0001262039-17-000017 | 10-Q | XBRL Viewer

Net Income Per Share (Tables)

3 Months Ended

Mar. 31, 2017

Schedule of Earnings Per Share, Basic and Diluted

A reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share is as follows (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Numerator:
Net income	$	10,717	$	2,118

Denominator:
Basic shares:
Weighted-average common stock outstanding-basic	174,489		171,745
Diluted shares:
Weighted-average common stock outstanding-basic	174,489		171,745
Effect of potentially dilutive securities:
RSUs	2,216		1,020
Stock options	1,523		1,632
ESPP	50		24
Weighted-average shares used to compute diluted net income per share	178,278		174,421
Net income per share:
Basic	$	0.06	$	0.01
Diluted	$	0.06	$	0.01

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following weighted-average shares of common stock were excluded from the computation of diluted net income per share for the periods presented, as their effect would have been antidilutive (in thousands):



	Three Months Ended
	March 31, 2017	March 31, 2016
RSUs	2,505	6,351
Stock options	1,118	1,559
ESPP	262	282
	3,885	8,192

Investments in Privately-Held Companies	3 Months Ended
Investments in Privately-Held Companies	Mar. 31, 2017
Investments, All Other Investments [Abstract]
INVESTMENTS IN PRIVATELY-HELD COMPANIES	INVESTMENTS IN PRIVATELY HELD COMPANIES Our investments in the equity securities of privately held companies totaled $11.3 million and $10.3 million as of March 31, 2017 and December 31, 2016, respectively. These investments are accounted for as cost-basis investments, as we own less than 20% of the voting securities in each these investments and do not have the ability to exercise significant influence over operating and financial policies of the respective entities. These investments are carried at historical cost and are recorded as other assets on our condensed consolidated balance sheets and would be measured at fair value if indicators of impairment existed. As of March 31, 2017, no events have occurred that would adversely affect the carrying value of these investments. As of March 31, 2017, we determined that we had a variable interest in these privately held companies. However, we determined that we were not the primary beneficiary as we did not have the power to direct their activities that most significantly affect their economic performance. The variable interest entities are not required to be consolidated in our condensed consolidated financial statements.

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2017	Apr. 28, 2017
DEI [Abstract]
Entity Registrant Name	FORTINET INC
Entity Central Index Key	0001262039
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding		175,760,937

Goodwill and Other Intangible Assets - Net - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2017 (remainder)	$ 6,280
2018	6,885
2019	5,406
2020	2,364
Total	$ 20,935	$ 23,228

Subsequent Event (Details) - Subsequent Event ft² in Thousands, $ in Millions	1 Months Ended
	Apr. 30, 2017 USD ($) ft²
Subsequent Event [Line Items]
Area of real estate purchased (in sq. ft) \| ft²	282
Cash payment to acquire real estate \| $	$ 85.0

Goodwill and Other Intangible Assets - Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Finite-Lived Intangible Assets, Net [Abstract]
Gross	$ 38,484		$ 38,484
Accumulated Amortization	17,549		15,256
Total	20,935		23,228
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross	40,084		40,084
Net	22,535		24,828
Amortization expense	$ 2,300	$ 1,200
Developed Technologies and Other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	3 years 9 months 18 days	3 years 9 months 15 days
Finite-Lived Intangible Assets, Net [Abstract]
Gross	$ 23,984		23,984
Accumulated Amortization	10,000		8,750
Total	$ 13,984		15,234
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	4 years 8 months 12 days	4 years 8 months 5 days
Finite-Lived Intangible Assets, Net [Abstract]
Gross	$ 14,500		14,500
Accumulated Amortization	7,549		6,506
Total	6,951		7,994
In Process Research and Development [Member]
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
In-process research and development	$ 1,600		$ 1,600

Net Income Per Share

3 Months Ended

Mar. 31, 2017

Earnings Per Share [Abstract]

NET INCOME PER SHARE

Basic net income per share is computed by dividing net income by the weighted-average number of shares of common stock outstanding during the period. Diluted net income per share is computed by dividing net income by the weighted-average number of shares of common stock outstanding, plus the dilutive effects of restricted stock units (“RSUs”), stock options and the employee stock purchase plan (“ESPP”). Dilutive shares of common stock are determined by applying the treasury stock method.

A reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share is as follows (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Numerator:
Net income	$	10,717	$	2,118

Denominator:
Basic shares:
Weighted-average common stock outstanding-basic	174,489		171,745
Diluted shares:
Weighted-average common stock outstanding-basic	174,489		171,745
Effect of potentially dilutive securities:
RSUs	2,216		1,020
Stock options	1,523		1,632
ESPP	50		24
Weighted-average shares used to compute diluted net income per share	178,278		174,421
Net income per share:
Basic	$	0.06	$	0.01
Diluted	$	0.06	$	0.01



	Three Months Ended
	March 31, 2017	March 31, 2016
RSUs	2,505	6,351
Stock options	1,118	1,559
ESPP	262	282
	3,885	8,192

Stockholders' Equity

3 Months Ended

Mar. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCKHOLDERS' EQUITY

STOCKHOLDERS’ EQUITY

Stock-Based Compensation Plans

We have stock-based compensation plans pursuant to which we have granted stock options and RSUs. We also have an ESPP for all eligible employees. As of March 31, 2017, there were a total of 50,087,833 shares of common stock available for grant under our stock-based compensation plans.

Restricted Stock Units

The following table summarizes the activity and related information for RSUs for the periods presented below (in thousands, except per share amounts):



	Restricted Stock Units Outstanding
	Number of Shares		Weighted-Average Grant Date Fair Value per Share
Balance—December 31, 2016	9,509		$	31.01
Granted	2,582		37.21
Forfeited	(301	)	33.80
Vested	(1,299	)	27.43
Balance—March 31, 2017	10,491		$	33.04

As of March 31, 2017, total compensation expense related to unvested RSUs that were granted to employees and non-employees under the 2009 Plan, but not yet recognized, was $310.3 million. This expense is expected to be amortized on a straight-line basis over a weighted-average vesting period of 2.9 years.

RSUs settle into shares of common stock upon vesting. Upon the vesting of the RSUs, we net-settle the RSUs and withhold a portion of the shares to satisfy minimum statutory employee withholding taxes. Total payment for the employees’ tax obligations to the taxing authorities is reflected as a financing activity within the condensed consolidated statements of cash flows.

The following summarizes the number and value of the shares withheld for employee taxes (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Shares withheld for taxes	413		343
Amount withheld for taxes	$	13,693	$	9,441

Employee Stock Options

The following table summarizes the weighted-average assumptions relating to our employee stock options:



	Three months Ended
	March 31, 2017		March 31, 2016
Expected term in years	4.4		4.3
Volatility	36	%	43	%
Risk-free interest rate	1.9	%	1.1	%
Dividend rate	—	%	—	%

The following table summarizes the stock option activity and related information for the periods presented below (in thousands, except exercise prices and contractual life):



	Options Outstanding
	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Balance—December 31, 2016	6,187		$	23.79
Granted	498		37.24
Forfeited	(46	)	27.24
Exercised	(855	)	14.67
Balance—March 31, 2017	5,784		$	26.27
Options vested and expected to vest—March 31, 2017	5,784		$	26.27	3.4	$	71,951
Options exercisable—March 31, 2017	3,820		$	23.91	2.2	$	56,071

The aggregate intrinsic value represents the pre-tax difference between the exercise price of stock options and the quoted market price of our common stock on March 31, 2017, for all in-the-money stock options. As of March 31, 2017, total compensation expense related to unvested stock options granted to employees but not yet recognized was $19.5 million. This expense is expected to be amortized on a straight-line basis over a weighted-average period of 3.0 years.

Additional information related to our stock options is summarized below (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Weighted-average fair value per share granted	$	12.22	$	8.68
Intrinsic value of options exercised	17,898		19,424
Fair value of options vested	3,395		2,084

Employee Stock Purchase Plan

In determining the fair value of the ESPP, we use the Black-Scholes option pricing model that employs the following weighted-average assumptions:



	Three Months Ended
	March 31, 2017		March 31, 2016
Expected term in years	0.5		0.5
Volatility	33	%	48	%
Risk-free interest rate	0.7	%	0.4	%
Dividend rate	—	%	—	%

Additional information related to the ESPP is provided below (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Weighted-average fair value per share granted	$	9.28	$	7.19
Shares issued under the ESPP	634		614
Weighted-average price per share issued	$	27.97	$	20.49

Stock-based Compensation Expense

Stock-based compensation expense is included in costs and expenses as follows (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Cost of product revenue	$	342	$	280
Cost of service revenue	2,310		2,134
Research and development	7,898		7,143
Sales and marketing	19,026		15,815
General and administrative	3,755		3,530
Total stock-based compensation expense	$	33,331	$	28,902

The following table summarizes stock-based compensation expense by award type (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
RSUs	$	29,041	$	25,103
Stock options	1,845		1,954
ESPP	2,445		1,845
Total stock-based compensation expense	$	33,331	$	28,902

Total income tax benefit associated with stock-based compensation that is recognized in the condensed consolidated statements of operations is as follows (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Income tax benefit associated with stock-based compensation	$	6,645	$	7,321

