Fortinet (FTNT) 10-Q 8 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 31, 2016
Document Information [Line Items]
Entity Registrant Name	FORTINET INC
Entity Central Index Key	1,262,039
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		173,039,498

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 647,513	$ 543,277
Short-term investments	382,909	348,074
Accounts receivable—net of reserves for sales returns and doubtful accounts of $14,582 and $6,228 at September 30, 2016 and December 31, 2015, respectively	238,988	259,563
Inventory	93,731	83,868
Prepaid expenses and other current assets	31,732	35,761
Total current assets	1,394,873	1,270,543
LONG-TERM INVESTMENTS	240,228	272,959
DEFERRED TAX ASSETS	189,434	119,216
PROPERTY AND EQUIPMENT—net	126,109	91,067
OTHER INTANGIBLE ASSETS—net	27,849	17,640
GOODWILL	14,553	4,692
OTHER ASSETS	17,114	14,393
TOTAL ASSETS	2,010,160	1,790,510
CURRENT LIABILITIES:
Accounts payable	57,530	61,500
Accrued liabilities	37,280	33,028
Accrued payroll and compensation	65,610	61,111
Income taxes payable	7,795	8,379
Deferred revenue	582,145	514,652
Total current liabilities	750,360	678,670
DEFERRED REVENUE	352,647	276,651
INCOME TAX LIABILITIES	67,996	60,624
OTHER LIABILITIES	16,069	19,188
Total liabilities	1,187,072	1,035,133
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS’ EQUITY:
Common stock, $0.001 par value—300,000 shares authorized; 173,513 and 171,399 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively	173	171
Additional paid-in capital	779,669	687,658
Accumulated other comprehensive income (loss)	153	(933)
Retained earnings	43,093	68,481
Total stockholders’ equity	823,088	755,377
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 2,010,160	$ 1,790,510

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) Parenthetical - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Reserves for sales returns and doubtful accounts	$ 14,582	$ 6,228
Common Stock, par value (dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized	300,000	300,000
Common Stock, shares issued	173,513	171,399
Common Stock, shares outstanding	173,513	171,399

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
REVENUE:
Product	$ 127,972	$ 119,737	$ 389,185	$ 332,023
Service	188,674	140,331	523,428	380,716
Total revenue	316,646	260,068	912,613	712,739
COST OF REVENUE:
Product	50,267	46,167	152,368	134,932
Service	34,532	25,534	94,578	69,869
Total cost of revenue	84,799	71,701	246,946	204,801
GROSS PROFIT:
Product	77,705	73,570	236,817	197,091
Service	154,142	114,797	428,850	310,847
Total gross profit	231,847	188,367	665,667	507,938
OPERATING EXPENSES:
Research and development	47,239	42,110	137,495	115,315
Sales and marketing	154,831	120,994	463,628	333,531
General and administrative	22,006	21,220	63,629	51,199
Restructuring charges	2,283	5,883	3,164	5,883
Total operating expenses	226,359	190,207	667,916	505,928
OPERATING INCOME (LOSS)	5,488	(1,840)	(2,249)	2,010
INTEREST INCOME	1,888	1,333	5,339	4,119
OTHER EXPENSE—net	(787)	(653)	(3,449)	(2,160)
INCOME (LOSS) BEFORE INCOME TAXES	6,589	(1,160)	(359)	3,969
PROVISION FOR (BENEFIT FROM) INCOME TAXES	298	(9,329)	(7,380)	(6,552)
NET INCOME	$ 6,291	$ 8,169	$ 7,021	$ 10,521
Net income per share
Basic (in dollars per share)	$ 0.04	$ 0.05	$ 0.04	$ 0.06
Diluted (in dollars per share)	$ 0.04	$ 0.05	$ 0.04	$ 0.06
Weighted-average shares outstanding:
Basic (in shares)	173,335	171,648	172,212	169,898
Diluted (in shares)	177,938	177,897	176,046	175,963

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 6,291	$ 8,169	$ 7,021	$ 10,521
Other comprehensive income (loss):
Unrealized gains (losses) on investments	(879)	337	1,670	400
Tax provision (benefit)	(308)	118	584	141
Other comprehensive income (loss)—net of taxes	(571)	219	1,086	259
Comprehensive income	$ 5,720	$ 8,388	$ 8,107	$ 10,780

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 7,021	$ 10,521
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	34,896	22,206
Amortization of investment premiums	3,828	5,770
Stock-based compensation	90,342	67,001
Other non-cash items—net	4,846	2,681
Changes in operating assets and liabilities:
Accounts receivable—net	12,788	20,923
Inventory	(24,555)	(12,427)
Deferred tax assets	(35,005)	(28,297)
Prepaid expenses and other current assets	4,301	(7,806)
Other assets	(2,595)	(264)
Accounts payable	(1,584)	(9,842)
Accrued liabilities	598	(3,296)
Accrued payroll and compensation	3,253	(1,895)
Other liabilities	(3,119)	(1,232)
Deferred revenue	142,867	136,193
Income taxes payable	6,789	13,753
Net cash provided by operating activities	244,671	213,989
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investments	(370,573)	(329,687)
Sales of investments	21,805	35,384
Maturities of investments	344,959	364,256
Purchases of property and equipment	(50,319)	(29,013)
Payments made in connection with business acquisition, net of cash acquired	(22,087)	(38,025)
Net cash provided by (used in) investing activities	(76,215)	2,915
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	42,292	63,543
Taxes paid related to net share settlement of equity awards	(29,886)	(22,989)
Repurchase and retirement of common stock	(75,000)	0
Payments of debt assumed in connection with business acquisition	(1,626)	0
Net cash provided by (used in) financing activities	(64,220)	40,554
NET INCREASE IN CASH AND CASH EQUIVALENTS	104,236	257,458
CASH AND CASH EQUIVALENTS—Beginning of period	543,277	283,254
CASH AND CASH EQUIVALENTS—End of period	647,513	540,712
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes—net of refunds	20,534	15,272
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Transfers of evaluation units from inventory to property and equipment	15,627	13,695
Liability for purchase of property and equipment and asset retirement obligations	8,325	2,243
Equity awards assumed in connection with business acquisition	$ 0	$ 471

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
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 (“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, 2015, contained in our Annual Report on Form 10-K (the “Form 10-K”) filed with the SEC on February 26, 2016. 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 and nine months ended September 30, 2016 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, 2015 is derived from the audited consolidated financial statements for the year ended December 31, 2015. 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 and nine months ended September 30, 2016 , except for changes to our policy related to stock-based compensation expense. For more information, refer to the “Recently Adopted Accounting Standards.” Recently Adopted Accounting Standards In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09—Compensation—Stock Compensation—Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”). The new guidance changes the accounting for certain aspects of stock-based payments to employees and requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled. In addition, cash flows related to excess tax benefits will no longer be separately classified as a financing activity apart from other income tax cash flows. The standard also allows us to repurchase more of an employee’s shares for tax withholding purposes without triggering liability accounting, clarifies that all cash payments made on an employee’s behalf for withheld shares should be presented as a financing activity on our cash flows statement, and provides an accounting policy election to account for forfeitures as they occur. We elected to early adopt the new guidance in the second quarter of 2016. The primary impact of the adoption was the recognition of excess tax benefits in our provision for income taxes rather than paid-in capital, as well as the adjustment in stock-based compensation expense as a result of our change in forfeiture policy. The new guidance eliminates the requirement to delay the recognition of excess tax benefits until it reduces current taxes payable. We adopted this change on a modified retrospective basis, and recorded unrecognized excess tax benefits of $32.4 million as a cumulative-effect adjustment, which increased retained earnings on January 1, 2016. The new guidance also requires us to record, subsequent to the adoption, excess tax benefits and tax deficiencies in the period these arise. As a result, our provision for income taxes decreased by $3.6 million during the first quarter of 2016. Under the new guidance, we have elected to change our policy and have started to recognize forfeitures of awards as they occur. The change in forfeiture policy was adopted using a modified retrospective transition method. We recorded a cumulative-effect adjustment to decrease retained earnings by $0.8 million upon transition on January 1, 2016 and a retrospective decrease of stock-based compensation of $2.0 million during the first quarter of 2016. The amendment to the minimum statutory withholding tax requirements was adopted on a modified retrospective basis. The adoption had no impact on the January 1, 2016 retained earnings. In addition, we adopted the presentation of taxes paid related to net share settlement of equity awards as a financing activity on the statement of cash flows on a retrospective basis. Our adoption had no impact to any of the periods presented in our consolidated cash flows statements since such cash flows have historically been presented as a financing activity. The adoption of ASU 2016-09 impacted our previously reported quarterly results for the three months ended March 31, 2016, as well as our weighted average shares outstanding—diluted, as follows (in thousands, except for earnings per share): Three Months Ended March 31, 2016 As Reported As Adjusted Statements of Operations: Stock-based compensation expense $ 30,881 $ 28,901 Benefit from income taxes $ (1,809 ) $ (5,376 ) Net income (loss) $ (3,429 ) $ 2,118 Net income (loss) per share—Basic $ (0.02 ) $ 0.01 Net income (loss) per share—Diluted $ (0.02 ) $ 0.01 Weighted-average shares outstanding—Diluted 171,745 174,421 March 31, 2016 As Reported As Adjusted Balance Sheets: Deferred tax assets $ 131,696 $ 167,625 Additional paid-in capital $ 718,849 $ 717,671 Retained earnings $ 23,089 $ 60,196 In September 2015, the FASB issued ASU 2015-16—Business Combinations—Simplifying the Accounting for Measurement-Period Adjustments, which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, acquirers must recognize measurement-period adjustments during the period in which they determine the amounts, including the effect on earnings of any amounts they would have recorded in previous periods if the accounting had been completed at the acquisition date. We adopted ASU 2015-16 on January 1, 2016. The adoption of ASU 2015-16 has not had any impact on our consolidated financial statements. Recent Accounting Standards Not Yet Effective 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 August 2016, the FASB issued ASU 2016-15—Statement of Cash Flows—Classification of Certain Cash Receipts and Cash Payments, which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. ASU 2016-15 is effective for us beginning on January 1, 2018. Early adoption is permitted, including adoption in an interim period. We are currently evaluating the impact of adopting ASU 2016-15 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 ASU 2016-13 will have on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02—Leases, which amends lease accounting requirements to begin recording assets and liabilities arising from leases on the balance sheet. 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. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. We expect our assets and liabilities to increase as a result of the adoption of this standard. We are currently evaluating the impact of adopting ASU 2016-02 on our consolidated financial statements. In May 2014, the FASB issued ASU 2014-09—Revenue from Contracts with Customers, which creates a single, joint revenue standard that is consistent across all industries and markets for companies that prepare their financial statements in accordance with GAAP. Under ASU 2014-09, an entity is required to recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services. In July 2015, the FASB decided to delay the effective date of the new revenue standard by one year. In March 2016, the FASB issued ASU 2016-08, which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, which clarifies the implementation guidance on identifying performance obligations and licensing. In May 2016, the FASB issued ASU 2016-12—Revenue from Contracts with Customers—Narrow-scope Improvements and Practical Expedients, which amends the guidance on collectability, noncash consideration, presentation of sales tax and transition. These standards will be effective for us beginning on January 1, 2018. We are currently evaluating the impact of these new standards on our consolidated financial statements.

