amortized over an expected benefit period that is longer than the Company’s previous policy of amortizing the deferred amounts over the specific revenue contract term for the associated contract. The Company applied ASC 606 using two practical expedients: 1) for the reporting periods presented before January 1, 2018, the Company won’t disclose the amount of the transaction price allocated to the remaining performance obligations or an explanation of when the Company expects to recognize that amount as revenue; 2) the Company won’t disclose the amount of the transaction price allocated to the remaining performance obligations for contracts with an original expected length of one year or less. Select condensed consolidated balance sheet line items, which reflect the adoption of the new standard, are as follows: December 31, 2017 As Previously Reported Adjustments As Adjusted Assets Accounts receivable, net $ 109,325 $ (1,629 ) $ 107,696 Deferred commissions, current $ 27,144 $ (895 ) $ 26,249 Long-term deferred commissions $ 5,811 $ 46,143 $ 51,954 Liabilities Accrued liabilities $ 63,926 $ 1,577 $ 65,503 Deferred revenue $ 381,915 $ (17,394 ) $ 364,521 Long-term deferred revenue $ 69,873 $ (6,555 ) $ 63,318 Stockholders’ Equity Accumulated deficit $ (554,444 ) $ 65,991 $ (488,453 ) Select unaudited condensed consolidated statements of operations line items, which reflect the adoption of the new standard, are as follows: Three Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Revenue: Subscription $ 118,928 $ (225 ) $ 118,703 Hardware and services 3,401 337 3,738 Total revenue $ 122,329 $ 112 $ 122,441 Gross profit $ 87,836 $ 112 $ 87,948 Operating expense: Sales and marketing $ 62,454 $ (2,328 ) $ 60,126 Operating loss $ (19,272 ) $ 2,440 $ (16,832 ) Net loss $ (25,935 ) $ 2,440 $ (23,495 ) Net loss per share, basic and diluted $ (0.59 ) $ 0.05 $ (0.54 ) Six Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Revenue: Subscription $ 229,853 $ 1,941 $ 231,794 Hardware and services 5,726 556 6,282 Total revenue $ 235,579 $ 2,497 $ 238,076 Gross profit $ 168,710 $ 2,497 $ 171,207 Operating expense: Sales and marketing $ 121,186 $ (5,140 ) $ 116,046 Operating loss $ (37,223 ) $ 7,637 $ (29,586 ) Net loss $ (51,415 ) $ 7,637 $ (43,778 ) Net loss per share, basic and diluted $ (1.18 ) $ 0.18 $ (1.00 ) Select unaudited condensed consolidated statement of cash flows line items, which reflect the adoption of the new standard are as follows: Six Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (51,415 ) $ 7,637 $ (43,778 ) Adjustments to reconcile net loss to net cash provided by operating activities: Amortization of deferred commissions $ — $ 13,275 $ 13,275 Changes in assets and liabilities: Accounts receivable $ (2,725 ) $ (21 ) $ (2,746 ) Deferred commissions $ 791 $ (18,414 ) $ (17,623 ) Accrued liabilities $ 4,014 $ 551 $ 4,565 Deferred revenue $ 48,168 $ (3,028 ) $ 45,140 Net cash provided by operating activities $ 66,955 $ — $ 66,955 The core principle of ASC 606 is to recognize revenue to depict the transfer of services or products to customers in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services or products. The principle is achieved through the following five-step approach: • Identification of the contract, or contracts, with the customer - The Company considers the terms and conditions of the contract and its customary business practice in identifying its contracts under ASC 606. The Company determines it has a contract with a customer when the contract is approved, the Company can identify each party’s rights regarding the services and products to be transferred, the Company can identify the payment terms for the services and products, the Company has determined the customer has the ability and intent to pay and the contract has commercial substance. At contract inception, the Company evaluates whether two or more contracts should be combined and accounted for as a single contract and whether the combined contract or single contract includes more than one performance obligation. The Company applies judgment in determining the customer’s ability and intent to pay, which is based on a variety of factors, including the customer’s historical payment experience or, in the case of a new customer, credit and financial information pertaining to the customer. • Identification of the performance obligation in the contract - Performance obligations promised in a contract are identified based on the services or products that will be transferred to the customer that are both i) capable of being distinct, whereby the customer can benefit from the service or product either on its own or together with other resources that are readily available from third parties or from the Company, and ii) distinct in the context of the contract, whereby the transfer of the services or products is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised services or products, the Company applies judgment to determine whether promised services or products are capable of being distinct and distinct in the context of the contract. If these criteria are not met the promised services or products are accounted for as a combined performance obligation. • Determination of the transaction price - The transaction price is determined based on the consideration to which the Company expects to be entitled in exchange for transferring services and products to the customer. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. None of the Company’s contracts contain a significant financing component. • Allocation of the transaction price to the performance obligations in the contract - If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation based on a relative standalone selling price, or SSP, basis. • Recognition of revenue when, or as, the Company satisfies a performance obligation - The Company recognizes revenue when control of the services or products are transferred to the customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services or products. The Company records its revenue net of any value added or sales tax. The Company generates sales directly through its sales team and, to a growing extent, through its channel partners. Sales to channel partners are made at a discount and revenues are recorded at this discounted price once all revenue recognition criteria are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company, and these partners do not carry any inventory of the Company’s products or solutions. Payment from channel partners is not contingent on the partner’s success in sales to end-customers. In the event that the Company offers rebates, joint marketing funds, or other incentive programs to a partner, recorded revenues are reduced by these amounts accordingly. Payment terms on invoiced amounts are typically 30 to 45 days. Disaggregation of Revenue The Company derives its revenue primarily from: (1) subscription service revenue; (2) subscription software revenue, and (3) hardware and services, which include professional service and training revenue provided to customers related to their use of the platform. The following table presents the Company’s revenue disaggregation: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Subscription service revenue $ 165,365 $ 115,811 $ 317,985 $ 224,137 Subscription software revenue 3,654 2,892 9,821 7,657 Hardware and services 2,856 3,738 6,530 6,282 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076 Subscription service revenue Subscription service revenue is derived from a subscription-based enterprise licensing model with contract terms typically ranging from one to three years, and consists of (1) subscription fees from the licensing of the Company’s security-as-a-service platform and it’s various components, (2) subscription fees for software with support and related future updates where the software updates are critical to the customers’ ability to derive benefit from the software due to the fast changing nature of the technology. These function together as one performance obligation, and (3) subscription fees for the right to access the Company’s customer support services for software with significant standalone functionality and support services for hardware. The hosted on-demand service arrangements do not provide customers with the right to take possession of the software supporting the hosted services. Support revenue is derived from ongoing security updates, upgrades, bug fixes, and maintenance. A time-elapsed method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription service revenue is generally recognized on a straight-line basis over the contract term beginning on the date access is provided, as long as other revenue recognition criteria have been met. Most of the company’s contracts are non-cancelable over the contract term. Customers typically have the right to terminate their contract for cause if the Company fails to perform in accordance with the contractual terms. Some of the Company’s customers have the option to purchase additional subscription services at a stated price. These options are evaluated on a case-by-case basis but generally do not provide a material right as they are priced at or above the Company’s SSP and, as such, would not result in a separate performance obligation. Subscription software revenue Subscription software revenue is primarily derived from term-based software that is deployed on the customers’ own servers and has significant standalone functionality, is recognized upon transfer of control to the customer. The control for subscription software is transferred at the later of delivery to the customer or the software license start date. Hardware and services Hardware revenue consists of amounts derived from the sale of the Company’s on-premise hardware appliance, which is recognized upon passage of control, which occurs upon shipment of the product. Professional services revenue consists of fees associated with consulting, implementation and training services for assisting customers in implementing and expanding the use of the Company’s services and products. These services are distinct from subscription, subscription software licenses and hardware. Professional services do not result in significant customization of the Company’s services and products. The Company recognizes revenue related to the professional services as they are performed. Contracts with multiple performance obligations Most of the Company’s contracts with customers contain multiple performance obligations that are distinct and accounted for separately. The transaction price allocated to subscription services and subscription software that does not have significant standalone functionality is determined by considering factors such as historical pricing practices, and the selling price of hardware and professional services is estimated using a cost plus model. The selling price for support of a functional subscription software license is calculated as a percentage of functional subscription software license value which is derived by analyzing internal pricing practice, customer expectations, and industry practice. Variable Consideration Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of variable consideration. The amount of variable consideration that is included in the transaction price is constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue will not occur when the uncertainty is resolved. If the Company’s services or products do not meet certain service level commitments, the Company’s customers are entitled to receive service credits representing a form of variable consideration. The Company has not historically experienced any significant incidents affecting the defined levels of reliability and performance as required by the Company’s subscription contracts. Accordingly, any estimated refunds related to these contracts in the condensed consolidated financial statements are not material during the periods presented. Unbilled accounts receivables Unbilled accounts receivable represents amounts for which the Company has recognized revenue, pursuant to its revenue recognition policy, for software licenses already delivered and professional services already performed, but billed in arrears and for which the Company believes it has an unconditional right to payment. The unbilled accounts receivable balance, included in accounts receivable in the condensed consolidated balance sheet, was $1,090 Deferred commissions The Company capitalizes sales commissions and associated payroll taxes paid to internal sales personnel, and referral fees paid to independent third-parties, that are incremental to the acquisition of customer contracts. These costs are recorded as deferred commissions on the condensed consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are incremental and would not have occurred absent the customer contract. Sales commissions for renewal of a subscription contract are not considered commensurate with the commissions paid for the acquisition of the initial subscription contract given the substantive difference in commission rate between new and renewal contracts. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of five years while commissions paid related to renewal contracts are amortized over a contractual renewal period. Amortization is recognized based on the expected future revenue streams under the customer contracts. Amortization of deferred sales commissions is included in sales and marketing expense in the accompanying condensed consolidated statements of operations. The Company determines the period of benefit for commissions paid for the acquisition of the initial subscription contract by taking into consideration its initial estimated customer life and the technological life of the Company’s software and related significant features. The Company classifies deferred commissions as current or long-term based on the timing of when the Company expects to recognize the expense. The Company periodically reviews these deferred commission costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these deferred contract acquisition costs. There were no material impairment losses recorded during the periods presented. For the three and six months ended June 30, 2018, the Company capitalized $12,715 and $21,929 of commission costs, respectively, and amortized $8,334 and $16,708, respectively. For the three and six months ended June 30, 2017, the Company capitalized $10,874 and $17,623, respectively, of commission costs, respectively, and amortized $6,666 and $13,275, respectively. Deferred product costs Deferred product costs are the incremental costs to fulfill a contract that are directly associated with each non-cancellable customer contract and primarily consist of royalty payments made to third parties, from whom the Company has obtained licenses to integrate certain software into its products. The deferred product costs are recognized based on the contractual term, and included in cost of revenue in the accompanying condensed consolidated statements of operations. The Company classifies deferred product costs as current or long-term based on the timing of when the Company expects to recognize the expense. For the three and six months ended June 30, 2018, the Company capitalized $758 and $1,436 of deferred product costs, respectively, and amortized $611 and $1,183, respectively. For the three and six months ended June 30, 2017, the Company capitalized $600 $1,164 of deferred product costs, respectively, and amortized $869 and $1,523 Deferred revenue The Company records deferred revenue when cash payments are received, or invoices are issued in advance of the Company’s performance, and generally recognizes revenue over the contractual term. The Company recognized $149,817 and $237,395 of revenue during the three and six months ended June 30, 2018, respectively, that was included in the deferred revenue balances at the beginning of the respective periods. The Company recognized $101,114 $165,210 The Company recognized $2,091 and $2,584 of revenue during the three and six months ended June 30, 2018, respectively, related to the performance obligations satisfied in prior periods. The Company recognized $1,054 $1,034 The acquisition of Wombat Securities, Inc. (see Note 3 “Acquisitions”) on February 28, 2018, increased deferred revenue by $14,700, of which $6,720 was recognized in the six month period ended June 30, 2018. Remaining performance obligations Contracted revenue as of June 30, 2018 that has not yet been recognized (“contracted not recognized”) was $389,492, which includes deferred revenue and non-cancellable amounts that will be invoiced and recognized as revenue in future periods and excludes contracts with an original expected length of one year or less. The Company expects 62% 37%

