A10 Networks (ATEN) 10-Q 3 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 26, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Trading Symbol	ATEN
Entity Registrant Name	A10 Networks, Inc.
Entity Central Index Key	1,580,808
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		70,766,245

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 46,385	$ 28,975
Marketable securities	85,773	85,372
Accounts receivable, net of allowances of $2,476 and $3,619, respectively	41,370	66,755
Inventory	15,385	15,070
Prepaid expenses and other current assets	7,336	5,137
Total current assets	196,249	201,309
Property and equipment, net	8,266	8,219
Goodwill and intangible assets	7,218	7,940
Other non-current assets	4,930	3,870
Total assets	216,663	221,338
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable	8,318	9,851
Accrued liabilities	25,396	31,525
Deferred revenue	61,840	61,334
Total current liabilities	95,554	102,710
Deferred revenue, non-current	30,671	31,574
Other non-current liabilities	794	988
Total liabilities	127,019	135,272
Commitments and contingencies (Note 5)
Stockholders' equity:
Common stock, $0.00001 par value: 500,000 shares authorized; 70,573 and 67,873 shares issued and outstanding, respectively	1	1
Additional paid-in-capital	344,817	328,869
Accumulated other comprehensive loss	(46)	(45)
Accumulated deficit	(255,128)	(242,759)
Total stockholders' equity	89,644	86,066
Total liabilities and stockholders' equity	$ 216,663	$ 221,338

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 2,476	$ 3,619
Common Stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	70,573,000	67,873,000
Common stock, shares outstanding (in shares)	70,573,000	67,873,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Products	$ 32,100	$ 38,797	$ 71,806	$ 75,171
Services	21,589	18,333	42,169	35,763
Total revenue	53,689	57,130	113,975	110,934
Cost of revenue:
Products	8,070	9,804	17,854	18,502
Services	4,623	4,405	8,983	8,934
Total cost of revenue	12,693	14,209	26,837	27,436
Gross profit	40,996	42,921	87,138	83,498
Operating expenses:
Sales and marketing	25,561	26,773	51,824	53,541
Research and development	16,490	14,486	33,532	29,263
General and administrative	6,989	7,230	14,150	13,891
Litigation and settlement expense	0	202	0	1,993
Total operating expenses	49,040	48,691	99,506	98,688
Loss from operations	(8,044)	(5,770)	(12,368)	(15,190)
Other income (expense), net:
Interest expense	(64)	(126)	(108)	(252)
Interest and other income (expense), net	(26)	1,020	816	1,235
Total other income (expense), net	(90)	894	708	983
Loss before income taxes	(8,134)	(4,876)	(11,660)	(14,207)
Provision for income taxes	135	59	509	263
Net loss	$ (8,269)	$ (4,935)	$ (12,169)	$ (14,470)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.12)	$ (0.08)	$ (0.18)	$ (0.22)
Weighted-average shares used in computing net loss per share:
Basic and diluted (in shares)	69,770	64,861	69,173	64,584

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (8,269)	$ (4,935)	$ (12,169)	$ (14,470)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities	0	32	(1)	88
Comprehensive loss	$ (8,269)	$ (4,903)	$ (12,170)	$ (14,382)

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (12,169)	$ (14,470)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	4,332	3,717
Stock-based compensation	9,279	8,481
Other non-cash items	386	1,051
Changes in operating assets and liabilities:
Accounts receivable, net	25,071	17,535
Inventory	(2,214)	2,846
Prepaid expenses and other assets	(3,196)	(479)
Accounts payable	(1,810)	(2,668)
Accrued liabilities	(5,544)	348
Deferred revenue	(397)	2,960
Other	33	(65)
Net cash provided by operating activities	13,771	19,256
Cash flows from investing activities:
Purchases of marketable securities	(47,074)	(92,682)
Proceeds from sales and maturities of marketable securities	46,542	7,609
Payment for acquisition	0	(4,380)
Purchases of property and equipment	(1,513)	(2,588)
Net cash used in investing activities	(2,045)	(92,041)
Cash flows from financing activities:
Proceeds from issuance of common stock under employee equity incentive plans	7,207	3,350
Repurchase and retirement of common stock	(816)	0
Payment of contingent consideration	(650)	0
Other	(57)	(50)
Net cash provided by financing activities	5,684	3,300
Net increase (decrease) in cash and cash equivalents	17,410	(69,485)
Cash and cash equivalents - beginning of period	28,975	98,117
Cash and cash equivalents - end of period	46,385	28,632
Non-cash investing and financing activities:
Common stock issued under asset purchase agreement	0	1,313
Inventory transfers to property and equipment	1,899	1,112
Purchases of property and equipment included in accounts payable	$ 440	$ 428

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business A10 Networks, Inc. (together with our subsidiaries, “we”, “our” or “us”) was incorporated in California in 2004 and reincorporated in Delaware in March 2014. We are headquartered in San Jose, California and have wholly-owned subsidiaries throughout the world including Asia and Europe. Our solutions enable our customers to secure and optimize the performance of their data center and cloud applications and secure their users, applications and infrastructure from internet, web and network threats at scale. Our product portfolio consists of six advanced application delivery and security products: Application Delivery Controllers (“ADC”), Lightning Application Delivery Service (“Lightning ADS”), Carrier Grade Network Address Translation (“CGN”), Threat Protection System (“TPS”), SSL Insight (“SSLi”) and Convergent Firewall (“CFW”). They are available in a variety of form factors, such as optimized hardware appliances, bare metal software, virtual appliances, and cloud-native software. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include those of A10 Networks, Inc. and its subsidiaries after elimination of all intercompany accounts and transactions. We have prepared the accompanying unaudited condensed consolidated financial statement pursuant to the rules and regulations of the United States Securities and Exchange Commission (the “SEC”). As permitted under these rules and regulations, we have condensed or omitted certain financial information and footnote disclosures we normally include in our annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). These financial statements have been prepared on the same basis as our annual financial statements and, in management's opinion, reflect all adjustments consisting only of normal recurring adjustments that are necessary for a fair presentation of our financial information. Our interim period operating results do not necessarily indicate the results that may be expected for any other interim period or for the full fiscal year. These financial statements and accompanying notes should be read in conjunction with the financial statements and accompanying notes thereto in our Annual Report on Form 10-K for the year ended December 31, 2016 on file with the SEC (our “Annual Report”). Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Those estimates and assumptions affect revenue recognition and deferred revenue, allowance for doubtful accounts, sales return reserve, valuation of inventory, fair value of marketable securities, contingencies and litigation, acquisition related purchase price allocations, accrued liabilities, and the determination of fair value of stock-based compensation. These estimates are based on information available as of the date of the condensed consolidated financial statements; therefore, actual results could differ from management’s estimates. Significant Accounting Policies There have been no material changes to our significant accounting policies as compared to the significant accounting policies described in our Annual Report. Concentration of Credit Risk and Significant Customers Financial instruments that potentially subject us to concentrations of credit risk consist of cash, cash equivalents, marketable securities and accounts receivable. Our cash, cash equivalents and marketable securities are held and invested in high-credit quality financial instruments by recognized financial institutions and therefore subject to minimum credit risk. Our accounts receivable are unsecured and represent amounts due to us based on contractual obligations of our customers. We mitigate credit risk in respect to accounts receivable by performing periodic credit evaluations based on a number of factors, including past transaction experience, evaluation of credit history and review of the invoicing terms of the contract. We generally do not require our customers to provide collateral to support accounts receivable. Significant customers, including distribution channel partners and direct customers, are those which represent more than 10% of our total revenue for each period presented or our gross accounts receivable balance as of each respective balance sheet date. Revenues from our significant customers as a percentage of our total revenue are as follows: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Customer A (a distribution channel partner) 10% * 11% * Customer B (a distribution channel partner) * 11% * 11% Customer C (a direct customer) * 10% * * * represents less than 10% of total revenue As of June 30, 2017 , one customer accounted for 15% of our total gross accounts receivable. As of December 31, 2016 , three customers accounted for 15% , 13% and 11% of our total gross accounts receivable. Recent Accounting Pronouncements Not Yet Effective In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will supersede most of the existing revenue recognition guidance under U.S. GAAP. This ASU requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and requires the capitalization of incremental customer acquisition costs and amortization of these costs over the contract period or estimated customer life which will result in the recognition of a contract asset on our balance sheets. This standard is effective for annual periods beginning after December 15, 2017 and interim periods within that reporting period. The ASU allows for either full retrospective or modified retrospective adoption. We intend to adopt the standard in the first quarter of 2018 applying the modified retrospective method. While we are continuing to assess all potential impacts of the new standard, we currently do not believe this standard will have a material impact on revenue recognized in our condensed consolidated financial statements. We are in the process of evaluating both the impact of capitalizing and amortizing incremental customer acquisition costs, such as sales commissions on our service contracts, and the disclosure requirements relating to this standard. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This new accounting standard primarily requires lessees to recognize most leases on their balance sheets but record expenses on their income statements in a manner similar to current accounting. For lessors, the guidance modifies the classification criteria and the accounting for sales-type and direct financing leases. This standard is effective for annual periods beginning after December 15, 2018 with early adoption permitted. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , which removes the requirement to compare the implied fair value of goodwill with its carrying amount as part of step 2 of the goodwill impairment test. As a result, under this ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the impairment loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. This standard is effective prospectively for annual periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting, to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. This standard is effective for annual periods beginning after December 15, 2017 and interim periods within that reporting period. Early adoption is permitted, including adoption in any interim period. The amendments will be applied prospectively to an award modified on or after the adoption date. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements. There have been no other recent accounting pronouncements or changes in accounting pronouncements that are of significance or potential significance to us.