Share Repurchase Program

In January 2016, our board of directors approved the 2016 Share Repurchase Program (the “2016 Repurchase Program”), which authorizes the repurchase of up to $200.0 million of our outstanding common stock through December 31, 2017. In October 2016, our board of directors authorized the purchase of an additional $100.0 million of shares of our common stock under the 2016 Repurchase Program, increasing our current authorization to $300.0 million through December 31, 2017. Under the 2016 Repurchase Program, share repurchases may be made by us from time to time in privately negotiated transactions or in open market transactions. The 2016 Repurchase Program does not require us to purchase a minimum number of shares, and may be suspended, modified or discontinued at any time without prior notice. There were no shares repurchased under the 2016 Repurchase Program during the three months ended March 31, 2017. As of March 31, 2017, $189.2 million remained available for future share repurchases under the 2016 Repurchase Program.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Property and Equipment—Net

3 Months Ended

Mar. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT—Net

PROPERTY AND EQUIPMENT—NET

Property and equipment—net consisted of the following (in thousands):



	March 31, 2017			December 31, 2016
Computer equipment and software	$	70,048		$	65,323
Building and building improvements	56,373			49,783
Land	44,198			35,079
Leasehold improvements	20,542			18,699
Evaluation units	19,701			20,173
Furniture and fixtures	14,153			13,995
Construction-in-progress	6,201			4,669
Total property and equipment	231,216			207,721
Less: accumulated depreciation	(75,740		)	(70,472		)
Property and equipment—net	$	155,476		$	137,249

Depreciation expense was $11.2 million and $9.4 million for the three months ended March 31, 2017 and March 31, 2016, respectively.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation and Preparation	Basis of Presentation and Preparation—The unaudited condensed consolidated financial statements of Fortinet, Inc. and its wholly owned subsidiaries (collectively, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information, as well as the instructions to Form 10-Q pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, and should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2016, contained in our Annual Report on Form 10-K filed with the SEC on March 1, 2017. In the opinion of management, all adjustments, which includes normal recurring adjustments, considered necessary for a fair presentation have been included. All intercompany balances, transactions and cash flows have been eliminated. The results of operations for the three months ended March 31, 2017 are not necessarily indicative of the results for the full year or for any future periods. The condensed consolidated balance sheet as of December 31, 2016 is derived from the audited consolidated financial statements for the year ended December 31, 2016. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. There have been no material changes to our significant accounting policies as of and for the three months ended March 31, 2017, except for changes to our policies related to inventory and business combinations. For more information, refer to the “Recently Adopted Accounting Standards.”
Recently Adopted Accounting Standards and Recent Accounting Standards Not Yet Effective	Recently Adopted Accounting Standards In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-01—Business Combinations: Clarifying the Definition of a Business, which clarifies the definition of a business to assist organizations with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. We elected to early adopt ASU 2017-01 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2017-01 did not have a material impact on our consolidated financial statements. In July 2015, the FASB issued ASU 2015-11—Inventory: Simplifying the Measurement of Inventory, which requires entities to measure most inventory at the lower of cost and net realizable value, replacing the former methodology of measuring inventory at the lower of cost or market. We adopted ASU 2015-11 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2015-11 did not have a significant impact on our consolidated financial statements. Recent Accounting Standards Not Yet Effective In January 2017, the FASB issued ASU 2017-04—Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment. ASU 2017-04 eliminates Step 2 from the goodwill impairment test which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. Under ASU 2017-04, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount, and should recognize an impairment loss for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the loss not exceeding the total amount of goodwill allocated to that reporting unit. ASU 2016-06 will be effective for us beginning on January 1, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. At adoption, this update will require a prospective approach. We intend to adopt ASU 2017-04 in the fourth quarter of 2017. We do not believe that ASU 2017-04 will have a material impact on our consolidated financial statements. In October 2016, the FASB issued ASU 2016-16—Income Taxes: —Intra-Entity Transfer of Assets Other Than Inventory, which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. ASU 2016-06 will be effective for us beginning on January 1, 2018. We are currently evaluating the impact of adopting ASU 2016-16 on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13—Financial Instruments—Credit Losses—Measurement of Credit Losses on Financial Instruments, which requires measurement and recognition of expected credit losses for financial assets held. ASU 2016-13 is effective for us beginning on January 1, 2020, with the option to adopt early on January 1, 2019. We are currently evaluating the impact of adopting ASU 2016-13 on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02—Leases, which requires the recognition of right-of-use assets and lease liabilities on the consolidated balance sheet for substantially all leases. The new guidance includes a number of optional practical expedients that entities may elect to apply. The new guidance will also require significant additional disclosures about the amount, timing and uncertainty of cash flows from leases. This new guidance will be effective for us beginning on January 1, 2019, using a modified retrospective approach. We currently anticipate to early adopt ASU 2016-02 on January 1, 2018. Our ability to early adopt is dependent on system readiness, including software procured from third-party providers, if any, and the completion of our analysis of information necessary to quantify the impact on the prior period financial statements. Based on our current lease portfolio, we estimate the value of leased assets and liabilities that may be recognized could be at least $50.0 million. We are continuing to evaluate the impact of ASU 2016-02 and our estimate is subject to change. We do not believe that ASU 2016-02 will have a material impact on our consolidated statements of operations. In May 2014, the FASB issued ASU 2014-09—Revenue from Contracts with Customers, which outlines a single, comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The core principle of ASU 2014-09 is to recognize revenue 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, accordingly, it is possible more judgment and estimates may be required within the revenue recognition process than is 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. The FASB has recently issued several amendments to ASU 2014-09, including clarification on accounting for licenses of intellectual property and identifying performance obligations. ASU 2014-09 will be effective for us beginning January 1, 2018. The two permitted transition methods under ASU 2014-09 are the full retrospective method, in which case ASU 2014-09 would be applied to each prior reporting period presented and the cumulative effect of applying ASU 2014-09 would be recognized at the earliest period shown, or the modified retrospective method, in which case the cumulative effect of applying ASU 2014-09 would be recognized at the date of initial application. Currently, we are in the process of reviewing our historical contracts to quantify the impact on our consolidated financial statements. Depending on the results of our review, there could be changes to the timing of revenue recognition and certain sales commission and related costs associated with obtaining and fulfilling our customer contracts. These changes may include the acceleration of revenue and associated costs on sales to certain channel partners that are currently accounted for only once the product is sold through to the end-customer. We will be required to capitalize and amortize incremental costs related to obtaining customer contracts, such as sales commission costs. We are also in the process of assessing the appropriate changes to our business processes and upgrading our systems and controls to support recognition and disclosure under ASU 2014-09. We otherwise expect to complete our assessment process, including selecting a transition method for adoption, in the next two quarters of 2017.

Defined Contribution Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Matching contribution on employee contributions, Percent	50.00%
Maximum contribution percentage of each employee's eligible earnings, Percent	4.00%
Matching contributions to the RRSP and 401(k) Plans	$ 1.3	$ 1.0

Investments in Privately-Held Companies (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Investments, All Other Investments [Abstract]
Investments in equity securities of privately-held companies	$ 11.3	$ 10.3

Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 10,717	$ 2,118
Other comprehensive income:
Change in unrealized loss on investments	425	1,888
Tax provision related to change in unrealized loss on investments	149	661
Other comprehensive income—net of taxes	276	1,227
Comprehensive income	$ 10,993	$ 3,345

Segment Information (Tables)

3 Months Ended

Mar. 31, 2017

Segment Reporting [Abstract]

Revenue and Accounts Receivable from external customers by geographic region



	Three Months Ended
Revenue	March 31, 2017		March 31, 2016
Americas:
U.S.	$	90,772	$	75,558
Canada	37,345		31,305
Latin America (“LATAM”)	18,247		13,183
Total Americas	146,364		120,046
Europe, Middle East and Africa (“EMEA”)	126,149		105,491
Asia Pacific (“APAC”)	68,063		59,039
Total revenue	$	340,576	$	284,576

The following customers, each of which is a distributor, accounted for 10% or more of our revenue:



	Three Months Ended
	March 31, 2017		March 31, 2016
Exclusive Networks Group	20	%	19	%
Fine Tec Computers	12	%	*

* Represents less than 10%

The following customers, each of which is a distributor, accounted for 10% or more of net accounts receivable:



	March 31, 2017		December 31, 2016
Exclusive Networks Group	22	%	26	%
Fine Tec Computers	15	%	10	%

Property and equipment by geographic region



Property and Equipment—net	March 31, 2017		December 31, 2016
Americas:
U.S.	$	111,464	$	96,414
Canada	16,274		12,881
LATAM	475		607
Total Americas	128,213		109,902
EMEA:
France	12,854		13,241
Other EMEA	6,232		6,391
Total EMEA	19,086		19,632
APAC	8,177		7,715
Total property and equipment—net	$	155,476	$	137,249

Goodwill and Other Intangible Assets - Net , Changes in Carrying Amount of Goodwill (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 14,553,000	$ 14,553,000
Goodwill impairment	$ 0

