Arista Networks (ANET) 10-K 12 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 06, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	Arista Networks, Inc.
Entity Central Index Key	1596532
Trading Symbol	ANET
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$1,702,757,925
Entity Common Stock, Shares Outstanding		66,244,550

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
CURRENT ASSETS:
Cash and cash equivalents	$240,031	$113,664
Marketable securities	209,426	0
Accounts receivable, net of allowances of $3,094 and $2,339, respectively	96,982	77,999
Inventories	80,519	67,094
Deferred tax assets	12,252	12,356
Prepaid expenses and other current assets	40,269	7,653
Investments	0	4,000
Total current assets	679,479	282,766
Property and equipment, net	71,558	67,204
Deferred tax assets	11,510	4,541
Investments, non-current	36,636	0
Other assets	11,840	10,009
TOTAL ASSETS	811,023	364,520
CURRENT LIABILITIES:
Accounts payable	32,428	20,111
Accrued liabilities	40,369	21,539
Deferred revenue	60,327	41,306
Convertible notes payable, related party	0	24,743
Accrued interest payable, related party	0	4,484
Convertible notes payable	0	74,050
Accrued interest payable	0	12,967
Other current liabilities	11,249	10,144
Total current liabilities	144,373	209,344
Income taxes payable	17,323	14,716
Lease financing obligations, non-current	42,547	43,152
Deferred revenue, non-current	46,141	17,598
Other long-term liabilities	4,981	1,978
TOTAL LIABILITIES	255,365	286,788
Commitments and contingencies (Note 6)
STOCKHOLDERS’ EQUITY:
Preferred stock	0	0
Common stock, $0.0001 par value—1,000,000 and 176,000 shares authorized as of December 31, 2014 and December 31, 2013; 65,528 and 31,927 shares issued and outstanding as of December 31, 2014 and December 31, 2013	7	3
Additional paid-in capital	426,171	28,737
Retained earnings	129,814	42,964
Accumulated other comprehensive income (loss)	-334	36
TOTAL STOCKHOLDERS’ EQUITY	555,658	77,732
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	811,023	364,520
Convertible Preferred Stock
STOCKHOLDERS’ EQUITY:
Preferred stock	$0	$5,992

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Allowances	$3,094	$2,339
Preferred stock, par value (in dollars per share)	$0.00
Preferred stock, shares authorized (in shares)	100,000,000	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized (in shares)	1,000,000,000	176,000,000
Common stock, shares issued (in shares)	65,528,000	31,927,000
Common stock, shares outstanding (in shares)	65,528,000	31,927,000
Convertible Preferred Stock
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized (in shares)	0	24,000,000
Preferred stock, shares issued (in shares)	0	24,000,000
Preferred stock, shares outstanding (in shares)	0	24,000,000
Preferred stock, aggregate liquidation preference	$0	$6,000

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue	$584,106	$361,224	$193,408
Cost of revenue	192,015	122,686	61,252
Gross profit	392,091	238,538	132,156
Operating expenses:
Research and development	148,909	98,587	55,155
Sales and marketing	85,338	55,115	28,603
General and administrative	32,331	18,688	8,501
Total operating expenses	266,578	172,390	92,259
Income from operations	125,513	66,148	39,897
Other income (expense), net:
Interest expense—related party	-782	-1,739	-1,735
Interest expense	-5,498	-5,380	-5,322
Other income (expense), net	2,275	-754	135
Total other income (expense), net	-4,005	-7,873	-6,922
Income before provision for income taxes	121,508	58,275	32,975
Provision for income taxes	34,658	15,815	11,626
Net income	86,850	42,460	21,349
Net income attributable to common stockholders:
Basic	68,889	20,777	9,622
Diluted	$70,524	$21,780	$9,662
Net income per share attributable to common stockholders:
Basic (in dollars per share)	$1.42	$0.76	$0.39
Diluted (in dollars per share)	$1.29	$0.72	$0.39
Weighted-average shares used in computing net income per share attributable to common stockholders:
Basic (in shares)	48,427	27,320	24,711
Diluted (in shares)	54,590	30,051	24,901

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$86,850	$42,460	$21,349
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	-217	-2	4
Change in net unrealized loss on available-for-sale securities	-153	0	0
Other comprehensive income (loss)	-370	-2	4
Comprehensive income	$86,480	$42,458	$21,353

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Convertible notes payable	Convertible Preferred Stock	Preferred Stock	Preferred Stock	Common Stock	Common Stock	Common Stock	Additional Paid-In Capital	Additional Paid-In Capital	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income
In Thousands, except Share data, unless otherwise specified	USD ($)	USD ($)	USD ($)	USD ($)	Convertible Preferred Stock	USD ($)	Convertible notes payable	Convertible Preferred Stock	USD ($)	Convertible notes payable	Convertible Preferred Stock	USD ($)	USD ($)
					USD ($)			USD ($)		USD ($)	USD ($)
Beginning balance at Dec. 31, 2011	($8,194)			$5,992		$3			$6,622			($20,845)	$34
Beginning balance (in shares) at Dec. 31, 2011				24,000,000		29,788,120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,349											21,349
Other comprehensive income, net of tax	4												4
Tax benefit for equity incentive plans	39								39
Stock-based compensation	4,703								4,703
Vesting of stock options and restricted stock	861								861
Exercise of stock options (in shares)						498,490
Exercise of stock options, net of repurchases	104								104
Exercise of stock purchase rights (in shares)						20,000
Exercise of stock purchase rights	44								44
Ending balance at Dec. 31, 2012	18,910			5,992		3			12,373			504	38
Ending balance (in shares) at Dec. 31, 2012				24,000,000		30,306,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	42,460											42,460
Other comprehensive income, net of tax	-2												-2
Tax benefit for equity incentive plans	552								552
Stock-based compensation	10,159								10,159
Vesting of stock options and restricted stock	4,041								4,041
Exercise of stock options (in shares)						1,600,245
Exercise of stock options, net of repurchases	1,453								1,453
Exercise of stock purchase rights (in shares)						21,250
Exercise of stock purchase rights	159								159
Ending balance at Dec. 31, 2013	77,732			5,992		3			28,737			42,964	36
Ending balance (in shares) at Dec. 31, 2013				24,000,000		31,927,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	86,850											86,850
Other comprehensive income, net of tax	-370												-370
Tax benefit for equity incentive plans	17,358								17,358
Stock-based compensation	27,619								27,619
Exercise of stock options (in shares)	1,349,000
Issuance of common stock from initial public offering, net of offering costs (in shares)						6,038,000
Issuance of common stock from initial public offering, net of offering costs	239,055					1			239,054
Shares issued upon conversion (in shares)					-24,000,000		1,543,000	24,000,000
Conversion of convertible preferred stock and notes payable into common stock upon initial public offering		66,338	0		-5,992			3		66,338	5,989
Conversion of notes payable and accrued interest, related party, into common stock upon initial public offering (in shares)							701,000
Conversion of notes payable and accrued interest, related party, into common stock upon initial public offering		30,153								30,153
Vesting of stock options and restricted stock	4,095								4,095
Exercise of stock options, net of repurchases (in shares)						1,319,000
Exercise of stock options, net of repurchases	6,828								6,828
Ending balance at Dec. 31, 2014	$555,658			$0		$7			$426,171			$129,814	($334)
Ending balance (in shares) at Dec. 31, 2014				0		65,528,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$86,850	$42,460	$21,349
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,021	5,044	1,779
Stock-based compensation	27,619	10,159	4,703
Deferred income taxes	-6,774	-8,831	-3,722
Provision for bad debts	860	191	326
Realized gain on notes receivable	-4,000	0	0
Amortization of debt discount	527	1,118	1,040
Write-off of debt discount on notes payable	680	0	0
Excess tax benefit on stock based-compensation	-17,436	-882	-95
Other	348	0	0
Changes in operating assets and liabilities:
Accounts receivable	-19,844	-28,289	-22,043
Inventories	-13,425	-49,179	-7,153
Prepaid expenses and other current assets	-32,616	2,981	-5,009
Other assets	-4,261	-305	-173
Accounts payable	14,007	3,865	3,842
Accrued liabilities	18,874	11,967	6,544
Deferred revenue	47,564	34,127	13,451
Interest payable	-1,630	4,501	4,512
Interest payable—related party	670	1,500	1,504
Income taxes payable	4,377	2,141	4,914
Other liabilities	2,105	2,080	537
Net cash provided by operating activities	114,516	34,648	26,306
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	-13,134	-20,316	-3,312
Purchases of marketable securities	-210,019	0	0
Proceeds from repayment of notes receivable	8,000	1,000	0
Change in restricted cash	4,040	0	-4,040
Other investing activities	-38,249	-175	-5,000
Net cash used in investing activities	-249,362	-19,491	-12,352
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from initial public offering, net of issuance cost	239,315	0	0
Repayment on notes payable	-20,000	0	0
Principal payments of lease financing obligations	-793	0	0
Proceeds from issuance of common stock upon exercising options, net of repurchases	25,379	9,004	3,882
Excess tax benefit on stock-based compensation	17,436	882	95
Net cash provided by financing activities	261,337	9,886	3,977
Effect of exchange rate changes	-124	-34	-1
NET INCREASE IN CASH AND CASH EQUIVALENTS	126,367	25,009	17,930
CASH AND CASH EQUIVALENTS—Beginning of period	113,664	88,655	70,725
CASH AND CASH EQUIVALENTS—End of period	240,031	113,664	88,655
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes	44,770	16,806	15,114
Cash paid for interest— notes payable	3,639	0	0
Cash paid for interest— lease financing obligation	2,809	0	0
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Increase in accounts payable and accrued liabilities related to property and equipment	1,240	2,668	886
Acquisition of building with financing obligation	456	18,718	25,253
Unpaid deferred offering costs	261	0	0
Convertible Notes Payable
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Conversion of stock upon initial public offering	66,338	0	0
Convertible notes payable—related party
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Conversion of stock upon initial public offering	30,153	0	0
Preferred Stock
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Conversion of stock upon initial public offering	$5,992	$0	$0