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value Measurements	Marketable Securities and Fair Value Measurements Marketable Securities Marketable securities, classified as available-for-sale, consisted of the following (in thousands): June 30, 2017 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Certificates of deposit $ 13,500 $ 4 $ (1 ) $ 13,503 $ 12,499 $ 9 $ — $ 12,508 Corporate securities 42,516 5 (31 ) 42,490 42,765 9 (42 ) 42,732 U.S. Treasury and agency securities 3,493 — (12 ) 3,481 5,190 — (14 ) 5,176 Commercial paper 9,463 2 (1 ) 9,464 11,470 1 (2 ) 11,469 Asset-backed securities 16,847 — (12 ) 16,835 13,493 — (6 ) 13,487 $ 85,819 $ 11 $ (57 ) $ 85,773 $ 85,417 $ 19 $ (64 ) $ 85,372 During the six months ended June 30, 2017 and 2016 , we did not reclassify any amount to earnings from accumulated other comprehensive loss related to unrealized gains or losses. The following table summarizes the cost and estimated fair value of marketable securities based on stated effective maturities as of June 30, 2017 (in thousands): Amortized Cost Fair Value Less than 1 year $ 50,898 $ 50,881 Mature in 1 - 3 years 34,921 34,892 $ 85,819 $ 85,773 All available-for-sale securities have been classified as current based on management's ability to use the funds in current operations. Marketable securities in an unrealized loss position consisted of the following (in thousands): Less Than 12 Months 12 Months or More Total As of June 30, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Certificates of deposit $ 3,499 $ (1 ) $ — $ — $ 3,499 $ (1 ) Corporate securities 30,063 (25 ) 1,498 (6 ) 31,561 (31 ) U.S. Treasury and agency securities 3,480 (12 ) — — 3,480 (12 ) Commercial paper 4,984 (1 ) — — 4,984 (1 ) Asset-backed securities 16,835 (12 ) — — 16,835 (12 ) $ 58,861 $ (51 ) $ 1,498 $ (6 ) $ 60,359 $ (57 ) Less Than 12 Months 12 Months or More Total As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Corporate securities $ 28,537 $ (42 ) $ — $ — $ 28,537 $ (42 ) U.S. Treasury and agency securities 5,176 (14 ) — — 5,176 (14 ) Commercial paper 8,974 (2 ) — — 8,974 (2 ) Asset-backed securities 10,664 (6 ) — — 10,664 (6 ) $ 53,351 $ (64 ) $ — $ — $ 53,351 $ (64 ) Based on evaluation of securities that have been in a continuous loss position, we did not recognize any other-than-temporary impairment charges during the six months ended June 30, 2017 and 2016 . Fair Value Measurements The following is a summary of our cash, cash equivalents and marketable securities measured at fair value on a recurring basis (in thousands): June 30, 2017 December 31, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 36,050 $ — $ — $ 36,050 $ 18,672 $ — $ — $ 18,672 Cash equivalents 10,335 — — 10,335 10,303 — — 10,303 Certificates of deposit — 13,503 — 13,503 — 12,508 — 12,508 Corporate securities — 42,490 — 42,490 — 42,732 — 42,732 U.S. Treasury and agency securities — 3,481 — 3,481 — 5,176 — 5,176 Commercial paper — 9,464 — 9,464 — 11,469 — 11,469 Asset-backed securities — 16,835 — 16,835 — 13,487 — 13,487 $ 46,385 $ 85,773 $ — $ 132,158 $ 28,975 $ 85,372 $ — $ 114,347 There were no transfers between Level 1 and Level 2 fair value measurement categories during the six months ended June 30, 2017 and 2016 .

Condensed Consolidated Financia

Condensed Consolidated Financial Statement Details	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Condensed Consolidated Financial Statement Details	Condensed Consolidated Financial Statement Details Inventory June 30, December 31, (in thousands) Raw materials $ 6,795 $ 6,669 Finished goods 8,590 8,401 Total inventory $ 15,385 $ 15,070 Property and Equipment, Net Useful Life June 30, December 31, (in years) (in thousands) Equipment 1-3 $ 45,252 $ 41,815 Software 1-3 3,824 3,801 Furniture and fixtures 1-3 865 865 Leasehold improvements 2-8 2,775 2,724 Construction in progress — 258 Property and equipment, gross 52,716 49,463 Less: accumulated depreciation (44,450 ) (41,244 ) Property and equipment, net $ 8,266 $ 8,219 Depreciation expense on property and equipment was $1.8 million each for the three months ended June 30, 2017 and 2016 , and $3.6 million and $3.7 million for the six months ended June 30, 2017 and 2016 , respectively. Goodwill and Intangible Assets Goodwill as of June 30, 2017 and December 31, 2016 was $1.3 million . Purchased intangible assets, net, consisted of the following (in thousands): June 30, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Developed technology $ 5,050 $ (1,010 ) $ 4,040 $ 5,050 $ (505 ) $ 4,545 Patents 2,936 (1,065 ) 1,871 2,936 (848 ) 2,088 Total $ 7,986 $ (2,075 ) $ 5,911 $ 7,986 $ (1,353 ) $ 6,633 Amortization expense related to purchased intangible assets was $0.4 million and $33,000 for the three months ended June 30, 2017 and 2016 , respectively, and $0.7 million and $0.1 million for the six months ended June 30, 2017 and 2016 , respectively. Purchased intangible assets are amortized over a remaining weighted average useful life of 4.1 years. Future amortization expense for purchased intangible assets as of June 30, 2017 is as follows (in thousands): Fiscal Year Remainder of 2017 $ 721 2018 1,442 2019 1,442 2020 1,442 2021 864 $ 5,911 Accrued Liabilities June 30, December 31, (in thousands) Accrued compensation and benefits $ 18,968 $ 22,326 Accrued tax liabilities 1,787 3,340 Other 4,641 5,859 Total accrued liabilities $ 25,396 $ 31,525 Deferred Revenue June 30, December 31, (in thousands) Deferred revenue: Products $ 3,319 $ 4,182 Services 89,192 88,726 Total deferred revenue 92,511 92,908 Less: current portion (61,840 ) (61,334 ) Non-current portion $ 30,671 $ 31,574