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Acquisitions	3. Acquisitions Acquisitions are accounted for under the purchase method of accounting in which the tangible and identifiable intangible assets and liabilities of each acquired company are recorded at their respective fair values as of each acquisition date, including an amount for goodwill representing the difference between the respective acquisition consideration and fair values of identifiable net assets. The Company believes that for each acquisition, the combined entities will achieve savings in corporate overhead costs and opportunities for growth through expanded geographic and customer segment diversity with the ability to leverage additional products and capabilities. These factors, among others, contributed to a purchase price in excess of the estimated fair value of each acquired company’s net identifiable assets acquired and, as a result, goodwill was recorded in connection with each acquisition. Goodwill related to each acquisition below is not deductible for tax purposes. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to value assets acquired and liabilities assumed at the acquisition date, these estimates and assumptions are subject to refinement. When additional information becomes available, such as finalization of negotiations of working capital adjustments and tax related matters, the Company may revise its preliminary purchase price allocation. As a result, during the preliminary purchase price allocation period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill. Subsequent to the purchase price allocation period, adjustments to assets acquired or liabilities assumed are recognized in the operating results. 2018 Acquisitions Wombat Security Technologies, Inc. On February 28, 2018 (the “Wombat Acquisition Date”), pursuant to the terms of the merger agreement, the Company acquired all shares of Wombat Security Technologies, Inc. (“Wombat”), a leader for phishing simulation and security awareness computer-based training. By collecting data from Wombat’s PhishAlarm solution, the Company has access to data on phishing campaigns as seen by non-Company customers, providing broader visibility and insight to the Proofpoint Nexus platform. With this acquisition, the Company’s customers can leverage the industry’s first solution combining the Company’s advanced threat protection with Wombat’s phishing simulation and computer-based security awareness training. With the combined solutions, the Company’s customers can: • Use real detected phishing attacks for simulations, assessing users based on the threats that are actually targeting them; • Both investigate and take action on user-reporting phishing, leveraging orchestration and automation to find real attacks, quarantine emails in users’ inboxes, and lock user accounts to limit risk; • Train users in the moment immediately after they click for both simulated and real phishing attacks. The Company also expects to achieve savings in corporate overhead costs for the combined entities. These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition. The Company has estimated fair values of acquired tangible assets, intangible assets and liabilities at the Wombat Acquisition Date. The amounts reported are considered provisional as the Company is completing the valuation work to determine the fair value of certain assets and liabilities acquired, largely with respect to working capital adjustments. The results of operations and the provisional fair values of the acquired assets and liabilities assumed have been included in the accompanying condensed consolidated financial statements since the Wombat Acquisition Date. At the Wombat Acquisition Date, the consideration transferred was $225,366, net of cash acquired of $13,452. Of the consideration transferred, $22,500 was held in escrow to secure indemnification obligations, which has not been released as of the filing date of this Quarterly Report on Form 10-Q. The Company incurred $719 in acquisition-related costs which were recorded within operating expenses for the six months ended June 30, 2018. The Company recorded $10,283 in revenue from Wombat for the six months ended June 30, 2018, and due to the continued integration of the combined businesses, it was impractical to determine the earnings. Per the terms of the merger agreement, unvested in-the-money stock options held by Wombat employees were canceled and paid off using the same amount per option as for the common share less applicable exercise price for each option. The fair value of $1,580 of these unvested options was attributed to pre-combination service and included in consideration transferred. The fair value of unvested options of $1,571 was allocated to post-combination services and expensed in the three months ended March 31, 2018. Also, as part of the merger agreement, 51 shares of the Company’s common stock were deferred for certain key employees with the total fair value of $5,458 (see Note 8 “Equity Award Plans”), which was not included in the purchase price. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and their fair value is expensed as stock-based compensation expense over the vesting period. The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 23,344 N/A Fixed assets 954 N/A Customer relationships 37,800 7 Order backlog 6,800 2 Core/developed technology 35,200 4 Trade name 2,400 4 Deferred revenue (14,700 ) N/A Deferred tax liability, net (14,725 ) N/A Other liabilities (1,120 ) N/A Goodwill 162,865 Indefinite $ 238,818 2017 Acquisitions Cloudmark, Inc. On November 21, 2017 (the “Cloudmark Acquisition Date”), pursuant to the terms of the merger agreement, the Company acquired all shares of Cloudmark, Inc. (“Cloudmark”), a leader in messaging security and threat intelligence for internet service providers and mobile carriers worldwide. As part of the acquisition, Cloudmark’s Global Threat Network will be incorporated into Company’s cloud-based Nexus platform, which powers its email, social media, mobile, and SaaS security effectiveness. The Company believes that with this acquisition, it will benefit from increased messaging threat intelligence from the analysis of billions of daily emails, malicious domain intelligence, and visibility into fraudulent and malicious SMS messages directed to mobile carriers worldwide. The Company also expects to achieve savings in corporate overhead costs for the combined entities. These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition. The Company has provisionally estimated fair values of acquired tangible and intangible assets and assumed liabilities at the Cloudmark Acquisition Date. The amounts reported are considered provisional as the Company is completing the valuation work to determine the fair value of certain assets and liabilities acquired, largely with respect to working capital adjustments. The results of operations and the provisional fair values of the acquired assets and liabilities assumed have been included in the accompanying condensed consolidated financial statements since the Cloudmark Acquisition Date. At the Cloudmark Acquisition Date, the consideration transferred was $107,283, net of cash acquired of $31,973. Of the consideration transferred, $16,700 was held in escrow to secure indemnification obligations, which has not been released as of the filing date of this Quarterly Report on Form 10-Q. Per the terms of the merger agreement, unvested stock options and unvested restricted stock units held by Cloudmark employees were canceled and exchanged for the Company’s unvested stock options and unvested restricted stock units, respectively. The fair value of $91 of these unvested awards was attributed to pre-combination services and included in consideration transferred. The fair value of $1,180 was allocated to post-combination services. The unvested awards are subject to the recipient’s continued service with the Company, and $1,180 will be recognized ratably as stock-based compensation expense over the required remaining service period. The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 37,390 N/A Fixed assets 543 N/A Non-current assets 50 N/A Liabilities (4,565 ) N/A Deferred revenue (15,400 ) N/A Customer relationships 15,300 8 Order backlog 1,400 1 Core/developed technology 18,500 4 Deferred tax liability, net (7,905 ) N/A Goodwill 93,943 Indefinite $ 139,256 WebLife Balance, Inc. On November 30, 2017 (the “WebLife Acquisition Date”), pursuant to the terms of a merger agreement, the Company acquired all shares of WebLife Balance, Inc. (“WebLife”), a browser isolation offerings vendor, to extend its advanced threat protection capabilities into personal email, while preserving the privacy of its users. The Company has estimated fair values of acquired tangible assets, intangible assets and liabilities at the WebLife Acquisition Date. The amounts reported are considered provisional as the Company is completing the valuation work to determine the fair value of certain assets and liabilities acquired, largely with respect to working capital adjustments. The results of operations and the provisional fair values of the acquired assets and liabilities assumed have been included in the accompanying condensed consolidated financial statements since the WebLife Acquisition Date. At the WebLife Acquisition Date, the consideration transferred was $48,765, net of cash acquired of $278. Of the consideration transferred, $6,203 was held in escrow to secure indemnification obligations, which has not been released as of the filling date of this Quarterly Report on Form 10-Q. Per the terms of the merger agreement, unvested stock options held by WebLife employees were canceled and exchanged for the Company’s unvested awards. The fair value of $333 of these unvested options was attributed to pre-combination service and included in consideration transferred. The fair value of $1,468 was allocated to post-combination services. The unvested awards are subject to the recipient’s continued service with the Company, and $1,468 will be recognized ratably as stock-based compensation expense over the required remaining service period. Also, as part of the merger agreement, 107 shares of the Company’s common stock were deferred for certain key employees with the total fair value of $9,652 (see Note 8 “Equity Award Plans”), which was not included in the purchase price. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and their fair value is expensed as stock-based compensation expense over the vesting period. The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 534 N/A Fixed assets 23 N/A Liabilities (88 ) N/A Deferred revenue (700 ) N/A Customer relationships 600 5 Core/developed technology 16,600 5 Deferred tax liability, net (4,440 ) N/A Goodwill 36,514 Indefinite $ 49,043 Pro Forma Financial Information (unaudited) The following unaudited pro forma financial information presents the combined results of operations for the three and six months ended June 30, 2018 and 2017 as though the Wombat acquisition had occurred as of January 1, 2017, with adjustments to give effect to pro forma events that are directly attributable to the acquisition such as amortization expense of acquired intangible assets, stock-based compensation directly attributable to the acquisition and acquisition-related transaction costs. Accordingly, these unaudited pro forma results are presented for informational purposes only and are not necessarily indicative of what the actual results of operations of the combined company would have been if the acquisition had occurred at the beginning of the period presented, nor are they indicative of future results of operations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue $ 171,875 $ 131,691 $ 340,970 $ 255,792 Net loss $ (34,289 ) $ (26,830 ) $ (46,685 ) $ (53,360 ) Basic and diluted net loss per share $ (0.67 ) $ (0.61 ) $ (0.92 ) $ (1.22 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	4. Goodwill and Intangible Assets The goodwill activity and balances are presented below: June 30, 2018 Beginning balance as of December 31, 2017 $ 297,704 Acquisition during period 162,865 Purchase accounting adjustments 23 Closing balance $ 460,592 Intangible assets, excluding goodwill, consisted of the following: June 30, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 154,069 $ (65,574 ) $ 88,495 $ 118,869 $ (52,554 ) $ 66,315 Customer relationships 71,400 (10,092 ) 61,308 33,600 (5,918 ) 27,682 Trade names and patents 3,330 (1,095 ) 2,235 930 (825 ) 105 Order backlog 9,100 (2,783 ) 6,317 2,300 (800 ) 1,500 $ 237,899 $ (79,544 ) $ 158,355 $ 155,699 $ (60,097 ) $ 95,602 Amortization of intangible assets expense was $11,241 and $4,153 for the three months ended June 30, 2018 and 2017, respectively, and $19,447 and $8,323 for the six months ended June 30, 2018 and 2017, respectively. Future estimated amortization of intangible assets expense as of June 30, 2018 are presented below: Year ending December 31, 2018, remainder $ 21,710 2019 39,650 2020 34,566 2021 31,698 2022 13,501 Thereafter 17,230 $ 158,355