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Summary of Significant Accounting Policies

Organization and Summary Significant Accounting Policies

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 enterprise. 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.

Initial Public Offering

On June 6, 2014, we completed our initial public offering (the “IPO”) in which we sold 6,037,500 shares of our common stock at a public offering price of $43.00 per share, which included 787,500 shares of common stock issued pursuant to the exercise in full of the over-allotment option granted to the underwriters. The IPO resulted in proceeds of $239.1 million, net of underwriting discounts and commissions of $15.6 million and other issuance costs of $5.0 million. In connection with the closing of the IPO, all of our outstanding convertible preferred stock automatically converted into 24,000,000 shares of common stock on a one-to-one basis.

Upon the closing of our IPO, all noteholders with the exception of one noteholder converted the principal and accrued interest amount outstanding under their subordinated convertible promissory notes into shares of our common stock at the IPO price of $43.00 per share. The noteholder, who did not elect to so convert, was paid a total of $23.6 million which included principal and accrued interest less applicable withholding taxes of $1.1 million. The remainder of the noteholders converted the remaining debt balance of approximately $96.5 million including principal and accrued interest into 2.2 million shares of our common stock.

Basis of Presentation

The accompanying consolidated financial statements include the accounts of Arista Networks, Inc. and our wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated. Our consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP).

Use of Estimates

The preparation of the accompanying consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes. Those estimates and assumptions include, but are not limited to, revenue recognition and deferred revenue; allowance for doubtful accounts and sales return reserve; 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 consolidated financial statements.

Consolidation of Variable Interest Entities

We use a qualitative approach in assessing the consolidation requirement for variable interest entities (VIEs). This approach focuses on determining whether we have the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance and whether we have the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the VIE. For all periods presented in the accompanying consolidated financial statements, we have determined that we are not the primary beneficiary of any VIEs. However, in the event that we are the primary beneficiary of a VIE entity, the assets, liabilities, and results of operations of the VIE will be included in our consolidated financial statements.

Business Concentrations

We work closely with third parties to manufacture and deliver our products. As of December 31, 2014 and 2013, two suppliers provided all of our electronic manufacturing services. 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, restricted cash, accounts receivable and notes receivable. Our cash, cash equivalents and restricted cash 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. Our notes receivable are secured and represent amounts due to us from a private company. We mitigate credit risk in respect to the notes receivable by performing ongoing credit evaluations of the borrower to assess the probability of collecting all amounts due to us under the existing contractual terms.

We market and sell our products through both our direct sales force and our channel partners, including distributors, value-added resellers, system integrators and original equipment manufacturer (“OEM”) partners. Significant customers are those which represent more than 10% of our total net revenue during the period or net accounts receivable balance at each respective balance sheet date. For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:

Revenue

Accounts Receivable

Year Ended December 31,

December 31,

Customers

2014

2013

2012

2014

2013

Customer A

15

%

22

%

15

%

15

%

17

%

Customer B

*

*

*

*

11

%

*less than 10%

Reclassifications

As a result of a change in classification, we have reclassified our spare parts inventory from inventory to other current and non-current assets as of December 31, 2014. Spare parts inventory are used to satisfy our warranty obligations, and are not available for sale or used in the production process. Prior year balances have been adjusted to conform to this new classification for comparability purposes.

Comprehensive Income

Comprehensive income is comprised of net income and other comprehensive income. Unrealized gains and losses on available-for-sale investments and foreign currency translation adjustments are included in our other comprehensive income or loss.

Cash and Cash Equivalents

We consider all highly liquid investments with stated maturity of three months or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of cash on deposit with various financial institutions and highly liquid investments in money market funds. Interest is accrued as earned.

Marketable Securities

We invest our excess cash primarily in money market and highly liquid debt instruments of the U.S. government. We classify all highly liquid investments with stated maturities of greater than three months as marketable securities. We determine the appropriate classification of our investments in marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified and accounted for our marketable securities as available-for-sale. We may or may not hold securities with stated maturities greater than 12 months until maturity. After consideration of our risk versus reward objectives, as well as our liquidity requirements, we may sell these securities prior to their stated maturities. As we view these securities as available to support current operations, we classify securities with maturities beyond 12 months as current assets under the caption marketable securities in the accompanying consolidated balance sheets. We carry these securities at fair value, and report the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be other-than-temporary, which we record as other income (expense), net. We determine any realized gains or losses on the sale of marketable securities on a specific identification method, and we record such gains and losses as a component of interest and other income, net.

Fair Value Measurements

Our assets and liabilities which require fair value measurement consist of cash and cash equivalents, restricted cash, marketable securities, accounts receivable, investments, accounts payable, accrued liabilities and convertible notes payable. Cash equivalents, restricted cash, accounts receivable, accounts payable and accrued liabilities are stated at carrying amounts as reported in the consolidated financial statements, which approximates fair value due to their short term nature. For certain investments where we have elected the fair value option, these investments are stated at fair value. The carrying amounts of our convertible notes payable approximate fair value as the stated interest rates approximate market rates currently available to us.

Assets and liabilities recorded at fair value on a recurring basis in the accompanying consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of the inputs used to measure fair value instruments as follows:

Level I—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level II—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level III—Unobservable inputs that are supported by little or no market data for the related assets or liabilities and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Our financial instruments consist of Level I and Level III assets. Level I assets include highly liquid money market funds that are included in cash and cash equivalents and U.S. government notes classified as marketable securities. Level III assets that were measured on a recurring basis consisted solely of our notes receivable. We classified the notes receivable as Level III, as we used unobservable inputs to the valuation methodology that were significant to the fair value measurement, and the valuation required management judgment due to the absence of quoted market prices. We measured the fair value for certain investments based upon the probability-weighted present value of expected future investment returns, considering each of the possible future outcomes available to us. The significant unobservable inputs used in the fair value measurement of the convertible notes are the scenario probabilities and the discount rate estimated at the valuation date. Generally, increases (decreases) in the discount rate would result in a directionally opposite impact to the fair value measurement of the notes. Also, changes in the probability scenarios would have had varying impacts depending on the weighting of each specific scenario. More weighting towards a change in control or an equity financing by the investee would result in an increase in fair value of the notes receivable.

Restricted Cash

We had restricted cash pledged as collateral representing a security deposit required for a facility lease. As of December 31, 2013, we had classified the restricted cash of $4.0 million as other assets in our accompanying consolidated balance sheet. We did not have any restricted cash as of December 31, 2014.