Credit Facility

Credit Facility	6 Months Ended
	Jun. 30, 2017
Line of Credit Facility [Abstract]
Credit Facility	Credit Facility In November 2016, we entered into a loan and security agreement (the “2016 Credit Facility”) with Silicon Valley Bank ("SVB"), as the lender. The 2016 Credit Facility provides a three -year, $25.0 million revolving credit subfacility, which includes a maximum of $25.0 million letter of credit subfacility. When the balance of our cash, cash equivalents and marketable securities minus outstanding revolving loans and letters of credit equals or exceeds $50.0 million , loans may be advanced under the 2016 Credit Facility up to the full $25.0 million . When the balance of our cash, cash equivalents and marketable securities minus outstanding revolving loans and letters of credit falls below $50.0 million , loans may be advanced under the 2016 Credit Facility based on a borrowing base equal to a specified percentage of the value of our eligible accounts receivable. The loans bear interest, at our option, at (i) the prime rate reported in The Wall Street Journal, minus 0.50% or (ii) a LIBOR rate determined in accordance with the 2016 Credit Facility, plus 2.50% . We are required to pay customary closing fees, commitment fees and letter of credit fees for a facility of this size and type. Our obligations under the 2016 Credit Facility are secured by substantially all of our assets, excluding our intellectual property. The 2016 Credit Facility contains customary affirmative and negative covenants. In addition, the 2016 Credit Facility requires us to maintain compliance with an adjusted quick ratio of not less than 1.50:1.00, as determined in accordance with the 2016 Credit Facility. As of June 30, 2017 , we had no outstanding balance under the 2016 Credit Facility and were in compliance with all facility covenants.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings From time to time, we may be party or subject to various legal proceedings and claims, either asserted or unasserted, which arise in the ordinary course of business, including proceedings and claims that relate to intellectual property matters. Some of these proceedings have involved, and may involve in the future, claims that are subject to substantial uncertainties and unascertainable damages. Lease Commitments We lease various operating spaces in the United States, Asia and Europe under non-cancelable operating lease arrangements that expire on various dates through April 2022 . These arrangements require us to pay certain operating expenses, such as taxes, repairs and insurance, and contain renewal and escalation clauses. We recognize rent expense under these arrangements on a straight-line basis over the term of the lease. Guarantees and Indemnifications In the normal course of business, we provide indemnifications to customers against claims of intellectual property infringement made by third parties arising from the use of our products. Other guarantees or indemnification arrangements include guarantees of product and service performance, and standby letters of credit for lease facilities and corporate credit cards. We have not recorded a liability related to these indemnification and guarantee provisions, and our guarantees and indemnification arrangements have not had any significant impact on our consolidated financial statements to date.