Fair Value Measurements and Inv

Fair Value Measurements and Investments	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements and Investments	5. Fair Value Measurements and Investments Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (i.e., the “exit price”) in an orderly transaction between market participants at the measurement date. A hierarchy for inputs used in measuring fair value has been defined to minimize the use of unobservable inputs by requiring the use of observable market data when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on active market data. Unobservable inputs are inputs that reflect the Company’s assumptions about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. The fair value hierarchy prioritizes the inputs into three broad levels: • Level 1: Quoted (unadjusted) prices in active markets for identical assets or liabilities. The Company’s Level 1 assets generally consist of money market funds. • Level 2: Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities 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 asset or liability. The Company’s Level 2 assets and liabilities generally consist of corporate debt securities, commercial papers, U.S. agency and Treasury securities and convertible senior notes. • Level 3: Unobservable inputs to the valuation methodology that are supported by little or no market activity and that are significant to the measurement of the fair value of the assets or liabilities. Level 3 assets and liabilities include those whose fair value measurements are determined using pricing models, discounted cash flow methodologies or similar valuation techniques, as well as significant management judgment or estimation. In connection with the acquisition of Return Path in 2016, a liability was recognized on the Return Path Acquisition Date for the estimate of the fair value of the Company’s contingent payment. The Company determined the fair value of the Acquisition-related contingent liability based on the estimated amount and timing of future contract assignments, and the probability of success. This fair value measurement is based on significant inputs not observable in the market and thus represent Level 3 measurement. The following tables summarize, for each category of assets or liabilities carried at fair value, the respective fair value as of June 30, 2018 and December 31, 2017 and the classification by level of input within the fair value hierarchy: June 30, 2018 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 71,136 $ 71,136 $ — $ — Commercial paper 14,967 — 14,967 — Corporate debt securities 1,000 — 1,000 — Short-term investments: Corporate debt securities 2,899 — 2,899 — Commercial paper 16,933 — 16,933 — Total financial assets $ 106,935 $ 71,136 $ 35,799 $ — December 31, 2017 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 231,828 $ 231,828 $ — $ — Commercial paper 7,995 — 7,995 — U.S agency securities 1,996 — 1,996 — Short-term investments: Corporate debt securities 11,600 — 11,600 — Commercial paper 27,939 — 27,939 — U.S. agency securities 3,991 — 3,991 — U.S. Treasury securities 1,996 — 1,996 — Total financial assets $ 287,345 $ 231,828 $ 55,517 $ — Liabilities Acquisition-related contingent consideration liability $ 634 $ — $ — $ 634 Based on quoted market prices as of June 30, 2018, the fair values of the 0.75% Convertible Senior Notes were approximately $332,350, determined using Level 2 inputs as they are not actively traded in markets. The following table represents a reconciliation of the Acquisition-related contingent consideration liability measured at fair value on a recurring basis, using significant unobservable inputs (Level 3): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Beginning balance $ — $ 4,221 $ 634 $ 8,233 Payments during the period — (2,054 ) (555 ) (4,620 ) Adjustments to fair value during the period recorded in general and administrative expenses — (284 ) (79 ) (1,730 ) Ending balance $ — $ 1,883 $ — $ 1,883 The carrying amounts of the Company’s cash equivalents, accounts receivable and accounts payable approximate their fair values due to their short maturities. Investments The cost and fair value of the Company’s cash and cash equivalents and available-for-sale investments as of June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 27,122 $ — $ — $ 27,122 Money market funds 71,136 — — 71,136 Corporate debt securities 1,000 — — 1,000 Commercial paper 14,967 — — 14,967 Total $ 114,225 $ — $ — $ 114,225 Short-term investments: Corporate debt securities $ 2,899 $ — $ — $ 2,899 Commercial paper 16,933 — — 16,933 Total $ 19,832 $ — $ — $ 19,832 December 31, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 44,253 $ — $ — $ 44,253 Money market funds 231,828 — — 231,828 Commercial paper 7,995 — — 7,995 U.S. agency securities 1,996 — — 1,996 Total $ 286,072 $ — $ — $ 286,072 Short-term investments: Corporate debt securities $ 11,607 $ — $ (7 ) $ 11,600 Commercial paper 27,939 — — 27,939 U.S. agency securities 3,992 — (1 ) 3,991 U.S. Treasury securities 1,997 — (1 ) 1,996 Total $ 45,535 $ — $ (9 ) $ 45,526 As of June 30, 2018 and December 31, 2017, all investments mature in less than one year. Estimated fair values for marketable securities are based on quoted market prices for the same or similar instruments. The Company reviews its investments on a quarterly basis to identify and evaluate investments that have an indication of possible impairment and has determined that no other-than-temporary impairments were required to be recognized during the three and six months ended June 30, 2018.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases The Company leases certain of its facilities under non-cancellable operating leases with various expiration dates through 2027. Premises rent expense was $2,754 and $1,892 for the three months ended June 30, 2018 and 2017, respectively, and $5,375 and $3,671 for the six months ended June 30, 2018 and 2017, respectively. Capital Lease In July 2015, the Company entered into a lease agreement (the “July 2015 Lease”) to lease certain office equipment with expiration in August 2020. The July 2015 Lease bears an annual interest rate of 6.5%. The lease is secured by fixed assets used in the Company’s office locations. At June 30, 2018, future annual minimum lease payments under non-cancellable operating and capital leases were as follows: Capital Leases Operating Leases Year ending December 31, 2018, remainder $ 20 $ 10,383 2019 37 17,657 2020 21 10,613 2021 — 5,558 2022 — 5,382 Thereafter — 6,942 Total minimum lease payments 78 $ 56,535 Less: Amount representing interest (5 ) Present value of capital lease obligations 73 Less: current portion (35 ) Long-term portion of capital lease obligations $ 38 Contingencies Under the indemnification provisions of the Company’s customer agreements, the Company agrees to indemnify and defend and hold harmless its customers against, among other things, infringement of any patent, trademark or copyright under any country’s laws or the misappropriation of any trade secret arising from the customers’ legal use of the Company’s solutions. The exposure to the Company under these indemnification provisions is generally limited to the total amount paid by the customers under the applicable customer agreement. However, certain indemnification provisions potentially expose the Company to losses in excess of the aggregate amount paid to the Company by the customer under the applicable customer agreement. To date, there have been no claims against the Company or its customers pursuant to these indemnification provisions. Legal Contingencies From time to time, the Company may be involved in legal proceedings and subject to claims in the ordinary course of business. For lawsuits where the Company is the defendant, the Company is in the process of defending these litigation matters, and while there can be no assurances and the outcomes of these matters are currently not determinable, the Company currently believes that there are no existing claims or proceedings that are likely to have a material adverse effect on the Company’s financial position, results of operations or cash flows.

Convertible Senior Notes

Convertible Senior Notes	6 Months Ended
	Jun. 30, 2018
Senior Longterm Notes Current And Noncurrent [Abstract]
Convertible Senior Notes	7. Convertible Senior Notes 0.75% Convertible Senior Notes due June 2020 On June 17, 2015, the Company issued $200,000 principal amount of 0.75% Convertible Senior Notes (the “0.75% Notes”) due 2020 in a private offering to qualified institutional buyers (“Holders”) pursuant to Rule 144A under the Securities Act of 1934, as amended (the “Securities Act”). The initial Holders of the 0.75% Notes also had an option to purchase an additional $30,000 in principal amount which was exercised in full. The net proceeds after the agent’s discount and issuance costs of $6,581 from the 0.75% Notes offering were approximately $223,419. The Company uses the net proceeds for working capital and general corporate purposes, which may include funding the Company’s operations, capital expenditures, and potential acquisitions of businesses, products or technologies. The 0.75% Notes bear interest at 0.75% per year, payable semi-annually in arrears every June 15 and December 15, beginning on December 15, 2015. The 0.75% Notes are unsecured and rank senior in right of payment to any indebtedness expressly subordinated in right of payment to the 0.75% Notes. They rank equally with the Company’s other existing and future unsecured indebtedness that is not subordinated and are structurally subordinated to any current or future secured indebtedness to the extent of the value of the assets securing the indebtedness and other liabilities of the Company’s subsidiaries. The initial conversion rate is 12.3108 shares of the Company’s common stock per $1 principal amount of notes which equates to 2,831 shares of common stock, or a conversion price equivalent of $81.23 per share of common stock. Throughout the term of the 0.75% Notes, the conversion rate may be adjusted upon the occurrence of certain events, such as the payment of cash dividends or issuance of stock warrants. The 0.75% Notes mature on June 15, 2020, unless repurchased, redeemed or converted in accordance with their terms prior to such date. At the Company’s option, on or after June 20, 2018, the Company was able to redeem all or a portion of the 0.75% Notes at 100% of the principal amount, plus any accrued and unpaid interest, under certain conditions. Prior to December 15, 2019, the 0.75% Notes will be convertible at the option of the Holders only upon the satisfaction of certain conditions and during certain periods if any of the following events occur: • during the calendar quarter commencing after September 30, 2015, if the last reported sale price of the Company’s common stock is greater than or equal to 130% of the applicable conversion price on each such trading day for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the preceding calendar quarter; • during the 5 business day period after any 5 consecutive trading day period in which the trading price, as defined, per $1 principal amount of the 0.75% Notes for each trading day of such measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate on each such trading day; • upon a notice of redemption by the Company; or • upon the occurrence of specified corporate transactions. Subsequent to December 15, 2019, Holders may convert their 0.75% Notes at the applicable conversion rate at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date. When converted, the Company may settle the 0.75% Notes in shares of the Company’s common stock, cash, or some combination of each. Holders of the 0.75% Notes also have the right to require the Company to repurchase all or a portion of the 0.75% Notes at 100% of the principal amount, plus accrued and unpaid special interest, if any, upon the occurrence of certain fundamental changes to the Company. In accordance with the authoritative accounting guidance, the Company allocated the total amount of the 0.75% Notes into liability and equity components. The carrying value of the liability component at issuance was calculated as the present value of its cash flows using a discount rate of 6.5% based on the blended rate between the yield rate for a Moody’s B1 rating and the average debt rate for comparable convertible transactions from similar companies. The difference between the 0.75% Notes principal and the carrying value of the liability component, representing the value of conversion premium assigned to the equity component, was recorded as an increase to additional paid in capital and as a debt discount on the issuance date. The equity component is being accreted using the effective interest rate method over the period from the issuance date through June 15, 2020 as a non-cash charge to interest expense. The amount recorded to additional paid in capital is not remeasured as long as it continues to meet the conditions for equity classification. Upon issuance of the 0.75% Notes, the Company recorded $174,359 as debt and $55,641 as additional paid in capital within stockholders’ equity. Additionally, the debt discount and issuance costs were allocated based on the total amount incurred to the liability and equity components using the same proportions as the proceeds from the 0.75% Notes. The equity issuance costs of $1,592 were recorded as a decrease to additional paid-in capital at the issuance date. The following tables presents the carrying values of the 0.75% Notes as of June 30, 2018 and December 31, 2017: June 30, 2018 December 31, 2017 Liability component: Principal $ 230,000 $ 230,000 Less: debt discount and issuance costs, net of amortization (25,989 ) (32,142 ) Net carrying amount $ 204,011 $ 197,858 Equity component (1) $ 54,049 $ 54,049 (1) Recorded on the condensed consolidated balance sheets as additional paid-in capital, net of the issuance costs in equity 1.25% Convertible Senior Notes due December 2018 On December 11, 2013, the Company issued $175,000 principal amount of 1.25% Convertible Senior Notes (the “1.25% Notes”) due 2018 in a private offering to Holders pursuant to Rule 144A under the Securities Act. The initial Holders of the 1.25% Notes also had an option to purchase an additional $26,250 in principal amount which was exercised in full. The net proceeds after the agent’s discount and issuance costs of $5,803 from the 1.25% Notes offering were approximately $195,446. The Company used the net proceeds for working capital and general corporate purposes, which included funding the Company’s operations, capital expenditures, and acquisitions of businesses, products or technologies believed to be of strategic importance. The 1.25% Notes bore interest at 1.25% per year, payable semi-annually in arrears every June 15 and December 15, beginning on June 15, 2014. During the year ended December 31, 2017, the entire $201,250 of the principal amount of the 1.25% Notes was converted into 5,159 shares of common stock, with the remaining $14 paid in cash. For the three and six months ended June 30, 2018 and 2017, the Company incurred the following interest expense related to the convertible senior notes: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Interest expense related to contractual interest coupon $ 431 $ 1,060 $ 862 $ 2,120 Amortization of debt discount and issuance costs 3,100 5,484 6,153 10,888 $ 3,531 $ 6,544 $ 7,015 $ 13,008