Foreign Currency

The functional currency of our foreign subsidiaries is either the U.S. dollar or their local currency.

Transaction re-measurement-Assets and liabilities denominated in a currency other than the foreign subsidiaries’ functional currency are re-measured into the functional currency using exchange rates in effect at the end of the reporting period, with gains and losses recorded in other income (expense), net in the consolidated statements of income. We recognized $0.6 million, $0.1 million and $0.2 million in transaction losses for the years ended December 31, 2014, 2013 and 2012, respectively.

Translation-Assets and liabilities of subsidiaries denominated in foreign functional currencies are translated into U.S. dollars at the closing exchange rate on the balance sheet date and equity related balances are translated at historical exchange rates. Revenues, costs and expenses in foreign functional currencies are translated using average exchange rates that approximate those in effect during the period. Translation adjustments are accumulated as a separate component of accumulated other comprehensive income within stockholders’ equity (deficit).

Accounts Receivable, Allowance for Doubtful Accounts, and Sales Return Reserves

Accounts receivable are recorded at the invoiced amount, net of allowances for doubtful accounts, and sales return reserves. We estimate our allowance for doubtful accounts based upon the collectability of the receivables in light of historical trends, adverse situations that may affect our customers’ ability to pay and prevailing economic conditions. This evaluation is done in order to identify issues which may impact the collectability of receivables and related estimated required allowance. Revisions to the allowance are recorded as an adjustment to bad debt expense. After appropriate collection efforts are exhausted, specific accounts receivable deemed to be uncollectible are charged against the allowance in the period they are deemed uncollectible. Recoveries of accounts receivable previously written-off are recorded as credits to bad debt expense. We estimate our sales return reserves based on historical return rates applied against current period gross revenues. Specific customer returns and allowances are considered when determining our sales return reserve estimate. Revisions to the reserve are recorded as adjustments to revenue and the sales return reserves.

We mitigate credit risk in respect to accounts receivable by performing ongoing credit evaluations of our customers and channel partners to assess the probability of accounts receivable collection based on a number of factors, including past transaction experience with the customer or channel partner, evaluation of credit history, the credit limits extended and review of the invoicing terms of the arrangement. In situations where a partner or customer may be thinly capitalized and we have limited payment history with it, we will either establish a small credit limit or require it to prepay their purchases.

Inventories

Inventories primarily consist finished goods purchased from third party contract manufacturers and are stated at the lower of cost (computed using the first-in, first-out method) or market value. Manufacturing overhead costs and inbound shipping costs are included in the cost of inventory. In addition, we also purchase certain strategic component inventory, including integrated circuits which are consigned to our contract manufacturers. We record a provision when inventory is determined to be in excess of anticipated demand, or obsolete, to adjust inventory to its estimated realizable value. For the years ended December 31, 2014, 2013 and 2012, we incurred inventory write-downs of $2.8 million, $5.3 million and $3.2 million, respectively.

We outsource most of our manufacturing and supply chain management operations to two third-party contract manufacturers and as a result, a significant portion of our cost of revenue consists of payments to them. Our third-party contract manufacturers purchase and own a portion of the material used to build our switch products until they are shipped to us, at which time our third-party contract manufacturers invoice us. In addition, we also purchase certain strategic component inventory, including integrated circuits which are consigned to our third-party contract manufacturers. As of December 31, 2014 and 2013, our strategic component inventory consigned to others was $17.1 million and $18.3 million, respectively, and are included in raw materials.

Our finished goods inventory consists of our finished switch products and accessories. This inventory is located principally at third-party direct fulfillment facilities in California, the Netherlands and Singapore.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method over the shorter of the estimated useful lives of the related assets, generally from one to five years, 30 years for buildings or the lease term for leasehold improvements. The leased building under our build to suit lease is capitalized and included in property and equipment as we were involved in the construction funding and did not meet the “sale-leaseback” criteria.

Investments

Investments in Privately-held Companies

In 2014, we have equity investments in privately-held companies. Our investments are accounted for under the cost method and are included in investments, non-current in the accompanying consolidated balance sheets. Initial measurement of our investments under the cost method were recorded at historical cost which represents our initial investment in the privately-held companies.  We will periodically assess and evaluate our cost method investments for impairment and perform an assessment based on evaluation of overall financial performance, industry and market conditions, and other relevant events or factors deemed necessary that may affect carrying value. If we determine that a decrease in the equity investments should be recognized given impairment that is considered “other-than-temporary” in nature, we will write-down the carrying amount to its revised new fair value.

Notes Receivable

In 2014, we also entered into an unsecured promissory note with a privately held company which was recorded at cost.

In 2012, we entered into secured note purchase agreements with a private company to provide them with cash advances. We elected the fair value option to account for these investments and recorded unrealized gains and losses in earnings at each subsequent reporting date. Accordingly, these notes receivable were remeasured to fair value at the end of each reporting period. Upfront costs and fees incurred in conjunction with entering into notes receivable were expensed and recognized in earnings as incurred. Gains and losses from the change in fair value, as well as interest income, were recorded in other income (expense), net in the accompanying consolidated statements of income at each reporting period. In 2014, we received payment in full from the borrower equal to two times our outstanding principal balance as well as the unpaid accrued interest through the payment date.

Impairment of Long-Lived Assets and Investments

The carrying amounts of our long-lived assets, including property and equipment and investments in privately-held companies, are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows the asset is expected to generate over their remaining lives. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired asset. No impairment of any long-lived assets was identified for any of the periods presented.

Revenue Recognition

We generate revenue from sales of switching products which incorporate our EOS software and accessories such as cables and optics to direct customers and channel partners together with post contract customer support (“PCS”). We typically sell products and PCS in a single transaction. We recognize revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery or performance has occurred; the sales price is fixed or determinable; and collectability is reasonably assured.

We define each of the four criteria above as follows:

•

Persuasive evidence of an arrangement exists. Evidence of an arrangement consists of stand-alone purchase orders or purchase orders issued pursuant to the terms and conditions of a master sales agreement. It is our practice to identify an end customer prior to shipment to a reseller or distributor.

•

Delivery or performance has occurred. We use shipping documents or written evidence of customer acceptance, when applicable, to verify delivery or performance. We recognize product revenue upon transfer of title and risk of loss, which primarily is upon shipment to customers. We do not have significant obligations for future performance, such as customer acceptance provisions, rights of return or pricing credits, associated with our product sales. In instances where substantive acceptance provisions are specified in the customer arrangement, revenue is deferred until all acceptance criteria have been met.

•

The sales price is fixed or determinable. We assess whether the sales price is fixed or determinable based on payment terms and whether the sales price is subject to refund or adjustment.

•

Collectability is reasonably assured. We assess probability of collectability on a customer-by-customer basis. Our customers and channel partners are subjected to a credit review process that evaluates their financial condition and ability to pay for products and services.

PCS is offered under renewable, fee-based contracts, which includes technical support, hardware repair and replacement parts beyond standard warranty, bug fixes, patches and unspecified upgrades on a when-and-if-available basis. We initially defer PCS revenue and recognize it ratably over the life of the PCS contract, with the related expenses recognized as incurred. PCS contracts usually have a term of one to three years. We include billed but unearned PCS revenue in deferred revenue.

We report revenue net of sales taxes. We include shipping charges billed to customers in revenue and the related shipping costs are included in cost of goods sold.

Multiple-Element Arrangements

Most of our arrangements, other than renewals of PCS, are multiple element arrangements with a combination of products and PCS. Products and PCS generally qualify as separate units of accounting. Our hardware deliverables include EOS software, which together deliver the essential functionality of our products. For multiple element arrangements, we allocate revenue to each unit of accounting based on the relative selling price. The relative selling price for each element is based upon the following hierarchy: vendor-specific objective evidence (“VSOE”), if available; third-party evidence (“TPE”), if VSOE is not available; and best estimate of selling price (“BESP”), if neither VSOE nor TPE is available. As we have not been able to establish VSOE or TPE for our products and most of our services, we generally utilize BESP for the purposes of allocating revenue to each unit of accounting.