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term in years	4 years 4 months 24 days	4 years 3 months 26 days
Volatility	36.00%	43.00%
Risk-free interest rate	1.90%	1.10%
Dividend rate	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance - Beginning (in shares)	6,187,000
Granted (in shares)	498,000
Forfeited (in shares)	(46,000)
Exercised (in shares)	(855,000)
Balance - Ending (in shares)	5,784,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance - Beginning (in dollars per share)	$ 23.79
Granted (in dollars per share)	37.24
Forfeited (in dollars per share)	27.24
Exercised (in dollars per share)	14.67
Balance - Ending (in dollars per share)	$ 26.27
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options vested and expected to vest, Outstanding (in shares)	5,784,000
Options vested and expected to vest, Weighted average exercise price (in dollars per share)	$ 26.27
Options vested and expected to vest, Weighted average remaining contractual life (in years)	3 years 5 months 12 days
Options vested and expected to vest, Aggregate intrinsic value	$ 71,951
Options exercisable, Outstanding (in shares)	3,820,000
Options exercisable, Weighted average exercise price (in dollars per share)	$ 23.91
Options exercisable, Weighted average remaining contractual life (in years)	2 years 2 months 1 day
Options exercisable, Aggregate intrinsic value	$ 56,071
Compensation cost not yet recognized	$ 19,500
Compensation cost not yet recognized period of recognition	2 years 11 months 19 days
Weighted-average fair value per share granted	$ 12.22	$ 8.68
Intrinsic value of options exercised	$ 17,898	$ 19,424
Total fair value of awards vested	$ 3,395	$ 2,084
Stock-based Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining shares available for grant under the plans	50,087,833
Share Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, remaining repurchase amount	$ 189,200

Financial Instruments and Fair Value

3 Months Ended

Mar. 31, 2017

Financial Instruments and Fair Value [Abstract]

FINANCIAL INSTRUMENTS AND FAIR VALUE

The following tables summarize our investments (in thousands):



	March 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	405,681	$	80	$	(754	)	$	405,007
Commercial paper	110,434		68		(26		)	110,476
U.S. government and agency securities	55,764		2		(89		)	55,677
Municipal bonds	46,227		24		(59		)	46,192
Certificates of deposit and term deposits ⁽¹⁾	404		—		—			404
Total available-for-sale securities	$	618,510	$	174	$	(928	)	$	617,756

	December 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	379,494	$	43	$	(925	)	$	378,612
Commercial paper	95,110		23		(25		)	95,108
U.S. government and agency securities	64,604		16		(79		)	64,541
Municipal bonds	59,257		3		(235		)	59,025
Certificates of deposit and term deposits ⁽¹⁾	4,219		—		—			4,219
Total available-for-sale securities	$	602,684	$	85	$	(1,264	)	$	601,505

⁽¹⁾ The majority of our certificates of deposit and term deposits are foreign deposits.

The following tables show the gross unrealized losses and the related fair values of our investments that have been in a continuous unrealized loss position (in thousands):



	March 31, 2017
	Less Than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	325,615	$	(751	)	$	11,751	$	(3	)	$	337,366	$	(754	)
U.S. government and agency securities	46,388		(89		)	—		—			46,388		(89		)
Municipal bonds	26,833		(59		)	—		—			26,833		(59		)
Commercial paper	31,172		(26		)	—		—			31,172		(26		)
Total available-for-sale securities	$	430,008	$	(925	)	$	11,751	$	(3	)	$	441,759	$	(928	)



	December 31, 2016
	Less Than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	311,980	$	(910	)	$	13,541	$	(15	)	$	325,521	$	(925	)
Municipal bonds	52,200		(235		)	—		—			52,200		(235		)
U.S. government and agency securities	33,430		(79		)	—		—			33,430		(79		)
Commercial paper	17,394		(25		)	—		—			17,394		(25		)
Total available-for-sale securities	$	415,004	$	(1,249	)	$	13,541	$	(15	)	$	428,545	$	(1,264	)

The contractual maturities of our investments were as follows (in thousands):



	March 31, 2017		December 31, 2016
Due within one year	$	375,423	$	376,522
Due within one to three years	242,333		224,983
Total	$	617,756	$	601,505

Available-for-sale securities are reported at fair value, with unrealized gains and losses, net of tax, included as a separate component of stockholders’ equity and in comprehensive income. Realized gains and losses on available-for-sale securities are insignificant in the periods presented and are included in Other income (expense)—net in our condensed consolidated statements of operations. We use the specific identification method to determine the cost basis of investments sold.

The unrealized losses on our available-for-sale securities were caused by fluctuations in market value and interest rates as a result of the economic environment. As the decline in market value are attributable to changes in market conditions and not credit quality, and because we have concluded currently that we neither intend to sell nor is it more likely than not that we will be required to sell these investments prior to a recovery of par value, we do not consider these investments to be other-than temporarily impaired as of March 31, 2017.

Fair Value Accounting—We apply the following fair value hierarchy for disclosure of the inputs used to measure fair value. This hierarchy prioritizes the inputs into three broad levels as follows:

Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments.

Level 3—Unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation.

We measure the fair value of money market funds and certain U.S. government and agency securities using quoted prices in active markets for identical assets. The fair value of all other financial instruments was based on quoted prices for similar assets in active markets, or model driven valuations using significant inputs derived from or corroborated by observable market data.

We classify investments within Level 1 if quoted prices are available in active markets for identical securities.

We classify items within Level 2 if the investments are valued using model driven valuations using observable inputs such as quoted market prices, benchmark yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Investments are held by custodians who obtain investment prices from a third-party pricing provider that incorporates standard inputs in various asset price models.

Fair Value of Financial Instruments

Assets Measured at Fair Value on a Recurring Basis

The following tables present the fair value of our financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 (in thousands):



	March 31, 2017								December 31, 2016
	Aggregate Fair Value		Quoted Prices in Active Markets For Identical Assets		Significant Other Observable Remaining Inputs		Significant Other Unobservable Remaining Inputs		Aggregate Fair Value		Quoted Prices in Active Markets For Identical Assets		Significant Other Observable Remaining Inputs		Significant Other Unobservable Remaining Inputs
			(Level 1)		(Level 2)		(Level 3)				(Level 1)		(Level 2)		(Level 3)
Assets:
Corporate debt securities	$	405,007	$	—	$	405,007	$	—	$	378,612	$	—	$	378,612	$	—
Commercial paper	119,965		—		119,965		—		105,097		—		105,097		—
U.S. government and agency securities	55,677		45,222		10,455		—		64,541		52,082		12,459		—
Municipal bonds	46,192		—		46,192		—		59,025		—		59,025		—
Money market funds	21,069		21,069		—		—		38,649		38,649		—		—
Certificates of deposit and term deposits	404		—		404		—		4,219		—		4,219		—
Total	$	648,314	$	66,291	$	582,023	$	—	$	650,143	$	90,731	$	559,412	$	—

Reported as:
Cash equivalents	$	30,558							$	48,638
Short-term investments	375,423								376,522
Long-term investments	242,333								224,983
Total	$	648,314							$	650,143

There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2017.

Income Taxes , Narrative (Details) - USD ($)	3 Months Ended
Income Taxes , Narrative (Details) - USD ($)	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Tax Contingency [Line Items]
Effective tax rate (percent)	(32.00%)	165.00%
Excess tax benefits from stock options	$ 5,500,000	$ 3,600,000
Unrecognized tax benefits, end of year	69,400,000		$ 65,500,000
Unrecognized tax benefits that would favoraby affect effective tax rate	67,700,000
Accrued interest and penalties related to uncertain tax benefits	10,500,000		$ 9,500,000
Unrecognized tax benefits subject to significant change over next 12 months	$ 0

Defined Contribution Plans	3 Months Ended
Defined Contribution Plans	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
DEFINED CONTRIBUTION PLANS	DEFINED CONTRIBUTION PLANS Our tax-deferred savings plan under our 401(k) Plan, permits participating employees to defer a portion of their pre-tax earnings. In Canada, we have a Group Registered Retirement Savings Plan Program (the “RRSP”), which permits participants to make tax deductible contributions. Our board of directors approved 50% matching contributions on employee contributions up to 4% of each employee’s eligible earnings. Our matching contributions to our 401(k) Plan and the RRSP for the three months ended March 31, 2017 and March 31, 2016 were $1.3 million and $1.0 million, respectively.

