Proofpoint (PFPT) 10-Q 2 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2016	Jul. 22, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
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		42,034,568

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 367,260	$ 346,205
Short-term investments	44,860	60,032
Accounts receivable, net of allowance for doubtful accounts of $179 and $199 as of June 30, 2016 and December 31, 2015, respectively	57,756	54,522
Inventory	302	485
Other deferred cost, current	1,770	2,228
Deferred commissions, current	18,687	19,314
Prepaid expenses and other current assets	5,987	5,695
Total current assets	496,622	488,481
Property and equipment, net	43,426	34,501
Other deferred cost, noncurrent	336	314
Goodwill	133,769	133,769
Intangible assets, net	34,556	41,330
Deferred commissions, noncurrent	3,494	3,488
Other noncurrent assets	3,984	3,733
Total assets	716,187	705,616
Current liabilities
Accounts payable	17,484	14,081
Accrued liabilities	30,314	35,053
Notes payable and lease obligations, current	33	32
Deferred rent, current	551	496
Deferred revenue, current	215,759	182,195
Total current liabilities	264,141	231,857
Convertible senior notes	355,967	345,699
Long-term Debt and Capital Lease Obligations	106	123
Deferred rent, noncurrent	1,967	2,033
Other long term liabilities	4,422	1,188
Deferred revenue, noncurrent	38,611	41,531
Total liabilities	665,214	622,431
Stockholders’ equity
Convertible preferred stock, $0.0001 par value, 5,000 shares authorized	0	0
Common stock, $0.0001 par value; 200,000 shares authorized; 41,947 and 40,840 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	4	4
Additional paid-in capital	478,828	441,104
Accumulated Other Comprehensive Income (Loss), Net of Tax	(2)	(23)
Accumulated deficit	(427,857)	(357,900)
Total stockholders’ equity	50,973	83,185
Total liabilities and stockholders’ equity	$ 716,187	$ 705,616

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets Parenthetical - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Allowance for doubtful accounts receivable, current	$ 179	$ 199
Preferred Stock, Shares Authorized	5,000	5,000
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
Par value of common stock (USD per share)	$ 0.0001	$ 0.0001
Common Stock, Shares Authorized	200,000	200,000
Common stock issued (in shares)	41,947	40,840
Common stock outstanding (in shares)	41,947	40,840

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue:
Subscription		$ 87,318	$ 61,778	$ 164,715	$ 117,634
Hardware and services		2,586	1,768	4,192	3,675
Revenue, net		89,904	63,546	168,907	121,309
Cost of revenue:
Subscription		23,198	16,829	44,880	33,163
Hardware and services		3,460	2,995	6,602	5,949
Total cost of revenue	[1],[2]	26,658	19,824	51,482	39,112
Gross profit		63,246	43,722	117,425	82,197
Operating expense:
Research and development		23,588	18,659	46,241	34,367
Selling and Marketing Expense		48,664	35,638	95,187	68,589
General and administrative		22,999	8,495	33,603	15,828
Total operating expense	[1],[2]	95,251	62,792	175,031	118,784
Operating loss		(32,005)	(19,070)	(57,606)	(36,587)
Interest expense		(5,809)	(3,332)	(11,609)	(6,185)
Other income (expense), net		(302)	(80)	(300)	(1,260)
Loss before (provision for) benefit from income taxes		(38,116)	(22,482)	(69,515)	(44,032)
(Provision for) benefit from income taxes		(185)	(112)	(442)	(274)
Total Net loss		$ (38,301)	$ (22,594)	$ (69,957)	$ (44,306)
Earnings Per Share, Basic and Diluted		$ (0.92)	$ (0.57)	$ (1.69)	$ (1.13)
Weighted Average Number of Shares Outstanding, Basic and Diluted		41,605	39,567	41,349	39,264
Intangible amortization expense		$ 3,369	$ 2,917	$ 6,774	$ 5,624
Cost of subscription revenue [Member]
Operating expense:
Stock-based Compensation Expense		1,721	1,148	3,359	2,263
Intangible amortization expense		2,118	1,589	4,235	2,969
Cost of hardware and services revenue [Member]
Operating expense:
Stock-based Compensation Expense		392	250	745	504
Research and development [Member]
Operating expense:
Stock-based Compensation Expense		5,877	5,762	11,479	9,700
Intangible amortization expense		15	23	30	46
Sales and marketing [Member]
Operating expense:
Stock-based Compensation Expense		6,718	5,157	13,536	10,026
Intangible amortization expense		1,236	1,304	2,509	2,597
General and administrative [Member]
Operating expense:
Stock-based Compensation Expense		4,000	2,918	8,072	5,168
Intangible amortization expense		$ 0	$ 1	$ 0	$ 12
[1]	Includes intangible amortization expense as follows:Three Months Ended June 30, 2016 2015Cost of subscription revenue2,118 1,589Research and development15 23Sales and marketing1,236 1,304General and administrative— 1
[2]	Includes stock‑based compensation expense as follows: Three Months Ended June 30, 2016 2015Cost of subscription revenue1,721 1,148Cost of hardware and services revenue392 250Research and development5,877 5,762Sales and marketing6,718 5,157General and administrative4,000 2,918

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Total Net loss	$ (38,301)	$ (22,594)	$ (69,957)	$ (44,306)
Other comprehensive loss, net of tax
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	5	21	25
Comprehensive loss	$ (38,301)	$ (22,589)	$ (69,936)	$ (44,281)

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Total Net loss	$ (69,957)	$ (44,306)
Depreciation and amortization	14,621	11,427
Loss on disposal of property and equipment	288	115
Accretion of investments	35	206
Allowance for Doubtful Accounts Receivable, Recoveries	(20)	(252)
Stock‑based compensation	37,191	27,661
Amortization of debt issuance costs and accretion of debt discount	10,268	4,962
Foreign Currency Transaction Gain (Loss), before Tax	35	1,064
Changes in assets and liabilities, net of effect of acquisitions:
Accounts receivable	(3,279)	(2,533)
Inventory	183	64
Other Deferred Product Costs	435	(341)
Deferred Commissions	621	(2,340)
Prepaid Expense	(533)	(782)
Other current assets	104	585
Deferred Income Taxes	(167)	144
Noncurrent assets	51	109
Accounts payable	5,959	825
Accrued liabilities	(755)	(2,855)
Deferred rent	(12)	(221)
Deferred revenue	30,643	20,566
Net cash provided by operating activities	25,711	14,098
Cash flows from investing activities
Proceeds from sale and maturity of short-term investments	68,900	25,959
Payments to Acquire Available-for-sale Securities	53,742	0
Purchase of property and equipment	(16,194)	(10,427)
Payments to acquire businesses, net of cash acquired	0	(31,624)
Net cash used in investing activities	(1,036)	(16,092)
Cash flows from financing activities
Proceeds from issuance of common stock, net of repurchases	10,335	9,676
Tax Withholdings Related To Net Share Settlements of Restricted Stock Awards and Units	(12,572)	(8,427)
Repayments of equipment financing loans	(16)	(693)
Holdback payments for prior acquisitions	(1,397)	0
Net cash provided by financing activities	(3,650)	224,346
Effect of Exchange Rate on Cash and Cash Equivalents	30	(545)
Net (decrease) increase in cash and cash equivalents	21,055	221,807
Proceeds from convertible debt	0	223,790
Cash and cash equivalents
Beginning of period	346,205	180,337
End of period	367,260	402,144
Supplemental disclosure of noncash investing and financing information
Unpaid purchase of property and equipment	5,773	5,949
Liability awards converted to equity	$ 6,059	$ 1,745