Equity Award Plans

Equity Award Plans	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Award Plans	8. Equity Award Plans Stock-Based Compensation Plans On March 30, 2012, the Board of Directors and the Company’s stockholders approved the 2012 Equity Incentive Plan (the “2012 Plan”), which became effective in April 2012. The Company has six equity incentive plans: the Company’s 2002 stock option plan (the “2002 Plan”), the 2012 Plan and four plans assumed by the Company upon various business acquisitions. The assumed plans are the Cloudmark plan, the WebLife plan, and two FireLayers plans. Upon the Company’s initial public offering, all shares that were reserved under the 2002 Plan but not issued, and shares issued but subsequently returned to the plan through forfeitures, cancellations and repurchases became part of the 2012 Plan and no further shares will be granted pursuant to the 2002 Plan. No further shares will be granted pursuant to the assumed plans. All outstanding stock awards under the 2002 Plan, the assumed plans and 2012 Plan will continue to be governed by their existing terms. Under the 2012 Plan, the Company has the ability to issue incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), restricted stock awards, stock bonus awards, stock appreciation rights (“SARs”), restricted stock units (“RSUs”), and performance stock units (“PSUs”). The 2012 Plan also allows direct issuance of common stock to employees, outside directors and consultants at prices equal to the fair market value at the date of grant of options or issuance of common stock. Additionally, the 2012 Plan provides for the grant of performance cash awards to employees, directors and consultants. The Company has the right to repurchase any unvested shares (at the option exercise price) of common stock issued directly or under option exercises. The right of repurchase generally expires over the vesting period. Stock bonus and other liability awards are accounted for as liability-classified awards, because the obligations are based predominantly on fixed monetary amounts that are generally known at the inception of the obligation, to be settled with a variable number of shares of the Company’s common stock. Under the equity incentive plans, the term of an option grant shall not exceed ten years from the date of its grant and options generally vest over a three to four-year period, with vesting on a monthly or annual interval. Under the 2012 Plan, 20,316 shares of common stock are reserved for issuance to eligible participants. As of June 30, 2018, 4,652 shares were available for future grant. Restricted stock awards generally vest over a four-year period. The Company net-share settles equity awards held by employees by withholding shares upon vesting to satisfy tax withholding obligations. The shares withheld to satisfy employee tax withholding obligations are returned to the Company’s 2012 Plan and will be available for future issuance. Payments for employee’s tax obligations to the tax authorities are recognized as a reduction to additional paid-in capital and reflected as financing activities in the Company’s consolidated statements of cash flows. Stock Options There were no options granted during the three and six months ended June 30, 2018 and 2017. The Company realized no income tax benefit from stock option exercises in each of the periods presented due to recurring losses and the valuation allowances for deferred tax assets. Stock option activity under the Plan is as follows: Shares subject to Options Outstanding Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Balance at December 31, 2017 2,040 $ 22.88 5.17 $ 134,511 Options exercised (288 ) 14.81 Options forfeited and expired (11 ) 50.48 Balance at June 30, 2018 1,741 $ 24.05 4.77 $ 158,844 The total intrinsic value of options exercised was $27,181 and $53,497 for the six months ended June 30, 2018 and 2017, respectively. Total cash proceeds from such option exercises were $4,276 and $7,112 for the six months ended June 30, 2018 and 2017, respectively. The fair value of option grants that vested was $1,925 and $4,385 for the six months ended June 30, 2018 and 2017, respectively. As of June 30, 2018, the Company had unamortized stock-based compensation expense of $4,655 related to stock options that will be recognized over the average remaining vesting term of the options of 1.36 years. Restricted Stock and Performance Stock Units A following table summarized the activity of RSUs and PSUs: RSUs and PSUs Outstanding Number of Shares Granted Fair Value Per Unit Awarded and unvested at December 31, 2017 3,540 $ 71.77 Awards granted 1,265 117.47 Awards vested (752 ) 62.66 Awards forfeited (315 ) 86.88 Awarded and unvested at June 30, 2018 3,738 $ 87.79 As of June 30, 2018, there was $252,205 of unamortized stock-based compensation expense related to unvested RSUs, which is expected to be recognized over a weighted average period of 2.89 years. The Company granted 166 and 177 PSUs in the six months ended June 30, 2018 and 2017, respectively. The PSU vesting conditions were based on individual performance targets. Unamortized stock-based compensation expense was $28,155 as of June 30, 2018. Stock Bonus and Other Liability Awards The total accrued liability for the stock bonus and other liability awards was $6,062 and $8,502 as of June 30, 2018 and December 31, 2017, respectively. During the six months ended June 30, 2018 and 2017, 61 and 85 shares, respectively, of common stock earned under the stock bonus program were issued. Stock-based compensation expense related to stock bonus program was $6,022 and $2,573 for the six months ended June 30, 2018 and 2017, respectively. In March 2015, the Company issued liability awards with a fair value of $6,885, which vested annually over a three-year period and were subject to continuous service and other conditions. The liability was settled with a variable number of shares of the Company’s common stock. During the six months ended June 30, 2018 and 2017, 20 and 29 shares, respectively, were vested and issued. The Company recognized $408 and $1,137 of stock-based compensation expense related to these liability awards in the six months ended June 30, 2018 and 2017, respectively. There are no outstanding liability awards as of June 30, 2018. Employee Stock Purchase Plan On March 30, 2012, the Board of Directors and the Company’s stockholders approved the 2012 Employee Stock Purchase Plan (the “ESPP”), which became effective in April 2012. A total of 745 shares of the Company’s common stock were initially reserved 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 with 2013 by the number of shares equal to 1% of the Company’s shares outstanding on the immediately preceding December 31, but not to exceed 1,490 shares, unless the Board of Directors, in its discretion, determines to make a smaller increase. As of June 30, 2018, there were 1,998 shares of the Company’s common stock available for future issuance under the ESPP. As of June 30, 2018, the Company expects to recognize $621 of the total unamortized compensation cost related to employee purchases under the ESPP over a weighted average period of 0.4 years. Restricted Stock and Deferred Shares The Company granted 111 shares of restricted stock in 2016 to certain key employees with the total fair value of $8,669 with annual vesting term of three years. The Company recognized $1,432 of stock-based compensation expense in each of the six months ended June 30, 2018 and 2017. As of June 30, 2018, there was $3,804 of unamortized stock-based compensation expense related to the unvested shares of restricted stock. The shares of restricted stock are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and are expensed over the vesting period. They are considered issued and outstanding shares of the Company at the grant date and have the same rights as other shares of common stock. As part of the WebLife acquisition, 107 shares were deferred for certain key employees with the total fair value of $9,652, and a vesting period between three and four years. The Company recognized $1,197 of stock-based compensation in the six months ended June 30, 2018. As of June 30, 2018, there was $8,249 of unamortized stock-based compensation expense related to the unvested deferred shares. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the deferral date, and are expensed over the vesting period. As part of the Wombat acquisition, 51 shares were deferred for certain key employees with the total fair value of $5,458, and a vesting period of two years. The Company recognized $912 of stock-based compensation in the six months ended June 30, 2018. As of June 30, 2018, there was $4,546 of unamortized stock-based compensation expense related to the unvested deferred shares. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the deferral date, and are expensed over the vesting period.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Loss per Share	9. Net Loss per Share Basic net loss per share of common stock is calculated by dividing the net loss 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 basic net loss per share of common stock excludes those shares subject to repurchase related to stock options or restricted stock that were exercised or issued prior to vesting as these shares are not deemed to be issued for accounting purposes until they vest. Diluted net loss per share of common stock is computed by dividing the net loss using the weighted‑average number of shares of common stock, excluding common stock subject to repurchase, and, if dilutive, potential shares of common stock outstanding during the period. Basic and diluted net loss per common share was the same for all periods presented as the impact of all potentially dilutive securities outstanding was anti-dilutive. The following table presents the potentially dilutive common shares outstanding that were excluded from the computation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: June 30, 2018 June 30, 2017 Stock options to purchase common stock 1,741 2,407 Restricted stock units 3,738 3,319 Employee stock purchase plan 97 102 Common stock subject to repurchase 181 127 Bonus and other liability awards 53 56 1.25% Convertible senior notes — 5,158 0.75% Convertible senior notes 2,831 2,831 Total 8,641 14,000

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	10. Segment Reporting Operating segments are reported in a manner consistent with the internal reporting supported and defined by the components of an enterprise about which separate financial information is available, provided and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is its Chief Executive Officer. The Company’s Chief Executive Officer reviews financial information presented on a consolidated basis. The Company has one business activity, and there are no segment managers who are held accountable for operations, operating results and plans for levels or components below the consolidated unit level. Accordingly, the Company determined that it has one operating and reportable segment. The following sets forth total revenue by solutions offered by the Company and by geographic area. Revenue by geographic area is based upon the billing address of the customer: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue by solution: Advanced Threat $ 129,208 $ 88,680 $ 252,821 $ 172,182 Compliance 42,667 33,761 81,515 65,894 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue: United States $ 140,504 $ 102,517 $ 274,160 $ 199,991 Rest of world 31,371 19,924 60,176 38,085 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076 Long-lived assets by geographic area are presented below: June 30, 2018 December 31, 2017 Long-lived assets: United States $ 61,765 $ 66,134 Rest of world 14,176 7,483 Total long-lived assets $ 75,941 $ 73,617

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The Company’s quarterly provision for income taxes is based on an estimated effective annual income tax rate. The Company’s quarterly provision for income taxes also includes the tax impact of certain unusual or infrequently occurring items, if any, including changes in judgment about valuation allowances and effects of changes in tax laws or rates, in the interim period in which they occur. Income tax expense (benefit) from the three and six months ended June 30, 2018 was $114 and $(13,958) on pre-tax losses of $34,184 and $60,412, respectively. The Company recognized income tax expense of $999 and $2,433 on pre-tax losses of $22,496 and $41,345 for the three and six months ended June 30, 2017, respectively. The income tax rate for the three and six months ended June 30, 2018 varied from the United States statutory income tax rate primarily due to valuation allowances in the United States whereby pre-tax losses and income do not result in the recognition of corresponding income tax benefits and expenses and also the recognition of a $14,725 deferred tax benefit in the U.S. related to changes in the Company’s valuation allowance resulting from the Wombat business acquisition. The income tax rate for the three and six months ended June 30, 2017 varied from the United States statutory income tax rate primarily due to valuation allowances in the United States whereby pre-tax losses and income do not result in the recognition of corresponding income tax benefits and expenses. The Company’s effective tax rate for the six months ended June 30, 2018 and 2017 was 23% and negative 6%, respectively. In December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act significantly impacted the future ongoing U.S. corporate income tax by lowering the U.S. corporate income tax rates from 34% to 21%, providing for unlimited net operating loss carry-forward periods, and implementing a territorial tax system, among other changes. The reduction of the U.S. corporate tax rate required the Company to revalue its U.S. deferred tax assets and liabilities to the recently enacted federal rate of 21% in the quarter ended December 31, 2017 which resulted in a $87,621 reduction of certain of the Company’s US deferred tax assets which are offset by a full valuation allowance. This transitional impact also resulted in a deferred tax benefit of $2,024 in the quarter ended December 31, 2017 related to a reduction in a US deferred tax liability on certain long-lived acquired intangibles. As part of the transition to the new territorial tax system, the Act imposes a one-time repatriation tax on deemed repatriation of historical earnings of foreign subsidiaries. Based on the current evaluation of the company’s operations, no repatriation tax charge is anticipated due to negative earnings and profits in the Company’s foreign subsidiaries. The Company continues to appropriately refine such amounts within the measurement period allowed by Staff Accounting Bulletin (“SAB”) No. 118, which will continue through the end of 2018. In addition, further interpretations from U.S. Federal and state governments and regulatory organizations may change the accounting treatment of the provisional tax liability. As of June 30, 2018, the amounts recorded for the Tax Act remain provisional for the repatriation tax, the remeasurement of deferred taxes, and our reassessment of permanently reinvested earnings, uncertain tax positions and valuation allowances. These estimates may be impacted by further analysis and future clarification and guidance regarding available tax accounting methods and elections, earnings and profits computations, state tax conformity to federal tax changes, among others. The Company reviews the likelihood that it will realize the benefit of its deferred tax assets and, therefore, the need for valuation allowances, on a quarterly basis. There is no corresponding income tax benefit recognized with respect to losses incurred and no corresponding income tax expense recognized with respect to earnings generated in jurisdictions with a valuation allowance. This causes variability in the Company’s effective tax rate. The Company intends to maintain the valuation allowances until it is more likely than not that the net deferred tax assets will be realized. During the three months ended March 31, 2017, the Company transferred certain intellectual property rights from its wholly owned subsidiary in Israel to the United States. Although the transfer of intellectual property rights between consolidated entities did not result in any gain in the consolidated statements of operations, the transfer did result in a taxable gain in Israel. In the Company’s financial statements ending before January 1, 2018, taxes incurred related to the intercompany transaction have been treated as a prepaid tax asset in the Company’s consolidated balance sheet and were being amortized to income tax expense over the life of the intellectual property. Effective January 1, 2018, pursuant to the Company’s modified prospective adoption of ASU 2016-16, the Company’s remaining prepaid tax asset of $3,216 was recorded as an increase to accumulated deficit. As of June 30, 2018, the Company’s gross uncertain tax benefits totaled $14,922, excluding related accrued interest and penalties of $349. As of June 30, 2018, $5,045 of the Company’s uncertain tax benefits, including related accrued interest and penalties, would impact the effective tax rate if recognized. During the six months ended June 30, 2018, the Company’s gross uncertain tax benefits increased $425. The increase is comprised of a $671 increase for tax positions taken in the current period, offset by a $209 decrease for tax positions taken in prior periods and a $37 decrease related to statute of limitation expirations. The Company is currently under audit by the Israel Tax Authority for tax years 2013 through 2017. Related to the audit by the Israel Tax Authority it is reasonably possible that the Company’s uncertain tax positions could change within the next 12 months. An estimate of the range of any change cannot be made. The Company believes it has recorded all appropriate provisions for all jurisdictions and open years. However, the Company can give no assurance that taxing authorities will not propose adjustments that would increase its tax liabilities. The Company is not currently under audit by the IRS or any similar taxing authority in any other material jurisdiction.