Condensed Consolidated Statements of Operations (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
REVENUE:
Product	$ 135,253	$ 124,572
Service	205,323	160,004
Total revenue	340,576	284,576
COST OF REVENUE:
Product	55,297	49,313
Service	35,267	28,331
Total cost of revenue	90,564	77,644
GROSS PROFIT:
Product	79,956	75,259
Service	170,056	131,673
Total gross profit	250,012	206,932
OPERATING EXPENSES:
Research and development	51,195	44,754
Sales and marketing	170,400	146,103
General and administrative	22,577	19,439
Restructuring charges	430	328
Total operating expenses	244,602	210,624
OPERATING INCOME (LOSS)	5,410	(3,692)
INTEREST INCOME	2,392	1,746
OTHER INCOME (EXPENSE)—NET	302	(1,312)
INCOME (LOSS) BEFORE INCOME TAXES	8,104	(3,258)
BENEFIT FROM INCOME TAXES	(2,613)	(5,376)
NET INCOME	$ 10,717	$ 2,118
Net income per share (Note 7):
Basic (in dollars per share)	$ 0.06	$ 0.01
Diluted (in dollars per share)	$ 0.06	$ 0.01
Weighted-average shares outstanding:
Basic (in shares)	174,489	171,745
Diluted (in shares)	178,278	174,421

Financial Instruments and Fair Value , Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 618,510	$ 602,684
Unrealized Gains	174	85
Unrealized Losses	(928)	(1,264)
Fair Value	617,756	601,505
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	430,008	415,004
Less Than 12 Months, Unrealized Losses	(925)	(1,249)
12 Months or Greater, Fair Value	11,751	13,541
12 Months or Greater, Unrealized Losses	(3)	(15)
Total, Fair Value	441,759	428,545
Total, Unrealized Losses	(928)	(1,264)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Due within one year	375,423	376,522
Due within one to three years	242,333	224,983
Fair Value	617,756	601,505
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	405,681	379,494
Unrealized Gains	80	43
Unrealized Losses	(754)	(925)
Fair Value	405,007	378,612
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	325,615	311,980
Less Than 12 Months, Unrealized Losses	(751)	(910)
12 Months or Greater, Fair Value	11,751	13,541
12 Months or Greater, Unrealized Losses	(3)	(15)
Total, Fair Value	337,366	325,521
Total, Unrealized Losses	(754)	(925)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	405,007	378,612
Municipal bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	46,227	59,257
Unrealized Gains	24	3
Unrealized Losses	(59)	(235)
Fair Value	46,192	59,025
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	26,833	52,200
Less Than 12 Months, Unrealized Losses	(59)	(235)
12 Months or Greater, Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total, Fair Value	26,833	52,200
Total, Unrealized Losses	(59)	(235)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	46,192	59,025
Certificates of deposit and term deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	404	4,219
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	404	4,219
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	404	4,219
U.S. government and agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	55,764	64,604
Unrealized Gains	2	16
Unrealized Losses	(89)	(79)
Fair Value	55,677	64,541
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	46,388	33,430
Less Than 12 Months, Unrealized Losses	(89)	(79)
12 Months or Greater, Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total, Fair Value	46,388	33,430
Total, Unrealized Losses	(89)	(79)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	55,677	64,541
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	110,434	95,110
Unrealized Gains	68	23
Unrealized Losses	(26)	(25)
Fair Value	110,476	95,108
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	31,172	17,394
Less Than 12 Months, Unrealized Losses	(26)	(25)
12 Months or Greater, Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total, Fair Value	31,172	17,394
Total, Unrealized Losses	(26)	(25)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	$ 110,476	$ 95,108

Restructuring Charges

3 Months Ended

Mar. 31, 2017

Restructuring and Related Activities [Abstract]

RESTRUCTURING CHARGES

In 2016 and 2015, we implemented plans to restructure and further improve efficiencies in our operations due primarily to acquisitions. The remaining restructuring reserve as of March 31, 2017 is included in accrued liabilities on the condensed consolidated balance sheets and is expected to be paid in 2017. Restructuring charges related to these plans consisted primarily of employee severance and other one-time benefits paid in cash and are included in operating expense in the condensed consolidated statements of operations.

Activities related to the restructuring actions are summarized as follows (in thousands):



	Three Months Ended
	March 31, 2017			March 31, 2016
Balance at beginning of period	$	1,151		$	3,918
Costs incurred	430			328
Cash payments	(567		)	(1,407		)
Non-cash items	—			(89		)
Balance at end of period	$	1,014		$	2,750

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Our effective tax rate was a benefit of (32)% for the three months ended March 31, 2017, compared to an effective tax rate of 165% for the same period last year. The effective tax rates for the periods presented are comprised of U.S. federal and state taxes, withholding taxes and foreign income taxes. The tax rate for the three months ended March 31, 2017 was impacted by the excess tax benefits of $5.5 million on stock options, which was a significant benefit on our income before income taxes. The tax rate for the three months ended March 31, 2016 was also impacted by significant excess tax benefits of $3.6 million on stock options on our loss before income taxes. As of March 31, 2017 and December 31, 2016, unrecognized tax benefits were $69.4 million and $65.5 million, respectively. The total amount of $67.7 million in unrecognized tax benefits, if recognized, would favorably affect our effective tax rate. It is our policy to classify accrued interest and penalties related to uncertain tax benefits in the provision for income taxes. As of March 31, 2017 and December 31, 2016, accrued interest and penalties were $10.5 million and $9.5 million, respectively. As of March 31, 2017, there was no unrecognized tax benefits that we expect would change significantly over the next 12 months. We file income tax returns in the U.S. federal jurisdiction and in various U.S. state and foreign jurisdictions. Generally, we are no longer subject to U.S. state and non-U.S. income tax examinations by tax authorities for tax years prior to 2009. We are no longer subject to examination by U.S federal income tax authorities for tax years prior to 2012. We are currently under examination by U.S federal income tax authorities for tax years 2012, 2013 and 2014. We have filed a waiver extending the statute of limitations to September 15, 2018 for U.S. federal income tax returns for tax years 2012 and 2013. In addition, the tax authorities in France are examining the inter-company relationship between Fortinet, Inc., Fortinet France and Fortinet Singapore. Subsequent to the three months ended March 31, 2017, we received a notice from the French tax authorities that an audit was officially opened for tax years from 2007 to 2015. Our Japan tax audit for tax years 2013, 2014 and 2015 was closed with no material adjustment.

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Contractual Obligation, Fiscal Year Maturity Schedule

The following table summarizes our future principal contractual obligations as of March 31, 2017 (in thousands):



	Total		2017 (remainder)		2018		2019		2020		2021		Thereafter
Operating lease commitments	$	61,354	$	13,083	$	14,401	$	11,972	$	9,497	$	4,088	$	8,313
Inventory purchase commitments	68,846		68,846		—		—		—		—		—
Other contractual commitments and open purchase orders	71,534		60,959		8,402		1,522		560		91		—
Total	$	201,734	$	142,888	$	22,803	$	13,494	$	10,057	$	4,179	$	8,313

Inventory (Tables)

3 Months Ended

Mar. 31, 2017

Inventory Disclosure [Abstract]

Inventory

Inventory consisted of the following (in thousands):



	March 31, 2017		December 31, 2016
Raw materials	$	16,540	$	18,924
Finished goods	88,438		87,963
Inventory	$	104,978	$	106,887

Stockholders' Equity , Allocation of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 33,331	$ 28,902
Income tax benefit from employee stock option plans	6,645	7,321
Cost of product revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	342	280
Cost of service revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2,310	2,134
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	7,898	7,143
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	19,026	15,815
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3,755	3,530
Restricted Stock Units (RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	29,041	25,103
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,845	1,954
ESPP [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,445	$ 1,845

Net Income Per Share , Calculation of Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Line Items]
Net income	$ 10,717	$ 2,118
Basic shares:
Weighted-average common shares outstanding-basic (in shares)	174,489	171,745
Diluted shares:
Weighted-average common shares outstanding-basic (in shares)	174,489	171,745
Effect of potentially dilutive securities:
Weighted-average shares used to compute diluted net income per share (in shares)	178,278	174,421
Basic (in dollars per share)	$ 0.06	$ 0.01
Diluted (in dollars per share)	$ 0.06	$ 0.01
Restricted Stock Units (RSUs) [Member]
Effect of potentially dilutive securities:
Employee stock options and purchase rights (in shares)	2,216	1,020
Stock Options [Member]
Effect of potentially dilutive securities:
Employee stock options and purchase rights (in shares)	1,523	1,632
ESPP [Member]
Effect of potentially dilutive securities:
Employee stock options and purchase rights (in shares)	50	24

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Inventory, Net [Abstract]
Raw materials	$ 16,540	$ 18,924
Finished goods	88,438	87,963
Inventory	$ 104,978	$ 106,887

Stockholders' Equity , Additional Information Related To ESPP (Details) - Employee Stock Purchase Plan [Member] - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per share granted (in dollars per share)	$ 9.28	$ 7.19
Shares issued under the ESPP (in shares)	634	614
Weighted-average price per share issued (in dollars per share)	$ 27.97	$ 20.49

Property and Equipment—Net (Tables)

3 Months Ended

Mar. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment - Net

Property and equipment—net consisted of the following (in thousands):



	March 31, 2017			December 31, 2016
Computer equipment and software	$	70,048		$	65,323
Building and building improvements	56,373			49,783
Land	44,198			35,079
Leasehold improvements	20,542			18,699
Evaluation units	19,701			20,173
Furniture and fixtures	14,153			13,995
Construction-in-progress	6,201			4,669
Total property and equipment	231,216			207,721
Less: accumulated depreciation	(75,740		)	(70,472		)
Property and equipment—net	$	155,476		$	137,249

Stockholders' Equity , Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares withheld for taxes	413	343
Tax withholding upon vesting of restricted stock awards	$ 13,693	$ 9,441
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance, beginning (shares)	9,509
Granted (shares)	2,582
Forfeited (shares)	(301)
Vested (shares)	(1,299)
Balance, ending (shares)	10,491
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Balance, weighted-average grant-date fair value per share (in dollars per share)—beginning	$ 31.01
Granted, weighted-average grant-date fair value per share (in dollars per share)	37.21
Forfeited, weighted-average grant-date fair value per share (in dollars per share)	33.80
Vested, weighted-average grant-date fair value per share (in dollars per share)	27.43
Balance, weighted-average grant-date fair value per share (in dollars per share)—ending	$ 33.04
Compensation cost not yet recognized	$ 310,300
Compensation cost not yet recognized period of recognition	2 years 11 months 1 day