The Company and Summary of Sign

The Company and Summary of Significant Accounting Policies (Notes)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
The Company and Summary of Significant Accounting Policies	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 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-as-a-service platform is comprised of an integrated suite of on-demand data protection solutions, including threat protection, incident response, regulatory compliance, archiving, governance, eDiscovery, and secure communication. Basis of Presentation and Consolidation These condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All inter-company transactions and balances have been eliminated in consolidation. Starting January 1, 2016, the Company began separately presenting the effect of exchange rate changes on cash and cash equivalents in its condensed consolidated statements of cash flows due to growing operations in foreign currency environments. Amounts in the comparable prior period have been reclassified to conform to the current period presentation. The Company completed a number of acquisitions during the year ended December 31, 2015, which are more fully described in Note 2, "Acquisitions". The condensed consolidated financial statements include the results of operations from these business combinations from their date of acquisition. 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, 2015 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. The results of operations for the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for other interim periods or for future years. 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, 2015 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. Refer to "Sales Commissions" below regarding the Company's change in accounting policy for sales commissions effective January 1, 2016. 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, 2016 . 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 7 Non-compete agreements 2 4 Order backlog 1 3 Trade names and trademarks 1 5 Revenue Recognition The Company derives its revenue primarily from two sources: (1) subscription revenue for rights related to the use of the security-as-a-service platform and (2) hardware, training and professional services revenue provided to customers related to their use of the platform. The Company records its revenues net of any value added or sales tax. Subscription revenue is derived from a subscription‑based enterprise licensing model with contract terms typically ranging from one to three years, and consists of (i) subscription fees from the licensing of the security-as-a-service platform, (ii) subscription fees for access to the on-demand elements of the platform and (iii) subscription fees for the right to access the Company’s customer support services. Revenue is recognized when all of the following criteria have been met: • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • Sales price is fixed or determinable; and • Collectability is reasonably assured. 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. From time to time, certain third parties that the Company has an arrangement with provide the Company with referrals for which the Company pays a referral fee. The referral fee paid could vary depending on the level of effort. These fees are recorded in sales and marketing expense in proportion to the related revenue streams consistent with the sales commissions accounting. The Company did not incur any material referral fee expenses during the three and six months ended June 30, 2016 and 2015. The Company applies industry-specific software revenue recognition guidance to transactions involving the licensing of software, as well as related support, training, and other professional services. The Company has analyzed all of the elements included in its multiple element software arrangements and has determined that it does not have sufficient VSOE of fair value to allocate revenue to its subscription and software license agreements, support, training and professional services. The Company defers all revenue under the software arrangement until the commencement of the subscription services and any associated professional services. Once the subscription services and the associated professional services have commenced, the entire fee from the arrangement is recognized ratably over the remaining period of the arrangement. If the professional services are essential to the functionality of the subscription, then the revenue recognition does not commence until such services are completed. The Company's revenue arrangements typically include subscription services to its security-as-a-service platform. These hosted on demand service arrangements do not provide customers with the right to take possession of the software supporting the hosted services. Certain arrangements also include the sale of hardware appliances. Revenue from hardware appliances containing software components and hardware components that function together to deliver the hardware appliance's essential functionality is excluded from the scope of the industry specific revenue recognition guidance. The Company recognizes revenue from its hosted on demand services in accordance with general revenue recognition accounting guidance. Only revenue derived from the licensing of the software is recognized in accordance with the industry specific revenue guidance. When a sales arrangement contains multiple elements, such as hardware appliances, subscription services, customer support services, and/or professional services, the Company allocates revenue to each unit of accounting or element based on a selling price hierarchy. An element constitutes a separate unit of accounting when the delivered item has standalone value and delivery of the undelivered element is probable and within the Company's control. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence (“VSOE”) of selling price. If VSOE does not exist, the Company uses third-party evidence (“TPE”) of selling price. If neither VSOE nor TPE of selling price exist for a deliverable, the Company uses its best estimate of selling price ("BESP") for that deliverable. Revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for each element. The Company determines BESP for an individual element within a multiple element revenue arrangement using the same methods utilized to determine the selling price of an element sold on a standalone basis. The Company estimates the selling price for its subscription solutions by considering internal factors such as historical pricing practices and it estimates the selling price of hardware and other services using a cost plus model. Hardware appliance revenue is recognized upon shipment. Subscription and support revenue are recognized over the contract period commencing on the start date of the contract. Professional services and training, when sold with hardware appliances or subscription and support services, are accounted for separately when those services have standalone value. In determining whether professional services and training services can be accounted for separately from subscription and support services, the Company considers the following factors: availability of the services from other vendors, the nature of the services, and the dependence of the subscription services on the customer’s decision to buy the professional services. If professional services and training do not qualify for separate accounting, the Company recognizes the professional services and training ratably over the contract term of the subscription services. Delivery generally occurs when the hardware appliance is delivered to a common carrier freight on board shipping point by the Company or the hosted service has been activated and communicated to the customer accordingly. The Company’s fees are typically considered to be fixed or determinable at the inception of an arrangement and are negotiated at the outset of an arrangement, generally based on specific products and quantities to be delivered. In the event payment terms are provided that differ significantly from the Company's standard business practices, the fees are deemed to not be fixed or determinable and revenue is recognized as the fees become paid. The Company assesses collectability based on a number of factors, including credit worthiness of the customer and past transaction history of the customer. Through June 30, 2016 , the Company has not experienced significant credit losses. Deferred Revenue Deferred revenue primarily consists of billings or payments received in advance of revenue recognition from the sale of the Company’s subscription fees, training and professional services. Once the revenue recognition criteria are met, this revenue is recognized ratably over the term of the associated contract. 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, 2016 and 2015 . Sales Commissions Effective January 1, 2016, the Company changed its accounting policy for sales commissions that are incremental and directly related to its customer sales contracts in which revenue is deferred. These commission costs are accrued and capitalized upon execution of a non-cancelable customer contract, and subsequently expensed over the term of such contract in proportion to the related future revenue streams. For commission costs where revenue is recognized, the related commission costs are recorded in the period of revenue recognition. Prior to this change in accounting policy, commission costs were expensed in the period in which they were incurred. The adoption of this accounting policy change has been applied retrospectively to all periods presented in this Quarterly Report on Form 10-Q, in which the cumulative effect of the change has been reflected as of the beginning of the first period presented. Deferred commissions as of June 30, 2016 and December 31, 2015 were $22,181 and $22,802 , respectively. During the three and six months ended June 30, 2016, the Company deferred $9,109 and $15,038 of commission costs and amortized $8,249 and $15,660 within sales and marketing expense, respectively. During the three and six months ended June 30, 2015, the Company deferred $7,392 and $11,892 of commission costs and amortized $5,013 and $9,552 within sales and marketing expense, respectively. The Company believes this change in accounting policy is preferable as the direct and incremental commission costs are closely related to the revenue, and therefore they should be recorded as an asset and recognized as an expense over the same period that the related revenue is recognized. The cumulative effect of the change on accumulated deficit was $15,060 as of December 31, 2014. The following tables present the changes to the financial statement lines as a result of the accounting change for the periods presented in the accompanying unaudited Condensed Consolidated Financial Statements: Condensed Consolidated Balance Sheet As of December 31, 2015 As reported Adjustment As adjusted Short-term deferred commissions $ — $ 19,314 $ 19,314 Long-term deferred commissions $ — $ 3,488 $ 3,488 Accumulated deficit $ (380,702 ) $ 22,802 $ (357,900 ) Condensed Consolidated Statement of Operations Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Operating expenses: Sales and marketing $ 38,017 $ (2,379 ) $ 35,638 $ 70,929 $ (2,340 ) $ 68,589 Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Net loss per share, basic and diluted $ (0.63 ) $ 0.06 $ (0.57 ) $ (1.19 ) $ 0.06 $ (1.13 ) Weighted average shares outstanding, basic and diluted 39,567 — 39,567 39,264 — 39,264 Condensed Consolidated Statement of Comprehensive Loss Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Unrealized gains on short-term investments, net $ 5 $ — $ 5 $ 25 $ — $ 25 Comprehensive loss $ (24,968 ) $ 2,379 $ (22,589 ) $ (46,621 ) $ 2,340 $ (44,281 ) There have been no changes, other than as discussed above, in the Company's significant accounting policies for the three and six months ended June 30, 2016, as compared to the significant accounting policies described in the Company's Annual Form 10-K for the year ended December 31, 2015. Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 changes the impairment model for most financial assets, and will require the use of an expected loss model in place of the currently used incurred loss method. Under this model, entities will be required to estimate the lifetime expected credit loss on such instruments and record an allowance to offset the amortized cost basis of the financial asset, resulting in a net presentation of the amount expected to be collected on the financial asset. The update to the standard is effective for interim and annual periods beginning after December 15, 2019. The Company is currently evaluating the impact of the adoption of ASU 2016-13 on its consolidated financial statements. In March 2016, FASB issued Accounting Standards Update No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes how companies account for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The update to the standard is effective for interim and annual periods beginning after December 15, 2016. The Company is currently evaluating the impact of the adoption of ASU 2016-09 on its consolidated financial statements. In February 2016, FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) (ASU 2016-02), which requires lessees to put most leases on their balance sheets but recognize the expenses on their statements of operations in a manner similar to current practice. ASU 2016-02 states that a lessee would recognize a lease liability for the obligation to make lease payments and a right-to-use asset for the right to use the underlying asset for the lease term. The new standard is effective for interim and annual periods beginning after December 15, 2018 and early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-02 on its consolidated financial statements. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASU 2014-09 defines a five step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than required under existing U.S. GAAP including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. Originally, ASU 2014-09 would be effective for the Company starting January 1, 2017 using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within ASU 2014-09; or (ii) retrospective with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application and providing certain additional disclosures as defined per ASU 2014-09. In July 2015, the FASB voted to amend ASU 2014-09 by approving a one-year deferral of the effective date as well as providing the option to early adopt the standard on the original effective date. The FASB has issued several updates to the standard which i) clarify the application of the principal versus agent guidance (ASU 2016-08); ii) clarify the guidance on inconsequential and perfunctory promises and licensing (ASU 2016-10) and iii) narrow-scope improvements and practical expedients (ASU 2016-12). The Company is currently evaluating the timing and impact of the adoption of the standard on its consolidated financial statements.

Acquisitions (Notes)

Acquisitions (Notes)	6 Months Ended
	Jun. 30, 2016
Acquisitions [Abstract]
Business Combination Disclosure [Text Block]	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, except for one of the acquisitions made in the fourth quarter of 2015, is 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. 2015 Acquisitions In the fourth quarter of the year ended December 31, 2015, the Company made two acquisitions that were accounted for as business combinations. The Company has provisionally estimated fair values of acquired tangible and intangible assets at the respective date of each acquisition. The amounts reported are considered provisional as the Company is completing the valuation work to determine the fair value of certain assets acquired. 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 from the respective date of each acquisition. The aggregate purchase price was $11,568 . The following table summarizes the fair values of acquired tangible and intangible assets, liabilities and goodwill: Estimated Estimated Current assets acquired $ 414 N/A Fixed assets acquired 73 N/A Liabilities assumed (234 ) N/A Deferred revenue assumed (1,400 ) N/A Deferred tax liability, net (45 ) N/A Customer relationships 2,800 7 Order Backlog 900 3 Developed technology 3,000 4 Goodwill 6,060 Indefinite $ 11,568 Marble Security, Inc. On July 22, 2015 (the "Marble Acquisition Date"), pursuant to the terms of an asset purchase agreement, the Company acquired certain assets of Marble Security, Inc. ("Marble"). The Marble mobile security technology proactively removes malicious mobile applications by leveraging its tight integration with the leading enterprise mobility management platforms, including MobileIron and AirWatch by VMware. The acquisition extends the Company’s threat intelligence and advanced threat protection for email and social media security into the realm of mobile devices. The results of operations and the fair values of the acquired assets and liabilities assumed have been included in the accompanying condensed consolidated financial statements since the Marble Acquisition Date. The total purchase price was $8,500 . Of the cash consideration paid, $1,700 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. Fair value of acquired assets The following table summarizes the fair values of acquired tangible, intangible assets and goodwill: Fair Value Estimated Fixed assets acquired $ 25 N/A Developed technology 7,300 4 Goodwill 1,175 Indefinite $ 8,500 Emerging Threats Pro, LLC On March 6, 2015 (the "Emerging Threats Acquisition Date"), pursuant to the terms of a purchase agreement, the Company acquired 100% of membership interests in Emerging Threats Pro, LLC ("Emerging Threats"). Based in Indianapolis, Indiana, Emerging Threats provides threat intelligence solutions to help protect networks from known or potentially malicious threats. With this acquisition, the Company integrated Emerging Threat's advanced threat intelligence solutions with its existing Targeted Attack Protection and Threat Response security solutions to advance threat detection and response across the completed attack chain. The combined technology provides customers with deeper insight into cyberthreats, enabling them to react faster to inbound cyberattacks, and to identify, block, and disable previously undetected malware already embedded in their organizations. The results of operations and the fair values of the acquired assets and liabilities assumed have been included in the accompanying condensed consolidated financial statements since the Emerging Threat Acquisition Date. The total purchase price was $31,803 , net of cash acquired of $52 , of which $3,662 was paid in the second quarter of 2015. Of the cash consideration paid, $6,000 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. Fair value of acquired assets and liabilities assumed The following table summarizes the fair values of tangible and intangible assets acquired, liabilities assumed and goodwill: Fair Value Estimated Current assets acquired $ 1,275 N/A Fixed assets acquired 174 N/A Liabilities assumed (448 ) N/A Deferred revenue assumed (700 ) N/A Holdback liability to the sellers (3,662 ) N/A Trade names 200 2 Customer relationships 4,200 7 Order Backlog 200 1 Developed technology 7,900 7 Goodwill 19,054 Indefinite $ 28,193

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Notes)	6 Months Ended
	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The goodwill activity and balances are presented below: Balance at December 31, 2015 $ 133,769 Add: Goodwill from acquisitions — Less: Other purchase price allocation adjustments to Goodwill — Balance at June 30, 2016 $ 133,769 Intangible Assets Intangible assets, excluding goodwill, consisted of the following: June 30, 2016 December 31, 2015 Gross Accumulated Net Gross Accumulated Net Developed technology $ 57,268 $ (32,853 ) $ 24,415 $ 57,268 $ (28,618 ) $ 28,650 Customer relationships 18,384 (9,391 ) 8,993 23,382 (12,291 ) 11,091 Non-compete agreements 500 (470 ) 30 804 (691 ) 113 Trade names and patents 930 (547 ) 383 1,006 (502 ) 504 Order backlog 1,100 (365 ) 735 1,300 (328 ) 972 $ 78,182 $ (43,626 ) $ 34,556 $ 83,760 $ (42,430 ) $ 41,330 Amortization of intangible assets expense was $3,369 and $2,917 for the three months ended June 30, 2016 and 2015 , respectively, and $6,774 and $5,624 for the six months ended June 30, 2016 and 2015 , respectively. Future estimated amortization of intangible assets expense as of June 30, 2016 are presented below: Year ending December 31, 2016, remainder $ 5,745 2017 9,174 2018 8,530 2019 5,164 2020 2,806 Thereafter 3,137 $ 34,556