Financial Instruments and Fair

Financial Instruments and Fair Value	9 Months Ended
	Sep. 30, 2016
Financial Instruments and Fair Value [Abstract]
FINANCIAL INSTRUMENTS AND FAIR VALUE	FINANCIAL INSTRUMENTS AND FAIR VALUE Our investments as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt securities $ 385,016 $ 425 $ (211 ) $ 385,230 Commercial paper 127,059 18 (43 ) 127,034 Municipal bonds 53,821 14 (36 ) 53,799 Certificates of deposit and term deposits (1) 4,322 — — 4,322 U.S. government and agency securities 52,686 72 (6 ) 52,752 Total available-for-sale securities $ 622,904 $ 529 $ (296 ) $ 623,137 December 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt securities $ 438,533 $ 30 $ (1,369 ) $ 437,194 Commercial paper 66,263 3 (34 ) 66,232 Municipal bonds 61,050 12 (40 ) 61,022 Certificates of deposit and term deposits (1) 14,897 — — 14,897 U.S. government and agency securities 41,727 3 (42 ) 41,688 Total available-for-sale securities $ 622,470 $ 48 $ (1,485 ) $ 621,033 (1) The majority of our certificates of deposit and term deposits are foreign deposits. The gross unrealized losses and the related fair values of our investments that have been in a continuous unrealized loss position as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 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 $ 157,390 $ (188 ) $ 37,548 $ (22 ) $ 194,938 $ (210 ) Commercial paper 19,320 (43 ) — — 19,320 (43 ) Municipal bonds 36,163 (37 ) — — 36,163 (37 ) U.S. government and agency securities 5,492 (6 ) — — 5,492 (6 ) Total available-for-sale securities $ 218,365 $ (274 ) $ 37,548 $ (22 ) $ 255,913 $ (296 ) December 31, 2015 Less Than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 348,534 $ (1,187 ) $ 42,033 $ (182 ) $ 390,567 $ (1,369 ) Commercial paper 31,977 (34 ) — — 31,977 (34 ) Municipal bonds 41,677 (36 ) 1,008 (4 ) 42,685 (40 ) U.S. government and agency securities 34,703 (42 ) — — 34,703 (42 ) Total available-for-sale securities $ 456,891 $ (1,299 ) $ 43,041 $ (186 ) $ 499,932 $ (1,485 ) The contractual maturities of our investments as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, December 31, Due within one year $ 382,909 $ 348,074 Due within one to three years 240,228 272,959 Total $ 623,137 $ 621,033 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 total comprehensive income. Realized gains and losses on available-for-sale securities are insignificant in the periods presented and are included in Other 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 September 30, 2016 . 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 fair values of our financial assets measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 December 31, 2015 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 $ 385,230 $ — $ 385,230 $ — $ 437,194 $ — $ 437,194 $ — Commercial paper 132,033 — 132,033 — 69,231 — 69,231 — Municipal bonds 53,799 — 53,799 — 61,022 — 61,022 — Certificates of deposit and term deposits 4,322 — 4,322 — 14,897 — 14,897 — Money market funds 21,886 21,886 — — 50,030 50,030 — — U.S. government and agency securities 52,752 42,243 10,509 — 41,688 25,693 15,995 — Total $ 650,022 $ 64,129 $ 585,893 $ — $ 674,062 $ 75,723 $ 598,339 $ — Reported as: Cash equivalents $ 26,885 $ 53,029 Short-term investments 382,909 348,074 Long-term investments 240,228 272,959 Total $ 650,022 $ 674,062 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2016 .

Inventory

Inventory	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Our inventory as of September 30, 2016 and December 31, 2015 consisted of (in thousands): September 30, December 31, Raw materials $ 19,690 $ 15,425 Finished goods 74,041 68,443 Inventory $ 93,731 $ 83,868 Inventory includes finished goods held by distributors where revenue is recognized on a sell-through basis of $1.4 million and $1.1 million as of September 30, 2016 and December 31, 2015 , respectively. Inventory also includes materials at contract manufacturers of $6.3 million and $4.9 million as of September 30, 2016 and December 31, 2015 , respectively.

Property and Equipment_Net

Property and Equipment—Net	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT—Net	PROPERTY AND EQUIPMENT—net Our property and equipment—net as of September 30, 2016 and December 31, 2015 consisted of (in thousands): September 30, December 31, Land $ 31,251 $ 21,683 Building and building improvements 44,513 28,841 Evaluation units 17,633 15,784 Computer equipment and software 62,585 45,632 Furniture and fixtures 13,127 8,901 Construction-in-progress 4,365 8,106 Leasehold improvements 16,501 11,179 Total property and equipment 189,975 140,126 Less: accumulated depreciation (63,866 ) (49,059 ) Property and equipment—net $ 126,109 $ 91,067 Depreciation expense was $10.2 million and $7.5 million during the three months ended September 30, 2016 and September 30, 2015 , respectively. Depreciation expense was $28.6 million and $20.3 million during the nine months ended September 30, 2016 and September 30, 2015 , respectively.

Investments in Privately-Held C

Investments in Privately-Held Companies	9 Months Ended
	Sep. 30, 2016
Investments, All Other Investments [Abstract]
INVESTMENTS IN PRIVATELY-HELD COMPANIES	INVESTMENTS IN PRIVATELY-HELD COMPANIES Our investments in the equity securities of three privately-held companies totaled $10.3 million as of September 30, 2016 and December 31, 2015 . Each of these investments are accounted for as cost-basis investments, as we own less than 20% of the voting securities 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 sheet and would be measured at fair value if indicators of impairment exist. As of September 30, 2016 , no events have occurred that would adversely affect the carrying value of these investments. 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 were not required to be consolidated in our condensed consolidated financial statements.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS AccelOps, Inc. On June 7, 2016, we completed our acquisition of AccelOps, Inc. (“AccelOps”), a provider of network security monitoring and analytics solutions for total cash consideration of $22.1 million , net of cash received. We believe this acquisition will extend the Fortinet Security Fabric (as defined below) by enhancing our network security visibility, security data analytics, and threat intelligence across multi-vendor solutions. The acquisition of AccelOps is accounted as a business combination in accordance with the Accounting Standards Codification Topic 805 “Business Combinations” (“ASC 805”) issued by the FASB. We use our best estimates and assumptions to assign fair value to the tangible and intangible assets acquired and liabilities assumed at the acquisition date. We included acquisition-related costs of $0.3 million in general and administrative expenses. The total purchase price was allocated to AccelOps’ identifiable tangible and intangible assets acquired and liabilities assumed based on their estimated fair values as of the acquisition date. The acquisition also included a contingent obligation for up to $4.0 million in future earn out payments to certain former stockholders of AccelOps if specified future financial targets are met for the three and six months period ended June 30, 2016 and December 31, 2016, respectively. The financial target for the three months period ended June 30, 2016 was not met. As of September 30, 2016, no fair value was assigned to the contingent consideration based on the estimated probability of attainment of the remaining target. We will remeasure the contingent consideration during the contingency period for the remaining target, with changes in fair value to be recorded in our consolidated statements of operations. Total allocation of the purchase price was (in thousands): Cash and cash equivalents $ 171 Accounts receivable 1,126 Prepaid expenses and other assets 430 Property and equipment 203 Deferred tax assets 3,435 Finite-lived intangible assets 14,900 Indefinite-lived intangible assets in process research and development 1,600 Goodwill 9,861 Total assets acquired 31,726 Deferred revenue 4,400 Accounts payable and accrued liabilities 3,348 Other liabilities 1,694 Total liabilities assumed 9,442 Total purchase price allocation $ 22,284 Finite-lived intangible assets consist of developed technology, customer relationships, and other intangible assets. AccelOps’ technology provides a software solution to manage security, performance and compliance from a single platform. The acquired developed technologies include software patents, know-how, process and designs. The value of customer relationships is attributable to the generation of a consistent income source and the avoidance of costs associated with creating new customer relationships. The estimated useful life and fair values of the acquired finite-lived intangible assets were as follows (in thousands, except for estimated useful life): Estimated Useful Life (in years) Fair Values Developed technologies 4 $ 12,400 Customer relationships 3 2,300 Other 2 200 Total $ 14,900 The developed technologies and other are amortized on a straight-line basis. The amortization expense of developed technologies and other intangibles are recorded in cost of service revenue. The amortization expense of customer relationships is amortized on an accelerated basis and is recorded in sales and marketing expenses. Indefinite-lived intangible assets consist of in-process research and development, which will begin to be amortized upon completion of development. The goodwill of $9.9 million represents the amount of the purchase price in excess of the fair value of the net tangible liabilities assumed and intangible assets acquired, including AccelOps’ assembled workforce. The goodwill recorded as part of the AccelOps acquisition is not deductible for U.S. federal income tax purposes. The financial results of this acquisition are considered immaterial for purposes of pro forma financial disclosures. Meru Networks, Inc. On July 8, 2015, we completed our acquisition of Meru Networks, Inc. (“Meru”), a provider of Wi-Fi networking products and services. In connection with the acquisition, we paid $41.8 million , comprised of cash consideration of $40.9 million , withholding tax liability of $0.4 million and $0.5 million in estimated fair value associated with restricted stock units (“RSUs”) of Meru that were converted for 53,401 shares of our common stock. We accounted for this transaction as a business combination. During the three and nine months ended September 30, 2015, we included acquisition-related costs of $1.7 million in general and administrative expenses. The total purchase price was allocated to Meru’s identifiable tangible and intangible assets acquired and liabilities assumed based on their estimated fair values as of the acquisition date. Total allocation of the purchase price was as follows (in thousands): Cash and cash equivalents $ 3,268 Accounts receivable 8,191 Inventory 11,610 Prepaid expenses and other assets 2,409 Property and equipment 920 Deferred tax assets 18,585 Finite-lived intangible assets 19,600 Goodwill 1,868 Total assets acquired 66,451 Deferred revenue 9,800 Accounts payable and accrued liabilities 14,887 Total liabilities assumed 24,687 Total purchase price allocation $ 41,764 The goodwill of $1.9 million represents the premium we paid over the fair value of the net tangible liabilities assumed and identified intangible assets acquired, due primarily to Meru’s assembled workforce. The goodwill recorded as part of the Meru acquisition is not deductible for U.S. federal income tax purposes. Intangible assets consist primarily of customer relationships and developed technologies. Customer relationships represent Meru’s installed base and the ability to sell existing, in-process and future versions of our products and services to its existing customers. Developed technologies represent the virtualized wireless local area network solutions offering centralized coordination and control of various access points on the network. This includes patented and unpatented technology, know-how, processes, designs and computer software. The estimated useful life and fair values of the acquired identifiable intangible assets were as follows (in thousands, except for estimated useful life): Estimated Useful Life (in years) Fair Values Customer relationships 5 $ 12,200 Developed technologies 4 7,200 Trade name 0.5 200 Total $ 19,600 Customer relationships and trade name are amortized and the amortization expense is recorded in sales and marketing expenses in the condensed consolidated statement of operations. Developed technologies are amortized and the amortization expense is recorded in cost of product revenue in the condensed consolidated statement of operations.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets - Net	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS - Net	GOODWILL AND OTHER INTANGIBLE ASSETS—net Goodwill Changes in the carrying amount of goodwill were (in thousands): Amount Balance—December 31, 2015 $ 4,692 Addition due to business acquisition 9,861 Balance—September 30, 2016 $ 14,553 There were no impairments to goodwill during the three and nine months ended September 30, 2016 . Other Intangible Assets—net Other intangible assets—net as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Finite-lived intangible assets: Customer relationships 4.7 $ 14,500 $ 4,735 $ 9,765 Developed technologies and other 3.8 23,984 7,500 16,484 38,484 12,235 26,249 Indefinite-lived intangible assets: In-process research and development 1,600 — 1,600 Total other intangible assets—net $ 40,084 $ 12,235 $ 27,849 December 31, 2015 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Customer relationships 5.0 $ 12,200 $ 1,220 $ 10,980 Developed technologies and other 3.6 11,384 4,724 6,660 Total other intangible assets—net $ 23,584 $ 5,944 $ 17,640 Amortization expense was $2.8 million and $1.3 million during the three months ended September 30, 2016 and September 30, 2015 , respectively. Amortization expense was $6.3 million and $1.9 million during the nine months ended September 30, 2016 and September 30, 2015 , respectively. The following table summarizes estimated future amortization expense of Other intangible assets—net with finite lives (in thousands): Amount Years: 2016 (remainder) $ 2,798 2017 8,450 2018 7,098 2019 5,540 2020 2,363 Total $ 26,249