Equity Incentive Plans and Stoc

Equity Incentive Plans and Stock-Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans and Stock-Based Compensation	Equity Incentive Plans and Stock-Based Compensation Equity Incentive Plans 2014 Equity Incentive Plan The 2014 Equity Incentive Plan (the “2014 Plan”) provides for the granting of stock options, restricted stock awards, restricted stock units (“RSUs”), performance-based RSUs (“PSUs”), stock appreciation rights, performance units and performance shares to our employees, consultants and members of our board of directors. In June 2015, our board of directors adopted and our stockholders approved an amendment and restatement of the 2014 Plan, which increased the number of shares available for issuance under the 2014 Plan by the number of shares granted under the 2008 Stock Plan (the “2008 Plan”) that were or may in the future be canceled or otherwise forfeited or repurchased after March 20, 2014. A maximum of 8,310,566 shares may become available from such awards granted under the 2008 Plan for issuance under the 2014 Plan. As of December 31, 2016 , we had 4,241,980 shares available for future grant. Annually, the shares authorized for the 2014 Plan increase by the least of (i) 8,000,000 shares, (ii) 5% of the outstanding shares of common stock on the last day of our immediately preceding fiscal year, or (iii) such other amount as determined by our Board of Directors. On January 1, 2017 , the number of shares in the 2014 Plan increased by 3,394,376 shares, representing 5% of the prior year end’s common stock outstanding. In addition, 266,799 shares granted under the 2008 Plan that had been canceled, forfeited or repurchased during the year ended December 31, 2016 became available for issuance under the 2014 Plan. As of June 30, 2017 , we had 5,927,133 shares available for future grant plus an additional 81,188 shares granted under the 2008 Plan that have been canceled, forfeited or repurchased during the six months ended June 30, 2017 . 2014 Employee Stock Purchase Plan The 2014 Employee Stock Purchase Plan (the "2014 Purchase Plan") provides for twenty-four month offering periods with four six-month purchase periods in each offering period. Employees purchase shares in each purchase period at 85% of the market value of our common stock at the beginning of the offering period or the end of the purchase period, whichever is lower. If the market value of our common stock at the end of the purchase period is less than the market value at the beginning of the offering period, participants will be withdrawn from the then current offering period following their purchase of shares, and automatically will be enrolled in the immediately following offering period. Participants may contribute up to 15% of their eligible compensation, subject to certain limits. Employees purchased 524,101 shares at an average price of $6.49 and 552,554 shares at an average price of $3.88 for the six months ended June 30, 2017 and 2016 , respectively. The intrinsic value of shares purchased during the six months ended June 30, 2017 and 2016 was $0.9 million and $1.3 million , respectively. The intrinsic value is calculated as the difference between the market value on the date of purchase and the purchase price of the shares. As of June 30, 2017 , we had 3,579,959 shares available for future issuance under the 2014 Purchase Plan. Stock-Based Compensation A summary of our stock-based compensation expense is as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock-based compensation by type of award: Stock options $ 791 $ 1,081 $ 1,610 $ 2,181 Stock awards 3,351 3,423 6,300 6,383 Employee stock purchase plan 821 (635 ) 1,369 (83 ) $ 4,963 $ 3,869 $ 9,279 $ 8,481 Stock-based compensation by category of expense: Cost of revenue $ 382 $ 224 $ 665 $ 589 Sales and marketing 1,888 1,732 3,424 3,817 Research and development 1,823 1,090 3,487 2,521 General and administrative 870 823 1,703 1,554 $ 4,963 $ 3,869 $ 9,279 $ 8,481 As of June 30, 2017 , we had $47.2 million of unrecognized stock-based compensation expense related to unvested stock-based awards which will be recognized over a weighted-average period of 2.6 years. The fair value of the options was estimated as of the grant date using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Expected term (in years) 4.7 * 4.7 4.9 Risk-free interest rate 1.74% * 1.74% 1.42% Volatility 42% * 42% 49% Dividend rate —% * —% —% * We did not grant stock options during the three months ended June 30, 2016 . The fair value of the employee stock purchase rights was estimated as of the grant date using the Black-Scholes option-pricing model with the following assumptions: Three and Six Months Ended June 30, 2017 2016 Expected term (in years) 1.3 1.3 Risk-free interest rate 1.12% 0.65% Volatility 38% 43% Dividend rate —% —% Stock Options The following tables summarize our stock option activities and related information: Number of Shares (thousands) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (thousands) Outstanding as of December 31, 2016 7,868 $ 4.82 Granted 135 $ 8.42 Exercised (1,130 ) $ 3.37 Canceled (1) (350 ) $ 6.38 Outstanding as of June 30, 2017 6,523 $ 5.07 5.7 $ 23,134 Vested and exercisable as of June 30, 2017 5,097 $ 4.93 5.1 $ 18,819 (1) Includes 81,188 shares of canceled stock options from the 2008 Plan that became available for issuance under the 2014 Plan. As of June 30, 2017 , the aggregate intrinsic value represents the excess of the closing price of our common stock of $8.44 over the exercise price of the outstanding in-the-money options. The following table provides information pertaining to our stock options (in thousands, except weighted-average fair value): Six Months Ended June 30, 2017 2016 Fair value of options granted $ 426 $ 1,603 Weighted-average fair value of options granted $ 3.15 $ 2.38 Intrinsic value of options exercised $ 6,429 $ 832 Stock Awards We have granted RSUs to our employees, consultants and members of our board of directors, and PSUs and market performance-based restricted stock units (“MSUs”) to certain executives. In 2014 and 2015, we granted 540,000 MSUs and 40,000 MSUs, respectively, to certain executives. These MSUs will vest if the closing price of our common stock remains above certain predetermined target prices for 20 consecutive trading days within a 4 -year period following the grant date, subject to continued service by the award holder. None of these MSUs were vested as of June 30, 2017 . In February 2016, we granted 547,000 PSUs with certain financial and operational targets. Actual performance resulted in participants achieving 80% of target, or approximately 414,000 shares, which will vest in annual tranches through February 2020 subject to continued service vesting requirements. In October 2016, we granted 60,641 PSUs with certain financial and operational targets. To the extent they become eligible to vest upon achievement of the performance targets, these PSUs additionally are subject to service condition vesting requirements with scheduled vesting dates of March 2017 through June 2018. As of June 30, 2017 , 12,128 shares had vested, 12,128 shares were forfeited, and the remaining shares were unvested and are eligible to vest based on achievement of performance targets. In March 2017, we granted 395,383 PSUs with certain financial targets. These PSUs will vest between ranges of 0% and 150% based on the actual performance, and are subject to service condition vesting requirements with 25% of the PSUs that become eligible to vest upon achievement of the performance targets scheduled to vest on each of the first, second, third and fourth year anniversaries following February 2017. None of these PSUs were vested as of June 30, 2017 . The following table summarizes our stock award activities and related information: Number of Shares (thousands) Weighted-Average Grant Date Fair Value Weighted-Average Remaining Vesting Term Aggregate Intrinsic Value (thousands) Outstanding as of December 31, 2016 5,959 $ 5.81 Granted 2,732 $ 8.73 Released (1,133 ) $ 6.13 Canceled (623 ) $ 5.64 Outstanding as of June 30, 2017 6,935 $ 6.92 1.8 $ 58,533 The aggregate intrinsic value of outstanding awards is calculated based on the closing price of our common stock of $8.44 on June 30, 2017 . The aggregate fair value of stock awards released as of the respective vesting dates was approximately $10.2 million and $1.8 million for the six months ended June 30, 2017 and 2016 , respectively. Stock Repurchase Program On October 27, 2016, we announced that our board of directors authorized a share repurchase program for up to $20.0 million of our common stock over 12 months. Under the repurchase authorization, shares may be purchased from time to time, subject to general business and market conditions and other investment opportunities, through open market purchases, privately negotiated transactions or other means. The repurchase authorization may be commenced, suspended or discontinued at any time at our discretion. During the six months ended June 30, 2017 , we repurchased 99,735 shares at an average price of $8.18 as a part of a publicly announced program. The repurchased shares were retired upon delivery to us. As of June 30, 2017 , we had $17.4 million remaining authorized to repurchase shares.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed using the weighted average number of common shares outstanding for the period. Diluted net loss per share is computed using the weighted average number of common shares outstanding for the period plus potential dilutive common shares, including stock options, RSUs and employee stock purchase rights, unless the potential common shares are anti-dilutive. Since we had net losses in the three and six months ended June 30, 2017 and 2016 , none of the potential dilutive common shares were included in the computation of diluted shares for these periods, as inclusion of such shares would have been anti-dilutive. The following table presents common shares related to potentially dilutive shares excluded from the calculation of diluted net loss per share as their effect would have been anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock options, RSUs and employee stock purchase rights 12,340 13,567 12,761 11,736 Common stock subject to repurchase 2 28 2 28 12,342 13,595 12,763 11,764

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded income tax expense of $0.1 million each for the three months ended June 30, 2017 and 2016 and $0.5 million and $0.3 million for the six months ended June 30, 2017 and 2016 , respectively, which primarily consisted of foreign taxes. Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the carrying amounts of existing assets and liabilities in the financial statements and their respective tax bases using tax rates expected to be in effect during the years in which the basis differences reverse. We believe it is more likely than not that our federal and state net deferred tax assets will not be fully realized. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of our deferred tax asset will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. A valuation allowance is recorded for loss carryforwards and other deferred tax assets where it is more likely than not that such deferred tax assets will not be realized. Accordingly, we continue to maintain a valuation allowance against all of our U.S. and certain foreign net deferred tax assets as of June 30, 2017 . We will continue to maintain a full valuation allowance against our net federal, state and certain foreign deferred tax assets until there is sufficient evidence to support recoverability of our deferred tax assets. We had $3.3 million of unrecognized tax benefits as of June 30, 2017 and December 31, 2016 . We do not anticipate a material change to our unrecognized tax benefits over the next twelve months. Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. Accrued interest and penalties related to unrecognized tax benefits are recognized as part of our income tax provision in our condensed consolidated statements of operations. We are subject to taxation in the United States, various states, and several foreign jurisdictions. Because we have net operating loss and credit carryforwards, there are open statutes of limitations in which federal, state and foreign taxing authorities may examine our tax returns for all years from 2004 through the current period. We are currently under examination by the Internal Revenue Service for our 2015 and 2014 tax returns.

Geographic Information

Geographic Information	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Geographic Information	Geographic Information The following table is a summary of revenue by geographic regions based on ship to location (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 United States $ 28,636 $ 31,345 $ 59,292 $ 60,945 Japan 8,406 10,954 21,485 21,838 Asia Pacific, excluding Japan 8,661 7,746 18,902 14,477 EMEA 6,786 5,860 11,994 10,927 Other 1,200 1,225 2,302 2,747 Total revenue $ 53,689 $ 57,130 $ 113,975 $ 110,934 Our long-lived assets which include property and equipment, net and intangible assets, net is primarily located in the United States. No other geographic regions comprised 10% or more of our long-lived assets as of June 30, 2017 and December 31, 2016 .