Defined Contribution Plan

Defined Contribution Plan	6 Months Ended
	Jun. 30, 2018
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Defined Contribution Plan	12. Defined Contribution Plan The Company’s tax-deferred savings plan is qualified under Section 401(k) of the United States Internal Revenue Code. Employees may make voluntary, tax-deferred contributions to the 401(k) Plan up to the statutorily prescribed annual limit. The Company makes discretionary matching contributions to the 401(k) Plan on behalf of employees up to the limit determined by the Board of Directors. The Company contributed $958 to the 401(k) Plan during both three and six months ended June 30, 2018.

The Company and Summary of Si20

The Company and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation These condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”), pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and note disclosures have been condensed or omitted pursuant to such rules and regulations. The accompanying Condensed Consolidated Balance Sheet as of December 31, 2017 is derived from audited financial statements as of that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. Certain prior period amounts have been adjusted due to the adoption of Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers: Topic 606 These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC. The Company’s significant accounting policies are described in Note 1 to those audited consolidated financial statements. See Note 2 “Revenue, Deferred Revenue and Deferred Contract Costs” for the summary of the new accounting policies under ASC 606.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates and such difference may be material to the financial statements.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill represents the excess of the purchase price of the acquired enterprise over the fair value of identifiable assets acquired and liabilities assumed. The Company performs an annual goodwill impairment test during the fourth quarter of a calendar year and more frequently if an event or circumstances indicates that impairment may have occurred. For the purposes of impairment testing, the Company has determined that it has one operating segment and one reporting unit. The Company performs a two-step impairment test of goodwill whereby the fair value of the reporting unit is compared to its carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets assigned to that unit, goodwill is not considered impaired and further testing is not required. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company must perform the second step of the impairment test in order to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of a reporting unit’s goodwill exceeds its implied fair value, then impairment loss equal to the difference is recorded. The identification and measurement of goodwill impairment involves the estimation of the fair value of the Company. The estimate of fair value of the Company, based on the best information available as of the date of the assessment, is subjective and requires judgment, including management assumptions about expected future revenue forecasts and discount rates, changes in the overall economy, trends in the stock price and other factors. No impairment indicators were identified by the Company as of June 30, 2018. Intangible assets consist of developed technology, customer relationships, non-compete arrangements, trademarks and patents and order backlog. The values assigned to intangibles are based on estimates and judgments regarding expectations for success and life cycle of solutions and technologies acquired. Intangible assets are amortized on a straight-line basis over their estimated lives, which approximate the pattern in which the economic benefits of the intangible assets are consumed, as follows (in years): Low High Patents 4 5 Developed technology 3 7 Customer relationships 2 8 Order backlog 1 3 Trade names and trademarks 1 5
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes all changes in equity that are not the result of transactions with stockholders. The Company’s comprehensive loss consists of its net loss and changes in unrealized gains (losses) from its available-for-sale investments. The Company had no material reclassifications out of accumulated other comprehensive loss into net loss for the three and six months ended June 30, 2018 and 2017.
New Accounting Pronouncements	Accounting Pronouncements Adopted in 2018 In May 2014, the FASB issued ASC 606 to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The standard contains a comprehensive new revenue recognition model that requires revenue to be recognized in a manner to depict the transfer of services or products to a customer at an amount that reflects the consideration expected to be received in exchange for those services or products. The FASB has issued several amendments to the standard, including clarifications on disclosure of prior-period and remaining performance obligations. The Company adopted ASC 606 effective January 1, 2018 using full retrospective transition method. Refer to Note 2 “Revenue, Deferred Revenue and Deferred Contract Costs” for more information. In October 2016, FASB issued ASU No. 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory In August 2016, FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ” ” Recent Accounting Pronouncements Not Yet Effective In January 2017, FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment In June 2016, FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842)

The Company and Summary of Si21

The Company and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Estimated Useful Life of Intangible Assets	Intangible assets are amortized on a straight-line basis over their estimated lives, which approximate the pattern in which the economic benefits of the intangible assets are consumed, as follows (in years): Low High Patents 4 5 Developed technology 3 7 Customer relationships 2 8 Order backlog 1 3 Trade names and trademarks 1 5

Revenue, Deferred Revenue and22

Revenue, Deferred Revenue and Deferred Contract Costs (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue From Contract With Customer [Abstract]
Impact of ASC 606 Adoption	Select condensed consolidated balance sheet line items, which reflect the adoption of the new standard, are as follows: December 31, 2017 As Previously Reported Adjustments As Adjusted Assets Accounts receivable, net $ 109,325 $ (1,629 ) $ 107,696 Deferred commissions, current $ 27,144 $ (895 ) $ 26,249 Long-term deferred commissions $ 5,811 $ 46,143 $ 51,954 Liabilities Accrued liabilities $ 63,926 $ 1,577 $ 65,503 Deferred revenue $ 381,915 $ (17,394 ) $ 364,521 Long-term deferred revenue $ 69,873 $ (6,555 ) $ 63,318 Stockholders’ Equity Accumulated deficit $ (554,444 ) $ 65,991 $ (488,453 ) Select unaudited condensed consolidated statements of operations line items, which reflect the adoption of the new standard, are as follows: Three Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Revenue: Subscription $ 118,928 $ (225 ) $ 118,703 Hardware and services 3,401 337 3,738 Total revenue $ 122,329 $ 112 $ 122,441 Gross profit $ 87,836 $ 112 $ 87,948 Operating expense: Sales and marketing $ 62,454 $ (2,328 ) $ 60,126 Operating loss $ (19,272 ) $ 2,440 $ (16,832 ) Net loss $ (25,935 ) $ 2,440 $ (23,495 ) Net loss per share, basic and diluted $ (0.59 ) $ 0.05 $ (0.54 ) Six Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Revenue: Subscription $ 229,853 $ 1,941 $ 231,794 Hardware and services 5,726 556 6,282 Total revenue $ 235,579 $ 2,497 $ 238,076 Gross profit $ 168,710 $ 2,497 $ 171,207 Operating expense: Sales and marketing $ 121,186 $ (5,140 ) $ 116,046 Operating loss $ (37,223 ) $ 7,637 $ (29,586 ) Net loss $ (51,415 ) $ 7,637 $ (43,778 ) Net loss per share, basic and diluted $ (1.18 ) $ 0.18 $ (1.00 ) Select unaudited condensed consolidated statement of cash flows line items, which reflect the adoption of the new standard are as follows: Six Months Ended June 30, 2017 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (51,415 ) $ 7,637 $ (43,778 ) Adjustments to reconcile net loss to net cash provided by operating activities: Amortization of deferred commissions $ — $ 13,275 $ 13,275 Changes in assets and liabilities: Accounts receivable $ (2,725 ) $ (21 ) $ (2,746 ) Deferred commissions $ 791 $ (18,414 ) $ (17,623 ) Accrued liabilities $ 4,014 $ 551 $ 4,565 Deferred revenue $ 48,168 $ (3,028 ) $ 45,140 Net cash provided by operating activities $ 66,955 $ — $ 66,955
Disaggregation of Revenue	The following table presents the Company’s revenue disaggregation: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Subscription service revenue $ 165,365 $ 115,811 $ 317,985 $ 224,137 Subscription software revenue 3,654 2,892 9,821 7,657 Hardware and services 2,856 3,738 6,530 6,282 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2018
Business Acquisition [Line Items]
Pro Forma Financial Information of Business Acquisitions	Accordingly, these unaudited pro forma results are presented for informational purposes only and are not necessarily indicative of what the actual results of operations of the combined company would have been if the acquisition had occurred at the beginning of the period presented, nor are they indicative of future results of operations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue $ 171,875 $ 131,691 $ 340,970 $ 255,792 Net loss $ (34,289 ) $ (26,830 ) $ (46,685 ) $ (53,360 ) Basic and diluted net loss per share $ (0.67 ) $ (0.61 ) $ (0.92 ) $ (1.22 )
Wombat
Business Acquisition [Line Items]
Summary of the Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Goodwill	The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 23,344 N/A Fixed assets 954 N/A Customer relationships 37,800 7 Order backlog 6,800 2 Core/developed technology 35,200 4 Trade name 2,400 4 Deferred revenue (14,700 ) N/A Deferred tax liability, net (14,725 ) N/A Other liabilities (1,120 ) N/A Goodwill 162,865 Indefinite $ 238,818
Cloudmark
Business Acquisition [Line Items]
Summary of the Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Goodwill	The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 37,390 N/A Fixed assets 543 N/A Non-current assets 50 N/A Liabilities (4,565 ) N/A Deferred revenue (15,400 ) N/A Customer relationships 15,300 8 Order backlog 1,400 1 Core/developed technology 18,500 4 Deferred tax liability, net (7,905 ) N/A Goodwill 93,943 Indefinite $ 139,256
WebLife Balance, Inc.
Business Acquisition [Line Items]
Summary of the Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Goodwill	The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill: Estimated Fair Value Estimated Useful Life (in years) Current assets $ 534 N/A Fixed assets 23 N/A Liabilities (88 ) N/A Deferred revenue (700 ) N/A Customer relationships 600 5 Core/developed technology 16,600 5 Deferred tax liability, net (4,440 ) N/A Goodwill 36,514 Indefinite $ 49,043

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill Activity and Balances	The goodwill activity and balances are presented below: June 30, 2018 Beginning balance as of December 31, 2017 $ 297,704 Acquisition during period 162,865 Purchase accounting adjustments 23 Closing balance $ 460,592
Components of Intangible Assets, Excluding Goodwill	Intangible assets, excluding goodwill, consisted of the following: June 30, 2018 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 154,069 $ (65,574 ) $ 88,495 $ 118,869 $ (52,554 ) $ 66,315 Customer relationships 71,400 (10,092 ) 61,308 33,600 (5,918 ) 27,682 Trade names and patents 3,330 (1,095 ) 2,235 930 (825 ) 105 Order backlog 9,100 (2,783 ) 6,317 2,300 (800 ) 1,500 $ 237,899 $ (79,544 ) $ 158,355 $ 155,699 $ (60,097 ) $ 95,602
Future Estimated Amortization of Intangible Assets Expense	Amortization of intangible assets expense was $11,241 and $4,153 for the three months ended June 30, 2018 and 2017, respectively, and $19,447 and $8,323 for the six months ended June 30, 2018 and 2017, respectively. Future estimated amortization of intangible assets expense as of June 30, 2018 are presented below: Year ending December 31, 2018, remainder $ 21,710 2019 39,650 2020 34,566 2021 31,698 2022 13,501 Thereafter 17,230 $ 158,355