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
NET INCOME PER SHARE	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 stock options, RSUs including performance stock units (“PSUs”), and our 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 Nine Months Ended September 30, September 30, September 30, September 30, Numerator: Net income $ 6,291 $ 8,169 $ 7,021 $ 10,521 Denominator: Basic shares: Weighted-average common stock outstanding-basic 173,335 171,648 172,212 169,898 Diluted shares: Weighted-average common stock outstanding-basic 173,335 171,648 172,212 169,898 Effect of potentially dilutive securities: Stock options 2,009 3,451 1,867 3,669 RSUs (including PSUs) 2,513 2,742 1,891 2,335 ESPP 81 56 76 61 Weighted-average shares used to compute diluted net income per share 177,938 177,897 176,046 175,963 Net income per share: Basic $ 0.04 $ 0.05 $ 0.04 $ 0.06 Diluted $ 0.04 $ 0.05 $ 0.04 $ 0.06 The following potentially dilutive 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 Nine Months Ended September 30, September 30, September 30, September 30, Stock options 836 265 1,067 271 RSUs (including PSUs) 2,409 1,331 3,946 1,026 ESPP 353 209 211 126 3,598 1,805 5,224 1,423

Restructuring Charges

Restructuring Charges	9 Months Ended
	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES The following table provides a summary of restructuring activity for the nine months ended September 30, 2016 (in thousands): Employee Severance and Other Benefits Contract Terminations and Other Charges Total Balance as of December 31, 2015 $ 3,689 $ 229 $ 3,918 Costs incurred 3,120 44 3,164 Less cash payments (5,060 ) (273 ) (5,333 ) Less non-cash charges (89 ) — (89 ) Balance as of September 30, 2016 $ 1,660 $ — $ 1,660 2015 Meru Restructuring In connection with the acquisition of Meru, we initiated planned cost reduction and restructuring activities to improve our cost structure and operational efficiencies starting in the third quarter of 2015. To date, we have incurred $7.9 million of charges related to this restructuring. These charges are primarily related to severance payments to be paid in cash and are included in operating expense in the condensed consolidated statements of operations of the period when incurred. We incurred $0.1 million and $0.3 million of charges related to this restructuring during the three and nine months ended September 30, 2016, respectively, and these charges are included in operating expense in the condensed consolidated statements of operations. We do not anticipate incurring additional charges related to this restructuring. The remaining restructuring reserve of $1.1 million is included in accrued liabilities on the condensed consolidated balance sheet as of September 30, 2016 and is expected to be paid within one year. 2016 Restructuring In the second and third quarter of 2016, we implemented a plan to restructure and further improve efficiencies in our operations due to the acquisition of AccelOps and certain other activities. We estimate that we will incur approximately $4.1 million of restructuring charges, primarily consisting of severance and other benefits, of which $2.2 million and $2.9 million were incurred during the three and nine months ended September 30, 2016 , respectively, and are included in operating expense in the condensed consolidated statements of operations. We expect to incur the remaining charges in the fourth quarter of 2016. The remaining restructuring reserve of $0.6 million is included in accrued liabilities on the condensed consolidated balance sheet as of September 30, 2016 and is expected to be paid within one year.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Our future principal contractual obligations as of September 30, 2016 were (in thousands): Total 2016 (remainder) 2017 2018 2019 2020 Thereafter Operating lease commitments $ 74,107 $ 5,756 $ 17,678 $ 14,653 $ 12,359 $ 10,497 $ 13,164 Inventory purchase commitments 116,494 90,169 26,325 — — — — Other contractual commitments and open purchase orders 48,864 33,805 11,466 2,451 855 287 — Total $ 239,465 $ 129,730 $ 55,469 $ 17,104 $ 13,214 $ 10,784 $ 13,164 Operating Leases —We lease certain facilities under various non-cancelable operating leases, which expire through 2026. 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 $6.1 million and $3.7 million during the three months ended September 30, 2016 and September 30, 2015 , respectively. Rent expense was $14.7 million and $9.7 million during the nine months ended September 30, 2016 and September 30, 2015 , 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 September 30, 2016 , we had $116.5 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 September 30, 2016 , we had $48.9 million in other contractual commitments that may not be cancelable. Warranties —Accrued warranty activities are summarized as follows (in thousands): Nine Months Ended September 30, September 30, Accrued warranty balance—beginning of the period $ 3,144 $ 4,269 Warranty costs incurred (2,260 ) (3,413 ) Provision for warranty for the period 925 3,638 Adjustment related to pre-existing warranties (279 ) (94 ) Accrued warranty balance—end of the period $ 1,530 $ 4,400 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, 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. We have not recorded any significant accrual for loss contingencies associated with such legal proceedings; determined that a significant unfavorable outcome is probable or reasonably possible; or determined that the amount or range of any possible significant loss is reasonably estimable. 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.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2016
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 and PSUs. We also have an ESPP for all eligible employees. As of September 30, 2016 , there were a total of 44,406,659 shares of common stock available for grant under our stock-based compensation plans. Restricted Stock Units The activity and related information for RSUs, including PSUs, was (in thousands, except per share amounts): Restricted Stock Units Outstanding Number of Shares Weighted-Average Grant Date Fair Value per Share Balance—December 31, 2015 9,257 $ 32.97 Granted 4,867 27.54 Forfeited (1,270 ) 32.12 Vested (2,864 ) 30.37 Balance—September 30, 2016 9,990 $ 30.99 As of September 30, 2016 , total compensation expense related to unvested RSUs, including PSUs, that were granted to employees and non-employees, but not yet recognized, was $273.0 million . This expense is expected to be amortized on a straight-line basis over a weighted-average vesting period of 2.85 years. We did not grant any PSUs during the three and nine months ended September 30, 2016 . The stock-based compensation expense related to PSU awards is not material. 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 number of shares and amount withheld for employee taxes were (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Shares withheld for taxes 347 245 937 590 Amount withheld for taxes $ 12,528 $ 11,628 $ 29,886 $ 22,989 Employee Stock Options The weighted-average assumptions relating to our employee stock options were: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Expected term in years 4.3 4.3 4.3 4.3 Volatility 38 % 37 % 42 % 38 % Risk-free interest rate 1.1 % 1.6 % 1.1 % 1.5 % Dividend rate — % — % — % — % The stock option activity and related information was (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, 2015 6,968 $ 20.03 Granted 1,405 $ 25.39 Forfeited (221 ) $ 34.91 Exercised (1,750 ) $ 10.37 Balance—September 30, 2016 6,402 $ 23.33 3.22 $ 89,714 Options exercisable—September 30, 2016 4,469 $ 21.26 1.99 $ 70,864 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 September 30, 2016 , for all in-the-money options. As of September 30, 2016 , total compensation expense related to unvested stock options granted to employees but not yet recognized was $16.8 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 Nine Months Ended September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Weighted-average fair value per share granted $ 10.62 $ 15.89 $ 9.08 $ 13.60 Intrinsic value of options exercised $ 9,340 $ 40,132 $ 35,593 $ 103,170 Fair value of options vested $ 1,706 $ 2,491 $ 4,583 $ 9,001 Employee Stock Purchase Plan In determining the fair value of our ESPP, we use the Black-Scholes option pricing model that employs the following weighted-average assumptions: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Expected term in years 0.5 0.5 0.5 0.5 Volatility 34 % 32 % 39 % 31 % Risk-free interest rate 0.5 % 0.2 % 0.4 % 0.1 % Dividend rate — % — % — % — % Additional information related to the ESPP is provided below (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Weighted-average fair value per share granted $ 8.07 $ 11.42 $ 7.68 $ 8.23 Shares issued under the ESPP 537 337 1,151 764 Weighted-average price per share issued $ 21.61 $ 28.05 $ 21.01 $ 24.30 Stock-based Compensation Expense Stock-based compensation expense is included in costs and expenses as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Cost of product revenue $ 309 $ 291 $ 887 $ 641 Cost of service revenue 2,238 1,849 6,495 5,141 Research and development 7,648 6,663 22,249 17,361 Sales and marketing 17,378 13,904 50,183 34,482 General and administrative 3,520 3,612 10,528 9,376 Total stock-based compensation expense $ 31,093 $ 26,319 $ 90,342 $ 67,001 The stock-based compensation expense by award type was (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, RSUs $ 27,342 $ 21,996 $ 79,244 $ 53,674 Stock options 1,516 2,669 5,062 9,141 ESPP 2,235 1,654 6,036 4,186 Total stock-based compensation expense $ 31,093 $ 26,319 $ 90,342 $ 67,001 Total income tax benefit associated with stock-based compensation that is recognized in the consolidated statements of operations is as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Income tax benefit associated with stock-based compensation $ 8,223 $ 5,224 $ 22,961 $ 12,867 Share Repurchase Program In January 2016, our board of directors approved a new Share Repurchase Program (the “Program”), which authorizes the repurchase of up to $200.0 million of our outstanding common stock through December 31, 2017. Under the Program, share repurchases may be made by us from time to time in privately negotiated transactions or in open market transactions. The 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. During the three and nine months ended September 30, 2016 , we repurchased 0.7 million and 2.7 million shares of common stock under the Program, respectively, in open market transactions at an average price of $36.04 and $27.82 per share, respectively, for an aggregate purchase price of $25.0 million and $75.0 million , respectively. As of September 30, 2016 , $125.0 million remained available for future share repurchases under the Program.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Our effective tax rate was 5% for the three months ended September 30, 2016 , compared to an effective tax rate of 804% for the same period last year. The effective tax rate was 2,053% for the nine months ended September 30, 2016 , compared to an effective tax rate of -165% for the same period last year. The effective tax rate for the periods presented was comprised of U.S. federal and state taxes, foreign withholding taxes and foreign income taxes. The changes in the tax provision for the periods presented were primarily due to the tax benefit from the adoption of the new accounting guidance relating to stock-based compensation. The effective tax rate for the three months ended September 30, 2016 was an expense as compared to a benefit for the same period last year. The increase in effective tax rate for the nine months ended September 30, 2016 was primarily due to additional tax benefits from the adoption of the new accounting guidance relating to stock-based compensation. As a result of the early adoption of the new guidance on stock-based compensation, we recorded income tax benefit of $2.5 million and $8.7 million during the three and nine months ended September 30, 2016, respectively. As of September 30, 2016 and December 31, 2015, unrecognized tax benefits were $64.9 million and $59.7 million , respectively. The total amount of $63.5 million in unrecognized tax benefits, if recognized, would favorably impact the effective tax rate. It is our policy to classify accrued interest and penalties related to unrecognized tax benefits in the provision for income taxes. As of September 30, 2016 , we had accrued $8.8 million for estimated interest related to uncertain tax positions. We file income tax returns in the U.S. federal jurisdiction, and various U.S. state and foreign jurisdictions. The statute of limitations is open for years that generated state net operating loss carryforwards and after 2009 for state jurisdictions. Additionally, we have foreign net operating losses that have an indefinite life. Generally, we are no longer subject to 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 tax authorities for tax years prior to 2012. We are currently under examination by U.S federal income tax authorities for the tax years 2012, 2013, and 2014. In addition, the tax authorities in France are examining the inter-company relationship between Fortinet, Inc., Fortinet France and Fortinet Singapore. We are in the early stages of this inquiry and as of yet no official audit has been opened. We are also under audit by the Japanese tax authorities for the years 2013, 2014 and 2015. We do not expect any material adjustments as a result of this audit.