Description of Business and S16

Description of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business A10 Networks, Inc. (together with our subsidiaries, “we”, “our” or “us”) was incorporated in California in 2004 and reincorporated in Delaware in March 2014. We are headquartered in San Jose, California and have wholly-owned subsidiaries throughout the world including Asia and Europe. Our solutions enable our customers to secure and optimize the performance of their data center and cloud applications and secure their users, applications and infrastructure from internet, web and network threats at scale. Our product portfolio consists of six advanced application delivery and security products: Application Delivery Controllers (“ADC”), Lightning Application Delivery Service (“Lightning ADS”), Carrier Grade Network Address Translation (“CGN”), Threat Protection System (“TPS”), SSL Insight (“SSLi”) and Convergent Firewall (“CFW”). They are available in a variety of form factors, such as optimized hardware appliances, bare metal software, virtual appliances, and cloud-native software.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include those of A10 Networks, Inc. and its subsidiaries after elimination of all intercompany accounts and transactions. We have prepared the accompanying unaudited condensed consolidated financial statement pursuant to the rules and regulations of the United States Securities and Exchange Commission (the “SEC”). As permitted under these rules and regulations, we have condensed or omitted certain financial information and footnote disclosures we normally include in our annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). These financial statements have been prepared on the same basis as our annual financial statements and, in management's opinion, reflect all adjustments consisting only of normal recurring adjustments that are necessary for a fair presentation of our financial information. Our interim period operating results do not necessarily indicate the results that may be expected for any other interim period or for the full fiscal year. These financial statements and accompanying notes should be read in conjunction with the financial statements and accompanying notes thereto in our Annual Report on Form 10-K for the year ended December 31, 2016 on file with the SEC (our “Annual Report”).
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Those estimates and assumptions affect revenue recognition and deferred revenue, allowance for doubtful accounts, sales return reserve, valuation of inventory, fair value of marketable securities, contingencies and litigation, acquisition related purchase price allocations, accrued liabilities, and the determination of fair value of stock-based compensation. These estimates are based on information available as of the date of the condensed consolidated financial statements; therefore, actual results could differ from management’s estimates.
Concentration of Credit Risk and Significant Customers	Concentration of Credit Risk and Significant Customers Financial instruments that potentially subject us to concentrations of credit risk consist of cash, cash equivalents, marketable securities and accounts receivable. Our cash, cash equivalents and marketable securities are held and invested in high-credit quality financial instruments by recognized financial institutions and therefore subject to minimum credit risk. Our accounts receivable are unsecured and represent amounts due to us based on contractual obligations of our customers. We mitigate credit risk in respect to accounts receivable by performing periodic credit evaluations based on a number of factors, including past transaction experience, evaluation of credit history and review of the invoicing terms of the contract. We generally do not require our customers to provide collateral to support accounts receivable. Significant customers, including distribution channel partners and direct customers, are those which represent more than 10% of our total revenue for each period presented or our gross accounts receivable balance as of each respective balance sheet date. R
Recently Adopted Accounting Guidance/Recent Accounting Pronouncements Not Yet Effective	ent Accounting Pronouncements Not Yet Effective In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will supersede most of the existing revenue recognition guidance under U.S. GAAP. This ASU requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and requires the capitalization of incremental customer acquisition costs and amortization of these costs over the contract period or estimated customer life which will result in the recognition of a contract asset on our balance sheets. This standard is effective for annual periods beginning after December 15, 2017 and interim periods within that reporting period. The ASU allows for either full retrospective or modified retrospective adoption. We intend to adopt the standard in the first quarter of 2018 applying the modified retrospective method. While we are continuing to assess all potential impacts of the new standard, we currently do not believe this standard will have a material impact on revenue recognized in our condensed consolidated financial statements. We are in the process of evaluating both the impact of capitalizing and amortizing incremental customer acquisition costs, such as sales commissions on our service contracts, and the disclosure requirements relating to this standard. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This new accounting standard primarily requires lessees to recognize most leases on their balance sheets but record expenses on their income statements in a manner similar to current accounting. For lessors, the guidance modifies the classification criteria and the accounting for sales-type and direct financing leases. This standard is effective for annual periods beginning after December 15, 2018 with early adoption permitted. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , which removes the requirement to compare the implied fair value of goodwill with its carrying amount as part of step 2 of the goodwill impairment test. As a result, under this ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the impairment loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. This standard is effective prospectively for annual periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting, to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. This standard is effective for annual periods beginning after December 15, 2017 and interim periods within that reporting period. Early adoption is permitted, including adoption in any interim period. The amendments will be applied prospectively to an award modified on or after the adoption date. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements. There have been no other recent accounting pronouncements or changes in accounting pronouncements that are of significance or potential significance to us.

Description of Business and S17

Description of Business and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Revenue as Percentage of Total Revenue	Revenues from our significant customers as a percentage of our total revenue are as follows: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Customer A (a distribution channel partner) 10% * 11% * Customer B (a distribution channel partner) * 11% * 11% Customer C (a direct customer) * 10% * * * represents less than 10% of total revenue

Marketable Securities and Fai18

Marketable Securities and Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Available-for-sale Securities	Marketable securities, classified as available-for-sale, consisted of the following (in thousands): June 30, 2017 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Certificates of deposit $ 13,500 $ 4 $ (1 ) $ 13,503 $ 12,499 $ 9 $ — $ 12,508 Corporate securities 42,516 5 (31 ) 42,490 42,765 9 (42 ) 42,732 U.S. Treasury and agency securities 3,493 — (12 ) 3,481 5,190 — (14 ) 5,176 Commercial paper 9,463 2 (1 ) 9,464 11,470 1 (2 ) 11,469 Asset-backed securities 16,847 — (12 ) 16,835 13,493 — (6 ) 13,487 $ 85,819 $ 11 $ (57 ) $ 85,773 $ 85,417 $ 19 $ (64 ) $ 85,372
Schedule of Cost and Estimated Fair Values of Available-for-sale Securities by Contractual Maturity	The following table summarizes the cost and estimated fair value of marketable securities based on stated effective maturities as of June 30, 2017 (in thousands): Amortized Cost Fair Value Less than 1 year $ 50,898 $ 50,881 Mature in 1 - 3 years 34,921 34,892 $ 85,819 $ 85,773
Continuous Unrealized Loss Position Less Than 12 months Related to Available-for-sale Securities	Marketable securities in an unrealized loss position consisted of the following (in thousands): Less Than 12 Months 12 Months or More Total As of June 30, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Certificates of deposit $ 3,499 $ (1 ) $ — $ — $ 3,499 $ (1 ) Corporate securities 30,063 (25 ) 1,498 (6 ) 31,561 (31 ) U.S. Treasury and agency securities 3,480 (12 ) — — 3,480 (12 ) Commercial paper 4,984 (1 ) — — 4,984 (1 ) Asset-backed securities 16,835 (12 ) — — 16,835 (12 ) $ 58,861 $ (51 ) $ 1,498 $ (6 ) $ 60,359 $ (57 ) Less Than 12 Months 12 Months or More Total As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Corporate securities $ 28,537 $ (42 ) $ — $ — $ 28,537 $ (42 ) U.S. Treasury and agency securities 5,176 (14 ) — — 5,176 (14 ) Commercial paper 8,974 (2 ) — — 8,974 (2 ) Asset-backed securities 10,664 (6 ) — — 10,664 (6 ) $ 53,351 $ (64 ) $ — $ — $ 53,351 $ (64 )
Schedule of Cash, Cash Equivalents and Available-for-sale Investments Measured at Fair Value on Recurring Basis	The following is a summary of our cash, cash equivalents and marketable securities measured at fair value on a recurring basis (in thousands): June 30, 2017 December 31, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 36,050 $ — $ — $ 36,050 $ 18,672 $ — $ — $ 18,672 Cash equivalents 10,335 — — 10,335 10,303 — — 10,303 Certificates of deposit — 13,503 — 13,503 — 12,508 — 12,508 Corporate securities — 42,490 — 42,490 — 42,732 — 42,732 U.S. Treasury and agency securities — 3,481 — 3,481 — 5,176 — 5,176 Commercial paper — 9,464 — 9,464 — 11,469 — 11,469 Asset-backed securities — 16,835 — 16,835 — 13,487 — 13,487 $ 46,385 $ 85,773 $ — $ 132,158 $ 28,975 $ 85,372 $ — $ 114,347