Restructuring Charges (Tables)

3 Months Ended

Mar. 31, 2017

Restructuring and Related Activities [Abstract]

Summary of Restructuring Activity

Activities related to the restructuring actions are summarized as follows (in thousands):



	Three Months Ended
	March 31, 2017			March 31, 2016
Balance at beginning of period	$	1,151		$	3,918
Costs incurred	430			328
Cash payments	(567		)	(1,407		)
Non-cash items	—			(89		)
Balance at end of period	$	1,014		$	2,750

Accumulated Other Comprehensive Loss (Tables)

3 Months Ended

Mar. 31, 2017

Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Accumulated Other Comprehensive (Loss) Income

The following table summarizes the changes in accumulated balances of other comprehensive loss (in thousands):



	March 31, 2017
	Unrealized losses on investments			Tax provision related to items of other comprehensive income or loss			Total
Beginning balance	$	(1,179	)	$	414		$	(765	)
Other comprehensive income before reclassifications	424			(149		)	275
Amounts reclassified from accumulated other comprehensive loss	1			—			1
Net current-period other comprehensive income	425			(149		)	276
Ending balance	$	(754	)	$	265		$	(489	)

Goodwill and Other Intangible Assets - Net (Tables)

3 Months Ended

Mar. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

Schedule of Finite-Lived and Indefinite-Lived Intangible Assets by Major Class

The following tables present other intangible assets—net as of March 31, 2017 and December 31, 2016 (in thousands, except years):



	March 31, 2017
	Weighted-Average Useful Life (in Years)	Gross		Accumulated Amortization		Net
Other intangible assets—net:
Finite-lived intangible assets:
Developed technologies and other	3.8	$	23,984	$	10,000	$	13,984
Customer relationships	4.7	14,500		7,549		6,951
		38,484		17,549		20,935

Indefinite-lived intangible assets:
In-process research and development		1,600		—		1,600
Total other intangible assets—net		$	40,084	$	17,549	$	22,535



	December 31, 2016
	Weighted-Average Useful Life (in Years)	Gross		Accumulated Amortization		Net
Other intangible assets—net:
Finite-lived intangible assets:
Developed technologies and other	3.8	$	23,984	$	8,750	$	15,234
Customer relationships	4.7	14,500		6,506		7,994
		38,484		15,256		23,228

Indefinite-lived intangible assets:
In-process research and development		1,600		—		1,600
Total other intangible assets—net		$	40,084	$	15,256	$	24,828

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The following table summarizes estimated future amortization expense of finite-lived intangible assets—net (in thousands):



	Amount
Years:
2017 (remainder)	$	6,280
2018	6,885
2019	5,406
2020	2,364
Total	$	20,935

Subsequent Event	3 Months Ended
Subsequent Event	Mar. 31, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT In April 2017, we purchased real estate property in Vancouver, Canada totaling approximately 282,000 square feet for a total cash payment of approximately $85.0 million.

Financial Instruments and Fair Value (Tables)

3 Months Ended

Mar. 31, 2017

Financial Instruments and Fair Value [Abstract]

Summary of Investments

The following tables summarize our investments (in thousands):



	March 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	405,681	$	80	$	(754	)	$	405,007
Commercial paper	110,434		68		(26		)	110,476
U.S. government and agency securities	55,764		2		(89		)	55,677
Municipal bonds	46,227		24		(59		)	46,192
Certificates of deposit and term deposits ⁽¹⁾	404		—		—			404
Total available-for-sale securities	$	618,510	$	174	$	(928	)	$	617,756

	December 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	379,494	$	43	$	(925	)	$	378,612
Commercial paper	95,110		23		(25		)	95,108
U.S. government and agency securities	64,604		16		(79		)	64,541
Municipal bonds	59,257		3		(235		)	59,025
Certificates of deposit and term deposits ⁽¹⁾	4,219		—		—			4,219
Total available-for-sale securities	$	602,684	$	85	$	(1,264	)	$	601,505

⁽¹⁾ The majority of our certificates of deposit and term deposits are foreign deposits.

Schedule of Unrealized Loss on Investments

The following tables show the gross unrealized losses and the related fair values of our investments that have been in a continuous unrealized loss position (in thousands):



	March 31, 2017
	Less Than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	325,615	$	(751	)	$	11,751	$	(3	)	$	337,366	$	(754	)
U.S. government and agency securities	46,388		(89		)	—		—			46,388		(89		)
Municipal bonds	26,833		(59		)	—		—			26,833		(59		)
Commercial paper	31,172		(26		)	—		—			31,172		(26		)
Total available-for-sale securities	$	430,008	$	(925	)	$	11,751	$	(3	)	$	441,759	$	(928	)



	December 31, 2016
	Less Than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	311,980	$	(910	)	$	13,541	$	(15	)	$	325,521	$	(925	)
Municipal bonds	52,200		(235		)	—		—			52,200		(235		)
U.S. government and agency securities	33,430		(79		)	—		—			33,430		(79		)
Commercial paper	17,394		(25		)	—		—			17,394		(25		)
Total available-for-sale securities	$	415,004	$	(1,249	)	$	13,541	$	(15	)	$	428,545	$	(1,264	)

Investments Classified by Contractual Maturity Date

The contractual maturities of our investments were as follows (in thousands):



	March 31, 2017		December 31, 2016
Due within one year	$	375,423	$	376,522
Due within one to three years	242,333		224,983
Total	$	617,756	$	601,505

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables present the fair value of our financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 (in thousands):



	March 31, 2017								December 31, 2016
	Aggregate Fair Value		Quoted Prices in Active Markets For Identical Assets		Significant Other Observable Remaining Inputs		Significant Other Unobservable Remaining Inputs		Aggregate Fair Value		Quoted Prices in Active Markets For Identical Assets		Significant Other Observable Remaining Inputs		Significant Other Unobservable Remaining Inputs
			(Level 1)		(Level 2)		(Level 3)				(Level 1)		(Level 2)		(Level 3)
Assets:
Corporate debt securities	$	405,007	$	—	$	405,007	$	—	$	378,612	$	—	$	378,612	$	—
Commercial paper	119,965		—		119,965		—		105,097		—		105,097		—
U.S. government and agency securities	55,677		45,222		10,455		—		64,541		52,082		12,459		—
Municipal bonds	46,192		—		46,192		—		59,025		—		59,025		—
Money market funds	21,069		21,069		—		—		38,649		38,649		—		—
Certificates of deposit and term deposits	404		—		404		—		4,219		—		4,219		—
Total	$	648,314	$	66,291	$	582,023	$	—	$	650,143	$	90,731	$	559,412	$	—

Reported as:
Cash equivalents	$	30,558							$	48,638
Short-term investments	375,423								376,522
Long-term investments	242,333								224,983
Total	$	648,314							$	650,143

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 10,717	$ 2,118
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,493	10,550
Amortization of investment premiums	973	1,497
Stock-based compensation	33,331	28,902
Other non-cash items—net	1,469	(372)
Changes in operating assets and liabilities:
Accounts receivable—net	42,437	38,920
Inventory	(3,545)	(527)
Deferred tax assets	(16,589)	(16,709)
Prepaid expenses and other current assets	(8,261)	1,029
Other assets	653	(911)
Accounts payable	(8,287)	(11,426)
Accrued liabilities	2,923	300
Accrued payroll and compensation	(5,267)	(2,945)
Other liabilities	(1,057)	(1,332)
Deferred revenue	61,776	46,106
Income taxes payable	4,983	5,391
Net cash provided by operating activities	129,749	100,591
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investments	(133,006)	(115,672)
Sales of investments	6,000	2,867
Maturities of investments	109,207	108,557
Purchases of property and equipment	(13,526)	(29,956)
Net cash used in investing activities	(31,325)	(34,204)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	29,515	17,785
Taxes paid related to net share settlement of equity awards	(13,693)	(9,441)
Repurchase and retirement of common stock	0	(50,000)
Net cash provided by (used in) financing activities	15,822	(41,656)
NET INCREASE IN CASH AND CASH EQUIVALENTS	114,246	24,731
CASH AND CASH EQUIVALENTS—Beginning of period	709,003	543,277
CASH AND CASH EQUIVALENTS—End of period	823,249	568,008
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Liability for purchase of property and equipment	18,704	7,843
Transfers of evaluation units from inventory to property and equipment	$ 5,681	$ 6,671

Condensed Consolidated Balance Sheets Parenthetical - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Reserves for sales returns and doubtful accounts	$ 11,685	$ 11,235
Common Stock, par value (dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized	300,000	300,000
Common Stock, shares issued	175,443	173,078
Common Stock, shares outstanding	175,443	173,078

Segment Information

3 Months Ended

Mar. 31, 2017

Segment Reporting [Abstract]

SEGMENT INFORMATION

SEGMENT AND SIGNIFICANT CUSTOMER INFORMATION

Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. Our chief operating decision maker is our chief executive officer. Our chief executive officer reviews financial information presented on a consolidated basis, accompanied by information about revenue by geographic region for purposes of allocating resources and evaluating financial performance. We have 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, we have determined that we have one operating segment, and therefore, one reportable segment.