•

VSOE—We determine VSOE based on our historical pricing and discounting practices for the specific products and services when sold separately. In determining VSOE, we require that a substantial majority of the stand-alone selling prices fall within a reasonably narrow pricing range.

•

TPE—When VSOE cannot be established for deliverables in multiple-element arrangements, we apply judgment with respect to whether we can establish a selling price based on TPE. TPE is determined based on competitor prices for interchangeable products or services when sold separately to similarly situated customers. However, as our products contain a significant element of proprietary technology and offer substantially different features and functionality, the comparable pricing of products with similar functionality typically cannot be obtained. Additionally, as we are unable to reliably determine what competitors products’ selling prices are on a stand-alone basis, we are not able to obtain reliable evidence of TPE of selling price.

•

BESP—When we are unable to establish selling price using VSOE or TPE, we use BESP in our allocation of arrangement consideration. The objective of BESP is to determine the price at which we would transact a sale if the product or service was sold regularly on a stand-alone basis. BESP is based on considering multiple factors including, but not limited to the sales channel (reseller, distributor or end customer), the geographies in which our products and services were sold (domestic or international) and size of the end customer.

We limit the amount of revenue recognition for delivered elements to the amount that is not contingent on the future delivery of products or services, future performance obligations, or subject to customer-specific return, acceptance or refund privileges.

We account for multiple agreements with a single partner as one arrangement if the contractual terms and/or substance of those agreements indicate that they may be so closely related that they are, in effect, parts of a single arrangement.

We may occasionally accept returns to address customer satisfaction issues even though there is no contractual provision for such returns. We estimate returns for sales to customers based on historical returns rates applied against current-period gross revenues. Specific customer returns and allowances are considered when determining our sales return reserve estimate.

Research and Development Expenses

Costs related to the research, design and development of our products are charged to research and development expenses as incurred. Software development costs are capitalized beginning when a product’s technological feasibility has been established and ending when the product is available for general release to customers. Generally, our products are released soon after technological feasibility has been established. As a result, costs incurred subsequent to achieving technological feasibility have not been significant and accordingly, all software development costs have been expensed as incurred.

Warranty

We offer a one-year warranty on all of our hardware products and a 90-day warranty against defects in the software embedded in the products. We accrue for potential warranty claims at the time of shipment as a component of cost of revenues based on historical experience and other relevant information. We accrue specifically identified reserves if and when we determine we have a systemic product failure. The accrued warranty liability is recorded in accrued liabilities in the accompanying consolidated balance sheets.

Post-Employment Benefits

We have a 401(k) Plan that covers substantially all of our employees in the U.S. For the years ended December 31, 2014, 2013 and 2012, we did not provide a discretionary company match to employee contributions.

Segment Reporting

Our chief operating decision maker is our Chief Executive Officer. Our Chief Executive Officer reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. We have one business activity and there are no segment managers who are held accountable for operations or operating results. Accordingly, we have determined that we operate as one reportable segment.

Stock-Based Compensation

We recognize stock-based compensation for stock-based awards, including stock options, restricted stock units (RSUs), restricted stock awards (“RSAs”), stock purchase rights from our employee stock purchase program based on the estimated fair value of the awards, net of estimated forfeitures. The fair value of each stock-based award and option is estimated on the grant date using the Black-Scholes option-pricing model. This model requires that at the date of grant we determine the fair value of the underlying common stock, the expected term of the award, the expected volatility of the price of our common stock, risk-free interest rates, and expected dividend yield of our common stock. RSUs are measured based on the fair market values of the underlying stock on the dates of grant.

The stock-based compensation expense, net of forfeitures, is recognized on a straight-line basis over the requisite service periods of the awards, which is generally two to five years. We estimate a forfeiture rate to calculate the stock-based compensation for our awards. Our forfeiture rate is based on an analysis of our actual historical forfeitures.

Excess tax benefits associated with stock option exercises and other equity awards are recognized in additional paid in capital. The income tax benefits resulting from stock awards that were credited to stockholders' equity were $17.4 million, $0.6 million and $39,000 for the years ended December 31, 2014, 2013 and 2012, respectively.

Income Taxes

We account for income taxes under the liability approach for deferred income taxes, which requires recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been recognized in our consolidated financial statements, but have not been reflected in our taxable income. Estimates and judgments occur in the calculation of certain tax liabilities and in the determination of the recoverability of certain deferred income tax assets, which arise from temporary differences and carryforwards. Deferred income tax assets and liabilities are measured using the currently enacted tax rates that apply to taxable income in effect for the years in which those tax assets are expected to be realized or settled. We regularly assess the likelihood that our deferred income tax assets will be realized based on the positive and negative evidence available. We record a valuation allowance to reduce the deferred tax assets to the amount that we are more likely than not to realize.

We regularly review our tax positions and benefits to be realized. We recognize tax liabilities based upon our estimate of whether, and to the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. We recognize interest and penalties related to income tax matters as income tax expense.

Net Income per Share of Common Stock

Basic and diluted net income per share attributable to common stockholders is calculated in conformity with the two-class method required for participating securities. We considered our Series A convertible preferred stock to be participating securities. Under the two-class method, net income attributable to common stockholders is determined by allocating undistributed earnings, calculated as net income less current period convertible preferred stock non-cumulative dividends, among our common stock and convertible preferred stock. In computing diluted net income attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Shares of common stock subject to repurchase resulting from the early exercise of employee stock options are considered participating securities. Diluted net income per share attributable to common stockholders is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding, including potential dilutive common shares assuming the dilutive effect of outstanding stock options using the treasury stock method. For purposes of this calculation, convertible preferred stock and options to purchase shares of common stock are considered to be common stock equivalents and are excluded from the calculation of diluted net income per share of common stock if their effect is antidilutive. Convertible notes payable were excluded from the calculation of diluted net income per share since such notes were convertible to common stock at the option of the holder only upon the occurrence of a contingent event, including change in control, initial public offering or prepayment of the convertible notes.

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 standard is effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2016. Early application is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. 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.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	We measure and report our cash equivalents, restricted cash, available-for-sale marketable securities and notes receivable at fair value. The following table set forth the fair value of our financial assets by level within the fair value hierarchy (in thousands):
		December 31, 2014
		Level I		Level II		Level III		Total
	Financial Assets
	Cash and cash equivalents:
	Money market funds	$	104,216	$	—	$	—	$	104,216
	Marketable securities:
	U.S. government notes	209,426		—		—		209,426
	Total financial assets	$	313,642	$	—	$	—	$	313,642
		December 31, 2013
		Level I		Level II		Level III		Total
	Financial Assets
	Cash and cash equivalents:
	Money market funds	$	47,036	$	—	$	—	$	47,036
	Other assets—Restricted cash:
	Money market funds	4,040		—		—		4,040
	Investments:
	Notes receivable(1)	—		—		4,000		4,000
	Total financial assets	$	51,076	$	—	$	4,000	$	55,076
	(1) There were no changes in the fair value of the Level III assets during the year ended December 31, 2013. In 2014, we increased the fair value of our Notes receivable by $4.0 million (See “Note 4 – Investments”). During the year ended December 31, 2014 and 2013, we had no transfers between levels of the fair value hierarchy of its assets measured at fair value. In October 2014, we received payment in full from the borrower equal to two times our outstanding principal balance as well as the unpaid accrued interest through the payment date.