Defined Contribution Plans

Defined Contribution Plans	9 Months Ended
	Sep. 30, 2016
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 the 401(k) Plan and RRSP for the three months ended September 30, 2016 and September 30, 2015 were $1.2 million and $0.9 million , respectively. Our matching contributions to the 401(k) Plan and RRSP during the nine months ended September 30, 2016 and September 30, 2015 were $3.4 million and $2.7 million , respectively.

Segment and Significant Custome

Segment and Significant Customer Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
SEGMENT AND SIGNIFICANT CUSTOMER 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 Nine Months Ended Revenue September 30, September 30, September 30, September 30, Americas: United States $ 83,049 $ 72,767 $ 239,417 $ 202,491 Canada 35,211 26,027 100,299 72,676 Other Americas 15,614 14,371 46,850 38,151 Total Americas 133,874 113,165 386,566 313,318 Europe, Middle East, and Africa (“EMEA”) 116,967 91,740 336,911 250,808 Asia Pacific (“APAC”) 65,805 55,163 189,136 148,613 Total revenue $ 316,646 $ 260,068 $ 912,613 $ 712,739 Property and Equipment — net September 30, December 31, Americas: United States $ 92,096 $ 61,064 Other Americas 9,872 8,972 Total Americas 101,968 70,036 EMEA: France 13,649 13,201 Other EMEA 6,199 3,977 Total EMEA 19,848 17,178 APAC 4,293 3,853 Total property and equipment—net $ 126,109 $ 91,067 The following customers, each of which is a distributor, accounted for 10% or more of our revenue: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Exclusive Networks Group 19 % 17 % 19 % 17 % Ingram Micro 10 % * * * * Represents less than 10% The following customers, each of which is a distributor, accounted for 10% or more of net accounts receivable: September 30, December 31, Exclusive Networks Group 20 % 23 % Fine Tec Computers 12 % * Ingram 10 % * * Represents less than 10%

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Net of Tax [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The changes in accumulated balances of other comprehensive income or loss were (in thousands): September 30, 2016 Unrealized Gains/Losses on Investments Tax benefit (provision) related to items of other comprehensive income or loss Total Beginning balance at December 31, 2015 $ (1,437 ) $ 504 $ (933 ) Other comprehensive income (loss) before reclassifications 1,668 (583 ) 1,085 Amounts reclassified from accumulated other comprehensive income (loss) 2 (1 ) 1 Net current-period other comprehensive income (loss) 1,670 (584 ) 1,086 Ending balance at September 30, 2016 $ 233 $ (80 ) $ 153 The details of reclassification out of accumulated other comprehensive income (loss) were (in thousands): Nine Months Ended September 30, 2016 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income is Presented Unrealized losses on investments $ 2 Other expense—net Tax benefit related to items of other comprehensive loss (1 ) Provision for income taxes Total reclassification for the period $ 1

Foreign Currency Derivatives

Foreign Currency Derivatives	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
FOREIGN CURRENCY DERIVATIVES	FOREIGN CURRENCY DERIVATIVES Our sales contracts are primarily denominated in U.S. dollars and therefore substantially all of our revenue is not subject to foreign currency translation risk. However, a substantial portion of our operating expenses incurred outside the United States is denominated in foreign currencies and is subject to fluctuations due to changes in foreign currency exchange rates, particularly changes in the Canadian dollar (“CAD”), Euro (“EUR”), Great British pound (“GBP”), and Chinese yen (“CNY”). To help protect against significant fluctuations in value and the volatility of future cash flows caused by changes in currency exchange rates, we engage in foreign currency risk management activities to hedge balance sheet items denominated in CAD. We do not use these contracts for speculative or trading purposes. All of the derivative instruments are with high quality financial institutions and we monitor the creditworthiness of these parties. These contracts typically have maturities between one and three months. Changes in the fair value of forward exchange contracts related to balance sheet accounts are insignificant and are included in Other expense—net in the condensed consolidated statement of operations. As of September 30, 2016 , the fair value of the forward exchange contracts was not material. Additionally, independent of any hedging activities, fluctuations in foreign currency exchange rates may cause us to recognize transaction gains and losses in our condensed consolidated statements of operations. Our hedging activities are intended to reduce, but not eliminate, the impact of currency exchange rate movements. As our hedging activities are relatively short-term in nature and are focused on the CAD, long-term material changes in the value of the U.S. dollar against other foreign currencies, such as the EUR, GBP and CNY could adversely impact our operating expenses in the future. The notional amount of forward exchange contracts to hedge balance sheet accounts as of September 30, 2016 and December 31, 2015 were (in thousands): Buy/Sell Notional Balance Sheet Contracts: Currency—As of September 30, 2016 CAD Sell $ 4,520 Currency—As of December 31, 2015 CAD Sell $ 7,011

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2016
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 related to matters that arose subsequent to the member joining our board of directors were not material during the three months ended September 30, 2016 and $0.9 million during the three months ended September 30, 2015 . No contingent fees were incurred during the three months ended September 30, 2016 and September 30, 2015. Expenses for legal services provided by the law firm related to matters that arose subsequent to the member joining our board of directors were $0.3 million and $3.7 million during the nine months ended September 30, 2016 and September 30, 2015 , respectively. Of such amounts, $0.5 million were incurred under contingent fee arrangements during the nine months ended September 30, 2015 . No contingent fees were incurred during the nine months ended September 30, 2016. Amounts due and payable to the law firm were $0.1 million and $5.3 million as of September 30, 2016 and December 31, 2015 , respectively.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Event	SUBSEQUENT EVENT Share Repurchase Program In October 2016, our board of directors authorized the repurchase of up to $100.0 million of shares of our common stock under the Program, increasing our current authorization to $300.0 million through December 2017.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
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 (“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, 2015, contained in our Annual Report on Form 10-K (the “Form 10-K”) filed with the SEC on February 26, 2016. 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 and nine months ended September 30, 2016 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, 2015 is derived from the audited consolidated financial statements for the year ended December 31, 2015. 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 and nine months ended September 30, 2016 , except for changes to our policy related to stock-based compensation expense. For more information, refer to the “Recently Adopted Accounting Standards.”
Recent Accounting Pronouncements	Recently Adopted Accounting Standards In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09—Compensation—Stock Compensation—Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”). The new guidance changes the accounting for certain aspects of stock-based payments to employees and requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled. In addition, cash flows related to excess tax benefits will no longer be separately classified as a financing activity apart from other income tax cash flows. The standard also allows us to repurchase more of an employee’s shares for tax withholding purposes without triggering liability accounting, clarifies that all cash payments made on an employee’s behalf for withheld shares should be presented as a financing activity on our cash flows statement, and provides an accounting policy election to account for forfeitures as they occur. We elected to early adopt the new guidance in the second quarter of 2016. The primary impact of the adoption was the recognition of excess tax benefits in our provision for income taxes rather than paid-in capital, as well as the adjustment in stock-based compensation expense as a result of our change in forfeiture policy. The new guidance eliminates the requirement to delay the recognition of excess tax benefits until it reduces current taxes payable. We adopted this change on a modified retrospective basis, and recorded unrecognized excess tax benefits of $32.4 million as a cumulative-effect adjustment, which increased retained earnings on January 1, 2016. The new guidance also requires us to record, subsequent to the adoption, excess tax benefits and tax deficiencies in the period these arise. As a result, our provision for income taxes decreased by $3.6 million during the first quarter of 2016. Under the new guidance, we have elected to change our policy and have started to recognize forfeitures of awards as they occur. The change in forfeiture policy was adopted using a modified retrospective transition method. We recorded a cumulative-effect adjustment to decrease retained earnings by $0.8 million upon transition on January 1, 2016 and a retrospective decrease of stock-based compensation of $2.0 million during the first quarter of 2016. The amendment to the minimum statutory withholding tax requirements was adopted on a modified retrospective basis. The adoption had no impact on the January 1, 2016 retained earnings. In addition, we adopted the presentation of taxes paid related to net share settlement of equity awards as a financing activity on the statement of cash flows on a retrospective basis. Our adoption had no impact to any of the periods presented in our consolidated cash flows statements since such cash flows have historically been presented as a financing activity. The adoption of ASU 2016-09 impacted our previously reported quarterly results for the three months ended March 31, 2016, as well as our weighted average shares outstanding—diluted, as follows (in thousands, except for earnings per share): Three Months Ended March 31, 2016 As Reported As Adjusted Statements of Operations: Stock-based compensation expense $ 30,881 $ 28,901 Benefit from income taxes $ (1,809 ) $ (5,376 ) Net income (loss) $ (3,429 ) $ 2,118 Net income (loss) per share—Basic $ (0.02 ) $ 0.01 Net income (loss) per share—Diluted $ (0.02 ) $ 0.01 Weighted-average shares outstanding—Diluted 171,745 174,421 March 31, 2016 As Reported As Adjusted Balance Sheets: Deferred tax assets $ 131,696 $ 167,625 Additional paid-in capital $ 718,849 $ 717,671 Retained earnings $ 23,089 $ 60,196 In September 2015, the FASB issued ASU 2015-16—Business Combinations—Simplifying the Accounting for Measurement-Period Adjustments, which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, acquirers must recognize measurement-period adjustments during the period in which they determine the amounts, including the effect on earnings of any amounts they would have recorded in previous periods if the accounting had been completed at the acquisition date. We adopted ASU 2015-16 on January 1, 2016. The adoption of ASU 2015-16 has not had any impact on our consolidated financial statements. Recent Accounting Standards Not Yet Effective 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 August 2016, the FASB issued ASU 2016-15—Statement of Cash Flows—Classification of Certain Cash Receipts and Cash Payments, which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. ASU 2016-15 is effective for us beginning on January 1, 2018. Early adoption is permitted, including adoption in an interim period. We are currently evaluating the impact of adopting ASU 2016-15 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 ASU 2016-13 will have on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02—Leases, which amends lease accounting requirements to begin recording assets and liabilities arising from leases on the balance sheet. 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. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. We expect our assets and liabilities to increase as a result of the adoption of this standard. We are currently evaluating the impact of adopting ASU 2016-02 on our consolidated financial statements. In May 2014, the FASB issued ASU 2014-09—Revenue from Contracts with Customers, which creates a single, joint revenue standard that is consistent across all industries and markets for companies that prepare their financial statements in accordance with GAAP. Under ASU 2014-09, an entity is required to recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services. In July 2015, the FASB decided to delay the effective date of the new revenue standard by one year. In March 2016, the FASB issued ASU 2016-08, which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, which clarifies the implementation guidance on identifying performance obligations and licensing. In May 2016, the FASB issued ASU 2016-12—Revenue from Contracts with Customers—Narrow-scope Improvements and Practical Expedients, which amends the guidance on collectability, noncash consideration, presentation of sales tax and transition. These standards will be effective for us beginning on January 1, 2018. We are currently evaluating the impact of these new standards on our consolidated financial statements.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Schedule of Effects of Adoption of New Accounting Pronouncement	The adoption of ASU 2016-09 impacted our previously reported quarterly results for the three months ended March 31, 2016, as well as our weighted average shares outstanding—diluted, as follows (in thousands, except for earnings per share): Three Months Ended March 31, 2016 As Reported As Adjusted Statements of Operations: Stock-based compensation expense $ 30,881 $ 28,901 Benefit from income taxes $ (1,809 ) $ (5,376 ) Net income (loss) $ (3,429 ) $ 2,118 Net income (loss) per share—Basic $ (0.02 ) $ 0.01 Net income (loss) per share—Diluted $ (0.02 ) $ 0.01 Weighted-average shares outstanding—Diluted 171,745 174,421 March 31, 2016 As Reported As Adjusted Balance Sheets: Deferred tax assets $ 131,696 $ 167,625 Additional paid-in capital $ 718,849 $ 717,671 Retained earnings $ 23,089 $ 60,196

