Overview and Basis of Presentation	6 Months Ended
Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview and Basis of Presentation	Overview and Basis of Presentation Organization Arista Networks, Inc. (together with our subsidiaries, “we,” “our” or “us”) is a supplier of cloud networking solutions that use software innovations to address the needs of large-scale Internet companies, cloud service providers and next-generation enterprises. Our cloud networking solutions consist of our Extensible Operating System, a set of network applications and our 10/40/100 Gigabit Ethernet switches. We were incorporated in October 2004 in the State of California under the name Arastra, Inc. In March 2008, we reincorporated in the State of Nevada and in October 2008 changed our name to Arista Networks, Inc. We reincorporated in the state of Delaware in March 2014. Our corporate headquarters are located in Santa Clara, California, and we have wholly-owned subsidiaries throughout the world, including North America, Europe, Asia and Australia. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (" U.S. GAAP") and following the requirements of the U.S. Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. In management’s opinion, the unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial information. The results for the three and six months ended June 30, 2015, are not necessarily indicative of the results expected for the full fiscal year. The condensed consolidated balance sheet as of December 31, 2014 has been derived from the audited consolidated financial statements at that date but does not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The accompanying unaudited condensed consolidated financial statements include the accounts of Arista Networks, Inc. and our wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and related footnotes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014, filed with the SEC on March 12, 2015 and our Amended Annual Report on Form 10-K/A for the fiscal year ended December 31, 2014, filed with the SEC on May 15, 2015. Commencing in the first quarter of fiscal 2015, we have disaggregated total revenue and cost of revenue into "Product" and "Service". Prior period balances have been reclassified to conform to this new presentation. There have been no changes in our significant accounting policies from those that were disclosed in our audited consolidated financial statements for the year ended December 31, 2014. Use of Estimates The preparation of the accompanying unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported and disclosed in the unaudited condensed consolidated financial statements and accompanying notes. Those estimates and assumptions include, but are not limited to, revenue recognition and deferred revenue; determination of fair value for stock-based awards; accounting for income taxes, including the valuation allowance on deferred tax assets and reserves for uncertain tax positions; valuation of inventory; valuation of warranty accruals; and the recognition and measurement of contingent liabilities. We evaluate our estimates and assumptions on an ongoing basis using historical experience and other factors and adjust those estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates, and those differences could be material to the unaudited condensed consolidated financial statements. Business Concentrations We work closely with third-party contract manufacturing suppliers to manufacture our products. As of June 30, 2015 and December 31, 2014, two suppliers provided essentially all of our electronic manufacturing services. Our contract manufacturing suppliers deliver our products to one of three third party direct fulfillment facilities where our EOS software is installed on our products. We and our fulfillment partners then perform labeling, final configuration, quality assurance testing and shipment to our customers. Our products rely on key components, including certain integrated circuit components and power supplies, some of which our contract manufacturers purchase on our behalf from a limited number of suppliers, including certain sole source providers. We do not have guaranteed supply contracts with any of our component suppliers, and our suppliers could delay shipments or cease manufacturing such products or selling them to us at any time. If we are unable to obtain a sufficient quantity of these components on commercially reasonable terms or in a timely manner, sales of our products could be delayed or halted entirely or we may be required to redesign our products. Quality or performance failures of our products or changes in our contractors’ or vendors’ financial or business condition could disrupt our ability to supply quality products to our customers. Any of these events could result in lost sales and damage to our end-customer relationships, which would adversely impact our business, financial condition and results of operations. Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, accounts receivable and notes receivable. Our cash and cash equivalents are invested in high quality financial instruments with banks and financial institutions. Such deposits may be in excess of insured limits provided on such deposits. 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 ongoing credit evaluations of our customers to assess the probability of accounts receivable collection based on a number of factors, including past transaction experience with the customer, evaluation of their credit history, the credit limits extended and review of the invoicing terms of the contract. We generally do not require our customers to provide collateral to support accounts receivable. We have recorded an allowance for doubtful accounts for those receivables that we have determined not to be collectible. We market and sell our products through both our direct sales force and our channel partners, including distributors, value-added resellers, system integrators, original equipment manufacturer (“OEM”) partners and in conjunction with various technology partners. Reclassifications We have reclassified deferred cost of revenue from inventories to other current assets as of June 30, 2015 as the balance does not represent property available for sale or used in the production process. Prior year balances have also been reclassified to conform to the current period presentation. Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue From Contracts With Customers, which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The new standard provides principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires significantly expanded disclosures about revenue recognition. In July 2015, the FASB deferred the effective date of the new revenue standard by one year. The standard is now effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2017. The guidance is effective for us for our first quarter of fiscal 2018. Early adoption would be permitted for all entities but not before the original public entity effective date. The standard permits the use of either the retrospective or cumulative effect transition method. The retrospective method requires a retrospective approach to each prior reporting period presented with the option to elect certain practical expedients as defined within the guidance. The cumulative approach requires a retrospective approach with the cumulative effect of initially applying the guidance recognized at the date of initial application and providing certain additional disclosures as defined per the guidance. We are currently reviewing the provisions of the standard and have not yet selected a transition method nor have we determined the effect of the standard on our consolidated financial statements. In April 2015, the FASB issued ASU No. 2015-05, Intangibles—Goodwill and Other—Internal-Use Software, which clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either run the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The guidance is effective for fiscal years beginning after December 15, 2015. The standard is effective for us for our first quarter of fiscal 2016. Early adoption is permitted. The guidance can be applied retrospectively to each prior reporting period presented or prospectively to arrangements entered into, or materially modified, after the effective date. We are currently assessing the impact this guidance may have on our consolidated financial statements as well as the transition method that we will use to adopt the guidance. In July 2015, the FASB issued ASU No, 2015-11, Inventory: Simplifying the Measurement of Inventory, which simplifies the measurement of inventory to be measured at the lower of cost or net realizable value. The guidance applies to inventory measured using First in First Out ("FIFO") or average cost. The guidance is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The standard is effective for us for our first quarter of fiscal 2017. The guidance can be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We are currently assessing the impact this guidance may have on our consolidated financial statements as well as the transition method that we will use to adopt the guidance.