Condensed Consolidated Financ19

Condensed Consolidated Financial Statement Details (Tables)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Schedule of Inventory	June 30, December 31, (in thousands) Raw materials $ 6,795 $ 6,669 Finished goods 8,590 8,401 Total inventory $ 15,385 $ 15,070
Schedule of Property and Equipment, Net	Useful Life June 30, December 31, (in years) (in thousands) Equipment 1-3 $ 45,252 $ 41,815 Software 1-3 3,824 3,801 Furniture and fixtures 1-3 865 865 Leasehold improvements 2-8 2,775 2,724 Construction in progress — 258 Property and equipment, gross 52,716 49,463 Less: accumulated depreciation (44,450 ) (41,244 ) Property and equipment, net $ 8,266 $ 8,219
Schedule of Acquired Intangible Assets	Purchased intangible assets, net, consisted of the following (in thousands): June 30, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Developed technology $ 5,050 $ (1,010 ) $ 4,040 $ 5,050 $ (505 ) $ 4,545 Patents 2,936 (1,065 ) 1,871 2,936 (848 ) 2,088 Total $ 7,986 $ (2,075 ) $ 5,911 $ 7,986 $ (1,353 ) $ 6,633
Schedule of Future Amortization Expense for Purchased Finite-lived Intangible Assets	Future amortization expense for purchased intangible assets as of June 30, 2017 is as follows (in thousands): Fiscal Year Remainder of 2017 $ 721 2018 1,442 2019 1,442 2020 1,442 2021 864 $ 5,911
Schedule of Accrued Liabilities	June 30, December 31, (in thousands) Accrued compensation and benefits $ 18,968 $ 22,326 Accrued tax liabilities 1,787 3,340 Other 4,641 5,859 Total accrued liabilities $ 25,396 $ 31,525
Schedule of Deferred Revenue	June 30, December 31, (in thousands) Deferred revenue: Products $ 3,319 $ 4,182 Services 89,192 88,726 Total deferred revenue 92,511 92,908 Less: current portion (61,840 ) (61,334 ) Non-current portion $ 30,671 $ 31,574

Equity Incentive Plans and St20

Equity Incentive Plans and Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock-based Compensation	A summary of our stock-based compensation expense is as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock-based compensation by type of award: Stock options $ 791 $ 1,081 $ 1,610 $ 2,181 Stock awards 3,351 3,423 6,300 6,383 Employee stock purchase plan 821 (635 ) 1,369 (83 ) $ 4,963 $ 3,869 $ 9,279 $ 8,481 Stock-based compensation by category of expense: Cost of revenue $ 382 $ 224 $ 665 $ 589 Sales and marketing 1,888 1,732 3,424 3,817 Research and development 1,823 1,090 3,487 2,521 General and administrative 870 823 1,703 1,554 $ 4,963 $ 3,869 $ 9,279 $ 8,481
Stock Options Valuation Assumptions	The fair value of the options was estimated as of the grant date using the Black-Scholes option-pricing model with the following assumptions: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Expected term (in years) 4.7 * 4.7 4.9 Risk-free interest rate 1.74% * 1.74% 1.42% Volatility 42% * 42% 49% Dividend rate —% * —% —% * We did not grant stock options during the three months ended June 30, 2016 .
Employee Stock Purchase Plan, Valuation Assumptions	The fair value of the employee stock purchase rights was estimated as of the grant date using the Black-Scholes option-pricing model with the following assumptions: Three and Six Months Ended June 30, 2017 2016 Expected term (in years) 1.3 1.3 Risk-free interest rate 1.12% 0.65% Volatility 38% 43% Dividend rate —% —%
Summary of Activity under Stock Option Plans	The following tables summarize our stock option activities and related information: Number of Shares (thousands) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (thousands) Outstanding as of December 31, 2016 7,868 $ 4.82 Granted 135 $ 8.42 Exercised (1,130 ) $ 3.37 Canceled (1) (350 ) $ 6.38 Outstanding as of June 30, 2017 6,523 $ 5.07 5.7 $ 23,134 Vested and exercisable as of June 30, 2017 5,097 $ 4.93 5.1 $ 18,819 (1) Includes 81,188 shares of canceled stock options from the 2008 Plan that became available for issuance under the 2014 Plan.
Stock Option Information	The following table provides information pertaining to our stock options (in thousands, except weighted-average fair value): Six Months Ended June 30, 2017 2016 Fair value of options granted $ 426 $ 1,603 Weighted-average fair value of options granted $ 3.15 $ 2.38 Intrinsic value of options exercised $ 6,429 $ 832
Summary of Restricted Stock Units Activity	The following table summarizes our stock award activities and related information: Number of Shares (thousands) Weighted-Average Grant Date Fair Value Weighted-Average Remaining Vesting Term Aggregate Intrinsic Value (thousands) Outstanding as of December 31, 2016 5,959 $ 5.81 Granted 2,732 $ 8.73 Released (1,133 ) $ 6.13 Canceled (623 ) $ 5.64 Outstanding as of June 30, 2017 6,935 $ 6.92 1.8 $ 58,533

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Summary of Anti-dilutive Shares	The following table presents common shares related to potentially dilutive shares excluded from the calculation of diluted net loss per share as their effect would have been anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Stock options, RSUs and employee stock purchase rights 12,340 13,567 12,761 11,736 Common stock subject to repurchase 2 28 2 28 12,342 13,595 12,763 11,764

Geographic Information (Tables)

Geographic Information (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Schedule of Total Revenue Based on Customer's Location	The following table is a summary of revenue by geographic regions based on ship to location (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 United States $ 28,636 $ 31,345 $ 59,292 $ 60,945 Japan 8,406 10,954 21,485 21,838 Asia Pacific, excluding Japan 8,661 7,746 18,902 14,477 EMEA 6,786 5,860 11,994 10,927 Other 1,200 1,225 2,302 2,747 Total revenue $ 53,689 $ 57,130 $ 113,975 $ 110,934

Description of Business and S23

Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Incorporation, year	2,004
Entity, state of incorporation	Delaware

Description of Business and S24

Description of Business and Summary of Significant Accounting Policies - Schedule of Revenue as Percentage of Total Revenue and Accounts Receivable as Percentage of Total Net Accounts Receivable (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Customer A | Revenue
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)	10.00%		11.00%
Customer A | Accounts Receivable
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)			15.00%		15.00%
Customer B | Revenue
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)		11.00%		11.00%
Customer B | Accounts Receivable
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)					13.00%
Customer C | Revenue
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)		10.00%
Customer C | Accounts Receivable
Entity Wide Revenue Major Customer [Line Items]
Percentage representation of significant customers (percent)					11.00%