Balance_Sheet_Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2014
Balance Sheet Components [Abstract]
Balance Sheet Components	Balance Sheet Components
	Marketable Securities
	The following table summarizes the unrealized gains and losses and fair value of our available-for-sale marketable securities (in thousands):
		December 31, 2014
		Amortized Cost			Unrealized Gains			Unrealized Losses			Fair Value
	U.S. government notes	$	209,671		$	—		$	(245	)	$	209,426
	We did not realized any other-than-temporary losses on our marketable securities for the year ended December 31, 2014. None of our marketable securities have been in continuous unrealized loss positions for greater than twelve months as of December 31, 2014.
	We did not hold any marketable securities as of December 31, 2013.
	We invest in marketable securities that have maximum maturities of up to two years and are generally deemed to be low risk based on their credit ratings from the major rating agencies. The longer the duration of these marketable securities, the more susceptible they are to changes in market interest rates and bond yields. As interest rates increase, those marketable securities purchased at a lower yield show a mark-to-market unrealized loss. The unrealized losses are due primarily to changes in credit spreads and interest rates. We expect to realize the full value of all these investments upon maturity or sale.  The weighted average remaining duration of our current marketable securities is approximately 0.8 years as of December 31, 2014.
	The following table summarizes the amortized cost and fair value of our marketable securities as of December 31, 2014, by contractual years-to-maturity (in thousands):
		Amortized Cost			Fair Value
	Due within one year	$	209,671		$	209,426
	Accounts Receivable, net
	Accounts receivable, net consists of the following (in thousands):
		December 31,
		2014			2013
	Accounts receivable	$	100,076		$	80,338
	Allowance for doubtful accounts	(1,063		)	(810		)
	Product sales return reserve	(2,031		)	(1,529		)
	Accounts receivable, net	$	96,982		$	77,999
	Allowance for Doubtful Accounts
	Activity in the allowance for doubtful accounts consists of the following (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Balance at the beginning of year	$	810		$	1,284		$	1,169
	Charged to expenses	860			191			326
	Deductions (write-offs)	(607		)	(665		)	(211		)
	Balance at the end of year	$	1,063		$	810		$	1,284
	Sales Return Reserve
	Activity in the sales return reserve consists of the following (in thousands):
		Year Ended December 31,
		2014			2013
	Balance at the beginning of year	$	1,529		$	—
	Charged against revenue	4,063			1,627
	Sales returns	(3,561		)	(98		)
	Balance at the end of year	$	2,031		$	1,529
	Inventories
	Inventories consist of the following (in thousands):
		December 31,
		2014			2013
	Raw materials	$	17,094		$	18,286
	Finished goods	63,425			48,808
	Total inventories	$	80,519		$	67,094
	Prepaid Expenses and Other Current Assets
	Prepaid expenses and other current assets consists of the following (in thousands):
		December 31,
		2014			2013
	Prepaid income taxes	$	25,212		$	134
	Other current assets	9,820			5,137
	Other prepaid and deposits	5,237			2,382
	Total prepaid expenses and other current assets	$	40,269		$	7,653
	Property and Equipment, net
	Property and equipment, net consists of the following (in thousands):
		December 31,
		2014			2013
	Equipment and machinery	$	18,265		$	13,733
	Computer hardware and software	7,772			3,688
	Furniture and fixtures	1,373			1,352
	Leasehold improvements	19,420			19,407
	Building	35,154			35,154
	Construction-in-process	6,532			1,056
	Property and equipment, gross	88,516			74,390
	Less: accumulated depreciation	(16,958		)	(7,186		)
	Property and equipment, net	$	71,558		$	67,204
Building consists of capitalized construction costs of our leased building in Santa Clara, California. Based on the terms of the lease agreement and due to our involvement in certain aspects of the construction, such as our financial involvement in structural elements of asset construction, making decisions related to tenant improvement costs and purchasing insurance not reimbursable by the buyer-lessor (the Landlord), we were deemed the owner of the building (for accounting purposes only) during the construction period. We maintain continued involvement in the property after construction was completed and lack transferability of the risks and rewards of ownership, primarily due to our required maintenance of a $4.0 million letter of credit. Due to our continuing involvement in the property post construction and lack of transferability of related risks and rewards of ownership to the Landlord after construction is complete, we account for the building as a financing obligation. See “Note 6-Commitments and Contingencies”. Accordingly, as of December 31, 2014 and December 31, 2013, we have recorded assets of $53.4 million and $53.3 million, respectively, representing the total costs of the building and improvements incurred, including the costs paid by the Landlord. The building was completed in 2013.
Depreciation expense was $10.0 million, $5.0 million and $1.8 million for the years ended December 31, 2014, 2013 and 2012, respectively.
Accrued Liabilities
Accrued liabilities consist of the following (in thousands):
	December 31,
	2014			2013
Accrued payroll related costs	$	30,749		$	9,103
Accrued warranty costs	3,204			5,075
Accrued manufacturing costs	1,089			3,835
Accrued professional fees	2,354			1,220
Accrued taxes	1,577			927
Other	1,396			1,379
Total accrued liabilities	$	40,369		$	21,539
Warranty Accrual
The following table summarizes the activity related to our accrued liability for estimated future warranty costs (in thousands):
	Year Ended December 31,
	2014			2013
Warranty accrual, beginning of period	$	5,075		$	5,314
Liabilities accrued for warranties issued during the period	2,611			4,290
Warranty costs incurred during the period	(2,163		)	(4,529		)
Adjustments related to change in estimate	(2,319		)	—
Warranty accrual, end of period	$	3,204		$	5,075
During the year ended December 31, 2013, we identified specific products that were failing in the field prematurely at higher than expected rates due to various component issues. There were no significant specific product warranty reserves recorded in 2014.
Other Current Liabilities
Other current liabilities consist of the following (in thousands):
	December 31,
	2014			2013
Liability for early exercised shares subject to repurchase	$	4,616		$	7,520
Sales tax payable	3,101			1,359
Lease financing obligations, current portion	1,087			818
Other	2,445			447
Total other current liabilities	$	11,249		$	10,144

Investments

Investments	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Investments	Notes Receivable
	In 2014, we entered into a $3.0 million promissory note with a privately held company which was recorded at cost. The interest rate on the promissory note is 8.0% per annum and is payable quarterly. All unpaid principal and accrued interest on the promissory note is due and payable on the earlier of August 26, 2017, or upon default.
	In 2012, we made a loan of $4.0 million to a private company. The interest rate on the notes receivable was 6.0% per annum. The notes were convertible into the private company’s preferred stock or any securities exchangeable for the private company’s preferred stock. All unpaid principal and accrued interest on the notes receivable was due and payable on the earlier of August 31, 2014, or upon default.
	On July 30, 2014, the borrower signed a definitive agreement to close a Corporate Transaction through a merger (i.e. a transaction in which 50% of the voting power is transferred) and the transaction was expected to close in the first quarter of 2015. Pursuant to this transaction and per the terms of our agreement, we increased the value of our convertible notes receivable by $4.0 million to $8.0 million in the third quarter of 2014. In October 2014, we received payment in full from the borrower equal to two times our outstanding principal balance as well as the unpaid accrued interest through the payment date.
	In conjunction with the notes receivable, we also entered into an Exclusivity and Supply Agreement (“Supply Agreement”) with the borrower. Under the terms of the Supply Agreement, the borrower has agreed to develop and produce certain products for us at mutually agreed on supply terms and with best in class pricing rights to us. In addition, any exclusive features developed between us and the borrower cannot be sold by the borrower to other customers for 24 months following the commercial availability of such production versions. The Supply Agreement does not have a maturity date. We determined that the fair value of the Supply Agreement on its inception was insignificant as the borrower is still in the development stage and there is no certainty that a commercial product will be developed.
	We determined that we had a variable interest in the borrower through our notes receivable. However, we determined that we were not the primary beneficiary as we did not have the power to direct the borrower’s activities that most significantly affect the borrower’s economic performance. We also determined that our investment in the borrower was not an equity-method investment as the notes receivable had different risk and reward characteristics than those of the borrower’s common stock. We elected the fair value option method of accounting for our notes receivable.