Overview and Basis of Presentation

Organization

Arista Networks, Inc. (together with our subsidiaries, “we,” “our” or “us”) is a supplier of cloud networking solutions that use software innovations to address the needs of large-scale Internet companies, cloud service providers and next-generation enterprises. Our cloud networking solutions consist of our Extensible Operating System, a set of network applications and our 10/40/100 Gigabit Ethernet switches. We were incorporated in October 2004 in the State of California under the name Arastra, Inc. In March 2008, we reincorporated in the State of Nevada and in October 2008 changed our name to Arista Networks, Inc. We reincorporated in the state of Delaware in March 2014. Our corporate headquarters are located in Santa Clara, California, and we have wholly-owned subsidiaries throughout the world, including North America, Europe, Asia and Australia.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (" U.S. GAAP") and following the requirements of the U.S. Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. In management’s opinion, the unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial information. The results for the three and six months ended June 30, 2015, are not necessarily indicative of the results expected for the full fiscal year.

The condensed consolidated balance sheet as of December 31, 2014 has been derived from the audited consolidated financial statements at that date but does not include all of the information and notes required by generally accepted accounting principles for complete financial statements.

The accompanying unaudited condensed consolidated financial statements include the accounts of Arista Networks, Inc. and our wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated.

The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and related footnotes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014, filed with the SEC on March 12, 2015 and our Amended Annual Report on Form 10-K/A for the fiscal year ended December 31, 2014, filed with the SEC on May 15, 2015.

Commencing in the first quarter of fiscal 2015, we have disaggregated total revenue and cost of revenue into "Product" and "Service". Prior period balances have been reclassified to conform to this new presentation.

There have been no changes in our significant accounting policies from those that were disclosed in our audited consolidated financial statements for the year ended December 31, 2014.

Use of Estimates

The preparation of the accompanying unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported and disclosed in the unaudited condensed consolidated financial statements and accompanying notes. Those estimates and assumptions include, but are not limited to, revenue recognition and deferred revenue; determination of fair value for stock-based awards; accounting for income taxes, including the valuation allowance on deferred tax assets and reserves for uncertain tax positions; valuation of inventory; valuation of warranty accruals; and the recognition and measurement of contingent liabilities. We evaluate our estimates and assumptions on an ongoing basis using historical experience and other factors and adjust those estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates, and those differences could be material to the unaudited condensed consolidated financial statements.