Financial Instruments and Fai27

Financial Instruments and Fair Value (Tables)	9 Months Ended
	Sep. 30, 2016
Financial Instruments and Fair Value [Abstract]
Summary of Investments	Our investments as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt securities $ 385,016 $ 425 $ (211 ) $ 385,230 Commercial paper 127,059 18 (43 ) 127,034 Municipal bonds 53,821 14 (36 ) 53,799 Certificates of deposit and term deposits (1) 4,322 — — 4,322 U.S. government and agency securities 52,686 72 (6 ) 52,752 Total available-for-sale securities $ 622,904 $ 529 $ (296 ) $ 623,137 December 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt securities $ 438,533 $ 30 $ (1,369 ) $ 437,194 Commercial paper 66,263 3 (34 ) 66,232 Municipal bonds 61,050 12 (40 ) 61,022 Certificates of deposit and term deposits (1) 14,897 — — 14,897 U.S. government and agency securities 41,727 3 (42 ) 41,688 Total available-for-sale securities $ 622,470 $ 48 $ (1,485 ) $ 621,033 (1) The majority of our certificates of deposit and term deposits are foreign deposits.
Schedule of Unrealized Loss on Investments	The gross unrealized losses and the related fair values of our investments that have been in a continuous unrealized loss position as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 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 $ 157,390 $ (188 ) $ 37,548 $ (22 ) $ 194,938 $ (210 ) Commercial paper 19,320 (43 ) — — 19,320 (43 ) Municipal bonds 36,163 (37 ) — — 36,163 (37 ) U.S. government and agency securities 5,492 (6 ) — — 5,492 (6 ) Total available-for-sale securities $ 218,365 $ (274 ) $ 37,548 $ (22 ) $ 255,913 $ (296 ) December 31, 2015 Less Than 12 Months 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Corporate debt securities $ 348,534 $ (1,187 ) $ 42,033 $ (182 ) $ 390,567 $ (1,369 ) Commercial paper 31,977 (34 ) — — 31,977 (34 ) Municipal bonds 41,677 (36 ) 1,008 (4 ) 42,685 (40 ) U.S. government and agency securities 34,703 (42 ) — — 34,703 (42 ) Total available-for-sale securities $ 456,891 $ (1,299 ) $ 43,041 $ (186 ) $ 499,932 $ (1,485 )
Investments Classified by Contractual Maturity Date	The contractual maturities of our investments as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, December 31, Due within one year $ 382,909 $ 348,074 Due within one to three years 240,228 272,959 Total $ 623,137 $ 621,033
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The fair values of our financial assets measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 December 31, 2015 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 $ 385,230 $ — $ 385,230 $ — $ 437,194 $ — $ 437,194 $ — Commercial paper 132,033 — 132,033 — 69,231 — 69,231 — Municipal bonds 53,799 — 53,799 — 61,022 — 61,022 — Certificates of deposit and term deposits 4,322 — 4,322 — 14,897 — 14,897 — Money market funds 21,886 21,886 — — 50,030 50,030 — — U.S. government and agency securities 52,752 42,243 10,509 — 41,688 25,693 15,995 — Total $ 650,022 $ 64,129 $ 585,893 $ — $ 674,062 $ 75,723 $ 598,339 $ — Reported as: Cash equivalents $ 26,885 $ 53,029 Short-term investments 382,909 348,074 Long-term investments 240,228 272,959 Total $ 650,022 $ 674,062

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventory	Our inventory as of September 30, 2016 and December 31, 2015 consisted of (in thousands): September 30, December 31, Raw materials $ 19,690 $ 15,425 Finished goods 74,041 68,443 Inventory $ 93,731 $ 83,868

Property and Equipment_Net (Tab

Property and Equipment—Net (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Our property and equipment—net as of September 30, 2016 and December 31, 2015 consisted of (in thousands): September 30, December 31, Land $ 31,251 $ 21,683 Building and building improvements 44,513 28,841 Evaluation units 17,633 15,784 Computer equipment and software 62,585 45,632 Furniture and fixtures 13,127 8,901 Construction-in-progress 4,365 8,106 Leasehold improvements 16,501 11,179 Total property and equipment 189,975 140,126 Less: accumulated depreciation (63,866 ) (49,059 ) Property and equipment—net $ 126,109 $ 91,067

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2016
AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation	Total allocation of the purchase price was (in thousands): Cash and cash equivalents $ 171 Accounts receivable 1,126 Prepaid expenses and other assets 430 Property and equipment 203 Deferred tax assets 3,435 Finite-lived intangible assets 14,900 Indefinite-lived intangible assets in process research and development 1,600 Goodwill 9,861 Total assets acquired 31,726 Deferred revenue 4,400 Accounts payable and accrued liabilities 3,348 Other liabilities 1,694 Total liabilities assumed 9,442 Total purchase price allocation $ 22,284
Schedule of Acquired Intangible Assets	The estimated useful life and fair values of the acquired finite-lived intangible assets were as follows (in thousands, except for estimated useful life): Estimated Useful Life (in years) Fair Values Developed technologies 4 $ 12,400 Customer relationships 3 2,300 Other 2 200 Total $ 14,900
Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation	Total allocation of the purchase price was as follows (in thousands): Cash and cash equivalents $ 3,268 Accounts receivable 8,191 Inventory 11,610 Prepaid expenses and other assets 2,409 Property and equipment 920 Deferred tax assets 18,585 Finite-lived intangible assets 19,600 Goodwill 1,868 Total assets acquired 66,451 Deferred revenue 9,800 Accounts payable and accrued liabilities 14,887 Total liabilities assumed 24,687 Total purchase price allocation $ 41,764
Schedule of Acquired Intangible Assets	The estimated useful life and fair values of the acquired identifiable intangible assets were as follows (in thousands, except for estimated useful life): Estimated Useful Life (in years) Fair Values Customer relationships 5 $ 12,200 Developed technologies 4 7,200 Trade name 0.5 200 Total $ 19,600

Goodwill and Other Intangible31

Goodwill and Other Intangible Assets - Net (Tables)	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of goodwill were (in thousands): Amount Balance—December 31, 2015 $ 4,692 Addition due to business acquisition 9,861 Balance—September 30, 2016 $ 14,553
Schedule of Finite-lived Intangible Assets	Other intangible assets—net as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Finite-lived intangible assets: Customer relationships 4.7 $ 14,500 $ 4,735 $ 9,765 Developed technologies and other 3.8 23,984 7,500 16,484 38,484 12,235 26,249 Indefinite-lived intangible assets: In-process research and development 1,600 — 1,600 Total other intangible assets—net $ 40,084 $ 12,235 $ 27,849 December 31, 2015 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Customer relationships 5.0 $ 12,200 $ 1,220 $ 10,980 Developed technologies and other 3.6 11,384 4,724 6,660 Total other intangible assets—net $ 23,584 $ 5,944 $ 17,640
Schedule of Indefinite-lived Intangible Assets	Other intangible assets—net as of September 30, 2016 and December 31, 2015 were (in thousands): September 30, 2016 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Finite-lived intangible assets: Customer relationships 4.7 $ 14,500 $ 4,735 $ 9,765 Developed technologies and other 3.8 23,984 7,500 16,484 38,484 12,235 26,249 Indefinite-lived intangible assets: In-process research and development 1,600 — 1,600 Total other intangible assets—net $ 40,084 $ 12,235 $ 27,849 December 31, 2015 Weighted-Average Useful Life (in Years) Gross Accumulated Amortization Net Other intangible assets—net: Customer relationships 5.0 $ 12,200 $ 1,220 $ 10,980 Developed technologies and other 3.6 11,384 4,724 6,660 Total other intangible assets—net $ 23,584 $ 5,944 $ 17,640
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table summarizes estimated future amortization expense of Other intangible assets—net with finite lives (in thousands): Amount Years: 2016 (remainder) $ 2,798 2017 8,450 2018 7,098 2019 5,540 2020 2,363 Total $ 26,249

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
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 Nine Months Ended September 30, September 30, September 30, September 30, Numerator: Net income $ 6,291 $ 8,169 $ 7,021 $ 10,521 Denominator: Basic shares: Weighted-average common stock outstanding-basic 173,335 171,648 172,212 169,898 Diluted shares: Weighted-average common stock outstanding-basic 173,335 171,648 172,212 169,898 Effect of potentially dilutive securities: Stock options 2,009 3,451 1,867 3,669 RSUs (including PSUs) 2,513 2,742 1,891 2,335 ESPP 81 56 76 61 Weighted-average shares used to compute diluted net income per share 177,938 177,897 176,046 175,963 Net income per share: Basic $ 0.04 $ 0.05 $ 0.04 $ 0.06 Diluted $ 0.04 $ 0.05 $ 0.04 $ 0.06
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potentially dilutive 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 Nine Months Ended September 30, September 30, September 30, September 30, Stock options 836 265 1,067 271 RSUs (including PSUs) 2,409 1,331 3,946 1,026 ESPP 353 209 211 126 3,598 1,805 5,224 1,423

Restructuring Charges (Tables)

Restructuring Charges (Tables)	9 Months Ended
	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Summary of Restructuring Activity	The following table provides a summary of restructuring activity for the nine months ended September 30, 2016 (in thousands): Employee Severance and Other Benefits Contract Terminations and Other Charges Total Balance as of December 31, 2015 $ 3,689 $ 229 $ 3,918 Costs incurred 3,120 44 3,164 Less cash payments (5,060 ) (273 ) (5,333 ) Less non-cash charges (89 ) — (89 ) Balance as of September 30, 2016 $ 1,660 $ — $ 1,660