Marketable Securities and Fai25

Marketable Securities and Fair Value Measurements - Estimate of Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 85,819	$ 85,417
Gross Unrealized Gains	11	19
Gross Unrealized Losses	(57)	(64)
Fair Value	85,773	85,372
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,500	12,499
Gross Unrealized Gains	4	9
Gross Unrealized Losses	(1)	0
Fair Value	13,503	12,508
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42,516	42,765
Gross Unrealized Gains	5	9
Gross Unrealized Losses	(31)	(42)
Fair Value	42,490	42,732
U.S. Treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,493	5,190
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12)	(14)
Fair Value	3,481	5,176
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,463	11,470
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(1)	(2)
Fair Value	9,464	11,469
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,847	13,493
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12)	(6)
Fair Value	$ 16,835	$ 13,487

Marketable Securities and Fai26

Marketable Securities and Fair Value Measurements - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized Cost
Less than 1 year	$ 50,898
Mature in 1 - 3 years	34,921
Amortized Cost	85,819	$ 85,417
Fair Value
Less than 1 year	50,881
Mature in 1 - 3 years	34,892
Fair Value	$ 85,773	$ 85,372

Marketable Securities and Fai27

Marketable Securities and Fair Value Measurements - Securities in Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value
Less Than 12 Months	$ 58,861	$ 53,351
12 Months or More	1,498	0
Total	60,359	53,351
Gross Unrealized Losses
Less Than 12 Months	(51)	(64)
12 Months or More	(6)	0
Total	57	64
Certificates of deposit
Fair Value
Less Than 12 Months	3,499
12 Months or More	0
Total	3,499
Gross Unrealized Losses
Less Than 12 Months	(1)
12 Months or More	0
Total	1
Corporate securities
Fair Value
Less Than 12 Months	30,063	28,537
12 Months or More	1,498	0
Total	31,561	28,537
Gross Unrealized Losses
Less Than 12 Months	(25)	(42)
12 Months or More	(6)	0
Total	31	42
U.S. Treasury and agency securities
Fair Value
Less Than 12 Months	3,480	5,176
12 Months or More	0	0
Total	3,480	5,176
Gross Unrealized Losses
Less Than 12 Months	(12)	(14)
12 Months or More	0	0
Total	12	14
Commercial paper
Fair Value
Less Than 12 Months	4,984	8,974
12 Months or More	0	0
Total	4,984	8,974
Gross Unrealized Losses
Less Than 12 Months	(1)	(2)
12 Months or More	0	0
Total	1	2
Asset-backed securities
Fair Value
Less Than 12 Months	16,835	10,664
12 Months or More	0	0
Total	16,835	10,664
Gross Unrealized Losses
Less Than 12 Months	(12)	(6)
12 Months or More	0	0
Total	$ 12	$ 6

Marketable Securities and Fai28

Marketable Securities and Fair Value Measurements - Schedule of Fair Value of Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial Assets
Marketable Securities	$ 85,773	$ 85,372
Total	132,158	114,347
Level 1
Financial Assets
Total	46,385	28,975
Level 2
Financial Assets
Total	85,773	85,372
Cash
Financial Assets
Cash and Cash Equivalents	36,050	18,672
Cash | Level 1
Financial Assets
Cash and Cash Equivalents	36,050	18,672
Cash equivalents
Financial Assets
Cash and Cash Equivalents	10,335	10,303
Cash equivalents | Level 1
Financial Assets
Cash and Cash Equivalents	10,335	10,303
Certificates of deposit
Financial Assets
Marketable Securities	13,503	12,508
Certificates of deposit | Level 2
Financial Assets
Marketable Securities	13,503	12,508
Corporate securities
Financial Assets
Marketable Securities	42,490	42,732
Corporate securities | Level 2
Financial Assets
Marketable Securities	42,490	42,732
U.S. Treasury and agency securities
Financial Assets
Marketable Securities	3,481	5,176
U.S. Treasury and agency securities | Level 2
Financial Assets
Marketable Securities	3,481	5,176
Commercial paper
Financial Assets
Marketable Securities	9,464	11,469
Commercial paper | Level 2
Financial Assets
Marketable Securities	9,464	11,469
Asset-backed securities
Financial Assets
Marketable Securities	16,835	13,487
Asset-backed securities | Level 2
Financial Assets
Marketable Securities	$ 16,835	$ 13,487

Condensed Consolidated Financ29

Condensed Consolidated Financial Statement Details - Schedule of Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 6,795	$ 6,669
Finished goods	8,590	8,401
Total inventory	$ 15,385	$ 15,070

Condensed Consolidated Financ30

Condensed Consolidated Financial Statement Details - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 52,716	$ 49,463
Less: accumulated depreciation	(44,450)	(41,244)
Property and equipment, net	8,266	8,219
Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	45,252	41,815
Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,824	3,801
Furniture and fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	865	865
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,775	2,724
Construction in progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 0	$ 258
Minimum | Equipment
Property Plant And Equipment [Line Items]
Useful life	1 year
Minimum | Software
Property Plant And Equipment [Line Items]
Useful life	1 year
Minimum | Furniture and fixtures
Property Plant And Equipment [Line Items]
Useful life	1 year
Minimum | Leasehold improvements
Property Plant And Equipment [Line Items]
Useful life	2 years
Maximum | Equipment
Property Plant And Equipment [Line Items]
Useful life	3 years
Maximum | Software
Property Plant And Equipment [Line Items]
Useful life	3 years
Maximum | Furniture and fixtures
Property Plant And Equipment [Line Items]
Useful life	3 years
Maximum | Leasehold improvements
Property Plant And Equipment [Line Items]
Useful life	8 years

Condensed Consolidated Financ31

Condensed Consolidated Financial Statement Details - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 1,800	$ 1,800	$ 3,600	$ 3,700
Goodwill	1,300		1,300		$ 1,300
Amortization expense related to intangible assets	$ 400	$ 33	$ 700	$ 100
Weighted average useful life of purchased intangible assets (in years)			4 years 1 month

Condensed Consolidated Financ32

Condensed Consolidated Financial Statement Details - Purchased Intangible Assets, net (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	$ 7,986	$ 7,986
Accumulated Amortization	(2,075)	(1,353)
Total	5,911	6,633
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	5,050	5,050
Accumulated Amortization	(1,010)	(505)
Total	4,040	4,545
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	2,936	2,936
Accumulated Amortization	(1,065)	(848)
Total	$ 1,871	$ 2,088

Condensed Consolidated Financ33

Condensed Consolidated Financial Statement Details - Future Amortization Expense of Acquired Intangibles (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Remainder of 2017	$ 721
2,018	1,442
2,019	1,442
2,020	1,442
2,021	864
Total	$ 5,911	$ 6,633

Condensed Consolidated Financ34

Condensed Consolidated Financial Statement Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 18,968	$ 22,326
Accrued tax liabilities	1,787	3,340
Other	4,641	5,859
Total accrued liabilities	$ 25,396	$ 31,525

Condensed Consolidated Financ35

Condensed Consolidated Financial Statement Details - Schedule of Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 92,511	$ 92,908
Less: current portion	(61,840)	(61,334)
Non-current portion	30,671	31,574
Products
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	3,319	4,182
Services
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 89,192	$ 88,726

Credit Facility (Details)

Credit Facility (Details) - Line of credit	1 Months Ended
	Nov. 30, 2016USD ($)	Jun. 30, 2017USD ($)
Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument term (in years)	3 years
Maximum borrowing capacity	$ 25,000,000
Debt covenant, net cash equals or exceeds, amount	50,000,000
Debt covenant, net cash falls below, amount	$ 50,000,000
Minimum adjusted quick ratio under debt compliance	1.50
Amount outstanding		$ 0
Letter of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 25,000,000
Prime Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable rate basis spread	0.50%
LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable rate basis spread	2.50%