Business Concentrations

We work closely with third-party contract manufacturing suppliers to manufacture our products. As of June 30, 2015 and December 31, 2014, two suppliers provided essentially all of our electronic manufacturing services. Our contract manufacturing suppliers deliver our products to one of three third party direct fulfillment facilities where our EOS software is installed on our products. We and our fulfillment partners then perform labeling, final configuration, quality assurance testing and shipment to our customers. Our products rely on key components, including certain integrated circuit components and power supplies, some of which our contract manufacturers purchase on our behalf from a limited number of suppliers, including certain sole source providers. We do not have guaranteed supply contracts with any of our component suppliers, and our suppliers could delay shipments or cease manufacturing such products or selling them to us at any time. If we are unable to obtain a sufficient quantity of these components on commercially reasonable terms or in a timely manner, sales of our products could be delayed or halted entirely or we may be required to redesign our products. Quality or performance failures of our products or changes in our contractors’ or vendors’ financial or business condition could disrupt our ability to supply quality products to our customers. Any of these events could result in lost sales and damage to our end-customer relationships, which would adversely impact our business, financial condition and results of operations.

Concentrations of Credit Risk

Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, accounts receivable and notes receivable. Our cash and cash equivalents are invested in high quality financial instruments with banks and financial institutions. Such deposits may be in excess of insured limits provided on such deposits.

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 ongoing credit evaluations of our customers to assess the probability of accounts receivable collection based on a number of factors, including past transaction experience with the customer, evaluation of their credit history, the credit limits extended and review of the invoicing terms of the contract. We generally do not require our customers to provide collateral to support accounts receivable. We have recorded an allowance for doubtful accounts for those receivables that we have determined not to be collectible.

We market and sell our products through both our direct sales force and our channel partners, including distributors, value-added resellers, system integrators, original equipment manufacturer (“OEM”) partners and in conjunction with various technology partners.

Reclassifications

We have reclassified deferred cost of revenue from inventories to other current assets as of June 30, 2015 as the balance does not represent property available for sale or used in the production process. Prior year balances have also been reclassified to conform to the current period presentation.

Recent Accounting Pronouncements

In May 2014, the FASB issued ASU No. 2014-09, Revenue From Contracts With Customers, which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The new standard provides principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires significantly expanded disclosures about revenue recognition. In July 2015, the FASB deferred the effective date of the new revenue standard by one year. The standard is now effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2017. The guidance is effective for us for our first quarter of fiscal 2018. Early adoption would be permitted for all entities but not before the original public entity effective date. The standard permits the use of either the retrospective or cumulative effect transition method. The retrospective method requires a retrospective approach to each prior reporting period presented with the option to elect certain practical expedients as defined within the guidance. The cumulative approach requires a retrospective approach with the cumulative effect of initially applying the guidance recognized at the date of initial application and providing certain additional disclosures as defined per the guidance. We are currently reviewing the provisions of the standard and have not yet selected a transition method nor have we determined the effect of the standard on our consolidated financial statements.

In April 2015, the FASB issued ASU No. 2015-05, Intangibles—Goodwill and Other—Internal-Use Software, which clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either run the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The guidance is effective for fiscal years beginning after December 15, 2015. The standard is effective for us for our first quarter of fiscal 2016. Early adoption is permitted. The guidance can be applied retrospectively to each prior reporting period presented or prospectively to arrangements entered into, or materially modified, after the effective date. We are currently assessing the impact this guidance may have on our consolidated financial statements as well as the transition method that we will use to adopt the guidance.

In July 2015, the FASB issued ASU No, 2015-11, Inventory: Simplifying the Measurement of Inventory, which simplifies the measurement of inventory to be measured at the lower of cost or net realizable value. The guidance applies to inventory measured using First in First Out ("FIFO") or average cost. The guidance is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The standard is effective for us for our first quarter of fiscal 2017. The guidance can be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We are currently assessing the impact this guidance may have on our consolidated financial statements as well as the transition method that we will use to adopt the guidance.