Debt_Obligations

Debt Obligations	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations
	Our debt obligations consist of the following (in thousands):
		December 31,
		2013
	Convertible notes payable—related party	$	25,000
	Convertible notes payable	75,000
	Total	100,000
	Less: Unamortized discount on notes payable	1,207
	Less: Current portion	98,793
	Total long-term portion of debt	$	—
	In January 2011, we sold $55.0 million aggregate principal amount of subordinated convertible promissory notes (“Convertible Notes”) to outside investors and $25.0 million aggregate principal amount of Convertible Notes to two trusts that are related to two of our co-founders. In June 2011, we sold an additional $20.0 million in Convertible Notes to outside investors. The Convertible Notes were convertible into shares of our common stock upon a change of control, a qualified IPO, or immediately prior to when the notes are to be voluntarily prepaid. The interest rate on the Convertible Notes was 6.0% per annum, computed on the basis of the actual number of days elapsed and a year of 365 days. All unpaid principal and accrued interest on the Convertible Notes were due and payable on the earlier of December 31, 2014 or upon the occurrence of an event of default, defined as: (i) failure to pay principal or interest when due; (ii) breaches of covenants; (iii) breaches of representations and warranties; (iv) failure to make other payment obligations resulting in the acceleration of maturity of indebtedness in excess of $10.0 million; (v) voluntary bankruptcy; (vi) involuntary bankruptcy; or (vii) certain adverse judgments. We could have voluntarily prepaid the Convertible Notes, in whole or in part, before the maturity date by giving each investor 10 days’ prior written notice. We were also required to prepay the Convertible Notes upon a change of control unless the investor elected to convert its Convertible Note immediately prior to the closing of such change of control.
	Upon the closing of our IPO all noteholders with the exception of one noteholder converted the principal and accrued interest amount outstanding under their subordinated convertible promissory notes into shares of our common stock at the IPO price of $43.00 per share. The noteholder, who did not elect to so convert, was paid a total of $23.6 million which included principal and accrued interest less applicable withholding taxes of $1.1 million. The remainder of the noteholders converted the remaining debt balance of approximately $96.5 million including principal and accrued interest into 2.2 million shares of our common stock.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Operating Leases
	We lease various operating spaces in North America, Europe, Asia and Australia under non-cancelable operating lease arrangements that expire on various dates through 2023. 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.
	As of December 31, 2014, the aggregate future minimum payments under non-cancelable operating leases consist of the following (in thousands):
	Years Ending December 31,
	2015	$	2,583
	2016	4,297
	2017	5,155
	2018	5,378
	2019	5,369
	Thereafter	22,407
	Total minimum future lease payments	$	45,189
	Rent expense for all operating leases amounted to $3.3 million, $3.6 million and $2.0 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Financing Obligation—Build-to-Suit Lease
	In August 2012, we executed a lease for a building under construction in Santa Clara, California which will serve as our new headquarters. The lease term is 120 months and commenced in August 2013.
	Based on the terms of the lease agreement and due to our involvement in certain aspects of the construction such as our financial involvement in structural elements of asset construction, making decisions related to tenant improvement costs and purchasing insurance not reimbursable by the buyer-lessor (the Landlord), we were deemed the owner of the building (for accounting purposes only) during the construction period. We maintained continued involvement in the property after construction was completed and lack transferability of the risks and rewards of ownership, primarily due to our required maintenance of a $4.0 million letter of credit. Due to our continuing involvement in the property post construction and lack of transferability of related risks and rewards of ownership to the Landlord after construction was complete, we account for the building and related improvements as a lease financing obligation. Accordingly, as of December 31, 2014 and December 31, 2013, we have recorded assets of $53.4 million and $53.3 million, representing the total costs of the building and improvements incurred, including the costs paid by the lessor (the legal owner of the building) and additional improvement costs paid by us, and a corresponding financing obligation of $43.6 million and $44.0 million, respectively. As of December 31, 2014, $1.1 million and $42.5 million were recorded as short-term and long-term financing obligations, respectively.
	As of December 31, 2014, the future minimum payments due under the lease financing obligation were as follows (in thousands):
	Years Ending December 31,
	2015	$	5,588
	2016	5,754
	2017	5,933
	2018	6,113
	2019	6,293
	Thereafter	25,287
	Total payments	54,968
	Less: interest and land lease expense	(34,770		)
	Total payments under facility financing obligations	20,198
	Property reverting to landlord	23,436
	Present value of obligation	43,634
	Less current portion	(1,087		)
	Long-term portion of obligation	$	42,547
	Upon completion of construction in the third quarter of 2013, we evaluated the de-recognition of the asset and liability under the sale-leaseback accounting guidance. We concluded that we have forms of continued economic involvement in the facility, and therefore did not meet with the provisions for sale-leaseback accounting. Therefore, the lease is accounted for as a financing obligation and lease payments will be attributed to (1) a reduction of the principal financing obligation; (2) imputed interest expense; and (3) land lease expense (which is considered an operating lease and a component of cost of goods sold and operating expenses) representing an imputed cost to lease the underlying land of the building. In addition, the underlying building asset is depreciated over the building’s estimated useful life of 30 years. At the conclusion of the initial lease term, we will de-recognize both the net book values of the asset and the remaining financing obligation.
	Purchase Commitments
	Our products are manufactured, assembled and tested by third-party contract manufacturers in Asia who procure components and assemble products on our behalf based on our forecasts. These forecasts are based on estimates of future demand for our products, historical trend analysis provided by our sales and product marketing organizations and adjusted for overall market conditions. In order to reduce manufacturing lead times and plan for adequate component supply, we may issue purchase orders to these third-party contract manufacturers and vendors that may not be cancelable. As of December 31, 2014 and December 31, 2013, our contract manufacturer liability was $0.3 million and $1.8 million for non-cancelable purchase commitments issued to our vendors. We have provided deposits to our third-party contract manufacturers and vendors to secure our obligations to purchase inventory. We had $2.3 million in restricted deposits as of December 31, 2014 and December 31, 2013. Deposits are classified in other assets in our accompanying consolidated balance sheets.
	Guarantees
	We have entered into agreements with some of our direct customers and channel partners that contain indemnification provisions relating to potential situations where claims could be alleged that our products infringe the intellectual property rights of a third party. We have at our option and expense the ability to repair any infringement, replace product with a non-infringing equivalent-in-function product or refund our customers the unamortized value of the product based on its estimated useful life. Other guarantees or indemnification agreements 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 guarantee and indemnification arrangements have not had any significant impact on our consolidated financial statements to date.
	Legal Proceedings
	OptumSoft, Inc. Matters
	On April 4, 2014, OptumSoft filed a lawsuit against us in the Superior Court of California, Santa Clara County titled OptumSoft, Inc. v. Arista Networks, Inc., in which it asserts (i) ownership of certain components of our EOS network operating system pursuant to the terms of a 2004 agreement between the companies and (ii) breaches of certain confidentiality and use restrictions in that agreement. Under the terms of the 2004 agreement, OptumSoft provided us with a non-exclusive, irrevocable, royalty-free license to software delivered by OptumSoft comprising a software tool used to develop certain components of EOS and a runtime library that is incorporated into EOS. The 2004 agreement places certain restrictions on our use and disclosure of the OptumSoft software and gives OptumSoft ownership of improvements, modifications and corrections to, and derivative works of, the OptumSoft software that we develop.
	In its lawsuit, OptumSoft has asked the Court to order us to (i) give OptumSoft copies of certain components of our software for evaluation by OptumSoft, (ii) cease all conduct constituting the alleged confidentiality and use restriction breaches, (iii) secure the return or deletion of OptumSoft’s alleged intellectual property provided to third parties, including our customers, (iv) assign ownership to OptumSoft of OptumSoft’s alleged intellectual property currently owned by us, and (v) pay OptumSoft’s alleged damages, attorney’s fees, and costs of the lawsuit. David Cheriton, one of our founders and a former member of our board of directors who resigned from our board of directors on March 1, 2014 and has no continuing role with us, is a founder and, we believe, the largest stockholder and director of OptumSoft. The 2010 David R. Cheriton Irrevocable Trust dtd July 27, 2010, a trust for the benefit of the minor children of Mr. Cheriton, is one of our largest stockholders. OptumSoft has identified in confidential documents certain software components it claims to own, which are generally applicable tools and utility subroutines and not networking specific code. We cannot assure which software components OptumSoft may ultimately claim to own in the litigation or whether such claimed components are material.