Fair Value Measurements and Inv

Fair Value Measurements and Investments (Notes)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value and Investments Disclosures	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. The following tables summarize, for each category of assets or liabilities carried at fair value, the respective fair value as of June 30, 2016 and December 31, 2015 and the classification by level of input within the fair value hierarchy: Balance as of Quoted Prices Significant Unobservable Assets Cash equivalents: Money market funds $ 334,357 $ 334,357 $ — $ — Commercial paper 801 — 801 — Short-term investments: Corporate debt securities 26,835 — 26,835 — Commercial papers 18,025 — 18,025 — Total financial assets $ 380,018 $ 334,357 $ 45,661 $ — Balance as of Quoted Prices Significant Unobservable Assets Cash equivalents: Money market funds $ 306,983 $ 306,983 $ — $ — Corporate debt securities 3,178 — 3,178 — Commercial paper 8,996 — 8,996 — Short-term investments: Corporate debt securities 36,527 — 36,527 — Commercial paper 16,290 — 16,290 — U.S. agency securities 5,414 — 5,414 — U.S. Treasury securities 1,801 — 1,801 — Total financial assets $ 379,189 $ 306,983 $ 72,206 $ — Based on quoted market prices as of June 30, 2016 , the fair values of the 0.75% and 1.25% Convertible Senior Notes were approximately $245,238 and $315,459 , respectively, determined using Level 2 inputs as they are not actively traded in markets. 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, 2016 and December 31, 2015 were as follows: June 30, 2016 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 32,102 $ — $ — $ 32,102 Money market funds 334,357 — — 334,357 Commercial paper 801 — — 801 Total $ 367,260 $ — $ — $ 367,260 Short-term investments: Corporate debt securities $ 26,838 $ 2 $ (5 ) $ 26,835 Commercial paper 18,025 — — 18,025 Total $ 44,863 $ 2 $ (5 ) $ 44,860 December 31, 2015 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 27,048 $ — $ — $ 27,048 Money market funds 306,983 — — 306,983 Corporate debt securities 3,178 — — 3,178 Commercial papers 8,996 — — 8,996 Total $ 346,205 $ — $ — $ 346,205 Short-term investments: Corporate debt securities $ 36,549 $ — $ (22 ) $ 36,527 Certificate of deposit 16,290 — — 16,290 U.S. agency securities 5,415 — (1 ) 5,414 U.S. Treasury securities 1,801 — — 1,801 Total $ 60,055 $ — $ (23 ) $ 60,032 As of June 30, 2016 and December 31, 2015 , 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 three and six months ended June 30, 2016 .

Commitments and Contingencies (

Commitments and Contingencies (Notes)	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company leases certain of its facilities under noncancellable operating leases with various expiration dates through 2020. Premises rent expense was $1,220 and $951 for the three months ended June 30, 2016 and 2015 , respectively, and $2,398 and $1,818 for six months ended June 30, 2016 and 2015 , respectively. Capital Leases In July 2012, the Company entered into two lease agreements to lease certain office equipment that expired in July and October 2015. These leases bore an annual interest rate of 4.5% . In July 2015, the Company entered into a new 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% . All leases are secured by fixed assets used in the Company's office locations. At June 30, 2016 , future annual minimum lease payments under noncancellable operating and capital leases were as follows: Capital Operating Year ending December 31, 2016, remainder $ 21 $ 5,902 2017 41 7,542 2018 39 5,187 2019 37 4,494 2020 21 1,473 Thereafter — 3,122 Total minimum lease payments 159 $ 27,720 Less: Amount representing interest (20 ) Present value of capital lease obligations 139 Less: current portion (33 ) Long-term portion of capital lease obligations $ 106 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. On December 16, 2013, Finjan, Inc. sued the Company and its wholly-owned subsidiary, Armorize Technologies, Inc., in the United States District Court, Northern District of California for alleged patent infringement of a variety of its patents, demanding preliminary and permanent injunctive relief, and unspecified damages. On June 3, 2016, the Company executed a Confidential Patent License, Settlement and Release Agreement with Finjan, Inc. The Company evaluated the transaction as a multiple-element arrangement and allocated the payment of $10,900 to each identifiable element using its relative fair value. Based on estimates of fair value, the Company determined that the primary benefit of the arrangement is avoided litigation cost and the release of any potential past claims, with no material value attributable to future use or benefit. Accordingly, the Company recorded a $10,900 settlement charge within general and administrative expense in its consolidated statements of operations. The Company paid $4,300 in June 2016, and will pay $3,300 on or before January 4, 2017, and $3,300 on or before January 3, 2018. The payables were recorded in accounts payable and other-long term liabilities, respectively, on the balance sheet as of June 30, 2016.

Convertible Senior Notes (Notes

Convertible Senior Notes (Notes)	6 Months Ended
	Jun. 30, 2016
Convertible Senior Notes [Abstract]
Convertible Senior Notes	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 believed to be of strategic importance. 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 will be 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. The Company may redeem the 0.75% Notes in shares of the Company’s common stock, cash, or some combination of each. 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. 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 a 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. 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," and together with the 0.75% Notes, the “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 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 believed to be of strategic importance. The 1.25% Notes bear interest at 1.25% per year, payable semi-annually in arrears every June 15 and December 15, beginning on June 15, 2014. On July 5, 2016, the Company and the Trustee executed a supplemental indenture to address an administrative issue with the timing of a redemption notice. The amendment did not adversely affect the right of any holder and therefore did not require their consent. The 1.25% Notes are unsecured and rank senior in right of payment to any indebtedness expressly subordinated in right of payment to the 1.25% 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 25.6271 shares of the Company’s common stock per $1 principal amount of notes which equates to 5,158 shares of common stock, or a conversion price equivalent of $39.02 per share of common stock. Throughout the term of the 1.25% 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 1.25% Notes mature on December 15, 2018 , unless repurchased, redeemed or converted in accordance with their terms prior to such date. At the Company's option, on or after December 20, 2016 , the Company will be able to redeem all or a portion of the 1.25% Notes at 100% of the principal amount, plus any accrued and unpaid interest, under certain conditions. The Company may redeem the 1.25% Notes in shares of the Company’s common stock, cash, or some combination of each. Prior to June 15, 2018 , the 1.25% 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 March 31, 2014, 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 1.25% 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 June 15, 2018 , Holders may convert their 1.25% 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. Holders of the 1.25% Notes also have the right to require the Company to repurchase all or a portion of the 1.25% 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 1.25% 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 a 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 1.25% 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 December 15, 2018 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 1.25% Notes, the Company recorded $156,672 as debt and $44,578 as additional paid in capital within stockholders' equity. Additionally, the 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 1.25% Notes. The equity issuance costs of $1,285 were recorded as a decrease to additional paid-in capital at the issuance date. The following tables presents the carrying values of all Notes as of June 30, 2016 and December 31, 2015: June 30, 2016 0.75% Notes 1.25% Notes Total Liability component: Principal $ 230,000 $ 201,250 $ 431,250 Less: debt discount and issuance costs, net of amortization (49,508 ) (25,775 ) (75,283 ) Net carrying amount $ 180,492 $ 175,475 $ 355,967 Equity component (1) $ 54,049 $ 43,293 $ 97,342 December 31, 2015 0.75% Notes 1.25% Notes Total Liability component: Principal $ 230,000 $ 201,250 $ 431,250 Less: debt discount and issuance costs, net of amortization (54,952 ) (30,599 ) (85,551 ) Net carrying amount $ 175,048 $ 170,651 $ 345,699 Equity component (1) $ 54,049 $ 43,293 $ 97,342 (1) Recorded on the accompanying Condensed Consolidated Balance Sheets as additional paid-in capital, net of the $2,877 issuance costs. For the three and six months ended June 30, 2016 and 2015 , the Company incurred the following interest expense related to the Notes: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Interest expense related to contractual interest coupon $ 1,060 $ 691 $ 2,120 $ 1,320 Amortization of debt discount and issuance costs 5,172 2,696 10,268 4,962 $ 6,232 $ 3,387 $ 12,388 $ 6,282

Stock Equity Plans (Notes)

Stock Equity Plans (Notes)	6 Months Ended
	Jun. 30, 2016
Equity Incentive Plans Held [Line Items]
Stock Equity Plans	Stock Equity 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 two equity incentive plans: the Company’s 2002 stock option plan (the “2002 Plan”) and the 2012 Plan. 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. All outstanding stock awards under the 2002 and 2012 Plans 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 2002 and 2012 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, 2016 , 6,659 shares were available for future grant. Restricted stock awards generally vest over a four -year period. Stock Options The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the common stock price and the assumed risk-free interest rate. The Company recognizes stock-based compensation expense for only those shares expected to vest over the requisite service period of the award. The Company determines its estimated forfeiture rate based on an analysis of its actual forfeitures and will continue to evaluate the appropriateness of the forfeiture rate based on recent forfeiture activity and expected future employee turnover, if any. Changes in the estimated forfeiture rate can have a significant effect on reported stock-based compensation expense, as the cumulative effect of adjusting the rate for all expense is recognized in the period the forfeiture estimate is changed. No compensation cost is recorded for options that do not vest and the compensation cost from vested options, whether forfeited or not, is not reversed. The weighted average fair value of stock options granted to employees was $22.82 during the three months ended June 30, 2016, and $28.23 and $27.81 during the three and six months ended June 30, 2015, respectively. The fair values were estimated on the grant dates using the Black-Scholes option-pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended 2016 2015 2016 2015 Expected life (in years) 5.31 - 6.08 5.31 - 6.08 5.31 - 6.08 5.31 - 6.08 Volatility 45 % 50 % 45 % 50% - 52% Risk-free interest rate 1.4 % 1.7 % 1.4 % 1.6% - 1.7% Dividend yield — % — % — % — % The estimate for expected life of options granted reflects the midpoint of the vesting term and the contractual life computed utilizing the simplified method as allowed by the SEC staff. The Company does not have significant historical share option exercise experience and hence considers the expected term assumption calculated using the simplified method to be reasonable. Starting January 1, 2016, the expected volatility of the Company's common stock is based on the Company's historical volatility. Prior to January 1, 2016, the common stock price volatility was determined based on the historical average volatilities of the common stock of a group of publicly-traded peer companies that operate in a similar industry as the Company did not have sufficient trading history for its common stock. The risk-free interest rate used was the Federal Reserve Bank's constant maturities interest rate commensurate with the expected life of the options in effect at the time of the grant. The expected dividend yield was zero, as the Company does not anticipate paying a dividend within the relevant time frame. 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, 2015 4,042 $ 15.10 5.77 $ 201,736 Options granted 212 51.35 Options exercised (554 ) 10.42 Options forfeited and canceled (23 ) 43.76 Balance at June 30, 2016 3,677 $ 17.72 5.71 $ 166,854 The total intrinsic value of options exercised was $24,629 and $40,237 for the six months ended June 30, 2016 and 2015 , respectively. Total cash proceeds from such option exercises were $5,778 and $6,520 for the six months ended June 30, 2016 and 2015 , respectively. The fair value of option grants that vested was $5,543 and $5,896 for the six months ended June 30, 2016 and 2015 , respectively. As of June 30, 2016 , the Company had unamortized stock-based compensation expense of $13,714 related to stock options, that will be recognized net of forfeitures over the average remaining vesting term of the options of 2.10 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, 2015 3,311 $ 47.94 Awards granted 711 52.53 Awards vested (611 ) 42.61 Awards forfeited (194 ) 52.37 Awarded and unvested at June 30, 2016 3,217 $ 49.70 As of June 30, 2016 , there was $98,107 of unamortized stock-based compensation expense related to unvested RSUs, which is expected to be recognized over a weighted average period of 2.95 years. The Company granted 105 and 172 PSUs in the six months ended June 30, 2016 and 2015, respectively. The PSU vesting conditions were based on individual performance targets. Unamortized expense was $10,437 as of June 30, 2016, net of estimated forfeitures. Stock Bonus and Other Liability Awards The total accrued liability for the stock bonus awards was $2,660 and $5,676 as of June 30, 2016 and December 31, 2015, respectively. During the six months ended June 30, 2016 and 2015, 93 and 27 shares, respectively, of common stock earned under the stock bonus program were issued. Stock based compensation expense related to stock bonus program was $2,602 and $1,459 for the six months ended June 30, 2016 and 2015, respectively. In March 2015, the Company issued liability awards with a fair value of $6,885 , which vest annually over a three-year period and are subject to continuous service and other conditions. The liability awards will be settled with a variable number of shares of the Company's common stock. During the six months ended June 30, 2016, 45 shares were vested and issued. The Company recognized $1,143 and $729 of stock-based compensation expense related to these liability awards for the six months ended June 30, 2016 and 2015, respectively. 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, 2016 , there were 1,459 shares of the Company's common stock available for future issuance under the ESPP. As of June 30, 2016 , the Company expects to recognize $1,200 of the total unamortized compensation cost related to employee purchases under the ESPP over a weighted average period of 0.4 years. Restricted Stock The Company granted 54 shares of restricted stock in the fourth quarter of 2014 to certain key employees with the total fair value of $2,357 and two-year cliff vesting in 2016. The Company recognized $589 of stock based compensation expense in each of the six month periods ended June 30, 2016 and 2015, respectively. As of June 30, 2016, there was $393 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.