Revenue by geographic region is based on the billing address of the customer. The following tables set forth revenue and property and equipment—net by geographic region (in thousands):



	Three Months Ended
Revenue	March 31, 2017		March 31, 2016
Americas:
U.S.	$	90,772	$	75,558
Canada	37,345		31,305
Latin America (“LATAM”)	18,247		13,183
Total Americas	146,364		120,046
Europe, Middle East and Africa (“EMEA”)	126,149		105,491
Asia Pacific (“APAC”)	68,063		59,039
Total revenue	$	340,576	$	284,576



Property and Equipment—net	March 31, 2017		December 31, 2016
Americas:
U.S.	$	111,464	$	96,414
Canada	16,274		12,881
LATAM	475		607
Total Americas	128,213		109,902
EMEA:
France	12,854		13,241
Other EMEA	6,232		6,391
Total EMEA	19,086		19,632
APAC	8,177		7,715
Total property and equipment—net	$	155,476	$	137,249

The following customers, each of which is a distributor, accounted for 10% or more of our revenue:



	Three Months Ended
	March 31, 2017		March 31, 2016
Exclusive Networks Group	20	%	19	%
Fine Tec Computers	12	%	*

* Represents less than 10%

The following customers, each of which is a distributor, accounted for 10% or more of net accounts receivable:



	March 31, 2017		December 31, 2016
Exclusive Networks Group	22	%	26	%
Fine Tec Computers	15	%	10	%

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8906-108599

+ Details

Commitments and Contingencies

3 Months Ended

Mar. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

The following table summarizes our future principal contractual obligations as of March 31, 2017 (in thousands):



	Total		2017 (remainder)		2018		2019		2020		2021		Thereafter
Operating lease commitments	$	61,354	$	13,083	$	14,401	$	11,972	$	9,497	$	4,088	$	8,313
Inventory purchase commitments	68,846		68,846		—		—		—		—		—
Other contractual commitments and open purchase orders	71,534		60,959		8,402		1,522		560		91		—
Total	$	201,734	$	142,888	$	22,803	$	13,494	$	10,057	$	4,179	$	8,313

Operating Leases—We lease certain facilities under various non-cancelable operating leases, which expire through 2024. Certain leases require us to pay variable costs such as taxes, maintenance, and insurance. The terms of certain operating leases also provide for renewal options and escalation clauses. Rent expense was $4.5 million and $4.6 million during the three months ended March 31, 2017 and March 31, 2016, respectively. Rent expense is recognized using the straight-line method over the term of the lease.

Inventory Purchase Commitments—Our independent contract manufacturers procure components and build our products based on our forecasts. These forecasts are based on estimates of future demand for our products, which are in turn based on historical trends and an analysis from our sales and marketing organizations, adjusted for overall market conditions. In order to reduce manufacturing lead times and plan for adequate component supply, we may issue purchase orders to some of our independent contract manufacturers which may not be cancelable. As of March 31, 2017, we had $68.8 million of open purchase orders with our independent contract manufacturers that may not be cancelable.

Other Contractual Commitments and Open Purchase Orders—In addition to commitments with contract manufacturers, we have open purchase orders and contractual obligations in the ordinary course of business for which we have not received goods or services. As of March 31, 2017, we had $71.5 million in other contractual commitments that may not be cancelable. We also had other contractual commitments for the purchase of certain real estate properties adjacent to our corporate headquarters amounting to $12.8 million, which we capitalized as part of property and equipment.

Litigation—We are involved in disputes, litigation, and other legal actions. For lawsuits where we are the defendant, we are in the process of defending these litigation matters, and while there can be no assurances and the outcome of these matters is currently not determinable, we currently believe that there are no existing claims or proceedings that are likely to have a material adverse effect on our financial position. There are many uncertainties associated with any litigation and these actions or other third-party claims against us may cause us to incur costly litigation fees, including contingent legal fees with related parties, costs and substantial settlement charges, and possibly subject us to damages and other penalties. In addition, the resolution of any intellectual property litigation may require us to make royalty payments, which could adversely affect our gross margins in future periods. If any of those events were to occur, our business, financial condition, results of operations, and cash flows could be adversely affected. The actual liability in any such matters may be materially different from our estimates, if any, which could result in the need to adjust the liability and record additional expenses. As required under ASC 450, Contingencies, issued by the FASB, we accrue for contingencies when we believe that a loss is probable and that we can reasonably estimate the amount of any such loss.

In October 2016, we received a letter from the United States Attorney’s Office for the Northern District of California requesting information relating to our compliance with the Trade Agreements Act. This inquiry is ongoing and we are fully cooperating with this inquiry.

Indemnification—Under the indemnification provisions of our standard sales contracts, we agree to defend our customers against third-party claims asserting various allegations such as product defects and infringement of certain intellectual property rights, which may include patents, copyrights, trademarks or trade secrets, and to pay judgments entered on such claims. In some contracts, our exposure under these indemnification provisions is limited by the terms of the contracts to certain defined limits, such as the total amount paid by our customer under the agreement. However, certain agreements include covenants, penalties and indemnification provisions including and beyond indemnification for third-party claims of intellectual property infringement and that could potentially expose us to losses in excess of the amount received under the agreement, and in some instances to potential liability that is not contractually limited. To date, there have been no material awards under such indemnification provisions.

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 823,249	$ 709,003
Short-term investments	375,423	376,522
Accounts receivable—Net of reserves for sales returns and doubtful accounts of $11,685 and $11,235 at March 31, 2017 and December 31, 2016, respectively	270,111	312,998
Inventory	104,978	106,887
Prepaid expenses and other current assets	42,321	33,306
Total current assets	1,616,082	1,538,716
LONG-TERM INVESTMENTS	242,333	224,983
DEFERRED TAX ASSETS	199,186	182,745
PROPERTY AND EQUIPMENT—NET	155,476	137,249
OTHER INTANGIBLE ASSETS—NET	22,535	24,828
GOODWILL	14,553	14,553
OTHER ASSETS	17,218	16,867
TOTAL ASSETS	2,267,383	2,139,941
CURRENT LIABILITIES:
Accounts payable	48,689	56,732
Accrued liabilities	43,449	35,640
Accrued payroll and compensation	73,204	78,138
Income taxes payable	14,129	13,588
Deferred revenue	677,114	645,342
Total current liabilities	856,585	829,440
DEFERRED REVENUE	420,937	390,007
INCOME TAX LIABILITIES	72,993	68,551
OTHER LIABILITIES	18,619	14,262
Total liabilities	1,369,134	1,302,260
COMMITMENTS AND CONTINGENCIES (Note 9)
STOCKHOLDERS’ EQUITY:
Common stock, $0.001 par value—300,000 shares authorized; 175,443 and 173,078 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	175	173
Additional paid-in capital	850,226	800,653
Accumulated other comprehensive loss	(489)	(765)
Retained earnings	48,337	37,620
Total stockholders’ equity	898,249	837,681
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 2,267,383	$ 2,139,941

Stockholders' Equity , ESPP Information (Details) - Employee Stock Purchase Plan [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	6 months	5 months 27 days
Volatility	33.00%	48.00%
Risk-free interest rate	0.70%	0.40%
Dividend rate	0.00%	0.00%

Segment Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
Segment Information (Details) $ in Thousands	Mar. 31, 2017 USD ($) Segment_Managers reportable_segment business_activity operating_segment	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Business activity (in business activities) \| business_activity	1
Segment managers responsible for operations (in segment managers) \| Segment_Managers	0
Number of operating segments (in operating segments) \| operating_segment	1
Number of reportable segments (in reportable segments) \| reportable_segment	1
Revenue	$ 340,576	$ 284,576
Property and equipment - net	155,476		$ 137,249
Total Americas
Segment Reporting Information [Line Items]
Revenue	146,364	120,046
Property and equipment - net	128,213		109,902
U.S.
Segment Reporting Information [Line Items]
Revenue	90,772	75,558
Property and equipment - net	111,464		96,414
CANADA
Segment Reporting Information [Line Items]
Revenue	37,345	31,305
Property and equipment - net	16,274		12,881
Latin America (“LATAM”)
Segment Reporting Information [Line Items]
Revenue	18,247	13,183
Property and equipment - net	475		607
EMEA
Segment Reporting Information [Line Items]
Revenue	126,149	105,491
Property and equipment - net	19,086		19,632
France
Segment Reporting Information [Line Items]
Property and equipment - net	12,854		13,241
Other EMEA
Segment Reporting Information [Line Items]
Property and equipment - net	6,232		6,391
APAC
Segment Reporting Information [Line Items]
Revenue	68,063	$ 59,039
Property and equipment - net	$ 8,177		$ 7,715
Exclusive Networks Group \| Customer Concentration Risk \| Sales Revenue
Segment Reporting Information [Line Items]
Customer concentration (percent)	20.00%		19.00%
Exclusive Networks Group \| Customer Concentration Risk \| Accounts Receivable
Segment Reporting Information [Line Items]
Customer concentration (percent)	22.00%		26.00%
Fin Tec Computers \| Customer Concentration Risk \| Sales Revenue
Segment Reporting Information [Line Items]
Customer concentration (percent)	12.00%
Fin Tec Computers \| Customer Concentration Risk \| Accounts Receivable
Segment Reporting Information [Line Items]
Customer concentration (percent)	15.00%		10.00%