	On April 14, 2014, we filed a cross-complaint against OptumSoft, in which we assert our ownership of the software components at issue and our interpretation of the 2004 agreement. Among other things, we assert that the language of the 2004 agreement and the parties’ long course of conduct support our ownership of the disputed software components. We ask the Court to declare our ownership of those software components, all similarly-situated software components developed in the future and all related intellectual property. We also assert that, even if we are found not to own any particular components at issue, such components are licensed to us under the terms of the 2004 agreement. However, there can be no assurance that our assertions will ultimately prevail in litigation. On the same day, we also filed an answer to OptumSoft’s claims, as well as affirmative defenses based in part on OptumSoft’s failure to maintain the confidentiality of its claimed trade secrets, its authorization of the disclosures it asserts and its delay in claiming ownership of the software components at issue. We have also taken additional steps to respond to OptumSoft’s allegations that we improperly used and/or disclosed OptumSoft confidential information. While we believe we have strong defenses to these allegations, we believe we have (i) revised our software to remove the elements we understand to be the subject of the claims relating to improper use and disclosure of OptumSoft confidential information and made the revised software available to our customers and (ii) removed information from our website that OptumSoft asserted disclosed OptumSoft confidential information.
	The Court set a trial date for Phase I of the proceedings, relating to contract interpretation and application of the contract to certain claimed source code for September 14, 2015. The remaining issues are currently scheduled to be tried in April 2016.
	At this stage of the litigation, we do not believe a loss is probable and we are unable to estimate a possible loss or range of possible loss.
	We intend to vigorously defend against any action brought against us by OptumSoft. However, we cannot be certain that, if litigated, any claims by OptumSoft would be resolved in our favor. For example, if it were determined that OptumSoft owned components of our EOS network operating system, we would be required to transfer ownership of those components and any related intellectual property to OptumSoft. If OptumSoft were the owner of those components, it could make them available to our competitors, such as through a sale or license. In addition, if OptumSoft were to bring actual litigation, it could assert additional or different claims against us, including claims that our license from OptumSoft is invalid. An adverse litigation ruling could result in a significant damages award against us and injunctive relief. In addition, if our license was ruled to have been terminated, and we were not able to negotiate a new license from OptumSoft on reasonable terms, we could be prohibited from selling products that incorporate OptumSoft intellectual property. Any such adverse ruling could materially adversely affect our business, prospects, results of operations and financial condition. Whether or not we prevail in a lawsuit, we expect that any litigation would be expensive, time-consuming and a distraction to management in operating our business.
	Net Navigation LLC Matters
	On April 23, 2014, Net Navigation LLC sued us for alleged infringement of U.S. Patent Nos. 5,901,147; 6,434,145; and 6,625,122 in U.S. District Court for the Eastern District of Texas. On June 30, 2014, we and Net Navigation LLC settled this dispute.
	Cisco Systems, Inc. (“Cisco”) Matters
	On December 5, 2014, Cisco filed two complaints against us in District Court for the Northern District of California, which are proceeding as Case No. 4-14-cv-0543 (“’043 Case”) and Case No. 4-14-cv-0544 (“’044 Case”). In the ’043 Case, Cisco alleges that we infringe U.S. Patent Nos. 6,377,577; 6,741,592; 7,023,853; 7,061,875; 7,162,537; 7,200,145; 7,224,668; 7,290,164; 7,340,597; 7,460,492; 8,051,211; and 8,356,296 (respectively, “the ’577 patent,” “the ’592 patent,” “the ’853 patent,” “the 875 patent,” “the ’537 patent,” “the ’145 patent,” “the ’668 patent,” “the ’164 patent,” “the ’597 patent,” “the ’492 patent,” “the ’211 patent,” and “the ’296 patent”). Cisco seeks, as relief for our alleged infringement in the ’043 Case, lost profits and/or reasonable royalty damages in an unspecified amount, including treble damages, attorney’s fees, and associated costs. Cisco also seeks injunctive relief in the ’043 Case. On February 10, 2015, the court granted our unopposed motion to stay the ’043 Case until the proceedings before the United States International Trade Commission (“USITC”) pertaining to the same patents (as discussed below) become final. In the ’044 Case, Cisco’s complaint alleges that we infringe U.S. Patent Nos. 7,047,526 and 7,953,886 and further alleges that we infringe numerous copyrights pertaining to Cisco’s “Command Line Interface” or “CLI.” As relief for our alleged patent infringement in the ’044 Case, Cisco seeks lost profits and/or reasonable royalty damages in an unspecified amount including treble damages, attorney’s fees, and associated costs as well as injunctive relief. As relief from our alleged copyright infringement, Cisco seeks damages in an unspecified amount in the form of alleged lost profits, profits from our alleged infringement, statutory damages, attorney’s fees and associated costs. Cisco also seeks injunctive relief against our alleged copyright infringement. On February 13, 2015, we answered the complaint in the ’044 Case, denying the patent and copyright infringement allegations and also raising numerous affirmative defenses. Trial has not been scheduled in either the ’043 or ’044 Cases.
	On December 19, 2014, Cisco filed two complaints against us in the USITC alleging that Arista has violated section 337 of the Tariff Act of 1930, as amended. The complaints have been instituted as ITC Inv. Nos. 337-TA-944 (“’944 Investigation”) and 337-TA-945 (“’945 Investigation). In the ’944 Investigation, Cisco alleges that certain Arista switching products infringe the ’592, ’537, ’145, ’164, ’597, and ’296 patents. In the ’945 Investigation, Cisco alleges that certain Arista switching products infringe the ’577, ’853, ’875, ’668, ’492, and ’211 patents. In both the ’944 and ’945 Investigations, Cisco seeks, among other things, a limited exclusion order barring entry into the United States of accused switch products (including 7000 Series of switches) and a cease and desist order against us regarding our accused switch products. On January 28, 2015, the Administrative Law Judge assigned to the ’944 Investigation set May 27, 2016 as the target date for completion of the ’944 Investigation. On February 11, 2015, we responded to the notices of investigation and complaints in the ’944 and ’945 Investigations by, among other things, denying any violation of section 337 of the Tariff Act and the patent infringement allegations, and raising numerous additional defenses. On February 19, 2015, the Administrative Law Judge assigned to the ’945 Investigation issued a procedural schedule calling for, among other events: issuance of an order construing the claims of the ’577, ’853, ’875, ’668, ’492, and ’211 patents tentatively on July 17, 2015; an evidentiary hearing on November 9-20, 2015; issuance of an initial determination regarding our alleged violations on April 26, 2016; and the target date for completion of the ’945 Investigation on August 26, 2016.
	At this stage of the litigation, we do not believe a loss is probable, and we are unable to estimate a possible or range of possible loss.
	We intend to vigorously defend against Cisco’s lawsuits, as summarized in the preceding paragraphs. However, we cannot be certain that, if litigated, any claims by Cisco would be resolved in our favor. For example, an adverse litigation ruling could result in a significant damages award against us, could further result in the above described injunctive relief (including, among other things, an order excluding our products from importation into the United States), could result in a requirement that we make substantial royalty payments to Cisco, and/or could require that we modify our products to the extent that we are found to infringe any valid claims asserted against us Cisco. Any such adverse ruling could materially adversely affect our business, prospects, results of operation and financial condition. To the extent that we reached a negotiated settlement with Cisco, the settlement could require payment of substantial royalties. Additionally, the existence of this lawsuit could cause concern among our customers and potential customers and could adversely affect our business and results of operations. Whether or not we prevail in the lawsuit, we expect that the litigation will be expensive, time-consuming and a distraction to management in operating our business.