Fair Value Measurements and I25

Fair Value Measurements and Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Summary of Assets or Liabilities Carried at Fair Value	The following tables summarize, for each category of assets or liabilities carried at fair value, the respective fair value as of June 30, 2018 and December 31, 2017 and the classification by level of input within the fair value hierarchy: June 30, 2018 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 71,136 $ 71,136 $ — $ — Commercial paper 14,967 — 14,967 — Corporate debt securities 1,000 — 1,000 — Short-term investments: Corporate debt securities 2,899 — 2,899 — Commercial paper 16,933 — 16,933 — Total financial assets $ 106,935 $ 71,136 $ 35,799 $ — December 31, 2017 Total Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 231,828 $ 231,828 $ — $ — Commercial paper 7,995 — 7,995 — U.S agency securities 1,996 — 1,996 — Short-term investments: Corporate debt securities 11,600 — 11,600 — Commercial paper 27,939 — 27,939 — U.S. agency securities 3,991 — 3,991 — U.S. Treasury securities 1,996 — 1,996 — Total financial assets $ 287,345 $ 231,828 $ 55,517 $ — Liabilities Acquisition-related contingent consideration liability $ 634 $ — $ — $ 634
Reconciliation of the Acquisition-Related Contingent Consideration Liability Measured at Fair Value	The following table represents a reconciliation of the Acquisition-related contingent consideration liability measured at fair value on a recurring basis, using significant unobservable inputs (Level 3): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Beginning balance $ — $ 4,221 $ 634 $ 8,233 Payments during the period — (2,054 ) (555 ) (4,620 ) Adjustments to fair value during the period recorded in general and administrative expenses — (284 ) (79 ) (1,730 ) Ending balance $ — $ 1,883 $ — $ 1,883
Summary of Cost and Fair Value of Cash and Cash Equivalents and Available-for-Sale Investments	The cost and fair value of the Company’s cash and cash equivalents and available-for-sale investments as of June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 27,122 $ — $ — $ 27,122 Money market funds 71,136 — — 71,136 Corporate debt securities 1,000 — — 1,000 Commercial paper 14,967 — — 14,967 Total $ 114,225 $ — $ — $ 114,225 Short-term investments: Corporate debt securities $ 2,899 $ — $ — $ 2,899 Commercial paper 16,933 — — 16,933 Total $ 19,832 $ — $ — $ 19,832 December 31, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 44,253 $ — $ — $ 44,253 Money market funds 231,828 — — 231,828 Commercial paper 7,995 — — 7,995 U.S. agency securities 1,996 — — 1,996 Total $ 286,072 $ — $ — $ 286,072 Short-term investments: Corporate debt securities $ 11,607 $ — $ (7 ) $ 11,600 Commercial paper 27,939 — — 27,939 U.S. agency securities 3,992 — (1 ) 3,991 U.S. Treasury securities 1,997 — (1 ) 1,996 Total $ 45,535 $ — $ (9 ) $ 45,526

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Future Annual Minimum Lease Payments under Non-cancellable Operating and Capital Leases	At June 30, 2018, future annual minimum lease payments under non-cancellable operating and capital leases were as follows: Capital Leases Operating Leases Year ending December 31, 2018, remainder $ 20 $ 10,383 2019 37 17,657 2020 21 10,613 2021 — 5,558 2022 — 5,382 Thereafter — 6,942 Total minimum lease payments 78 $ 56,535 Less: Amount representing interest (5 ) Present value of capital lease obligations 73 Less: current portion (35 ) Long-term portion of capital lease obligations $ 38

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	6 Months Ended
	Jun. 30, 2018
Senior Longterm Notes Current And Noncurrent [Abstract]
Summary of Carrying Values and Interest Expense Related to Convertible Senior Notes	The following tables presents the carrying values of the 0.75% Notes as of June 30, 2018 and December 31, 2017: June 30, 2018 December 31, 2017 Liability component: Principal $ 230,000 $ 230,000 Less: debt discount and issuance costs, net of amortization (25,989 ) (32,142 ) Net carrying amount $ 204,011 $ 197,858 Equity component (1) $ 54,049 $ 54,049 (1) Recorded on the condensed consolidated balance sheets as additional paid-in capital, net of the issuance costs in equity For the three and six months ended June 30, 2018 and 2017, the Company incurred the following interest expense related to the convertible senior notes: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Interest expense related to contractual interest coupon $ 431 $ 1,060 $ 862 $ 2,120 Amortization of debt discount and issuance costs 3,100 5,484 6,153 10,888 $ 3,531 $ 6,544 $ 7,015 $ 13,008

Equity Award Plans (Tables)

Equity Award Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Activity under Stock Incentive Plan	Stock option activity under the Plan is as follows: Shares subject to Options Outstanding Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Balance at December 31, 2017 2,040 $ 22.88 5.17 $ 134,511 Options exercised (288 ) 14.81 Options forfeited and expired (11 ) 50.48 Balance at June 30, 2018 1,741 $ 24.05 4.77 $ 158,844
Summary of RSUs and PSUs under Stock Incentive Plan	A following table summarized the activity of RSUs and PSUs: RSUs and PSUs Outstanding Number of Shares Granted Fair Value Per Unit Awarded and unvested at December 31, 2017 3,540 $ 71.77 Awards granted 1,265 117.47 Awards vested (752 ) 62.66 Awards forfeited (315 ) 86.88 Awarded and unvested at June 30, 2018 3,738 $ 87.79

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Common Shares Outstanding that were Excluded from the Computation of Diluted Net Loss per Share	The following table presents the potentially dilutive common shares outstanding that were excluded from the computation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: June 30, 2018 June 30, 2017 Stock options to purchase common stock 1,741 2,407 Restricted stock units 3,738 3,319 Employee stock purchase plan 97 102 Common stock subject to repurchase 181 127 Bonus and other liability awards 53 56 1.25% Convertible senior notes — 5,158 0.75% Convertible senior notes 2,831 2,831 Total 8,641 14,000

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Summary of Total Revenue by Solutions Offered by the Company	The following sets forth total revenue by solutions offered by the Company and by geographic area. Revenue by geographic area is based upon the billing address of the customer: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue by solution: Advanced Threat $ 129,208 $ 88,680 $ 252,821 $ 172,182 Compliance 42,667 33,761 81,515 65,894 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076
Summary of Total Revenue and Long-lived Assets by Geographic Area	Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenue: United States $ 140,504 $ 102,517 $ 274,160 $ 199,991 Rest of world 31,371 19,924 60,176 38,085 Total revenue $ 171,875 $ 122,441 $ 334,336 $ 238,076 Long-lived assets by geographic area are presented below: June 30, 2018 December 31, 2017 Long-lived assets: United States $ 61,765 $ 66,134 Rest of world 14,176 7,483 Total long-lived assets $ 75,941 $ 73,617

The Company and Summary of Si31

The Company and Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018USD ($)segmentreporting_unit	Dec. 31, 2017USD ($)
Intangible assets:
Number of operating and reportable segments | segment	1
Number of reporting units | reporting_unit	1
Goodwill, impairment loss	$ 0
ASU 2016-16
Intangible assets:
Increase in accumulated deficit due to ASU 2016-16 adoption		$ 3,216,000

The Company and Summary of Si32

The Company and Summary of Significant Accounting Policies - Summary of Estimated Lives of Intangible Assets (Details)	6 Months Ended
	Jun. 30, 2018
Minimum | Patents
Intangible assets:
Estimated life of intangible assets	4 years
Minimum | Developed Technology
Intangible assets:
Estimated life of intangible assets	3 years
Minimum | Customer Relationships
Intangible assets:
Estimated life of intangible assets	2 years
Minimum | Order Backlog
Intangible assets:
Estimated life of intangible assets	1 year
Minimum | Trade Names and Trademarks
Intangible assets:
Estimated life of intangible assets	1 year
Maximum | Patents
Intangible assets:
Estimated life of intangible assets	5 years
Maximum | Developed Technology
Intangible assets:
Estimated life of intangible assets	7 years
Maximum | Customer Relationships
Intangible assets:
Estimated life of intangible assets	8 years
Maximum | Order Backlog
Intangible assets:
Estimated life of intangible assets	3 years
Maximum | Trade Names and Trademarks
Intangible assets:
Estimated life of intangible assets	5 years

Revenue, Deferred Revenue and33

Revenue, Deferred Revenue and Deferred Contract Costs - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Feb. 28, 2018	Dec. 31, 2017
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Remaining performance obligations for contracts with an original expected length of one year or less.			true
Unbilled receivable	$ 1,090		$ 1,090			$ 603
Deferred revenue, revenue recognized	149,817	$ 101,114	237,395	$ 165,210
Revenue recognized related to the performance obligations satisfied in prior periods	2,091	1,054	2,584	1,034
Long-term Contract with Customer
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Contracted revenue not yet recognized	389,492		389,492
Wombat
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Deferred revenue, revenue recognized			6,720
Deferred revenue assumed from business acquisition					$ 14,700
Sales Commission
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Contract cost capitalized	12,715	10,874	21,929	17,623
Contract cost amortized	8,334	6,666	16,708	13,275
Product Cost
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Contract cost capitalized	758	600	1,436	1,164
Contract cost amortized	$ 611	$ 869	$ 1,183	$ 1,523
Minimum
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Period terms for payment			30 days
Maximum
Revenue, Deferred Revenue and Deferred Contract Costs[Line Items]
Period terms for payment			45 days

Revenue, Deferred Revenue and34

Revenue, Deferred Revenue and Deferred Contract Costs - Impact of ASC 606 Adoption (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Assets
Accounts receivable, net	$ 140,644		$ 140,644		$ 107,696
Deferred commissions, current	29,711		29,711		26,249
Long-term deferred commissions	53,712		53,712		51,954
Liabilities
Accrued liabilities	62,404		62,404		65,503
Deferred revenue	426,090		426,090		364,521
Long-term deferred revenue	65,147		65,147		63,318
Stockholders’ Equity
Accumulated deficit	(538,123)		(538,123)		(488,453)
Revenue:
Total revenue	171,875	$ 122,441	334,336	$ 238,076
Gross profit	121,103	87,948	236,507	171,207
Operating expense:
Sales and marketing	84,911	60,126	162,808	116,046
Operating loss	(30,364)	(16,832)	(54,114)	(29,586)
Net loss	$ (34,298)	$ (23,495)	$ (46,454)	$ (43,778)
Net loss per share, basic and diluted	$ (0.67)	$ (0.54)	$ (0.92)	$ (1)
Cash flows from operating activities
Net loss	$ (34,298)	$ (23,495)	$ (46,454)	$ (43,778)
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of deferred commissions			16,708	13,275
Changes in assets and liabilities:
Accounts receivable			(23,025)	(2,746)
Deferred commissions			(21,929)	(17,623)
Accrued liabilities			(4,498)	4,565
Deferred revenue			48,698	45,140
Net cash provided by operating activities			64,986	66,955
Subscription
Revenue:
Total revenue	169,019	118,703	327,806	231,794
Hardware and Service
Revenue:
Total revenue	$ 2,856	3,738	$ 6,530	6,282
As Previously Reported
Assets
Accounts receivable, net					109,325
Deferred commissions, current					27,144
Long-term deferred commissions					5,811
Liabilities
Accrued liabilities					63,926
Deferred revenue					381,915
Long-term deferred revenue					69,873
Stockholders’ Equity
Accumulated deficit					(554,444)
Revenue:
Total revenue		122,329		235,579
Gross profit		87,836		168,710
Operating expense:
Sales and marketing		62,454		121,186
Operating loss		(19,272)		(37,223)
Net loss		$ (25,935)		$ (51,415)
Net loss per share, basic and diluted		$ (0.59)		$ (1.18)
Cash flows from operating activities
Net loss		$ (25,935)		$ (51,415)
Changes in assets and liabilities:
Accounts receivable				(2,725)
Deferred commissions				791
Accrued liabilities				4,014
Deferred revenue				48,168
Net cash provided by operating activities				66,955
As Previously Reported | Subscription
Revenue:
Total revenue		118,928		229,853
As Previously Reported | Hardware and Service
Revenue:
Total revenue		3,401		5,726
Adjustments
Assets
Accounts receivable, net					(1,629)
Deferred commissions, current					(895)
Long-term deferred commissions					46,143
Liabilities
Accrued liabilities					1,577
Deferred revenue					(17,394)
Long-term deferred revenue					(6,555)
Stockholders’ Equity
Accumulated deficit					$ 65,991
Revenue:
Total revenue		112		2,497
Gross profit		112		2,497
Operating expense:
Sales and marketing		(2,328)		(5,140)
Operating loss		2,440		7,637
Net loss		$ 2,440		$ 7,637
Net loss per share, basic and diluted		$ 0.05		$ 0.18
Cash flows from operating activities
Net loss		$ 2,440		$ 7,637
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of deferred commissions				13,275
Changes in assets and liabilities:
Accounts receivable				(21)
Deferred commissions				(18,414)
Accrued liabilities				551
Deferred revenue				(3,028)
Adjustments | Subscription
Revenue:
Total revenue		(225)		1,941
Adjustments | Hardware and Service
Revenue:
Total revenue		$ 337		$ 556