Net Loss per Share (Notes)

Net Loss per Share (Notes)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Net Loss per Share	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: As of June 30, 2016 2015 Stock options to purchase common stock 3,677 4,620 Restricted stock units 3,217 3,160 Employee stock purchase plan 104 78 Common stock subject to repurchase 78 54 Bonus and other liability awards 125 158 1.25% Convertible senior notes 5,158 5,158 0.75% Convertible senior notes 2,831 2,831 Total 15,190 16,059

Segment Reporting (Notes)

Segment Reporting (Notes)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Segment Reporting	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. Starting January 1, 2016, the Company included privacy solutions into the "Archiving, Privacy and Governance" group. Amounts in the comparable prior period have been reclassified to conform to the current presentation. 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, 2016 2015 2016 2015 Total revenue by solution: Protection and Advanced Threat $ 64,797 $ 43,128 $ 121,259 $ 81,586 Archiving, Privacy and Governance 25,107 20,418 47,648 39,723 Total revenue $ 89,904 $ 63,546 $ 168,907 $ 121,309 Three Months Ended Six Months Ended June 30, 2016 2015 2016 2015 Total revenue: United States $ 74,907 $ 52,701 $ 140,356 $ 99,755 Rest of world 14,997 10,845 28,551 21,554 Total revenue $ 89,904 $ 63,546 $ 168,907 $ 121,309 Long-lived assets by geographic area are presented below: As of June 30, As of December 31, 2016 2015 Long-lived assets: United States $ 36,269 $ 29,514 Rest of world 7,157 4,987 Total long‑lived assets $ 43,426 $ 34,501

Income Taxes (Notes)

Income Taxes (Notes)	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	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 for the three and six months ended June 30, 2016 was $185 and $442 on pre-tax losses of $38,116 and $69,515 , respectively. The Company recognized income tax expense of $112 and $274 for the three and six months ended June 30, 2015 on pre-tax losses of $22,482 and $44,032 , respectively. The income tax rate for the three and six months ended June 30, 2016 and 2015 varies 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 each of the six months ended June 30, 2016 and 2015 was negative 0.6% . 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. As of June 30, 2016, the Company's gross uncertain tax benefits totaled $5,315 , excluding related accrued interest and penalties of $238 . As of June 30, 2016, $1,196 of the Company's uncertain tax benefits, including related accrued interest and penalties, would affect the effective tax rate if recognized. During the six months ended June 30, 2016, the Company's gross uncertain tax benefits increased $214 . The increase is comprised of a $257 increase for tax positions taken in the current period, a $5 decrease for tax positions taken in prior periods, offset by a $38 decrease related to statute of limitation expirations. The Company is not currently under audit by the IRS or any similar taxing authority in any other material jurisdiction. 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 and Summary of Si17

The Company and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2016
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 inter-company transactions and balances have been eliminated in consolidation. Starting January 1, 2016, the Company began separately presenting the effect of exchange rate changes on cash and cash equivalents in its condensed consolidated statements of cash flows due to growing operations in foreign currency environments. Amounts in the comparable prior period have been reclassified to conform to the current period presentation. The Company completed a number of acquisitions during the year ended December 31, 2015, which are more fully described in Note 2, "Acquisitions". The condensed consolidated financial statements include the results of operations from these business combinations from their date of acquisition. 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, 2015 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. The results of operations for the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for other interim periods or for future years. 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, 2015 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.
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, 2016 . 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 7 Non-compete agreements 2 4 Order backlog 1 3 Trade names and trademarks 1 5
Revenue Recognition	Revenue Recognition The Company derives its revenue primarily from two sources: (1) subscription revenue for rights related to the use of the security-as-a-service platform and (2) hardware, training and professional services revenue provided to customers related to their use of the platform. The Company records its revenues net of any value added or sales tax. Subscription revenue is derived from a subscription‑based enterprise licensing model with contract terms typically ranging from one to three years, and consists of (i) subscription fees from the licensing of the security-as-a-service platform, (ii) subscription fees for access to the on-demand elements of the platform and (iii) subscription fees for the right to access the Company’s customer support services. Revenue is recognized when all of the following criteria have been met: • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • Sales price is fixed or determinable; and • Collectability is reasonably assured. 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. From time to time, certain third parties that the Company has an arrangement with provide the Company with referrals for which the Company pays a referral fee. The referral fee paid could vary depending on the level of effort. These fees are recorded in sales and marketing expense in proportion to the related revenue streams consistent with the sales commissions accounting. The Company did not incur any material referral fee expenses during the three and six months ended June 30, 2016 and 2015. The Company applies industry-specific software revenue recognition guidance to transactions involving the licensing of software, as well as related support, training, and other professional services. The Company has analyzed all of the elements included in its multiple element software arrangements and has determined that it does not have sufficient VSOE of fair value to allocate revenue to its subscription and software license agreements, support, training and professional services. The Company defers all revenue under the software arrangement until the commencement of the subscription services and any associated professional services. Once the subscription services and the associated professional services have commenced, the entire fee from the arrangement is recognized ratably over the remaining period of the arrangement. If the professional services are essential to the functionality of the subscription, then the revenue recognition does not commence until such services are completed. The Company's revenue arrangements typically include subscription services to its security-as-a-service platform. These hosted on demand service arrangements do not provide customers with the right to take possession of the software supporting the hosted services. Certain arrangements also include the sale of hardware appliances. Revenue from hardware appliances containing software components and hardware components that function together to deliver the hardware appliance's essential functionality is excluded from the scope of the industry specific revenue recognition guidance. The Company recognizes revenue from its hosted on demand services in accordance with general revenue recognition accounting guidance. Only revenue derived from the licensing of the software is recognized in accordance with the industry specific revenue guidance. When a sales arrangement contains multiple elements, such as hardware appliances, subscription services, customer support services, and/or professional services, the Company allocates revenue to each unit of accounting or element based on a selling price hierarchy. An element constitutes a separate unit of accounting when the delivered item has standalone value and delivery of the undelivered element is probable and within the Company's control. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence (“VSOE”) of selling price. If VSOE does not exist, the Company uses third-party evidence (“TPE”) of selling price. If neither VSOE nor TPE of selling price exist for a deliverable, the Company uses its best estimate of selling price ("BESP") for that deliverable. Revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for each element. The Company determines BESP for an individual element within a multiple element revenue arrangement using the same methods utilized to determine the selling price of an element sold on a standalone basis. The Company estimates the selling price for its subscription solutions by considering internal factors such as historical pricing practices and it estimates the selling price of hardware and other services using a cost plus model. Hardware appliance revenue is recognized upon shipment. Subscription and support revenue are recognized over the contract period commencing on the start date of the contract. Professional services and training, when sold with hardware appliances or subscription and support services, are accounted for separately when those services have standalone value. In determining whether professional services and training services can be accounted for separately from subscription and support services, the Company considers the following factors: availability of the services from other vendors, the nature of the services, and the dependence of the subscription services on the customer’s decision to buy the professional services. If professional services and training do not qualify for separate accounting, the Company recognizes the professional services and training ratably over the contract term of the subscription services. Delivery generally occurs when the hardware appliance is delivered to a common carrier freight on board shipping point by the Company or the hosted service has been activated and communicated to the customer accordingly. The Company’s fees are typically considered to be fixed or determinable at the inception of an arrangement and are negotiated at the outset of an arrangement, generally based on specific products and quantities to be delivered. In the event payment terms are provided that differ significantly from the Company's standard business practices, the fees are deemed to not be fixed or determinable and revenue is recognized as the fees become paid. The Company assesses collectability based on a number of factors, including credit worthiness of the customer and past transaction history of the customer. Through June 30, 2016 , the Company has not experienced significant credit losses.
Deferred Revenue	Deferred Revenue Deferred revenue primarily consists of billings or payments received in advance of revenue recognition from the sale of the Company’s subscription fees, training and professional services. Once the revenue recognition criteria are met, this revenue is recognized ratably over the term of the associated contract.
Comprehensive Income (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, 2016 and 2015 .
Sales Commissions	Sales Commissions Effective January 1, 2016, the Company changed its accounting policy for sales commissions that are incremental and directly related to its customer sales contracts in which revenue is deferred. These commission costs are accrued and capitalized upon execution of a non-cancelable customer contract, and subsequently expensed over the term of such contract in proportion to the related future revenue streams. For commission costs where revenue is recognized, the related commission costs are recorded in the period of revenue recognition. Prior to this change in accounting policy, commission costs were expensed in the period in which they were incurred. The adoption of this accounting policy change has been applied retrospectively to all periods presented in this Quarterly Report on Form 10-Q, in which the cumulative effect of the change has been reflected as of the beginning of the first period presented. Deferred commissions as of June 30, 2016 and December 31, 2015 were $22,181 and $22,802 , respectively. During the three and six months ended June 30, 2016, the Company deferred $9,109 and $15,038 of commission costs and amortized $8,249 and $15,660 within sales and marketing expense, respectively. During the three and six months ended June 30, 2015, the Company deferred $7,392 and $11,892 of commission costs and amortized $5,013 and $9,552 within sales and marketing expense, respectively. The Company believes this change in accounting policy is preferable as the direct and incremental commission costs are closely related to the revenue, and therefore they should be recorded as an asset and recognized as an expense over the same period that the related revenue is recognized. The cumulative effect of the change on accumulated deficit was $15,060 as of December 31, 2014. The following tables present the changes to the financial statement lines as a result of the accounting change for the periods presented in the accompanying unaudited Condensed Consolidated Financial Statements: Condensed Consolidated Balance Sheet As of December 31, 2015 As reported Adjustment As adjusted Short-term deferred commissions $ — $ 19,314 $ 19,314 Long-term deferred commissions $ — $ 3,488 $ 3,488 Accumulated deficit $ (380,702 ) $ 22,802 $ (357,900 ) Condensed Consolidated Statement of Operations Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Operating expenses: Sales and marketing $ 38,017 $ (2,379 ) $ 35,638 $ 70,929 $ (2,340 ) $ 68,589 Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Net loss per share, basic and diluted $ (0.63 ) $ 0.06 $ (0.57 ) $ (1.19 ) $ 0.06 $ (1.13 ) Weighted average shares outstanding, basic and diluted 39,567 — 39,567 39,264 — 39,264 Condensed Consolidated Statement of Comprehensive Loss Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Unrealized gains on short-term investments, net $ 5 $ — $ 5 $ 25 $ — $ 25 Comprehensive loss $ (24,968 ) $ 2,379 $ (22,589 ) $ (46,621 ) $ 2,340 $ (44,281 ) There have been no changes, other than as discussed above, in the Company's significant accounting policies for the three and six months ended June 30, 2016, as compared to the significant accounting policies described in the Company's Annual Form 10-K for the
New Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 changes the impairment model for most financial assets, and will require the use of an expected loss model in place of the currently used incurred loss method. Under this model, entities will be required to estimate the lifetime expected credit loss on such instruments and record an allowance to offset the amortized cost basis of the financial asset, resulting in a net presentation of the amount expected to be collected on the financial asset. The update to the standard is effective for interim and annual periods beginning after December 15, 2019. The Company is currently evaluating the impact of the adoption of ASU 2016-13 on its consolidated financial statements. In March 2016, FASB issued Accounting Standards Update No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes how companies account for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The update to the standard is effective for interim and annual periods beginning after December 15, 2016. The Company is currently evaluating the impact of the adoption of ASU 2016-09 on its consolidated financial statements. In February 2016, FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) (ASU 2016-02), which requires lessees to put most leases on their balance sheets but recognize the expenses on their statements of operations in a manner similar to current practice. ASU 2016-02 states that a lessee would recognize a lease liability for the obligation to make lease payments and a right-to-use asset for the right to use the underlying asset for the lease term. The new standard is effective for interim and annual periods beginning after December 15, 2018 and early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-02 on its consolidated financial statements. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASU 2014-09 defines a five step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than required under existing U.S. GAAP including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. Originally, ASU 2014-09 would be effective for the Company starting January 1, 2017 using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within ASU 2014-09; or (ii) retrospective with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application and providing certain additional disclosures as defined per ASU 2014-09. In July 2015, the FASB voted to amend ASU 2014-09 by approving a one-year deferral of the effective date as well as providing the option to early adopt the standard on the original effective date. The FASB has issued several updates to the standard which i) clarify the application of the principal versus agent guidance (ASU 2016-08); ii) clarify the guidance on inconsequential and perfunctory promises and licensing (ASU 2016-10) and iii) narrow-scope improvements and practical expedients (ASU 2016-12). The Company is currently evaluating the timing and impact of the adoption of the standard on its consolidated financial statements.