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	Our future principal contractual obligations as of September 30, 2016 were (in thousands): Total 2016 (remainder) 2017 2018 2019 2020 Thereafter Operating lease commitments $ 74,107 $ 5,756 $ 17,678 $ 14,653 $ 12,359 $ 10,497 $ 13,164 Inventory purchase commitments 116,494 90,169 26,325 — — — — Other contractual commitments and open purchase orders 48,864 33,805 11,466 2,451 855 287 — Total $ 239,465 $ 129,730 $ 55,469 $ 17,104 $ 13,214 $ 10,784 $ 13,164
Schedule of Product Warranty Liability	Accrued warranty activities are summarized as follows (in thousands): Nine Months Ended September 30, September 30, Accrued warranty balance—beginning of the period $ 3,144 $ 4,269 Warranty costs incurred (2,260 ) (3,413 ) Provision for warranty for the period 925 3,638 Adjustment related to pre-existing warranties (279 ) (94 ) Accrued warranty balance—end of the period $ 1,530 $ 4,400

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The activity and related information for RSUs, including PSUs, was (in thousands, except per share amounts): Restricted Stock Units Outstanding Number of Shares Weighted-Average Grant Date Fair Value per Share Balance—December 31, 2015 9,257 $ 32.97 Granted 4,867 27.54 Forfeited (1,270 ) 32.12 Vested (2,864 ) 30.37 Balance—September 30, 2016 9,990 $ 30.99
Schedule of Share-based Compensation, Shares Withheld for Taxes	The number of shares and amount withheld for employee taxes were (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Shares withheld for taxes 347 245 937 590 Amount withheld for taxes $ 12,528 $ 11,628 $ 29,886 $ 22,989
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The weighted-average assumptions relating to our employee stock options were: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Expected term in years 4.3 4.3 4.3 4.3 Volatility 38 % 37 % 42 % 38 % Risk-free interest rate 1.1 % 1.6 % 1.1 % 1.5 % Dividend rate — % — % — % — %
Schedule of Share-based Compensation, Stock Options, Activity	The stock option activity and related information was (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, 2015 6,968 $ 20.03 Granted 1,405 $ 25.39 Forfeited (221 ) $ 34.91 Exercised (1,750 ) $ 10.37 Balance—September 30, 2016 6,402 $ 23.33 3.22 $ 89,714 Options exercisable—September 30, 2016 4,469 $ 21.26 1.99 $ 70,864
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 Nine Months Ended September 30, 2016 September 30, 2015 September 30, 2016 September 30, 2015 Weighted-average fair value per share granted $ 10.62 $ 15.89 $ 9.08 $ 13.60 Intrinsic value of options exercised $ 9,340 $ 40,132 $ 35,593 $ 103,170 Fair value of options vested $ 1,706 $ 2,491 $ 4,583 $ 9,001
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	In determining the fair value of our ESPP, we use the Black-Scholes option pricing model that employs the following weighted-average assumptions: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Expected term in years 0.5 0.5 0.5 0.5 Volatility 34 % 32 % 39 % 31 % Risk-free interest rate 0.5 % 0.2 % 0.4 % 0.1 % 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 Nine Months Ended September 30, September 30, September 30, September 30, Weighted-average fair value per share granted $ 8.07 $ 11.42 $ 7.68 $ 8.23 Shares issued under the ESPP 537 337 1,151 764 Weighted-average price per share issued $ 21.61 $ 28.05 $ 21.01 $ 24.30
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 Nine Months Ended September 30, September 30, September 30, September 30, Cost of product revenue $ 309 $ 291 $ 887 $ 641 Cost of service revenue 2,238 1,849 6,495 5,141 Research and development 7,648 6,663 22,249 17,361 Sales and marketing 17,378 13,904 50,183 34,482 General and administrative 3,520 3,612 10,528 9,376 Total stock-based compensation expense $ 31,093 $ 26,319 $ 90,342 $ 67,001
Schedule of Employee Service Share based Compensation Allocation of Recognized Period Costs by Award Type	The stock-based compensation expense by award type was (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, RSUs $ 27,342 $ 21,996 $ 79,244 $ 53,674 Stock options 1,516 2,669 5,062 9,141 ESPP 2,235 1,654 6,036 4,186 Total stock-based compensation expense $ 31,093 $ 26,319 $ 90,342 $ 67,001
Income Tax Benefit from Stock Option Plans	Total income tax benefit associated with stock-based compensation that is recognized in the consolidated statements of operations is as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Income tax benefit associated with stock-based compensation $ 8,223 $ 5,224 $ 22,961 $ 12,867

Segment and Significant Custo36

Segment and Significant Customer Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Revenue from external customers by geographic region	Three Months Ended Nine Months Ended Revenue September 30, September 30, September 30, September 30, Americas: United States $ 83,049 $ 72,767 $ 239,417 $ 202,491 Canada 35,211 26,027 100,299 72,676 Other Americas 15,614 14,371 46,850 38,151 Total Americas 133,874 113,165 386,566 313,318 Europe, Middle East, and Africa (“EMEA”) 116,967 91,740 336,911 250,808 Asia Pacific (“APAC”) 65,805 55,163 189,136 148,613 Total revenue $ 316,646 $ 260,068 $ 912,613 $ 712,739
Property and equipment by geographic region	Property and Equipment — net September 30, December 31, Americas: United States $ 92,096 $ 61,064 Other Americas 9,872 8,972 Total Americas 101,968 70,036 EMEA: France 13,649 13,201 Other EMEA 6,199 3,977 Total EMEA 19,848 17,178 APAC 4,293 3,853 Total property and equipment—net $ 126,109 $ 91,067
Schedule of Revenue by Major Customers	The following customers, each of which is a distributor, accounted for 10% or more of our revenue: Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Exclusive Networks Group 19 % 17 % 19 % 17 % Ingram Micro 10 % * * *
Schedule of Accounts Receivable by Major Customers	The following customers, each of which is a distributor, accounted for 10% or more of net accounts receivable: September 30, December 31, Exclusive Networks Group 20 % 23 % Fine Tec Computers 12 % * Ingram 10 % * * Represents less than 10%

Accumulated Other Comprehensi37

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in accumulated balances of other comprehensive income or loss were (in thousands): September 30, 2016 Unrealized Gains/Losses on Investments Tax benefit (provision) related to items of other comprehensive income or loss Total Beginning balance at December 31, 2015 $ (1,437 ) $ 504 $ (933 ) Other comprehensive income (loss) before reclassifications 1,668 (583 ) 1,085 Amounts reclassified from accumulated other comprehensive income (loss) 2 (1 ) 1 Net current-period other comprehensive income (loss) 1,670 (584 ) 1,086 Ending balance at September 30, 2016 $ 233 $ (80 ) $ 153
Reclassification out of Accumulated Other Comprehensive Income (Loss)	The details of reclassification out of accumulated other comprehensive income (loss) were (in thousands): Nine Months Ended September 30, 2016 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Statement Where Net Income is Presented Unrealized losses on investments $ 2 Other expense—net Tax benefit related to items of other comprehensive loss (1 ) Provision for income taxes Total reclassification for the period $ 1

Foreign Currency Derivatives (T

Foreign Currency Derivatives (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The notional amount of forward exchange contracts to hedge balance sheet accounts as of September 30, 2016 and December 31, 2015 were (in thousands): Buy/Sell Notional Balance Sheet Contracts: Currency—As of September 30, 2016 CAD Sell $ 4,520 Currency—As of December 31, 2015 CAD Sell $ 7,011

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Impact of Adoption of New Accounting Standard (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jan. 01, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock-based compensation expense	$ 31,093		$ 26,319	$ 90,342	$ 67,001
Benefit from income taxes	298		(9,329)	(7,380)	(6,552)
Net income (loss)	$ 6,291		$ 8,169	$ 7,021	$ 10,521
Basic income (loss) per share (in dollars per share)	$ 0.04		$ 0.05	$ 0.04	$ 0.06
Diluted earnings per share (in dollars per share)	$ 0.04		$ 0.05	$ 0.04	$ 0.06
Weighted-average shares used to compute diluted net income per share (in shares)	177,938		177,897	176,046	175,963
Deferred Tax Assets, Net, Noncurrent	$ 189,434			$ 189,434			$ 119,216
Additional paid-in capital	779,669			779,669			687,658
Retained earnings	43,093			43,093			$ 68,481
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in income tax provision	$ 2,500	$ 3,600		$ 8,700
Stock-based compensation expense		28,901
Benefit from income taxes		(5,376)
Net income (loss)		$ 2,118
Basic income (loss) per share (in dollars per share)		$ 0.01
Diluted earnings per share (in dollars per share)		$ 0.01
Weighted-average shares used to compute diluted net income per share (in shares)		174,421
Deferred Tax Assets, Net, Noncurrent		$ 167,625
Additional paid-in capital		717,671
Retained earnings		60,196
Accounting Standards Update 2016-09 [Member] | Decrease [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock-based compensation expense		(2,000)
Accounting Standards Update 2016-09 [Member] | As Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock-based compensation expense		30,881
Benefit from income taxes		(1,809)
Net income (loss)		$ (3,429)
Basic income (loss) per share (in dollars per share)		$ (0.02)
Diluted earnings per share (in dollars per share)		$ (0.02)
Weighted-average shares used to compute diluted net income per share (in shares)		171,745
Deferred Tax Assets, Net, Noncurrent		$ 131,696
Additional paid-in capital		718,849
Retained earnings		$ 23,089
Retained Earnings [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings						$ 32,400
Retained Earnings [Member] | Accounting Standards Update 2016-09 [Member] | Decrease [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings						$ 800

Financial Instruments and Fai40

Financial Instruments and Fair Value , Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 622,904	$ 622,470
Unrealized Gains	529	48
Unrealized Losses	(296)	(1,485)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	218,365	456,891
Less Than 12 Months, Unrealized Losses	(274)	(1,299)
12 Months or Greater, Fair Value	37,548	43,041
12 Months or Greater, Unrealized Losses	(22)	(186)
Total, Fair Value	255,913	499,932
Total, Unrealized Losses	(296)	(1,485)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Due within one year	382,909	348,074
Due within one to three years	240,228	272,959
Fair Value	623,137	621,033
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	385,016	438,533
Unrealized Gains	425	30
Unrealized Losses	(211)	(1,369)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	157,390	348,534
Less Than 12 Months, Unrealized Losses	(188)	(1,187)
12 Months or Greater, Fair Value	37,548	42,033
12 Months or Greater, Unrealized Losses	(22)	(182)
Total, Fair Value	194,938	390,567
Total, Unrealized Losses	(210)	(1,369)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	385,230	437,194
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	127,059	66,263
Unrealized Gains	18	3
Unrealized Losses	(43)	(34)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	19,320	31,977
Less Than 12 Months, Unrealized Losses	(43)	(34)
12 Months or Greater, Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total, Fair Value	19,320	31,977
Total, Unrealized Losses	(43)	(34)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	127,034	66,232
Municipal bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	53,821	61,050
Unrealized Gains	14	12
Unrealized Losses	(36)	(40)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	36,163	41,677
Less Than 12 Months, Unrealized Losses	(37)	(36)
12 Months or Greater, Fair Value	0	1,008
12 Months or Greater, Unrealized Losses	0	(4)
Total, Fair Value	36,163	42,685
Total, Unrealized Losses	(37)	(40)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	53,799	61,022
Certificates of deposit and term deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,322	14,897
Unrealized Gains	0	0
Unrealized Losses	0	0
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	4,322	14,897
U.S. government and agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52,686	41,727
Unrealized Gains	72	3
Unrealized Losses	(6)	(42)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less Than 12 Months, Fair Value	5,492	34,703
Less Than 12 Months, Unrealized Losses	(6)	(42)
12 Months or Greater, Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total, Fair Value	5,492	34,703
Total, Unrealized Losses	(6)	(42)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Fair Value	$ 52,752	$ 41,688