Equity Incentive Plans and St37

Equity Incentive Plans and Stock-Based Compensation - 2014 Equity Incentive Plan/ESPP (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2017	Jun. 10, 2015	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant (in shares)			81,188
2014 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant (in shares)			5,927,133		4,241,980
2014 Stock Incentive Plan | Reallocated 2008 Equity Plan Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for reallocation (in shares)			81,188		266,799
2014 Stock Incentive Plan | Prior Common Stock Outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of outstanding shares of common stock	5.00%
Additional shares authorized for future issuance (in shares)	3,394,376
2014 Stock Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares reserved for future issuance (in shares)					8,000,000
Percentage of outstanding shares of common stock					5.00%
2014 Stock Incentive Plan | Maximum | Reallocated 2008 Equity Plan Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for reallocation (in shares)		8,310,566
2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant (in shares)			3,579,959
Percentage of market value			85.00%
Percentage of eligible compensation			15.00%
2014 Employee Stock Purchase Plan | Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP shares purchased during period (in shares)			524,101	552,554
ESPP shares purchased during period (in dollars per share)			$ 6.49	$ 3.88
Intrinsic value of ESPP shares purchased			$ 0.9	$ 1.3

Equity Incentive Plans and St38

Equity Incentive Plans and Stock-Based Compensation - Schedule of Stock-based Compensation Awards Granted under Stock Option Plan in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 4,963	$ 3,869	$ 9,279	$ 8,481
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	382	224	665	589
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,888	1,732	3,424	3,817
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,823	1,090	3,487	2,521
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	870	823	1,703	1,554
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	791	1,081	1,610	2,181
Stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	3,351	3,423	6,300	6,383
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 821	$ (635)	$ 1,369	$ (83)

Equity Incentive Plans and St39

Equity Incentive Plans and Stock-Based Compensation - Stock-based Compensation/Stock Repurchase Program (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Oct. 27, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense related to unvested awards granted, not yet recognized	$ 47,200,000
Total compensation expense related to unvested awards granted, not yet recognized weighted-average period for recognition (in years)	2 years 7 months
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount authorized to be repurchased		$ 20,000,000
Number of shares repurchased during period (in shares)	99,735
Stock repurchased, average price per share (in dollars per share)	$ 8.18
Remaining authorized amount to purchase	$ 17,400,000

Equity Incentive Plans and St40

Equity Incentive Plans and Stock-Based Compensation - Summary of Valuation Assumptions (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days
Risk-free interest rate	1.12%	0.65%	1.12%	0.65%
Volatility	38.00%	43.00%	38.00%	43.00%
Dividend rate	0.00%	0.00%	0.00%	0.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	4 years 8 months 12 days		4 years 8 months 12 days	4 years 10 months 24 days
Risk-free interest rate	1.74%		1.74%	1.42%
Volatility	42.00%		42.00%	49.00%
Dividend rate	0.00%		0.00%	0.00%

Equity Incentive Plans and St41

Equity Incentive Plans and Stock-Based Compensation - Summary of Activity under Stock Option Plans (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)$ / sharesshares
Number of Shares (thousands)
Outstanding options, Beginning balance (in shares) | shares	7,868,000
Granted (in shares) | shares	135,000
Exercised (in shares) | shares	(1,130,000)
Canceled (in shares) | shares	(350,000)
Outstanding options, Ending balance (in shares) | shares	6,523,000
Vested and exercisable (in shares) | shares	5,097,000
Weighted-Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 4.82
Granted (in dollars per share) | $ / shares	8.42
Exercised (in dollars per share) | $ / shares	3.37
Canceled (in dollars per share) | $ / shares	6.38
Ending balance (in dollars per share) | $ / shares	5.07
Vested and exercisable at end of period (in dollars per share) | $ / shares	$ 4.93
Weighted-average remaining contractual term (in years)	5 years 8 months 12 days
Weighted average remaining contractual term, Vested and exercisable at end of period (in years)	5 years 1 month 6 days
Aggregate Intrinsic Value | $	$ 23,134
Aggregate Intrinsic Value, Vested and exercisable at end of period | $	$ 18,819
Number of shares available for future grant | shares	81,188
Closing price (in dollars per share) | $ / shares	$ 8.44

Equity Incentive Plans and St42

Equity Incentive Plans and Stock-Based Compensation - Information About Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			6 Months Ended		12 Months Ended
	Mar. 31, 2017	Oct. 31, 2016	Feb. 29, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options granted				$ 426	$ 1,603
Weighted-average fair value of options granted (in dollars per share)				$ 3.15	$ 2.38
Intrinsic value of options exercised				$ 6,429	$ 832
MSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						40,000	540,000
Number of consecutive trading days				20 days
Measurement period				4 years
Vested in period (in shares)				0
PSUs, February 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			547,000
Vested in period (in shares)			400,000
Actual performance vesting percentage			80.00%
PSUs, October 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		60,641
Vested in period (in shares)				12,128
Forfeited in period (in shares)				12,128
PSUs, March 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	395,383
Vested in period (in shares)				0
Vesting percentage	25.00%
PSUs, March 2017 | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	0.00%
PSUs, March 2017 | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	150.00%

Equity Incentive Plans and St43

Equity Incentive Plans and Stock-Based Compensation - Summary of RSU activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Aggregate Intrinsic Value (thousands)	$ 58,533
Closing price (in dollars per share)	$ 8.44
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	5,959
Granted (in shares)	2,732
Released (in shares)	(1,133)
Canceled (in shares)	(623)
Outstanding at end of period (in shares)	6,935
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 6.92
Granted (in dollars per share)	8.73
Released (in dollars per share)	6.13
Canceled (in dollars per share)	5.64
Outstanding at ending of period (in dollars per share)	$ 5.81
Weighted-Average Remaining Vesting Term (years)	1 year 9 months 18 days
Vested in period (in shares)	$ 10,200	$ 1,800

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Outstanding Shares of Common Stock Equivalents (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share Diluted [Line Items]
Anti-dilutive securities excluded from computation of diluted net income per share	12,342	13,595	12,763	11,764
Stock options, RSUs and employee stock purchase rights
Earnings Per Share Diluted [Line Items]
Anti-dilutive securities excluded from computation of diluted net income per share	12,340	13,567	12,761	11,736
Common stock subject to repurchase
Earnings Per Share Diluted [Line Items]
Anti-dilutive securities excluded from computation of diluted net income per share	2	28	2	28

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense	$ 135	$ 59	$ 509	$ 263
Unrecognized tax benefits	$ 3,300		$ 3,300		$ 3,300

Geographic Information - Schedu

Geographic Information - Schedule of Total Revenue Based on Customer's Location (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total revenue	$ 53,689	$ 57,130	$ 113,975	$ 110,934
United States
Segment Reporting Information [Line Items]
Total revenue	28,636	31,345	59,292	60,945
Japan
Segment Reporting Information [Line Items]
Total revenue	8,406	10,954	21,485	21,838
Asia Pacific, excluding Japan
Segment Reporting Information [Line Items]
Total revenue	8,661	7,746	18,902	14,477
EMEA
Segment Reporting Information [Line Items]
Total revenue	6,786	5,860	11,994	10,927
Other
Segment Reporting Information [Line Items]
Total revenue	$ 1,200	$ 1,225	$ 2,302	$ 2,747