Commitments and Contingencies Minimum Operating Lease Payments (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Operating Lease Commitments:
Operating lease commitments, 2017 (remainder)	$ 13,083
Operating lease commitments, 2018	14,401
Operating lease commitments, 2019	11,972
Operating lease commitments, 2020	9,497
Operating lease commitments, 2021	4,088
Operating lease commitments, Thereafter	8,313
Operating lease commitments	61,354
Inventory purchase commitments:
Inventory purchase commitments, 2017 (remainder)	68,846
Inventory purchase commitments, 2018	0
Inventory purchase commitments, 2019	0
Inventory purchase commitments, 2020	0
Inventory purchase commitments, 2021	0
Inventory purchase commitments, Thereafter	0
Inventory purchase commitments	68,846
Other contractual commitments and open purchase orders:
Other contractual commitments and open purchase orders, 2017 (remainder)	60,959
Other contractual commitments and open purchase orders, 2018	8,402
Other contractual commitments and open purchase orders, 2019	1,522
Other contractual commitments and open purchase orders, 2020	560
Other contractual commitments and open purchase orders, 2021	91
Other contractual commitments and open purchase orders, Thereafter	0
Other contractual commitments and open purchase orders	71,534
Contractual Obligation	201,734
Contractual Obligation, 2017 (remainder)	142,888
Contractual Obligation, 2018	22,803
Contractual Obligation, 2019	13,494
Contractual Obligation, 2020	10,057
Contractual Obligation, 2021	4,179
Contractual Obligation, Thereafter	$ 8,313

Goodwill and Other Intangible Assets - Net

3 Months Ended

Mar. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND OTHER INTANGIBLE ASSETS - Net

GOODWILL AND OTHER INTANGIBLE ASSETS—NET

Goodwill

As of March 31, 2017, we had goodwill of $14.6 million. There were no impairments to goodwill during the three months ended March 31, 2017 or during previous periods.

Other Intangible Assets—net

The following tables present other intangible assets—net as of March 31, 2017 and December 31, 2016 (in thousands, except years):



	March 31, 2017
	Weighted-Average Useful Life (in Years)	Gross		Accumulated Amortization		Net
Other intangible assets—net:
Finite-lived intangible assets:
Developed technologies and other	3.8	$	23,984	$	10,000	$	13,984
Customer relationships	4.7	14,500		7,549		6,951
		38,484		17,549		20,935

Indefinite-lived intangible assets:
In-process research and development		1,600		—		1,600
Total other intangible assets—net		$	40,084	$	17,549	$	22,535



	December 31, 2016
	Weighted-Average Useful Life (in Years)	Gross		Accumulated Amortization		Net
Other intangible assets—net:
Finite-lived intangible assets:
Developed technologies and other	3.8	$	23,984	$	8,750	$	15,234
Customer relationships	4.7	14,500		6,506		7,994
		38,484		15,256		23,228

Indefinite-lived intangible assets:
In-process research and development		1,600		—		1,600
Total other intangible assets—net		$	40,084	$	15,256	$	24,828

Amortization expense was $2.3 million and $1.2 million during the three months ended March 31, 2017 and March 31, 2016, respectively. The following table summarizes estimated future amortization expense of finite-lived intangible assets—net (in thousands):



	Amount
Years:
2017 (remainder)	$	6,280
2018	6,885
2019	5,406
2020	2,364
Total	$	20,935

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Inventory

3 Months Ended

Mar. 31, 2017

Inventory Disclosure [Abstract]

INVENTORY

Inventory consisted of the following (in thousands):



	March 31, 2017		December 31, 2016
Raw materials	$	16,540	$	18,924
Finished goods	88,438		87,963
Inventory	$	104,978	$	106,887

Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2017
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS The son of one member of our board of directors is a partner of an outside law firm that we utilize for certain complex litigation matters. Expenses for legal services provided by the law firm were $0.1 million and $0.3 million during the three months ended March 31, 2017 and March 31, 2016, respectively. Of such amounts, $0.2 million was incurred under contingent fee arrangements in the three months ended March 31, 2016. There were no expenses incurred under contingent fee arrangements during the three months ended March 31, 2017. Amounts due and payable to the law firm were $0.1 million as of March 31, 2017 and December 31, 2016.

Net Income Per Share , Anti Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	3,885	8,192
Restricted Stock Units (RSUs) [Member] \| Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	2,505	6,351
Stock Options [Member] \| Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	1,118	1,559
ESPP [Member] \| Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	262	282

Commitments and Contingencies (Details) - USD ($)	3 Months Ended
Commitments and Contingencies (Details) - USD ($)	Mar. 31, 2017	Mar. 31, 2016
Commitment
Rent expense	$ 4,500,000	$ 4,600,000
Inventory purchase commitments	68,846,000
Other contractual commitments and open purchase orders	71,534,000
Indemnification Provisions [Member]
Commitment
Awards under indemnification provisions	0
Commitment to Purchase Certain Real Estate Properties
Commitment
Other contractual commitments and open purchase orders	$ 12,800,000

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Preparation—The unaudited condensed consolidated financial statements of Fortinet, Inc. and its wholly owned subsidiaries (collectively, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information, as well as the instructions to Form 10-Q pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, and should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2016, contained in our Annual Report on Form 10-K filed with the SEC on March 1, 2017. In the opinion of management, all adjustments, which includes normal recurring adjustments, considered necessary for a fair presentation have been included. All intercompany balances, transactions and cash flows have been eliminated. The results of operations for the three months ended March 31, 2017 are not necessarily indicative of the results for the full year or for any future periods. The condensed consolidated balance sheet as of December 31, 2016 is derived from the audited consolidated financial statements for the year ended December 31, 2016. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. There have been no material changes to our significant accounting policies as of and for the three months ended March 31, 2017, except for changes to our policies related to inventory and business combinations. For more information, refer to the “Recently Adopted Accounting Standards.” Recently Adopted Accounting Standards In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-01—Business Combinations: Clarifying the Definition of a Business, which clarifies the definition of a business to assist organizations with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. We elected to early adopt ASU 2017-01 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2017-01 did not have a material impact on our consolidated financial statements. In July 2015, the FASB issued ASU 2015-11—Inventory: Simplifying the Measurement of Inventory, which requires entities to measure most inventory at the lower of cost and net realizable value, replacing the former methodology of measuring inventory at the lower of cost or market. We adopted ASU 2015-11 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2015-11 did not have a significant impact on our consolidated financial statements. Recent Accounting Standards Not Yet Effective In January 2017, the FASB issued ASU 2017-04—Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment. ASU 2017-04 eliminates Step 2 from the goodwill impairment test which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. Under ASU 2017-04, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount, and should recognize an impairment loss for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the loss not exceeding the total amount of goodwill allocated to that reporting unit. ASU 2016-06 will be effective for us beginning on January 1, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. At adoption, this update will require a prospective approach. We intend to adopt ASU 2017-04 in the fourth quarter of 2017. We do not believe that ASU 2017-04 will have a material impact on our consolidated financial statements. In October 2016, the FASB issued ASU 2016-16—Income Taxes: —Intra-Entity Transfer of Assets Other Than Inventory, which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. ASU 2016-06 will be effective for us beginning on January 1, 2018. We are currently evaluating the impact of adopting ASU 2016-16 on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13—Financial Instruments—Credit Losses—Measurement of Credit Losses on Financial Instruments, which requires measurement and recognition of expected credit losses for financial assets held. ASU 2016-13 is effective for us beginning on January 1, 2020, with the option to adopt early on January 1, 2019. We are currently evaluating the impact of adopting ASU 2016-13 on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02—Leases, which requires the recognition of right-of-use assets and lease liabilities on the consolidated balance sheet for substantially all leases. The new guidance includes a number of optional practical expedients that entities may elect to apply. The new guidance will also require significant additional disclosures about the amount, timing and uncertainty of cash flows from leases. This new guidance will be effective for us beginning on January 1, 2019, using a modified retrospective approach. We currently anticipate to early adopt ASU 2016-02 on January 1, 2018. Our ability to early adopt is dependent on system readiness, including software procured from third-party providers, if any, and the completion of our analysis of information necessary to quantify the impact on the prior period financial statements. Based on our current lease portfolio, we estimate the value of leased assets and liabilities that may be recognized could be at least $50.0 million. We are continuing to evaluate the impact of ASU 2016-02 and our estimate is subject to change. We do not believe that ASU 2016-02 will have a material impact on our consolidated statements of operations. In May 2014, the FASB issued ASU 2014-09—Revenue from Contracts with Customers, which outlines a single, comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The core principle of ASU 2014-09 is to recognize revenue 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, accordingly, it is possible more judgment and estimates may be required within the revenue recognition process than is 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. The FASB has recently issued several amendments to ASU 2014-09, including clarification on accounting for licenses of intellectual property and identifying performance obligations. ASU 2014-09 will be effective for us beginning January 1, 2018. The two permitted transition methods under ASU 2014-09 are the full retrospective method, in which case ASU 2014-09 would be applied to each prior reporting period presented and the cumulative effect of applying ASU 2014-09 would be recognized at the earliest period shown, or the modified retrospective method, in which case the cumulative effect of applying ASU 2014-09 would be recognized at the date of initial application. Currently, we are in the process of reviewing our historical contracts to quantify the impact on our consolidated financial statements. Depending on the results of our review, there could be changes to the timing of revenue recognition and certain sales commission and related costs associated with obtaining and fulfilling our customer contracts. These changes may include the acceleration of revenue and associated costs on sales to certain channel partners that are currently accounted for only once the product is sold through to the end-customer. We will be required to capitalize and amortize incremental costs related to obtaining customer contracts, such as sales commission costs. We are also in the process of assessing the appropriate changes to our business processes and upgrading our systems and controls to support recognition and disclosure under ASU 2014-09. We otherwise expect to complete our assessment process, including selecting a transition method for adoption, in the next two quarters of 2017.