The Company and Summary of Si18

The Company and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]		Condensed Consolidated Balance Sheet As of December 31, 2015 As reported Adjustment As adjusted Short-term deferred commissions $ — $ 19,314 $ 19,314 Long-term deferred commissions $ — $ 3,488 $ 3,488 Accumulated deficit $ (380,702 ) $ 22,802 $ (357,900 ) Condensed Consolidated Statement of Operations Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Operating expenses: Sales and marketing $ 38,017 $ (2,379 ) $ 35,638 $ 70,929 $ (2,340 ) $ 68,589 Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Net loss per share, basic and diluted $ (0.63 ) $ 0.06 $ (0.57 ) $ (1.19 ) $ 0.06 $ (1.13 ) Weighted average shares outstanding, basic and diluted 39,567 — 39,567 39,264 — 39,264 Condensed Consolidated Statement of Comprehensive Loss Three months ended June 30, 2015 Six months ended June 30, 2015 As reported Adjustment As adjusted As reported Adjustment As adjusted Net loss $ (24,973 ) $ 2,379 $ (22,594 ) $ (46,646 ) $ 2,340 $ (44,306 ) Unrealized gains on short-term investments, net $ 5 $ — $ 5 $ 25 $ — $ 25 Comprehensive loss $ (24,968 ) $ 2,379 $ (22,589 ) $ (46,621 ) $ 2,340 $ (44,281 )
Useful lives intangible assets [Table Text Block]	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 7 Non-compete agreements 2 4 Order backlog 1 3 Trade names and trademarks 1 5

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2016
Companies acquired in Q4 2015 [Member]
Business Acquisition [Line Items]
Schedule of purchase price [Table Text Block]	The aggregate purchase price was $11,568 . The following table summarizes the fair values of acquired tangible and intangible assets, liabilities and goodwill: Estimated Estimated Current assets acquired $ 414 N/A Fixed assets acquired 73 N/A Liabilities assumed (234 ) N/A Deferred revenue assumed (1,400 ) N/A Deferred tax liability, net (45 ) N/A Customer relationships 2,800 7 Order Backlog 900 3 Developed technology 3,000 4 Goodwill 6,060 Indefinite $ 11,568
Marble Security [Member]
Business Acquisition [Line Items]
Schedule of purchase price [Table Text Block]	The following table summarizes the fair values of acquired tangible, intangible assets and goodwill: Fair Value Estimated Fixed assets acquired $ 25 N/A Developed technology 7,300 4 Goodwill 1,175 Indefinite $ 8,500
Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Schedule of purchase price [Table Text Block]	The following table summarizes the fair values of tangible and intangible assets acquired, liabilities assumed and goodwill: Fair Value Estimated Current assets acquired $ 1,275 N/A Fixed assets acquired 174 N/A Liabilities assumed (448 ) N/A Deferred revenue assumed (700 ) N/A Holdback liability to the sellers (3,662 ) N/A Trade names 200 2 Customer relationships 4,200 7 Order Backlog 200 1 Developed technology 7,900 7 Goodwill 19,054 Indefinite $ 28,193

Goodwill and Intangible Asset20

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill [Table Text Block]	The goodwill activity and balances are presented below: Balance at December 31, 2015 $ 133,769 Add: Goodwill from acquisitions — Less: Other purchase price allocation adjustments to Goodwill — Balance at June 30, 2016 $ 133,769
Components of intangible assets excluding goodwill [Table Text Block]	Intangible assets, excluding goodwill, consisted of the following: June 30, 2016 December 31, 2015 Gross Accumulated Net Gross Accumulated Net Developed technology $ 57,268 $ (32,853 ) $ 24,415 $ 57,268 $ (28,618 ) $ 28,650 Customer relationships 18,384 (9,391 ) 8,993 23,382 (12,291 ) 11,091 Non-compete agreements 500 (470 ) 30 804 (691 ) 113 Trade names and patents 930 (547 ) 383 1,006 (502 ) 504 Order backlog 1,100 (365 ) 735 1,300 (328 ) 972 $ 78,182 $ (43,626 ) $ 34,556 $ 83,760 $ (42,430 ) $ 41,330
Future estimated amortization costs of intangible assets [Table Text Block]	Amortization of intangible assets expense was $3,369 and $2,917 for the three months ended June 30, 2016 and 2015 , respectively, and $6,774 and $5,624 for the six months ended June 30, 2016 and 2015 , respectively. Future estimated amortization of intangible assets expense as of June 30, 2016 are presented below: Year ending December 31, 2016, remainder $ 5,745 2017 9,174 2018 8,530 2019 5,164 2020 2,806 Thereafter 3,137 $ 34,556

Fair Value Measurements and I21

Fair Value Measurements and Investments (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair value, by balance sheet grouping [Table Text Block]	The following tables summarize, for each category of assets or liabilities carried at fair value, the respective fair value as of June 30, 2016 and December 31, 2015 and the classification by level of input within the fair value hierarchy: Balance as of Quoted Prices Significant Unobservable Assets Cash equivalents: Money market funds $ 334,357 $ 334,357 $ — $ — Commercial paper 801 — 801 — Short-term investments: Corporate debt securities 26,835 — 26,835 — Commercial papers 18,025 — 18,025 — Total financial assets $ 380,018 $ 334,357 $ 45,661 $ — Balance as of Quoted Prices Significant Unobservable Assets Cash equivalents: Money market funds $ 306,983 $ 306,983 $ — $ — Corporate debt securities 3,178 — 3,178 — Commercial paper 8,996 — 8,996 — Short-term investments: Corporate debt securities 36,527 — 36,527 — Commercial paper 16,290 — 16,290 — U.S. agency securities 5,414 — 5,414 — U.S. Treasury securities 1,801 — 1,801 — Total financial assets $ 379,189 $ 306,983 $ 72,206 $ —
Fair value of cash and cash equivalents, and investments [Table Text Block]	The cost and fair value of the Company’s cash and cash equivalents and available-for-sale investments as of June 30, 2016 and December 31, 2015 were as follows: June 30, 2016 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 32,102 $ — $ — $ 32,102 Money market funds 334,357 — — 334,357 Commercial paper 801 — — 801 Total $ 367,260 $ — $ — $ 367,260 Short-term investments: Corporate debt securities $ 26,838 $ 2 $ (5 ) $ 26,835 Commercial paper 18,025 — — 18,025 Total $ 44,863 $ 2 $ (5 ) $ 44,860 December 31, 2015 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash and cash equivalents: Cash $ 27,048 $ — $ — $ 27,048 Money market funds 306,983 — — 306,983 Corporate debt securities 3,178 — — 3,178 Commercial papers 8,996 — — 8,996 Total $ 346,205 $ — $ — $ 346,205 Short-term investments: Corporate debt securities $ 36,549 $ — $ (22 ) $ 36,527 Certificate of deposit 16,290 — — 16,290 U.S. agency securities 5,415 — (1 ) 5,414 U.S. Treasury securities 1,801 — — 1,801 Total $ 60,055 $ — $ (23 ) $ 60,032