Financial Instruments and Fai41

Financial Instruments and Fair Value , Fair Value Measurements (Details) - Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Estimate of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	$ 650,022	$ 674,062
Estimate of Fair Value [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	64,129	75,723
Estimate of Fair Value [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	585,893	598,339
Estimate of Fair Value [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	0	0
Estimate of 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	385,230	437,194
Estimate of 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
Estimate of 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	385,230	437,194
Estimate of Fair Value [Member] | Corporate debt securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Estimate of 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	132,033	69,231
Estimate of 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
Estimate of 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	132,033	69,231
Estimate of Fair Value [Member] | Commercial paper [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Estimate of 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	53,799	61,022
Estimate of 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
Estimate of 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	53,799	61,022
Estimate of Fair Value [Member] | Municipal bonds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Estimate of 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	4,322	14,897
Estimate of 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
Estimate of 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	4,322	14,897
Estimate of Fair Value [Member] | Certificates of deposit and term deposits [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Estimate of 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	21,886	50,030
Estimate of 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	21,886	50,030
Estimate of 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
Estimate of Fair Value [Member] | Money market funds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Estimate of 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	52,752	41,688
Estimate of 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	42,243	25,693
Estimate of 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	10,509	15,995
Estimate of Fair Value [Member] | U.S. government and agency securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Fair Value Disclosure	0	0
Reported as [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets, Fair Value Disclosure	650,022	674,062
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	26,885	53,029
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	382,909	348,074
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	$ 240,228	$ 272,959

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Inventory, Net [Abstract]
Raw materials	$ 19,690	$ 15,425
Finished goods	74,041	68,443
Inventory	93,731	83,868
Finished goods held by distributors	1,400	1,100
Materials at contract manufacturers	$ 6,300	$ 4,900

Property and Equipment_Net (Det

Property and Equipment—Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	$ 189,975		$ 189,975		$ 140,126
Less: accumulated depreciation	(63,866)		(63,866)		(49,059)
Property and equipment—net	126,109		126,109		91,067
Depreciation expense	10,200	$ 7,500	28,600	$ 20,300
Land [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	31,251		31,251		21,683
Building and building improvements [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	44,513		44,513		28,841
Evaluation units [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	17,633		17,633		15,784
Computer equipment and software [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	62,585		62,585		45,632
Furniture and fixtures [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	13,127		13,127		8,901
Construction-in-progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	4,365		4,365		8,106
Leasehold improvements [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property and equipment	$ 16,501		$ 16,501		$ 11,179

Investments in Privately-Held44

Investments in Privately-Held Companies (Details) $ in Millions	Sep. 30, 2016USD ($)privately_held_company	Dec. 31, 2015USD ($)privately_held_company
Investments, All Other Investments [Abstract]
Number of privately-held companies | privately_held_company	3	3
Investments in equity securities of privately-held companies | $	$ 10.3	$ 10.3

Business Combinations , Additio

Business Combinations , Additional Information (Details) - USD ($) $ in Thousands	Jun. 07, 2016	Jul. 08, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Cash consideration paid, net of cash received			$ 22,087	$ 38,025
Goodwill			$ 14,553		$ 4,692
AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Total cash consideration	$ 22,100
Total purchase price	22,284
Contingent obligation (up to)	4,000
Goodwill	9,861
Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Cash consideration paid, net of cash received		$ 40,900
Total purchase price		41,764
Withholding tax liability		400
Estimated fair value of earned equity awards assumed by Fortinet		500
Goodwill		1,868
General and administrative [Member] | AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Acquisition-related costs	$ 300
General and administrative [Member] | Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Acquisition-related costs		$ 1,700
Restricted Stock Units (RSUs) [Member] | Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Fortinet RSUs issued for conversion of Meru RSUs (shares)		53,401

Business Combinations , Purchas

Business Combinations , Purchase Price Allocations (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 07, 2016	Dec. 31, 2015	Jul. 08, 2015
Business Acquisition [Line Items]
Goodwill	$ 14,553		$ 4,692
AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		$ 171
Accounts receivable		1,126
Prepaid expenses and other assets		430
Property and equipment		203
Deferred tax assets		3,435
Finite-lived intangible assets		14,900
Indefinite-lived intangible assets in process research and development		1,600
Goodwill		9,861
Total assets acquired		31,726
Deferred revenue		4,400
Accounts payable and accrued liabilities		3,348
Other liabilities		1,694
Total liabilities assumed		9,442
Total purchase price allocation		$ 22,284
Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Cash and cash equivalents				$ 3,268
Accounts receivable				8,191
Inventory				11,610
Prepaid expenses and other assets				2,409
Property and equipment				920
Deferred tax assets				18,585
Finite-lived intangible assets				19,600
Goodwill				1,868
Total assets acquired				66,451
Deferred revenue				9,800
Accounts payable and accrued liabilities				14,887
Total liabilities assumed				24,687
Total purchase price allocation				$ 41,764

Business Combinations , Intangi

Business Combinations , Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Jun. 07, 2016	Jul. 08, 2015
AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Fair values	$ 14,900
Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Fair values		$ 19,600
Developed Technologies [Member] | AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life	4 years
Fair values	$ 12,400
Developed Technologies [Member] | Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life		4 years
Fair values		$ 7,200
Customer Relationships [Member] | AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life	3 years
Fair values	$ 2,300
Customer Relationships [Member] | Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life		5 years
Fair values		$ 12,200
Other Intangible Assets [Member] | AccelOps, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life	2 years
Fair values	$ 200
Trade Name [Member] | Meru Networks, Inc. [Member]
Business Acquisition [Line Items]
Estimated useful life		6 months
Fair values		$ 200

Goodwill and Other Intangible48

Goodwill and Other Intangible Assets - Net - Changes in Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)
Goodwill [Roll Forward]
Balance—December 31, 2015	$ 4,692
Addition due to business acquisition	9,861
Balance—September 30, 2016	$ 14,553

Goodwill and Other Intangible49

Goodwill and Other Intangible Assets - Net (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Intangible Assets [Line Items]
Goodwill	$ 14,553,000		$ 14,553,000		$ 4,692,000
Impairments to goodwill	0		0
Intangible Assets [Abstract]
Gross	38,484,000		38,484,000		23,584,000
Accumulated Amortization	12,235,000		12,235,000		5,944,000
Total	26,249,000		26,249,000		17,640,000
Intangible Assets [Abstract]
Total other intangible assets - gross	40,084,000		40,084,000
Total other intangible assets - net	27,849,000		27,849,000		$ 17,640,000
Amortization expense	2,800,000	$ 1,300,000	$ 6,300,000	$ 1,900,000
Customer Relationships [Member]
Intangible Assets [Line Items]
Weighted average useful life			4 years 8 months 5 days		5 years
Intangible Assets [Abstract]
Gross	14,500,000		$ 14,500,000		$ 12,200,000
Accumulated Amortization	4,735,000		4,735,000		1,220,000
Total	9,765,000		$ 9,765,000		$ 10,980,000
Developed Technology [Member]
Intangible Assets [Line Items]
Weighted average useful life			3 years 9 months 11 days		3 years 7 months 21 days
Intangible Assets [Abstract]
Gross	23,984,000		$ 23,984,000		$ 11,384,000
Accumulated Amortization	7,500,000		7,500,000		4,724,000
Total	16,484,000		16,484,000		$ 6,660,000
In-process Research and Development [Member]
Intangible Assets [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 1,600,000		$ 1,600,000

Goodwill and Other Intangible50

Goodwill and Other Intangible Assets - Net - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fiscal Years:
2016 (remainder)	$ 2,798
2,017	8,450
2,018	7,098
2,019	5,540
2,020	2,363
Total	$ 26,249	$ 17,640

Net Income Per Share , Calculat

Net Income Per Share , Calculation of Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Line Items]
Net income	$ 6,291	$ 8,169	$ 7,021	$ 10,521
Basic shares:
Weighted-average common shares outstanding-basic (in shares)	173,335	171,648	172,212	169,898
Diluted shares:
Weighted-average common shares outstanding-basic (in shares)	173,335	171,648	172,212	169,898
Effect of potentially dilutive securities:
Weighted-average shares used to compute diluted net income per share (in shares)	177,938	177,897	176,046	175,963
Net income per share:
Basic (in dollars per share)	$ 0.04	$ 0.05	$ 0.04	$ 0.06
Diluted (in dollars per share)	$ 0.04	$ 0.05	$ 0.04	$ 0.06
Stock Options [Member]
Effect of potentially dilutive securities:
Potentially dilutive securities (in shares)	2,009	3,451	1,867	3,669
RSUs (including PSUs) [Member]
Effect of potentially dilutive securities:
Potentially dilutive securities (in shares)	2,513	2,742	1,891	2,335
ESPP [Member]
Effect of potentially dilutive securities:
Potentially dilutive securities (in shares)	81	56	76	61

Net Income Per Share , Anti Dil

Net Income Per Share , Anti Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	3,598	1,805	5,224	1,423
Stock Options [Member] | Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	836	265	1,067	271
RSUs (including PSUs) [Member] | Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	2,409	1,331	3,946	1,026
ESPP [Member] | Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	353	209	211	126

Restructuring Charges , Restruc

Restructuring Charges , Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Cost and Reserve [Line Items]
Balance, beginning			$ 3,918
Costs incurred	$ 2,283	$ 5,883	3,164	$ 5,883
Less cash payments			(5,333)
Less non-cash charges			(89)
Balance, ending	1,660		1,660
Employee Severance and Other Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning			3,689
Costs incurred			3,120
Less cash payments			(5,060)
Less non-cash charges			(89)
Balance, ending	1,660		1,660
Contract Terminations and Other Charges [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning			229
Costs incurred			44
Less cash payments			(273)
Less non-cash charges			0
Balance, ending	$ 0		$ 0

Restructuring Charges , Additio

Restructuring Charges , Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 1,660		$ 1,660		$ 3,918
Costs incurred	2,283	$ 5,883	3,164	$ 5,883
2015 Meru Restructuring [Member] | Accrued Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	1,100		1,100
2015 Meru Restructuring [Member] | Meru Networks, Inc. [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred to date	7,900		7,900
Costs incurred	100		300
2016 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges expected	4,100		4,100
Costs incurred	2,200		2,900
2016 Restructuring [Member] | Accrued Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 600		$ 600

Commitments and Contingencies55

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 6,100	$ 3,700	$ 14,700	$ 9,700
Inventory purchase commitments	116,494		116,494
Other contractual commitments and open purchase orders	$ 48,864		$ 48,864

Commitments and Contingencies M

Commitments and Contingencies Minimum Operating Lease Payments (Details) $ in Thousands	Sep. 30, 2016USD ($)
Operating Lease Commitments:
Operating lease commitments, 2016 (remainder)	$ 5,756
Operating lease commitments, 2017	17,678
Operating lease commitments, 2018	14,653
Operating lease commitments, 2019	12,359
Operating lease commitments, 2020	10,497
Operating lease commitments, Thereafter	13,164
Operating lease commitments	74,107
Inventory purchase commitments:
Inventory purchase commitments, 2016 (remainder)	90,169
Inventory purchase commitments, 2017	26,325
Inventory purchase commitments, 2018	0
Inventory purchase commitments, 2019	0
Inventory purchase commitments, 2020	0
Inventory purchase commitments, Thereafter	0
Inventory purchase commitments	116,494
Other contractual commitments and open purchase orders:
Other contractual commitments and open purchase orders, 2016 (remainder)	33,805
Other contractual commitments and open purchase orders, 2017	11,466
Other contractual commitments and open purchase orders, 2018	2,451
Other contractual commitments and open purchase orders, 2019	855
Other contractual commitments and open purchase orders, 2020	287
Other contractual commitments and open purchase orders, Thereafter	0
Other contractual commitments and open purchase orders	48,864
Contractual Obligation, 2016 (remainder)	129,730
Contractual Obligation, 2017	55,469
Contractual Obligation, 2018	17,104
Contractual Obligation, 2019	13,214
Contractual Obligation, 2020	10,784
Contractual Obligation, Thereafter	13,164
Contractual Obligation	$ 239,465