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Compensation, Restricted Stock Units Award Activity

The following table summarizes the activity and related information for RSUs for the periods presented below (in thousands, except per share amounts):



	Restricted Stock Units Outstanding
	Number of Shares		Weighted-Average Grant Date Fair Value per Share
Balance—December 31, 2016	9,509		$	31.01
Granted	2,582		37.21
Forfeited	(301	)	33.80
Vested	(1,299	)	27.43
Balance—March 31, 2017	10,491		$	33.04

Schedule of Share-based Compensation, Shares Withheld for Taxes

The following summarizes the number and value of the shares withheld for employee taxes (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Shares withheld for taxes	413		343
Amount withheld for taxes	$	13,693	$	9,441

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following table summarizes the weighted-average assumptions relating to our employee stock options:



	Three months Ended
	March 31, 2017		March 31, 2016
Expected term in years	4.4		4.3
Volatility	36	%	43	%
Risk-free interest rate	1.9	%	1.1	%
Dividend rate	—	%	—	%

Schedule of Share-based Compensation, Stock Options, Activity

The following table summarizes the stock option activity and related information for the periods presented below (in thousands, except exercise prices and contractual life):



	Options Outstanding
	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Balance—December 31, 2016	6,187		$	23.79
Granted	498		37.24
Forfeited	(46	)	27.24
Exercised	(855	)	14.67
Balance—March 31, 2017	5,784		$	26.27
Options vested and expected to vest—March 31, 2017	5,784		$	26.27	3.4	$	71,951
Options exercisable—March 31, 2017	3,820		$	23.91	2.2	$	56,071

Schedule of Share-based Compensation, Stock Options, Activity, Additional Information

Additional information related to our stock options is summarized below (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Weighted-average fair value per share granted	$	12.22	$	8.68
Intrinsic value of options exercised	17,898		19,424
Fair value of options vested	3,395		2,084

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

In determining the fair value of the ESPP, we use the Black-Scholes option pricing model that employs the following weighted-average assumptions:



	Three Months Ended
	March 31, 2017		March 31, 2016
Expected term in years	0.5		0.5
Volatility	33	%	48	%
Risk-free interest rate	0.7	%	0.4	%
Dividend rate	—	%	—	%

Schedule of Share-based Payment Award Employee Stock Purchase Plan Additional Information

Additional information related to the ESPP is provided below (in thousands, except per share amounts):



	Three Months Ended
	March 31, 2017		March 31, 2016
Weighted-average fair value per share granted	$	9.28	$	7.19
Shares issued under the ESPP	634		614
Weighted-average price per share issued	$	27.97	$	20.49

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

Stock-based compensation expense is included in costs and expenses as follows (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Cost of product revenue	$	342	$	280
Cost of service revenue	2,310		2,134
Research and development	7,898		7,143
Sales and marketing	19,026		15,815
General and administrative	3,755		3,530
Total stock-based compensation expense	$	33,331	$	28,902

Schedule of Employee Service Share based Compensation Allocation of Recognized Period Costs by Award Type

The following table summarizes stock-based compensation expense by award type (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
RSUs	$	29,041	$	25,103
Stock options	1,845		1,954
ESPP	2,445		1,845
Total stock-based compensation expense	$	33,331	$	28,902

Income Tax Benefit from Stock Option Plans

Total income tax benefit associated with stock-based compensation that is recognized in the condensed consolidated statements of operations is as follows (in thousands):



	Three Months Ended
	March 31, 2017		March 31, 2016
Income tax benefit associated with stock-based compensation	$	6,645	$	7,321

Related Party Transactions (Details) - Law Firm where Board Member's Son is a Partner - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Related-party expenses incurred	$ 100,000	$ 300,000
Amounts due and payable to the law firm	100,000		$ 100,000
Contingency Fee Arrangement
Related Party Transaction [Line Items]
Related-party expenses incurred	$ 0	$ 200,000

Accumulated Other Comprehensive Loss

3 Months Ended

Mar. 31, 2017

Other Comprehensive Income (Loss), Net of Tax [Abstract]

ACCUMULATED OTHER COMPREHENSIVE LOSS

The following table summarizes the changes in accumulated balances of other comprehensive loss (in thousands):



	March 31, 2017
	Unrealized losses on investments			Tax provision related to items of other comprehensive income or loss			Total
Beginning balance	$	(1,179	)	$	414		$	(765	)
Other comprehensive income before reclassifications	424			(149		)	275
Amounts reclassified from accumulated other comprehensive loss	1			—			1
Net current-period other comprehensive income	425			(149		)	276
Ending balance	$	(754	)	$	265		$	(489	)

Amounts reclassified from accumulated other comprehensive loss for unrealized losses on investments and tax provision related to items of other comprehensive income or loss are recorded in Other income (expense)—net and in Benefit from income taxes, respectively.

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669619-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e640-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e716-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e709-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e637-108580

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e681-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Accumulated Other Comprehensive Loss (Changes in Accumulated Balances of Other Comprehensive Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive (Loss) Income [Roll Forward]
Beginning balance	$ (765)
Other comprehensive income before reclassifications	275
Amounts reclassified from accumulated other comprehensive loss	1
Net current-period other comprehensive income	276
Ending balance	(489)
Tax Benefit Related To Items of Other Comprehensive Income or Loss [Roll Forward]
Beginning balance, tax	414
Other comprehensive income before reclassifications, tax	(149)
Amounts reclassified from accumulated other comprehensive loss, tax	0
Net current-period other comprehensive income, tax	(149)
Ending balance, tax	265
Unrealized Gains and Losses on Investments [Member]
Accumulated Other Comprehensive (Loss) Income [Roll Forward]
Beginning balance	(1,179)
Other comprehensive income before reclassifications	424
Amounts reclassified from accumulated other comprehensive loss	1
Net current-period other comprehensive income	425
Ending balance	$ (754)

Property and Equipment—Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	$ 231,216		$ 207,721
Less: accumulated depreciation	(75,740)		(70,472)
Property and equipment - net	155,476		137,249
Depreciation expense	11,200	$ 9,400
Land [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	70,048		65,323
Building and building improvements [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	56,373		49,783
Computer equipment and software [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	44,198		35,079
Leasehold improvements and tooling [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	20,542		18,699
Evaluation units [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	19,701		20,173
Furniture and fixtures [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	14,153		13,995
Construction-in-progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	$ 6,201		$ 4,669

Stockholders' Equity , Share Repurchase Program (Details) - 2016 Share Repurchase Program [Member] - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2016	Mar. 31, 2017	Jan. 31, 2016
Share Repurchase Program [Line Items]
Stock repurchase program, authorized amount		$ 300.0	$ 200.0
Additional shares authorized	$ 100.0
Stock repurchase program, unused balance		$ 189.2

Summary of Significant Accounting Policies , Recent Accounting Pronouncements (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Pro Forma [Member] \| Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Expected increase to assets and liabilities upon adoption of new accounting pronouncement	$ 50.0

Restructuring Charges , Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Restructuring and Related Activities [Abstract]
Balance, beginning	$ 1,151	$ 3,918
Costs incurred	430	328
Cash payments	(567)	(1,407)
Non-cash items	0	(89)
Balance, ending	$ 1,014	$ 2,750

Financial Instruments and Fair Value , Fair Value Measurements (Details) - Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	$ 648,314	$ 650,143
Fair Value [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	66,291	90,731
Fair Value [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	582,023	559,412
Fair Value [Member] \| Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	405,007	378,612
Fair Value [Member] \| Corporate debt securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Fair Value [Member] \| Corporate debt securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	405,007	378,612
Fair Value [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	119,965	105,097
Fair Value [Member] \| Commercial paper [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Fair Value [Member] \| Commercial paper [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	119,965	105,097
Fair Value [Member] \| U.S. government and agency securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	55,677	64,541
Fair Value [Member] \| U.S. government and agency securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	45,222	52,082
Fair Value [Member] \| U.S. government and agency securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	10,455	12,459
Fair Value [Member] \| Municipal bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	46,192	59,025
Fair Value [Member] \| Municipal bonds [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Fair Value [Member] \| Municipal bonds [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	46,192	59,025
Fair Value [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	21,069	38,649
Fair Value [Member] \| Money market funds [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	21,069	38,649
Fair Value [Member] \| Money market funds [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Fair Value [Member] \| Certificates of deposit and term deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	404	4,219
Fair Value [Member] \| Certificates of deposit and term deposits [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Fair Value [Member] \| Certificates of deposit and term deposits [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	404	4,219
Reported as [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	648,314	650,143
Reported as [Member] \| Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	30,558	48,638
Reported as [Member] \| Short-term investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	375,423	376,522
Reported as [Member] \| Long-term investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	$ 242,333	$ 224,983