Commitments and Contingencies22

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Future annual minimum lease payments under noncancelable operating and capital leases [Table Text Block]	At June 30, 2016 , future annual minimum lease payments under noncancellable operating and capital leases were as follows: Capital Operating Year ending December 31, 2016, remainder $ 21 $ 5,902 2017 41 7,542 2018 39 5,187 2019 37 4,494 2020 21 1,473 Thereafter — 3,122 Total minimum lease payments 159 $ 27,720 Less: Amount representing interest (20 ) Present value of capital lease obligations 139 Less: current portion (33 ) Long-term portion of capital lease obligations $ 106

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	6 Months Ended
	Jun. 30, 2016
Convertible Senior Notes [Abstract]
Schedule of liability and equity components of convertible debt [Table Text Block]	June 30, 2016 and December 31, 2015: June 30, 2016 0.75% Notes 1.25% Notes Total Liability component: Principal $ 230,000 $ 201,250 $ 431,250 Less: debt discount and issuance costs, net of amortization (49,508 ) (25,775 ) (75,283 ) Net carrying amount $ 180,492 $ 175,475 $ 355,967 Equity component (1) $ 54,049 $ 43,293 $ 97,342 December 31, 2015 0.75% Notes 1.25% Notes Total Liability component: Principal $ 230,000 $ 201,250 $ 431,250 Less: debt discount and issuance costs, net of amortization (54,952 ) (30,599 ) (85,551 ) Net carrying amount $ 175,048 $ 170,651 $ 345,699 Equity component (1) $ 54,049 $ 43,293 $ 97,342 (1) Recorded on the accompanying Condensed Consolidated Balance Sheets as additional paid-in capital, net of the $2,877 issuance costs.
Schedule of convertible note interest and accretion [Table Text Block]	For the three and six months ended June 30, 2016 and 2015 , the Company incurred the following interest expense related to the Notes: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Interest expense related to contractual interest coupon $ 1,060 $ 691 $ 2,120 $ 1,320 Amortization of debt discount and issuance costs 5,172 2,696 10,268 4,962 $ 6,232 $ 3,387 $ 12,388 $ 6,282

Stock Equity Plans (Tables)

Stock Equity Plans (Tables)	6 Months Ended
	Jun. 30, 2016
Employee stock purchase plan
Valuation assumptions [Table Text Block]	The fair values were estimated on the grant dates using the Black-Scholes option-pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended 2016 2015 2016 2015 Expected life (in years) 5.31 - 6.08 5.31 - 6.08 5.31 - 6.08 5.31 - 6.08 Volatility 45 % 50 % 45 % 50% - 52% Risk-free interest rate 1.4 % 1.7 % 1.4 % 1.6% - 1.7% Dividend yield — % — % — % — %
Activity under stock option plan [Table Text Block]	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, 2015 4,042 $ 15.10 5.77 $ 201,736 Options granted 212 51.35 Options exercised (554 ) 10.42 Options forfeited and canceled (23 ) 43.76 Balance at June 30, 2016 3,677 $ 17.72 5.71 $ 166,854
Summary of RSUs awarded and unvested under stock option plan [Table Text Block]	RSUs and PSUs Outstanding Number of Shares Granted Fair Value Per Unit Awarded and unvested at December 31, 2015 3,311 $ 47.94 Awards granted 711 52.53 Awards vested (611 ) 42.61 Awards forfeited (194 ) 52.37 Awarded and unvested at June 30, 2016 3,217 $ 49.70

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Schedule of antidilutive securities excluded from computation of earnings per share [Table Text Block]	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: As of June 30, 2016 2015 Stock options to purchase common stock 3,677 4,620 Restricted stock units 3,217 3,160 Employee stock purchase plan 104 78 Common stock subject to repurchase 78 54 Bonus and other liability awards 125 158 1.25% Convertible senior notes 5,158 5,158 0.75% Convertible senior notes 2,831 2,831 Total 15,190 16,059

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Revenue from external customers by products and services [Table Text Block]	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, 2016 2015 2016 2015 Total revenue by solution: Protection and Advanced Threat $ 64,797 $ 43,128 $ 121,259 $ 81,586 Archiving, Privacy and Governance 25,107 20,418 47,648 39,723 Total revenue $ 89,904 $ 63,546 $ 168,907 $ 121,309
Total revenue and long-lived assets by geographic area [Table Text Block]	Three Months Ended Six Months Ended June 30, 2016 2015 2016 2015 Total revenue: United States $ 74,907 $ 52,701 $ 140,356 $ 99,755 Rest of world 14,997 10,845 28,551 21,554 Total revenue $ 89,904 $ 63,546 $ 168,907 $ 121,309 Long-lived assets by geographic area are presented below: As of June 30, As of December 31, 2016 2015 Long-lived assets: United States $ 36,269 $ 29,514 Rest of world 7,157 4,987 Total long‑lived assets $ 43,426 $ 34,501

The Company and Summary of Si27

The Company and Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Intangible assets:
Goodwill, impairment loss	$ 0
Minimum [Member] | Patents [Member]
Intangible assets:
Estimated life of intangible assets	4 years
Minimum [Member] | Developed technology rights [Member]
Intangible assets:
Estimated life of intangible assets	3 years
Minimum [Member] | Customer relationships [Member]
Intangible assets:
Estimated life of intangible assets	2 years
Minimum [Member] | Noncompete agreements [Member]
Intangible assets:
Estimated life of intangible assets	2 years
Minimum [Member] | Order or Production Backlog [Member]
Intangible assets:
Estimated life of intangible assets	1 year
Minimum [Member] | Trademarks and Trade Names [Member]
Intangible assets:
Estimated life of intangible assets	1 year
Maximum [Member] | Patents [Member]
Intangible assets:
Estimated life of intangible assets	5 years
Maximum [Member] | Developed technology rights [Member]
Intangible assets:
Estimated life of intangible assets	7 years
Maximum [Member] | Customer relationships [Member]
Intangible assets:
Estimated life of intangible assets	7 years
Maximum [Member] | Noncompete agreements [Member]
Intangible assets:
Estimated life of intangible assets	4 years
Maximum [Member] | Order or Production Backlog [Member]
Intangible assets:
Estimated life of intangible assets	3 years
Maximum [Member] | Trademarks and Trade Names [Member]
Intangible assets:
Estimated life of intangible assets	5 years

The Company and Summary of Si28

The Company and Summary of Significant Accounting Policies The Company and Summary of Significant Accounting Policies - Basis of Presentation and Consolidation (Details)	3 Months Ended
	Dec. 31, 2015
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Number of Businesses Acquired	2

The Company and Summary of Si29

The Company and Summary of Significant Accounting Policies Sales Commissions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting principle, sales and marketing expenses before adjustments		$ 38,017		$ 70,929
Change in accounting principle, effect on sales and marketing expenses		(2,379)		(2,340)
Selling and Marketing Expense	$ 48,664	35,638	$ 95,187	68,589
Change in accounting principle, effect on short-term deferred commissions					$ 19,314
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(24,973)		(46,646)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		2,379		2,340
Total Net loss	(38,301)	$ (22,594)	(69,957)	$ (44,306)
Change in accounting principle, effect on earnings per share before adjustment		$ (0.63)		$ (1.19)
Change in accounting principle, effect on earnings per share		$ 0.06		$ 0.06
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	$ 5	21	$ 25
Comprehensive loss before adjustment		(24,968)		(46,621)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(38,301)	$ (22,589)	(69,936)	$ (44,281)
Deferred commissions, noncurrent	3,494		3,494		3,488
Accumulated deficit before the change in accounting principle					(380,702)
Change in accounting principle, effect on accumulated deficit					22,802	$ 15,060
Accumulated deficit	$ (427,857)		$ (427,857)		(357,900)
Earnings Per Share, Basic and Diluted	$ (0.92)	$ (0.57)	$ (1.69)	$ (1.13)
Weighted Average Number of Shares Outstanding, Basic and Diluted	41,605	39,567	41,349	39,264
Deferred commissions, current	$ 18,687		$ 18,687		19,314
total deferred commissions	22,181		22,181		22,802
Sales Commissions and Fees	9,109	$ 7,392	15,038	$ 11,892
Change in accounting principle, effect on long-term deferred commissions					$ 3,488
Amortization of Deferred Sales Commissions	$ 8,249	$ 5,013	$ 15,660	$ 9,552

Acquisitions (Details)

Acquisitions (Details) $ in Thousands	Jul. 22, 2015USD ($)	Mar. 06, 2015USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)
Business Acquisition [Line Items]
Number of Businesses Acquired			2
Payments to acquire businesses, net of cash acquired				$ 0	$ 31,624
Goodwill			$ 133,769	$ 133,769
Companies acquired in Q4 2015 [Member]
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired			12
Acquisition in 4th Quarter of 2015 [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets			414
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Net			45
Goodwill			6,060
Recognized identifiable assets acquired and liabilities assumed, net			11,568
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			73
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Current and Noncurrent Liabilities, Not Otherwise Defined			(234)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			(1,400)
Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred		$ 3,662
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets		$ 1,275
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Business Combination, Consideration Transferred		$ 31,803
Cash Acquired from Acquisition		52
Contingent consideration arrangements, range of outcomes, value, high		6,000
Goodwill		19,054
Recognized identifiable assets acquired and liabilities assumed, net		28,193
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		174
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Current and Noncurrent Liabilities, Not Otherwise Defined		(448)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Revenue		700
Marble Security [Member]
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	$ 8,500
Contingent consideration arrangements, range of outcomes, value, high	1,700
Goodwill	1,175
Recognized identifiable assets acquired and liabilities assumed, net	8,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	25
Trademarks and Trade Names [Member] | Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles		$ 200
Acquired finite-lived intangible assets, weighted average useful life		2 years
Customer relationships [Member] | Acquisition in 4th Quarter of 2015 [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles			$ 2,800
Acquired finite-lived intangible assets, weighted average useful life			7 years
Customer relationships [Member] | Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles		$ 4,200
Acquired finite-lived intangible assets, weighted average useful life		7 years
Order or Production Backlog [Member] | Acquisition in 4th Quarter of 2015 [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles			$ 900
Acquired finite-lived intangible assets, weighted average useful life			3 years
Order or Production Backlog [Member] | Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles		$ 200
Acquired finite-lived intangible assets, weighted average useful life		1 year
Developed technology rights [Member] | Acquisition in 4th Quarter of 2015 [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles			$ 3,000
Acquired finite-lived intangible assets, weighted average useful life			4 years
Developed technology rights [Member] | Emerging Threats [Member] [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles		$ 7,900
Acquired finite-lived intangible assets, weighted average useful life		7 years
Developed technology rights [Member] | Marble Security [Member]
Business Acquisition [Line Items]
Recognized identifiable assets acquired and liabilities assumed, finite-lived intangibles	$ 7,300
Acquired finite-lived intangible assets, weighted average useful life	4 years

Goodwill and Intangible Asset31

Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Goodwill activity and balances
Opening balance	$ 133,769
Add: Goodwill from acquisitions	0
Less: Other adjustments to goodwill	0
Closing balance	$ 133,769