Revenue, Deferred Revenue and35

Revenue, Deferred Revenue and Deferred Contract Costs - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 171,875	$ 122,441	$ 334,336	$ 238,076
Subscription
Disaggregation of Revenue [Line Items]
Revenue	165,365	115,811	317,985	224,137
Software License
Disaggregation of Revenue [Line Items]
Revenue	3,654	2,892	9,821	7,657
Hardware and Service
Disaggregation of Revenue [Line Items]
Revenue	$ 2,856	$ 3,738	$ 6,530	$ 6,282

Revenue, Deferred Revenue and36

Revenue, Deferred Revenue and Deferred Contract Costs - Additional Information (Details 1) - Long-term Contract with Customer	Jun. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of contracted and not recognized revenue to be recognized	62.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of contracted and not recognized revenue to be recognized	37.00%

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	Feb. 28, 2018	Nov. 30, 2017	Nov. 21, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Preliminary purchase price allocation estimated period from the acquisition date	1 year
Payments to acquire businesses, net of cash acquired				$ 223,786	$ 0
Wombat
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	$ 225,366
Cash acquired from acquisitions	13,452
Escrow	22,500
Acquisition-related costs	719
Revenue recorded since acquisition date	10,283
Fair value of unvested awards attributed to pre-acquisition service	1,580
Fair value of unvested awards attributed to post-acquisition service	$ 1,571
Wombat | Restricted Stock
Business Acquisition [Line Items]
Number of shares deferred	51
Fair value of share-based deferred compensation issued	$ 5,458
Unamortized stock-based compensation expense				4,546
Cloudmark
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired			$ 107,283
Cash acquired from acquisitions			31,973
Escrow			16,700
Fair value of unvested awards attributed to pre-acquisition service			91
Unamortized stock-based compensation expense			$ 1,180
WebLife Balance, Inc.
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired		$ 48,765
Cash acquired from acquisitions		278
Escrow		6,203
Fair value of unvested awards attributed to pre-acquisition service		333
Unrecognized stock options compensation expense		$ 1,468
WebLife Balance, Inc. | Restricted Stock
Business Acquisition [Line Items]
Number of shares deferred		107
Fair value of share-based deferred compensation issued		$ 9,652
Unamortized stock-based compensation expense				$ 8,249

Acquisitions - Summary of the F

Acquisitions - Summary of the Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	Feb. 28, 2018	Nov. 30, 2017	Nov. 21, 2017	Jun. 30, 2018	Dec. 31, 2017
Fair value of assets acquired and liabilities assumed
Goodwill				$ 460,592	$ 297,704
Wombat
Fair value of assets acquired and liabilities assumed
Current assets	$ 23,344
Fixed assets	954
Liabilities	(1,120)
Deferred revenue	(14,700)
Deferred tax liability, net	(14,725)
Goodwill	162,865
Recognized identifiable assets acquired and liabilities assumed, net	238,818
Wombat | Customer Relationships
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets	$ 37,800
Acquired finite-lived intangible assets, weighted average useful life (in years)	7 years
Wombat | Order Backlog
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets	$ 6,800
Acquired finite-lived intangible assets, weighted average useful life (in years)	2 years
Wombat | Developed Technology
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets	$ 35,200
Acquired finite-lived intangible assets, weighted average useful life (in years)	4 years
Wombat | Trade Names
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets	$ 2,400
Acquired finite-lived intangible assets, weighted average useful life (in years)	4 years
Cloudmark
Fair value of assets acquired and liabilities assumed
Current assets			$ 37,390
Fixed assets			543
Non-current assets			50
Liabilities			(4,565)
Deferred revenue			(15,400)
Deferred tax liability, net			(7,905)
Goodwill			93,943
Recognized identifiable assets acquired and liabilities assumed, net			139,256
Cloudmark | Customer Relationships
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets			$ 15,300
Acquired finite-lived intangible assets, weighted average useful life (in years)			8 years
Cloudmark | Order Backlog
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets			$ 1,400
Acquired finite-lived intangible assets, weighted average useful life (in years)			1 year
Cloudmark | Developed Technology
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets			$ 18,500
Acquired finite-lived intangible assets, weighted average useful life (in years)			4 years
WebLife Balance, Inc.
Fair value of assets acquired and liabilities assumed
Current assets		$ 534
Fixed assets		23
Liabilities		(88)
Deferred revenue		(700)
Deferred tax liability, net		(4,440)
Goodwill		36,514
Recognized identifiable assets acquired and liabilities assumed, net		49,043
WebLife Balance, Inc. | Customer Relationships
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets		$ 600
Acquired finite-lived intangible assets, weighted average useful life (in years)		5 years
WebLife Balance, Inc. | Developed Technology
Fair value of assets acquired and liabilities assumed
Finite lived intangible assets		$ 16,600
Acquired finite-lived intangible assets, weighted average useful life (in years)		5 years

Acquisitions - Pro Forma Financ

Acquisitions - Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Combinations [Abstract]
Total revenue	$ 171,875	$ 131,691	$ 340,970	$ 255,792
Net loss	$ (34,289)	$ (26,830)	$ (46,685)	$ (53,360)
Basic and diluted net loss per share	$ (0.67)	$ (0.61)	$ (0.92)	$ (1.22)

Goodwill and Intangible Asset40

Goodwill and Intangible Assets - Schedule of Goodwill Activity and Balances (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Goodwill activity and balances
Beginning balance as of December 31, 2017	$ 297,704
Acquisition during period	162,865
Purchase accounting adjustments	23
Closing balance	$ 460,592

Goodwill and Intangible Asset41

Goodwill and Intangible Assets - Components of Intangible Assets, Excluding Goodwill (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Intangible assets excluding goodwill:
Gross Carrying Amount	$ 237,899	$ 155,699
Accumulated Amortization	(79,544)	(60,097)
Net Carrying Amount	158,355	95,602
Developed Technology
Intangible assets excluding goodwill:
Gross Carrying Amount	154,069	118,869
Accumulated Amortization	(65,574)	(52,554)
Net Carrying Amount	88,495	66,315
Customer Relationships
Intangible assets excluding goodwill:
Gross Carrying Amount	71,400	33,600
Accumulated Amortization	(10,092)	(5,918)
Net Carrying Amount	61,308	27,682
Trade Names and Patents
Intangible assets excluding goodwill:
Gross Carrying Amount	3,330	930
Accumulated Amortization	(1,095)	(825)
Net Carrying Amount	2,235	105
Order Backlog
Intangible assets excluding goodwill:
Gross Carrying Amount	9,100	2,300
Accumulated Amortization	(2,783)	(800)
Net Carrying Amount	$ 6,317	$ 1,500

Goodwill and Intangible Asset42

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Intangible assets excluding goodwill:
Intangible amortization expense	$ 11,241	$ 4,153	$ 19,447	$ 8,323

Goodwill and Intangible Asset43

Goodwill and Intangible Assets - Future Estimated Amortization of Intangible Assets Expense (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Future estimated amortization costs of intangible assets:
2018, remainder	$ 21,710
2,019	39,650
2,020	34,566
2,021	31,698
2,022	13,501
Thereafter	17,230
Net Carrying Amount	$ 158,355	$ 95,602

Fair Value Measurements and I44

Fair Value Measurements and Investments - Summary of Assets or Liabilities Carried at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Cash equivalents	$ 114,225	$ 286,072
Short-term investments	19,832	45,526
Total financial assets	106,935	287,345
Liabilities
Acquisition-related contingent consideration liability		634
Level 1
Assets
Total financial assets	71,136	231,828
Level 2
Assets
Total financial assets	35,799	55,517
Level 3
Liabilities
Acquisition-related contingent consideration liability		634
Money market funds
Assets
Cash equivalents	71,136	231,828
Money market funds | Level 1
Assets
Cash equivalents	71,136	231,828
Commercial paper
Assets
Cash equivalents	14,967	7,995
Short-term investments	16,933	27,939
Commercial paper | Level 2
Assets
Cash equivalents	14,967	7,995
Short-term investments	16,933	27,939
Corporate debt securities
Assets
Cash equivalents	1,000
Short-term investments	2,899	11,600
Corporate debt securities | Level 2
Assets
Cash equivalents	1,000
Short-term investments	$ 2,899	11,600
U.S. agency securities
Assets
Cash equivalents		1,996
Short-term investments		3,991
U.S. agency securities | Level 2
Assets
Cash equivalents		1,996
Short-term investments		3,991
U.S. Treasury securities
Assets
Short-term investments		1,996
U.S. Treasury securities | Level 2
Assets
Short-term investments		$ 1,996

Fair Value Measurements and I45

Fair Value Measurements and Investments - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 17, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Maximum investment maturity term		1 year
Other-than-temporary impairments	$ 0	$ 0
0.75% Convertible senior notes | Senior Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate, stated percentage			0.75%
0.75% Convertible senior notes | Senior Notes | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible debt, fair value disclosures	$ 332,350,000	$ 332,350,000

Fair Value Measurements and I46

Fair Value Measurements and Investments - Reconciliation of Acquisition-related Contingent Consideration Liability (Details) - Contingent Consideration - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	$ 4,221	$ 634	$ 8,233
Payments during the period	0	(2,054)	(555)	(4,620)
Adjustments to fair value during the period recorded in general and administrative expenses	0	(284)	(79)	(1,730)
Ending balance	$ 0	$ 1,883	$ 0	$ 1,883

Fair Value Measurements and I47

Fair Value Measurements and Investments - Summary of Cost and Fair Value of Cash and Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost	$ 114,225	$ 286,072
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value	114,225	286,072
Short-term investments, amortized cost	19,832	45,535
Short-term investments, unrealized gains	0	0
Short-term investments, unrealized losses	0	(9)
Short-term investments, fair value	19,832	45,526
Cash
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost	27,122	44,253
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value	27,122	44,253
Money market funds
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost	71,136	231,828
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value	71,136	231,828
Corporate debt securities
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost	1,000
Cash and cash equivalents, unrealized gains	0
Cash and cash equivalents, unrealized losses	0
Cash and cash equivalents, fair value	1,000
Short-term investments, amortized cost	2,899	11,607
Short-term investments, unrealized gains	0	0
Short-term investments, unrealized losses	0	(7)
Short-term investments, fair value	2,899	11,600
Commercial paper
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost	14,967	7,995
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value	14,967	7,995
Short-term investments, amortized cost	16,933	27,939
Short-term investments, unrealized gains	0	0
Short-term investments, unrealized losses	0	0
Short-term investments, fair value	$ 16,933	27,939
U.S. agency securities
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Cash and cash equivalents, amortized cost		1,996
Cash and cash equivalents, unrealized gains		0
Cash and cash equivalents, unrealized losses		0
Cash and cash equivalents, fair value		1,996
Short-term investments, amortized cost		3,992
Short-term investments, unrealized gains		0
Short-term investments, unrealized losses		(1)
Short-term investments, fair value		3,991
U.S. Treasury securities
Schedule of Cash and Cash Equivalents, and Investments [Line Items]
Short-term investments, amortized cost		1,997
Short-term investments, unrealized gains		0
Short-term investments, unrealized losses		(1)
Short-term investments, fair value		$ 1,996

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jul. 31, 2015
Debt Instrument [Line Items]
Operating lease rent expense	$ 2,754	$ 1,892	$ 5,375	$ 3,671
Capital Lease Obligations
Debt Instrument [Line Items]
Interest rate, stated percentage					6.50%