Commitments and Contingencies -

Commitments and Contingencies - Warranties (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Accrued warranty balance—beginning of the period	$ 3,144	$ 4,269
Warranty costs incurred	(2,260)	(3,413)
Provision for warranty for the period	925	3,638
Adjustment related to pre-existing warranties	(279)	(94)
Accrued warranty balance—end of the period	$ 1,530	$ 4,400

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Plan (Details)	Sep. 30, 2016shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Remaining shares available for grant under the plans	44,406,659

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Amount withheld for taxes			$ 29,886	$ 22,989
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			9,257,000
Granted			4,867,000
Forfeited			(1,270,000)
Vested			(2,864,000)
Balance, ending	9,990,000		9,990,000
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			$ 32.97
Granted, weighted-average grant-date fair value per share (in dollars per share)			27.54
Forfeited, weighted-average grant-date fair value per share (in dollars per share)			32.12
Vested, weighted-average grant-date fair value per share (in dollars per share)			30.37
Balance, weighted-average grant-date fair value per share (in dollars per share)—ending	$ 30.99		$ 30.99
Compensation cost not yet recognized	$ 273,000		$ 273,000
Compensation cost not yet recognized period of recognition			2 years 10 months 6 days
Shares withheld for taxes	347,000	245,000	937,000	590,000
Amount withheld for taxes	$ 12,528	$ 11,628	$ 29,886	$ 22,989
Performance Stock Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted	0		0

Stockholders' Equity - Employee

Stockholders' Equity - Employee Stock Options Activity (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term in years	4 years 3 months 29 days	4 years 3 months 18 days	4 years 3 months 29 days	4 years 3 months 18 days
Volatility	38.00%	37.00%	42.00%	38.00%
Risk-free interest rate	1.10%	1.60%	1.10%	1.50%
Dividend rate	0.00%	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance - Beginning (in shares)			6,968
Granted (in shares)			1,405
Forfeited (in shares)			(221)
Exercised (in shares)			(1,750)
Balance - Ending (in shares)	6,402		6,402
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance - Beginning (in dollars per share)			$ 20.03
Granted (in dollars per share)			25.39
Forfeited (in dollars per share)			34.91
Exercised (in dollars per share)			10.37
Balance - Ending (in dollars per share)	$ 23.33		$ 23.33
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, Weighted average remaining contractual life (in years)			3 years 2 months 19 days
Options outstanding, Aggregate intrinsic value	$ 89,714		$ 89,714
Options exercisable, Outstanding (in shares)	4,469		4,469
Options exercisable, Weighted average exercise price (in dollars per share)	$ 21.26		$ 21.26
Options exercisable, Weighted average remaining contractual life (in years)			1 year 11 months 27 days
Options exercisable, Aggregate intrinsic value	$ 70,864		$ 70,864
Compensation cost not yet recognized	$ 16,800		$ 16,800
Compensation cost not yet recognized period of recognition			2 years 11 months 30 days
Weighted-average fair value per share granted	$ 10.62	$ 15.89	$ 9.08	$ 13.60
Intrinsic value of options exercised	$ 9,340	$ 40,132	$ 35,593	$ 103,170
Total fair value of awards vested	$ 1,706	$ 2,491	$ 4,583	$ 9,001

Stockholders' Equity - ESPP Inf

Stockholders' Equity - ESPP Information (Details) - Employee Stock Purchase Plan [Member] - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	6 months	6 months	6 months	6 months
Volatility	34.00%	32.00%	39.00%	31.00%
Risk-free interest rate	0.50%	0.20%	0.40%	0.10%
Dividend rate	0.00%	0.00%	0.00%	0.00%
Weighted-average fair value per share granted (in dollars per share)	$ 8.07	$ 11.42	$ 7.68	$ 8.23
Shares issued under the ESPP (in shares)	537	337	1,151	764
Weighted-average price per share issued (in dollars per share)	$ 21.61	$ 28.05	$ 21.01	$ 24.30

Stockholders' Equity - Allocati

Stockholders' Equity - Allocation of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 31,093	$ 26,319	$ 90,342	$ 67,001
Income tax benefit associated with stock-based compensation	8,223	5,224	22,961	12,867
Cost of product revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	309	291	887	641
Cost of service revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2,238	1,849	6,495	5,141
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	7,648	6,663	22,249	17,361
Selling and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	17,378	13,904	50,183	34,482
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3,520	3,612	10,528	9,376
RSUs [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	27,342	21,996	79,244	53,674
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,516	2,669	5,062	9,141
ESPP [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,235	$ 1,654	$ 6,036	$ 4,186

Stockholders' Equity - Share Re

Stockholders' Equity - Share Repurchase Program (Details) - Share Repurchase Program [Member] - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Jan. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount			$ 200,000,000
Stock repurchased in the period, shares	693,000	2,700,000
Stock repurchased in the period, average price, per share (in dollars per share)	$ 36.04	$ 27.82
Stock repurchased in the period, value	$ 25,000,000	$ 75,000,000
Stock repurchase program, unused balance	$ 125,000,000	$ 125,000,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate (percent)	5.00%		804.00%	2053.00%	(165.00%)
Unrecognized tax benefits	$ 64.9			$ 64.9		$ 59.7
Unrecognized tax benefits that would favoraby affect effective tax rate	63.5			63.5
Accrued estimated interest related to uncertain tax positions	8.8			8.8
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in income tax provision	$ 2.5	$ 3.6		$ 8.7

Defined Contribution Plans (Det

Defined Contribution Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Matching contribution on employee contributions, Percent	50.00%	50.00%	50.00%	50.00%
Maximum contribution percentage of each employee's eligible earnings, Percent	4.00%	4.00%	4.00%	4.00%
Matching contributions to the 401(k) and RRSP Plans	$ 1.2	$ 0.9	$ 3.4	$ 2.7

Segment and Significant Custo66

Segment and Significant Customer Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)Segment_Managersbusiness_activityoperating_segmentreportable_segment	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
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	$ 316,646	$ 260,068	$ 912,613	$ 712,739
Property and equipment - net	126,109		126,109		$ 91,067
Americas [Member]
Segment Reporting Information [Line Items]
Revenue	133,874	113,165	386,566	313,318
Property and equipment - net	101,968		101,968		70,036
United States
Segment Reporting Information [Line Items]
Revenue	83,049	72,767	239,417	202,491
Property and equipment - net	92,096		92,096		61,064
Canada [Member]
Segment Reporting Information [Line Items]
Revenue	35,211	26,027	100,299	72,676
Other Americas [Member]
Segment Reporting Information [Line Items]
Revenue	15,614	14,371	46,850	38,151
Property and equipment - net	9,872		9,872		8,972
EMEA [Member]
Segment Reporting Information [Line Items]
Revenue	116,967	91,740	336,911	250,808
Property and equipment - net	19,848		19,848		17,178
France [Member]
Segment Reporting Information [Line Items]
Property and equipment - net	13,649		13,649		13,201
Other EMEA [Member]
Segment Reporting Information [Line Items]
Property and equipment - net	6,199		6,199		3,977
APAC [Member]
Segment Reporting Information [Line Items]
Revenue	65,805	$ 55,163	189,136	$ 148,613
Property and equipment - net	$ 4,293		$ 4,293		$ 3,853

Segment and Significant Custo67

Segment and Significant Customer Information , Significant Customers (Details) - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Exclusive Networks Group [Member] | Revenue [Member]
Customer Concentration [Line Items]
Concentration Risk, Percentage	19.00%	17.00%	19.00%	17.00%
Exclusive Networks Group [Member] | Accounts Receivable [Member]
Customer Concentration [Line Items]
Concentration Risk, Percentage			20.00%	23.00%
FineTec Computers [Member] | Accounts Receivable [Member]
Customer Concentration [Line Items]
Concentration Risk, Percentage			12.00%
Ingram [Member] | Revenue [Member]
Customer Concentration [Line Items]
Concentration Risk, Percentage	10.00%
Ingram [Member] | Accounts Receivable [Member]
Customer Concentration [Line Items]
Concentration Risk, Percentage			10.00%

Accumulated Other Comprehensi68

Accumulated Other Comprehensive Income (Loss) (Changes in Accumulated Balances of Other Comprehensive Income)(Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)
Accumulated Other Comprehensive (Loss) Income [Roll Forward]
Beginning balance at December 31, 2015	$ (933)
Other comprehensive income (loss) before reclassifications	1,085
Amounts reclassified from accumulated other comprehensive income (loss)	1
Net current-period other comprehensive income (loss)	1,086
Ending balance at September 30, 2016	153
Tax Benefit (Provision) Related to Items of Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance at December 31, 2015, tax	504
Other comprehensive income before reclassifications, tax	(583)
Amounts reclassified from accumulated other comprehensive income, tax	(1)
Net current-period other comprehensive income, tax	(584)
Ending balance at September 30, 2016, tax	(80)
Unrealized Gains and Losses on Investments [Member]
Accumulated Other Comprehensive (Loss) Income [Roll Forward]
Beginning balance at December 31, 2015	(1,437)
Other comprehensive income (loss) before reclassifications	1,668
Amounts reclassified from accumulated other comprehensive income (loss)	2
Net current-period other comprehensive income (loss)	1,670
Ending balance at September 30, 2016	$ 233

Accumulated Other Comprehensi69

Accumulated Other Comprehensive Income (Loss) (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
OTHER EXPENSE—net	$ (787)	$ (653)	$ (3,449)	$ (2,160)
Provision for income taxes	(298)	9,329	7,380	6,552
Net income (loss)	$ 6,291	$ 8,169	7,021	$ 10,521
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for income taxes			(1)
Net income (loss)			1
Unrealized losses on investments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
OTHER EXPENSE—net			$ 2

Foreign Currency Derivatives (D

Foreign Currency Derivatives (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
CAD [Member] | Sell [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	$ 4,520	$ 7,011
Minimum [Member]
Derivative [Line Items]
Derivative, term of contract	1 month
Maximum [Member]
Derivative [Line Items]
Derivative, term of contract	3 months

Related Party Transactions (Det

Related Party Transactions (Details) - Law Firm where Board Member's Son is a Partner [Member] - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Expenses for legal services		$ 900,000	$ 300,000	$ 3,700,000
Amounts due and payable to the law firm	$ 100,000		100,000		$ 5,300,000
Contingency Fee Arrangement [Member]
Related Party Transaction [Line Items]
Expenses for legal services	$ 0	$ 0	$ 0	$ 500,000

Subsequent Event (Details)

Subsequent Event (Details) - Share Repurchase Program [Member] - USD ($)	Oct. 31, 2016	Jan. 31, 2016
Subsequent Event [Line Items]
Stock repurchase program, authorized amount		$ 200,000,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock repurchase program, additional authorized amount	$ 100,000,000
Stock repurchase program, authorized amount	$ 300,000,000