Goodwill and Intangible Asset32

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	$ 78,182		$ 78,182		$ 83,760
Finite-lived intangible assets, accumulated amortization	(43,626)		(43,626)		(42,430)
Finite-lived intangible assets, net carrying amount	34,556		34,556		41,330
Intangible amortization expense	3,369	$ 2,917	6,774	$ 5,624
Future estimated amortization costs of intangible assets:
2016, remainder	5,745		5,745
2,017	9,174		9,174
2,018	8,530		8,530
2,019	5,164		5,164
2,020	2,806		2,806
Thereafter	3,137		3,137
Finite-lived intangible assets, net carrying amount	34,556		34,556		41,330
Developed technology rights [Member]
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	57,268		57,268		57,268
Finite-lived intangible assets, accumulated amortization	(32,853)		(32,853)		(28,618)
Finite-lived intangible assets, net carrying amount	24,415		24,415		28,650
Future estimated amortization costs of intangible assets:
Finite-lived intangible assets, net carrying amount	24,415		24,415		28,650
Customer relationships [Member]
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	18,384		18,384		23,382
Finite-lived intangible assets, accumulated amortization	(9,391)		(9,391)		(12,291)
Finite-lived intangible assets, net carrying amount	8,993		8,993		11,091
Future estimated amortization costs of intangible assets:
Finite-lived intangible assets, net carrying amount	8,993		8,993		11,091
Noncompete agreements [Member]
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	500		500		804
Finite-lived intangible assets, accumulated amortization	(470)		(470)		(691)
Finite-lived intangible assets, net carrying amount	30		30		113
Future estimated amortization costs of intangible assets:
Finite-lived intangible assets, net carrying amount	30		30		113
Trademarks and patents [Member]
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	930		930		1,006
Finite-lived intangible assets, accumulated amortization	(547)		(547)		(502)
Finite-lived intangible assets, net carrying amount	383		383		504
Future estimated amortization costs of intangible assets:
Finite-lived intangible assets, net carrying amount	383		383		504
Order or Production Backlog [Member]
Intangible assets excluding goodwill:
Finite-lived intangible assets, gross carrying amount	1,100		1,100		1,300
Finite-lived intangible assets, accumulated amortization	(365)		(365)		(328)
Finite-lived intangible assets, net carrying amount	735		735		972
Future estimated amortization costs of intangible assets:
Finite-lived intangible assets, net carrying amount	$ 735		$ 735		$ 972

Fair Value Measurements and I33

Fair Value Measurements and Investments - Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Fair value measurements and investments
Cash and cash equivalents	$ 367,260	$ 346,205	$ 402,144	$ 180,337
Cash and cash equivalents, fair value disclosures	367,260	346,205
Short-term investments, amortized cost basis	44,863	60,055
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5)	(23)
Short-term investments, fair value disclosures	44,860	60,032
Quoted prices in active markets for identical assets (Level 1) [Member]
Fair value measurements and investments
Assets, Fair Value Disclosure	334,357	306,983
Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Assets, Fair Value Disclosure	45,661	72,206
Estimate of Fair Value Measurement [Member]
Fair value measurements and investments
Assets, Fair Value Disclosure	380,018	379,189
Cash [Member]
Fair value measurements and investments
Cash and cash equivalents	32,102	27,048
Cash and cash equivalents, fair value disclosures	32,102	27,048
Money market funds [Member]
Fair value measurements and investments
Cash and cash equivalents	334,357	306,983
Cash and cash equivalents, fair value disclosures	334,357	306,983
Money market funds [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Fair value measurements and investments
Cash and cash equivalents, fair value disclosures	334,357	306,983
Corporate debt securities [Member]
Fair value measurements and investments
Cash and cash equivalents		3,178
Cash and cash equivalents, fair value disclosures		3,178
Short-term investments, amortized cost basis	26,838	36,549
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5)	(22)
Short-term investments, fair value disclosures	26,835	36,527
Corporate debt securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Cash and cash equivalents, fair value disclosures		3,178
Short-term investments, fair value disclosures	26,835	36,527
Commercial paper [Member]
Fair value measurements and investments
Cash and cash equivalents	801	8,996
Cash and cash equivalents, fair value disclosures	801	8,996
Short-term investments, amortized cost basis	18,025	16,290
Short-term investments, fair value disclosures	18,025	16,290
Commercial paper [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Cash and cash equivalents, fair value disclosures	801	8,996
Short-term investments, fair value disclosures	$ 18,025	16,290
US Government Agencies Debt Securities [Member]
Fair value measurements and investments
Short-term investments, amortized cost basis		5,415
Short-term investments, fair value disclosures		5,414
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Short-term investments, fair value disclosures		5,414
US Treasury Securities [Member]
Fair value measurements and investments
Short-term investments, amortized cost basis		1,801
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		(1)
Short-term investments, fair value disclosures		1,801
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Short-term investments, fair value disclosures		$ 1,801

Fair Value Measurements and I34

Fair Value Measurements and Investments Fair Value Measurements and Investments - Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures	$ 367,260	$ 346,205
Cash and cash equivalents	367,260	346,205	$ 402,144	$ 180,337
Short-term investments, amortized cost basis	44,863	60,055
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5	23
Short-term investments, fair value disclosures	44,860	60,032
Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Assets, Fair Value Disclosure	45,661	72,206
Cash [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures	32,102	27,048
Cash and cash equivalents	32,102	27,048
Money market funds [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures	334,357	306,983
Cash and cash equivalents	334,357	306,983
Corporate debt securities [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures		3,178
Cash and cash equivalents		3,178
Short-term investments, amortized cost basis	26,838	36,549
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5	22
Short-term investments, fair value disclosures	26,835	36,527
Corporate debt securities [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures		3,178
Short-term investments, fair value disclosures	26,835	36,527
Commercial paper [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures	801	8,996
Cash and cash equivalents	801	8,996
Short-term investments, amortized cost basis	18,025	16,290
Short-term investments, fair value disclosures	18,025	16,290
Commercial paper [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of cash and cash equivalents, and investments
Cash and cash equivalents, fair value disclosures	801	8,996
Short-term investments, fair value disclosures	18,025	16,290
US Government Agencies Debt Securities [Member]
Schedule of cash and cash equivalents, and investments
Short-term investments, amortized cost basis		5,415
Short-term investments, fair value disclosures		5,414
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of cash and cash equivalents, and investments
Short-term investments, fair value disclosures		5,414
US Treasury Securities [Member]
Schedule of cash and cash equivalents, and investments
Short-term investments, amortized cost basis		1,801
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		1
Short-term investments, fair value disclosures		1,801
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Schedule of cash and cash equivalents, and investments
Short-term investments, fair value disclosures		$ 1,801
Convertible Senior Notes 0 Point 75 [Member] | Convertible Notes Payable [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Convertible debt, fair value disclosures	245,238
Convertible Senior Notes 1 Point 25 Percent [Member] | Convertible Notes Payable [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value measurements and investments
Convertible debt, fair value disclosures	$ 315,459

Commitments and Contingencies35

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jul. 31, 2015	Jul. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Operating lease rent expense	$ 1,220	$ 951	$ 2,398	$ 1,818
Future annual minimum lease payments under noncancelable operating and capital leases
2015, remainder	21		21
2,016	41		41
2,017	39		39
2,018	37		37
2,019	21		21
Thereafter	0		0
Total minimum capital lease payments	159		159
Less: Amount representing interest	(20)		(20)
Present value of capital lease obligations	139		139
Less: Current portion	(33)		(33)
Long-term portion of capital lease obligations	106		106
Operating lease obligations
2015, remainder	5,902		5,902
2,016	7,542		7,542
2,017	5,187		5,187
2,018	4,494		4,494
2,019	1,473		1,473
Thereafter	3,122		3,122
Total minimum operating lease payments	$ 27,720		$ 27,720
Capital Lease Obligations [Member]
Debt instrument
Interest rate, stated percentage					6.50%	4.50%

Commitments and Contingencies L

Commitments and Contingencies Legal Contingencies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Loss in Period	$ 10,900
Loss Contingency, Damages Paid, Value	4,300
Settlement payable	$ 3,300

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) $ / shares in Units, shares in Thousands	Jun. 17, 2015USD ($)sharesd$ / shares	Dec. 11, 2013USD ($)sharesd$ / shares	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Debt instrument
Proceeds from convertible debt					$ 0	$ 223,790,000
Convertible senior notes			$ 355,967,000		355,967,000		$ 345,699,000
Amortization of debt issuance costs and accretion of debt discount					10,268,000	4,962,000
Convertible debt [Member]
Debt instrument
Convertible senior notes			355,967,000		355,967,000		345,699,000
Convertible Senior Notes 0 Point 75 [Member]
Debt instrument
Convertible senior notes			180,492,000		180,492,000		175,048,000
Convertible Senior Notes 1 Point 25 Percent [Member]
Debt instrument
Convertible senior notes			175,475,000		175,475,000		170,651,000
Issuance costs allocated to equity portion		$ 1,285,000
Convertible debt [Member]
Debt instrument
Carrying amount of equity component			97,342,000		97,342,000		97,342,000
Debt discount, net of amortization			(75,283,000)		(75,283,000)		(85,551,000)
Issuance costs allocated to equity portion			2,877,000		2,877,000
Interest expense, 1.25% coupon			1,060,000	$ 691,000	2,120,000	1,320,000
Amortization of debt issuance costs and accretion of debt discount			5,172,000	2,696,000	10,268,000	4,962,000
Interest expense, total			6,232,000	$ 3,387,000	12,388,000	$ 6,282,000
Debt Instrument, Face Amount			431,250,000		431,250,000		431,250,000
Convertible debt [Member] | Convertible Senior Notes 0 Point 75 [Member]
Debt instrument
Debt Issuance Cost, Gross, Noncurrent		5,803,000
Convertible debt [Member] | Zero Point Seven Five Percent Convertible Senior Notes Due June Twenty Twenty [Member]
Debt instrument
Face amount optional	$ 30,000,000
Debt Issuance Cost, Gross, Noncurrent	6,581,000
Proceeds from convertible debt	$ 223,419,000
Interest rate, stated percentage	0.75%
Conversion ratio, initial (in shares)	12.3108
Number of shares convertible, initial rate (in shares) | shares	2,831
Conversion price per share, initial (USD per share) | $ / shares	$ 81.23
Threshold percentage of stock price trigger	130.00%
Threshold trading days | d	20
Threshold consecutive trading days	30 days
Number of consecutive business days following consecutive trading day period	5 days
Debt Instrument Convertible Period Of Consecutive Trading Days	5 days
Trading price as percentage of closing price of common stock	98.00%
Effective rate used to amortize debt discount	6.50%
Convertible senior notes	$ 174,359,000
Carrying amount of equity component	55,641,000		54,049,000		54,049,000		54,049,000
Debt discount, net of amortization			(49,508,000)		(49,508,000)		(54,952,000)
Issuance costs allocated to equity portion	1,592,000
Debt Instrument, Face Amount	$ 200,000,000		230,000,000		230,000,000		230,000,000
Convertible debt [Member] | Convertible Senior Notes 1 Point 25 Percent [Member]
Debt instrument
Face amount optional		26,250,000
Proceeds from convertible debt		$ 195,446,000
Interest rate, stated percentage		1.25%
Conversion ratio, initial (in shares)		25.6271
Number of shares convertible, initial rate (in shares) | shares		5,158
Conversion price per share, initial (USD per share) | $ / shares		$ 39.02
Threshold percentage of stock price trigger		130.00%
Threshold trading days | d		20
Threshold consecutive trading days		30 days
Number of consecutive business days following consecutive trading day period		5 days
Debt Instrument Convertible Period Of Consecutive Trading Days		5 days
Trading price as percentage of closing price of common stock		98.00%
Effective rate used to amortize debt discount		6.50%
Convertible senior notes		$ 156,672,000
Carrying amount of equity component		44,578,000	43,293,000		43,293,000		43,293,000
Debt discount, net of amortization			(25,775,000)		(25,775,000)		(30,599,000)
Debt Instrument, Face Amount		$ 175,000,000	$ 201,250,000		$ 201,250,000		$ 201,250,000