Commitments and Contingencies49

Commitments and Contingencies - Future Annual Minimum Lease Payments under Non-cancellable Operating and Capital Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Future annual minimum lease payments under non-cancellable operating and capital leases
2018, remainder	$ 20
2,019	37
2,020	21
2,021	0
2,022	0
Thereafter	0
Total minimum capital lease payments	78
Less: Amount representing interest	(5)
Present value of capital lease obligations	73
Less: Current portion	(35)	$ (34)
Long-term portion of capital lease obligations	38
Operating lease obligations
2018, remainder	10,383
2,019	17,657
2,020	10,613
2,021	5,558
2,022	5,382
Thereafter	6,942
Total minimum operating lease payments	$ 56,535

Convertible Senior Notes - Addi

Convertible Senior Notes - Additional Information (Details) - Senior Notes $ / shares in Units, shares in Thousands	Jun. 17, 2015USD ($)sharesd$ / shares	Dec. 11, 2013USD ($)	Dec. 31, 2017USD ($)shares	Jun. 30, 2018USD ($)
0.75% Convertible senior notes
Debt Instrument [Line Items]
Face amount	$ 200,000,000
Debt interest rate	0.75%
Option to purchase additional principal amount	$ 30,000,000
Agent's discount and issuance costs	6,581,000
Proceeds from issuance of convertible senior notes, net of discount	$ 223,419,000
Conversion ratio, initial	12.3108
Number of shares convertible, initial rate | shares	2,831
Conversion price per share, initial (in dollars per share) | $ / shares	$ 81.23
Notes maturity date	Jun. 15, 2020
Percentage of principal amount that are redeemable	100.00%
Threshold percentage of stock price trigger	130.00%
Threshold trading days | d	20
Number of threshold consecutive trading days | d	30
Number of consecutive business days following consecutive trading day period	5 days
Number of consecutive trading days	5 days
Trading price as percentage of closing price of common stock	98.00%
Effective rate used to amortization debt discount	6.50%
Net carrying amount	$ 174,359,000		$ 197,858,000	$ 204,011,000
Carrying amount of the equity component net	55,641,000		54,049,000	$ 54,049,000
Issuance cost recorded at equity	$ 1,592,000
1.25% Convertible senior notes
Debt Instrument [Line Items]
Face amount		$ 175,000,000
Debt interest rate		1.25%
Option to purchase additional principal amount		$ 26,250,000
Agent's discount and issuance costs		5,803,000
Proceeds from issuance of convertible senior notes, net of discount		$ 195,446,000
Convertible senior notes converted to equity			$ 201,250,000
Shares of commons stock issued for conversion of convertible notes | shares			5,159
Repayment of convertible notes			$ 14,000

Convertible Senior Notes - Summ

Convertible Senior Notes - Summary of Carrying Values and Interest Expense Related to Convertible Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Jun. 17, 2015
Interest Expense, Debt
Amortization of debt discount and issuance costs			$ 6,153	$ 10,888
Senior Notes
Interest Expense, Debt
Interest expense related to contractual interest coupon	$ 431	$ 1,060	862	2,120
Amortization of debt discount and issuance costs	3,100	5,484	6,153	10,888
Total	3,531	$ 6,544	7,015	$ 13,008
Senior Notes | 0.75% Convertible senior notes
Liability component:
Principal	230,000		230,000		$ 230,000
Less: debt discount and issuance costs, net of amortization	(25,989)		(25,989)		(32,142)
Net carrying amount	204,011		204,011		197,858	$ 174,359
Equity component	$ 54,049		$ 54,049		$ 54,049	$ 55,641

Equity Award Plans - Stock-Base

Equity Award Plans - Stock-Based Compensation Plans - Additional Information (Details) shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018planshares	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans held by the company (number of plans)	6
2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares) | shares	20,316
Shares available for future grant under the stock plans (in shares) | shares	4,652
Stock options to purchase common stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term until award expiration	10 years
Award vesting period	4 years
Stock options to purchase common stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Restricted Stock | 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Various Acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans held by the company (number of plans)	4
FireLayers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans held by the company (number of plans)	2

Equity Award Plans - Stock Opti

Equity Award Plans - Stock Options - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	0	0	0	0
Stock options to purchase common stock
Stock option activity under the Plan, in weighted average exercise price:
Aggregate intrinsic value, exercised			$ 27,181	$ 53,497
Proceeds from stock options exercised			4,276	7,112
Fair value of options, vested in period			1,925	$ 4,385
Unrecognized stock options compensation expense	$ 4,655		$ 4,655
Average remaining vesting term			1 year 4 months 9 days

Equity Award Plans - Stock Op54

Equity Award Plans - Stock Option Activity under Stock Incentive Plan (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Stock option activity under the Plan
Outstanding, beginning of period (in shares)	2,040
Options exercised (in shares)	(288)
Options forfeited and expired (in shares)	(11)
Outstanding, ending of period (in shares)	1,741	2,040
Stock option activity under the Plan, in weighted average exercise price:
Balance at beginning of period (USD per share)	$ 22.88
Options exercised (USD per share)	14.81
Options forfeited and expired (USD per share)	50.48
Balance at ending of period (USD per share)	$ 24.05	$ 22.88
Weighted average remaining contractual term	4 years 9 months 7 days	5 years 2 months 1 day
Aggregate intrinsic value, outstanding	$ 158,844	$ 134,511

Equity Award Plans - Summary of

Equity Award Plans - Summary of RSUs and PSUs under Stock Incentive Plan (Details) - Restricted Stock Units and Performance Stock Units shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
RSU's outstanding, number of shares:
Awarded at beginning of period (in shares) | shares	3,540
Award granted (in shares) | shares	1,265
Awards vested (in shares) | shares	(752)
Awards forfeited (in shares) | shares	(315)
Awarded at end of period (in shares) | shares	3,738
RSUs outstanding, granted fair value per unit
Awarded at beginning of period (USD per share) | $ / shares	$ 71.77
Awards granted (USD per share) | $ / shares	117.47
Awards vested (USD per share) | $ / shares	62.66
Awards forfeited (USD per share) | $ / shares	86.88
Awarded at end of period (USD per share) | $ / shares	$ 87.79

Equity Award Plans - Restricted

Equity Award Plans - Restricted Stock and Performance Stock Units - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
RSU
RSUs outstanding, granted fair value per unit
Unamortized stock-based compensation expense	$ 252,205
Average remaining vesting term	2 years 10 months 20 days
Performance Shares
RSUs outstanding, granted fair value per unit
Unamortized stock-based compensation expense	$ 28,155
RSU's outstanding, number of shares:
Award granted (in shares)	166	177

Equity Award Plans - Stock Bonu

Equity Award Plans - Stock Bonus and Other Liability Awards - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	Mar. 06, 2015	Mar. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Bonus and other liability awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liability for the stock bonus and other liability awards			$ 6,062		$ 8,502
Stock earned and issued			61	85
Stock-based compensation expense			$ 6,022	$ 2,573
Liability Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock earned and issued			20	29
Stock-based compensation expense			$ 408	$ 1,137
Fair value of liability award issued	$ 6,885		$ 0
Award vesting period		3 years

Equity Award Plans - Employee S

Equity Award Plans - Employee Stock Purchase Plan - Additional Information (Details) - ESPP 2012 Plan - USD ($) shares in Thousands, $ in Thousands	Mar. 30, 2012	Jun. 30, 2018
Employee stock purchase plan
Number of shares authorized ESPP (in shares)	745
Annual increase period	8 years
Maximum number of shares to be available for grant ESPP (in shares)	1,490
Shares available for future grant under the stock plans (in shares)		1,998
Annual percentage increase of maximum number of shares reserved for issuance ESPP	1.00%
Unamortized stock-based compensation expense		$ 621
Average remaining vesting term		4 months 15 days

Equity Award Plans - Restrict59

Equity Award Plans - Restricted Stock and Deferred Shares - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	Feb. 28, 2018	Nov. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016
Weblife | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 1,197
Unamortized stock-based compensation expense			$ 8,249
Number of shares deferred		107
Fair value of share-based deferred compensation issued		$ 9,652
Weblife | Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred shares service term			3 years
Weblife | Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred shares service term			4 years
Wombat | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred shares service term	2 years
Stock-based compensation expense			$ 912
Unamortized stock-based compensation expense			4,546
Number of shares deferred	51
Fair value of share-based deferred compensation issued	$ 5,458
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred shares service term					3 years
Stock-based compensation expense			1,432	$ 1,432
Unamortized stock-based compensation expense			$ 3,804
Restricted Stock | FireLayers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period					111
Fair value of shares granted					$ 8,669

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Potentially Dilutive Common Shares Outstanding that were Excluded from the Computation of Diluted Net Loss per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	8,641	14,000
Stock options to purchase common stock
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	1,741	2,407
Restricted stock units
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	3,738	3,319
Employee stock purchase plan
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	97	102
Common stock subject to repurchase
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	181	127
Bonus and other liability awards
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	53	56
1.25% Convertible senior notes | Convertible debt
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	0	5,158
0.75% Convertible senior notes | Convertible debt
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	2,831	2,831

Segment Reporting - Additional

Segment Reporting - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018segment
Segment Reporting [Abstract]
Number of operating and reportable segments	1
Number of reportable segments	1

Segment Reporting - Summary of

Segment Reporting - Summary of Total Revenue by Solutions Offered by the Company (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from external customers
Total revenue	$ 171,875	$ 122,441	$ 334,336	$ 238,076
Advanced Threat
Revenue from external customers
Total revenue	129,208	88,680	252,821	172,182
Compliance
Revenue from external customers
Total revenue	$ 42,667	$ 33,761	$ 81,515	$ 65,894

Segment Reporting - Summary o63

Segment Reporting - Summary of Total Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment reporting:
Total revenue	$ 171,875	$ 122,441	$ 334,336	$ 238,076
United States
Segment reporting:
Total revenue	140,504	102,517	274,160	199,991
Rest of world
Segment reporting:
Total revenue	$ 31,371	$ 19,924	$ 60,176	$ 38,085

Segment Reporting - Summary o64

Segment Reporting - Summary of Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment reporting:
Total long-lived assets	$ 75,941	$ 73,617
United States
Segment reporting:
Total long-lived assets	61,765	66,134
Rest of world
Segment reporting:
Total long-lived assets	$ 14,176	$ 7,483

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Valuation allowance
Income tax expense (benefit)	$ 114,000		$ 999,000	$ (13,958,000)	$ 2,433,000
Loss before (provision for) benefit from income taxes	34,184,000		$ 22,496,000	60,412,000	41,345,000
Deferred income tax benefit				$ 14,896,000	$ 1,974,000
Effective income tax rate				23.00%	(6.00%)
Federal statutory income tax rate percent		34.00%		21.00%
Unrecognized tax benefits	14,922,000			$ 14,922,000
Accrued interest and penalties	349,000			349,000
Uncertain tax benefits that would affect effective tax rate if recognized	5,045,000			5,045,000
Increase (decrease) in gross uncertain tax benefits				425,000
Increase for tax positions taken in the current period				671,000
Decrease for tax positions taken in prior periods				209,000
Unrecognized tax benefits decrease related to statute of limitation expirations				37,000
ASU 2016-16
Valuation allowance
Increase in accumulated deficit due to ASU 2016-16 adoption		$ 3,216,000
Valuation Allowance
Valuation allowance
Income tax expense (benefit)				0
Operating Loss
Valuation allowance
Income tax expense (benefit)				0
Internal Revenue Service (IRS)
Valuation allowance
Reduction of certain U.S.deferred tax assets due to Tax Act		87,621,000
Provisional deferred tax benefits related to reduction in US deferred tax liability on acquired intangibles		$ 2,024,000
Wombat
Valuation allowance
Deferred income tax benefit	$ 14,725,000			$ 14,725,000

Defined Contribution Plan - Add

Defined Contribution Plan - Additional Information (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer discretionary matching contributions	$ 958	$ 958
Defined Contribution Plan, Tax Status [Extensible List]	us-gaap:QualifiedPlanMember	us-gaap:QualifiedPlanMember
Defined Contribution Plan, Sponsor Location [Extensible List]	country:US	country:US