Common Stock (Details)

Common Stock (Details) - $ / shares shares in Thousands	Jun. 30, 2016	Dec. 31, 2015
Stockholders' equity:
Preferred stock authorized (in shares)	5,000	5,000
Common Stock, Shares Authorized	200,000	200,000
Par value of common stock (USD per share)	$ 0.0001	$ 0.0001
Preferred Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Employee Stock Option [Member]
Number of shares of common stock reserved for future issuance
Shares available for future grant under the stock plans (in shares)	6,659
ESPP 2012 Plan [Member]
Number of shares of common stock reserved for future issuance
Shares available for future issuance under ESPP	1,459
2012 Equity Incentive Plan [Member] | Restricted stock units (RSUs) [Member]
Number of shares of common stock reserved for future issuance
Common stock issuable upon settlement of outstanding restricted stock units	3,217	3,311

Stock Equity Plans - Stock-Base

Stock Equity Plans - Stock-Based Compensation Plans (Details) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016shares	Jun. 30, 2015	Jun. 30, 2016planshares	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans held by the company (number of plans) | plan			2
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant under the stock plans (in shares)	6,659		6,659
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)	20,316		20,316
2012 Equity Incentive Plan [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend rate	0.00%	0.00%	0.00%	0.00%
2012 Equity Incentive Plan [Member] | Employee Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
2012 Equity Incentive Plan [Member] | Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term until award expiration			10 years
Award vesting period			4 years
2012 Equity Incentive Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years

Stock Equity Plans - Stock Opti

Stock Equity Plans - Stock Option Activity (Details) - Employee Stock Option [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant under the stock plans (in shares)	6,659			6,659
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per share	$ 22.82		$ 28.23		$ 27.81
Fair value assumptions
Expected dividend rate	0.00%		0.00%	0.00%	0.00%
Stock option activity under the Plan
Outstanding, beginning of period (in shares)				4,042
Options granted (in shares)				212
Options exercised (in shares)				(554)
Options forfeited and expired (in shares)				(23)
Outstanding, ending of period (in shares)	3,677	4,042		3,677		4,042
Stock option activity under the Plan, in weighted average exercise price:
Balance at beginning of period (USD per share)				$ 15.10
Options granted (USD per share)				51.35
Options exercised (USD per share)				10.42
Options forfeited and expired (USD per share)				43.76
Balance at ending of period (USD per share)	$ 17.72	$ 15.10		$ 17.72		$ 15.10
Weighted average remaining contractual term		5 years 9 months 7 days		5 years 8 months 16 days		5 years 9 months 6 days
Aggregate intrinsic value, outstanding	$ 166,854	$ 201,736		$ 166,854		$ 201,736
Aggregate intrinsic value, exercised				24,629	$ 40,237
Proceeds from stock options exercised				5,778	6,520
Fair value of options, vested in period				5,543	$ 5,896
Unamortized stock-based compensation expense	$ 13,714			$ 13,714
Average remaining vesting term				2 years 1 month 7 days
Maximum [Member] | 2012 Equity Incentive Plan [Member]
Fair value assumptions
Expected life	6 years 29 days		6 years 29 days	6 years 29 days	6 years 29 days
Weighted average volatility rate					52.00%
Risk free interest rate					1.70%
Minimum [Member] | 2012 Equity Incentive Plan [Member]
Fair value assumptions
Expected life	5 years 3 months 21 days		5 years 3 months 21 days	5 years 3 months 21 days	5 years 3 months 21 days
Weighted average volatility rate	45.00%		50.00%	45.00%	50.00%
Risk free interest rate	1.40%		1.70%	1.40%	1.60%

Stock Equity Plans - Restricted

Stock Equity Plans - Restricted Stock Units (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2014	Jun. 30, 2016	Jun. 30, 2015
RSUs outstanding, granted fair value per unit
Fair value of shares granted		$ 2,357
ESPP 2012 Plan [Member]
RSUs outstanding, granted fair value per unit
Unamortized stock-based compensation expense		$ 1,200
Average remaining vesting term		4 months 24 days
Restricted Stock [Member]
RSU's outstanding, number of shares:
Restricted Stock granted (in shares)	54
RSUs outstanding, granted fair value per unit
Unamortized stock-based compensation expense		$ 393
Stock-based Compensation Expense		$ 589
Restricted stock units (RSUs) [Member]
RSUs outstanding, granted fair value per unit
Average remaining vesting term		2 years 11 months 11 days
Restricted stock units (RSUs) [Member] | 2012 Equity Incentive Plan [Member]
RSU's outstanding, number of shares:
Awarded at beginning of period (in shares)		3,311
Restricted Stock granted (in shares)		711
Awards vested (in shares)		(611)
Awards forfeited (in shares)		(194)
Awarded at end of period (in shares)		3,217
RSUs outstanding, granted fair value per unit
Awarded at beginning of period (USD per share)		$ 47.94
Awards granted (USD per share)		52.53
Awards vested (USD per share)		42.61
Awards forfeited (USD per share)		52.37
Awarded at end of period (USD per share)		$ 49.70
Unamortized stock-based compensation expense		$ 98,107
Performance Shares [Member] | 2012 Equity Incentive Plan [Member]
RSUs outstanding, granted fair value per unit
Unamortized stock-based compensation expense		$ 10,437
Performance restricted stock units, Granted in Period		105	172
Stock Bonus Awards [Member] | 2012 Equity Incentive Plan [Member]
RSUs outstanding, granted fair value per unit
Stock-based Compensation Expense		$ 2,602	$ 1,459
Liability [Member]
RSUs outstanding, granted fair value per unit
Stock-based Compensation Expense		$ 1,143	$ 729

Stock Equity Plans - Employee S

Stock Equity Plans - Employee Stock Purchase Plan (Details) - USD ($) shares in Thousands, $ in Thousands	Mar. 30, 2012	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
2012 Equity Incentive Plan [Member]
Employee stock purchase plan
Number of shares authorized ESPP (in shares)		20,316		20,316
ESPP 2012 Plan [Member]
Employee stock purchase plan
Number of shares authorized ESPP (in shares)	745
Annual percentage increase of maximum number of shares reserved for issuance ESPP	1.00%
Maximum number of shares to be available for grant ESPP (in shares)	1,490
Increase in Common Stock Reserved and Available for Issuance ESPP		1,459		1,459
Unamortized stock-based compensation expense		$ 1,200		$ 1,200
Average remaining vesting term				4 months 24 days
Employee Stock Option [Member]
Employee stock purchase plan
Shares available for future grant under the stock plans (in shares)		6,659		6,659
Employee Stock Option [Member] | 2012 Equity Incentive Plan [Member]
Employee stock purchase plan
Expected dividend rate		0.00%	0.00%	0.00%	0.00%
Unamortized stock-based compensation expense		$ 13,714		$ 13,714
Average remaining vesting term				2 years 1 month 7 days
Employee Stock Option [Member] | Minimum [Member] | 2012 Equity Incentive Plan [Member]
Employee stock purchase plan
Expected life		5 years 3 months 21 days	5 years 3 months 21 days	5 years 3 months 21 days	5 years 3 months 21 days
Weighted average volatility rate		45.00%	50.00%	45.00%	50.00%
Risk free interest rate		1.40%	1.70%	1.40%	1.60%
Employee Stock Option [Member] | Maximum [Member] | 2012 Equity Incentive Plan [Member]
Employee stock purchase plan
Expected life		6 years 29 days	6 years 29 days	6 years 29 days	6 years 29 days
Weighted average volatility rate					52.00%
Risk free interest rate					1.70%

Stock Equity Plans Performance

Stock Equity Plans Performance Stock Units (Details) - 2012 Equity Incentive Plan [Member] - Performance Shares [Member] - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance restricted stock units, Granted in Period	105	172
Unamortized stock-based compensation expense	$ 10,437

Stock Equity Plans Stock Bonus

Stock Equity Plans Stock Bonus and Other Liability Awards (Details) - USD ($) shares in Thousands, $ in Thousands	Mar. 06, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value of Liability Award Issued	$ 6,885
2012 Equity Incentive Plan [Member] | Stock Bonus Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued stock bonuses, Current		$ 2,660		$ 5,676
Stock bonus awards, Shares Issued in Period		93	27
Stock-based Compensation Expense		$ 2,602	$ 1,459
Stock Issued During Period, Shares, New Issues		45

Net Loss per Share (Details)

Net Loss per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	15,190	16,059
Employee Stock Option [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	3,677	4,620
Employee stock purchase plan [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	104	78
Common stock subject to repurchase [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	78	54
Stock Bonus Awards [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	125	158
Convertible Senior Notes 1 Point 25 Percent [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	5,158	5,158
Restricted stock units (RSUs) [Member]
Antidilutive securities excluded from computation of earnings per share
Total antidilutive securities excluded from computation of earnings per share (in shares)	3,217	3,160
Convertible Senior Notes 0 Point 75 [Member]
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 - Revenue by

Segment Reporting - Revenue by Solution (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)segment	Jun. 30, 2015USD ($)
Revenue by Solution [Abstract]
Number of operating and reportable segments | segment			1
Revenue from external customers
Revenue	$ 89,904	$ 63,546	$ 168,907	$ 121,309
Protection and Advanced Threat [Member]
Revenue from external customers
Revenue	64,797	43,128	121,259	81,586
Archiving, Privacy and Governance [Member]
Revenue from external customers
Revenue	$ 25,107	$ 20,418	$ 47,648	$ 39,723

Segment Reporting - by Geograph

Segment Reporting - by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment reporting:
Revenue	$ 89,904	$ 63,546	$ 168,907	$ 121,309
Total long-lived assets	43,426		43,426		$ 34,501
United States [Member]
Segment reporting:
Revenue	74,907	52,701	140,356	99,755
Total long-lived assets	36,269		36,269		29,514
Rest of world [Member]
Segment reporting:
Revenue	14,997	$ 10,845	28,551	$ 21,554
Total long-lived assets	$ 7,157		$ 7,157		$ 4,987

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Valuation allowance
Income tax expense (benefit)	$ 185	$ 112	$ 442	$ 274
Loss before (provision for) benefit from income taxes	38,116	$ 22,482	$ 69,515	$ 44,032
Effective income tax rate			(0.60%)
Unrecognized tax benefits	5,315		$ 5,315
Accrued interest and penalties	238		238
Uncertain tax benefits that would affect effective tax rate if recognized	$ 1,196		1,196
Increase (decrease) in gross uncertain tax benefits			214
Increase for tax positions taken in the current period			257
Increase (decrease) for tax positions taken in prior periods			5
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations			$ 38