	In the ordinary course of business, we are a party to other claims and legal proceedings including matters relating to commercial, employee relations, business practices and intellectual property. We record a provision for contingent losses when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Based on currently available information, management does not believe that the ultimate outcome of these other unresolved matters is probable or estimable and not likely, individually and in the aggregate, to have a material adverse effect on our financial position, results of operations or cash flows. However, litigation is subject to inherent uncertainties and our view of these matters may change in the future. Were an unfavorable outcome to occur, there exists the possibility of a material adverse impact on our financial position, results of operations or cash flows for the period in which the unfavorable outcome occurs, and potentially in future periods.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation
	Total stock-based compensation expense related to options, restricted stock awards, employee stock purchases, restricted stock units and stock purchase rights granted were charged to the department to which the associated employee reported as follow (in thousands):
		Year Ended December 31,
		2014			2013				2012
	Cost of revenue	$	1,535		$	408			$	270
	Research and development 1	14,986			5,464				2,590
	Sales and marketing 1	7,643			2,985				1,078
	General and administrative	3,455			1,302				765
	Total stock-based compensation	$	27,619		$	10,159			$	4,703
	_________________
	1Includes modification charge of $0.5 million in 2014 related to acceleration of shares upon termination for two employees.
	Equity Award Plans
	During the year ended December 31, 2004, we adopted the 2004 Equity Incentive Plan (the “2004 Plan”) for the purpose of granting stock based awards to employees, directors and consultants. Awards granted under the 2004 Plan could be in the form of Incentive Stock Options (“ISOs”), Nonstatutory Stock Options (“NSOs”) or Restricted Stock Awards (“RSAs”). With the establishment of the 2011 Plan (as defined below), the 2004 Plan was terminated with respect to the grant of future awards but the 2004 Plan continues to govern awards previously issued thereunder. During the year ended December 31, 2011, we adopted the 2011 Equity Incentive Plan (the “2011 Plan”) for the purpose of granting stock based awards to employees, directors, and consultants. Awards granted under the 2011 Plan could have been ISOs, NSOs, RSAs, Stock Appreciation Rights (“SARs”) or Restricted Stock Units (“RSUs”). With the establishment of the 2014 Plan (as defined below), the 2011 Plan terminated with respect to the grant of future awards but the 2011 Plan continues to govern awards previously issued thereunder.
	2014 Plan
	In April 2014, the board of directors and stockholders approved the 2014 Equity Incentive Plan (the “2014 Plan”), effective on the first day that our common stock was publicly traded. A total of 6,510,000 shares of our common stock were initially reserved for issuance under the 2014 Plan. In addition, the shares reserved for issuance under our 2014 Plan will also include (a) those shares reserved but unissued under the 2011 Plan and 2004 Plan as of the effective date and (b) shares returned to our 2011 Plan and 2004 Plan as the result of expiration or termination of options (provided that the maximum number of shares that may be added to the 2014 Plan pursuant to (a) and (b) is 20,025,189 shares). The number of shares available for grant and issuance under the 2014 Plan will be increased automatically on January 1 of each year commencing with 2016 by the number of shares equal to 3% of our shares outstanding on the immediately preceding December 31, but not to exceed 12,500,000 shares, unless the board of directors, in its discretion, determines to make a smaller increase.
	2014 Employee Stock Purchase Plan
	In April 2014, the board of directors and stockholders approved the 2014 Employee Stock Purchase Plan (the “ESPP”). The ESPP became effective on the first day that our common stock was publicly traded. A total of 651,000 shares of our common stock are initially reserved for future issuance under the ESPP. The number of shares reserved for issuance under the ESPP increases automatically on January 1 of each year commencing with 2015 by the number of shares equal to 1% of our shares outstanding immediately preceding December 31, but not to exceed 2,500,000 shares, unless the board of directors, in its discretion, determines to make a smaller increase. On February 17, 2015, the board authorized the increase to shares available for issuance under the plan of 1% of the total shares outstanding on January1, 2015. The increase amounted to approximately 655,139 shares.
	Determination of Fair Value
	Employee Stock Plans
	For the years ended December 31, 2014, 2013 and 2012 the fair value of each stock option granted under our plans was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions and fair value per share:
		Year Ended December 31,
		2014		2013			2012
	Expected term (in years)	7.6		6.5			5.6
	Risk-free interest rate	2.2	%	1.7	%		0.9	%
	Expected volatility	47.7	%	51	%		51	%
	Dividend rate	—	%	—	%		—	%
	ESPP
	There were no stock purchases under the ESPP during the year ended December 31, 2014.  The following table summarizes the assumptions relating to our ESPP:
		Year Ended December 31,
		2014		2013		2012
	Expected term (in years)	1.4		N/A		N/A
	Risk-free interest rate	0.3	%	N/A		N/A
	Expected volatility	36.3	%	N/A		N/A
	Dividend rate	—	%	N/A		N/A
	As of December 31, 2014, the total unrecognized stock-based compensation expense for unvested ESPP shares, net of expected forfeitures, was $3.0 million, which is expected to be recognized over a weighted-average period of 1.6 years.
	Stock Option Activities
	The following table summarizes the option and RSA (Restricted Stock Award) activity under the 2004 Plan, 2011 Plan and 2014 Plan and related information:
				Options and RSAs Outstanding
		Shares		Number of			Weighted-				Weighted-	Aggregate
		Available for		Shares			Average				Average	Intrinsic
		Grant		Underlying			Exercise				Remaining	Value
		(in thousands)		Outstanding Options and RSAs			Price per Share				Contractual	of Stock
				(in thousands)							Term (Years) of	Options
											Stock Options	Outstanding
												(in thousands)
	Balance—December 31, 2013	8,941		11,245			$	6.82			8.8	$	254,319
	Authorized	6,510
	Options granted	(4,521	)	4,412			40.88
	Options exercised	—		(1,349	)		6.04
	Options canceled	654		(654	)		12.45
	Early exercised shares repurchased1	28		—			4.05
	Balance—December 31, 2014	11,612		13,654			$	17.63			8.3	$	598,775
	Vested and exercisable—December 31, 2014			3,397			$	5.36			7.4	$	188,223
	Vested and expected to vest—December 31, 2014			12,034			$	16.12			8.2	$	544,919
	_________________
	1Early exercised shares repurchased includes 2,000 shares that were originally granted out of our 2004 Plan and were subsequently retired.
	The weighted-average grant-date fair value of options granted during the year ended December 31, 2014 was $24.69 per share. The aggregate intrinsic value of options exercised for the year ended December 31, 2014 was $80.5 million.
	As of December 31, 2014, the total unrecognized stock-based compensation expense for unvested stock options, net of expected forfeitures, was $106.8 million, which is expected to be recognized over a weighted-average period of 4.4 years. The total fair value of options vested for the year ended December 31, 2014 was $16.5 million.
	Under the 2004 Plan and 2011 Plan, the options outstanding and vested and exercisable by exercise price at December 31, 2014 are as follows:
		Options Outstanding and Exercisable								Options Vested and Exercisable
	Range of Exercise Price	Number of		Weighted-		Weighted-				Number of		Weighted-
		Shares Underlying		Average		Average				Shares		Average
		Outstanding		Remaining		Exercise Price				Underlying		Exercise Price
		Options		Contractual		per Share				Outstanding		per Share
(in thousands)		Life (Years)				Options
						(in thousands)
$3.33	2,116		6.8		$	3.33			1,457		$	3.33
$4.16 - $4.18	2,272		7.6		4.17				875		4.17
$4.92 - $7.76	1,868		8		6.3				618		5.81
$8.77 - $10.18	2,624		8.6		9.73				313		9.5
$22.49 -$30.67	2,652		9.1		27.58				127		22.59
$34.12 - $68.34	1,888		9.6		50.84				7		36.38
$75.00 - $76.80	224		9.7		75.71				—		—
$84.00	10		9.7		84				—		—
	13,654		8.3		$	17.63			3,397		$	5.36
Restricted Stock Unit (RSU) Activities
A summary of the activity under our stock plans and changes during the reporting period and a summary of information related to RSUs are presented below (in thousands, except years and per share amounts):
	Number of		Weighted-				Weighted-Average		Aggregate Intrinsic Value
	Shares		Average Grant				Remaining
			Date Fair Value Per Share				Contractual Term (in years)
Unvested balance—December 31, 2013	—		—				0		—
RSUs granted	109		$	75.55
RSUs vested	—		—
RSUs forfeited/canceled	(1	)	75
Unvested balance—December 31, 2014	108		$	75.56			2		$	6,557
RSUs expected to vest—December 31, 2014	94		$	75.56			2		$	5,722
As of December 31, 2014, there was $6.5 million of unrecognized stock-based compensation expense related to unvested RSUs, net of estimated forfeitures. This amount is expected to be recognized over a weighted-average period of 3.8 years.
Restricted Stock Award Activities
A summary of our RSA activity and related information is as follows (in thousands, except per share amounts):
	Number of		Weighted-
	RSA’s		Average Grant
	Outstanding		Date Fair Value Per Share
Unvested balance—December 31, 2013	142		$	2.42
Vested	(57	)	2.5
Unvested balance—December 31, 2014	85		$	2.5
There were no RSAs granted during the year ended December 31, 2014. As of December 31, 2014, the total unrecognized stock-based compensation expense for outstanding RSAs, net of expected forfeitures, was $0.2 million, which is expected to be recognized over a weighted-average period of 1.8 years. As of December 31, 2014, the intrinsic value of the outstanding RSAs based on the estimated fair value of $60.76 per share was $5.0 million.
Early Exercise of Stock Options
We have historically allowed our employees and directors to exercise options granted under the 2011 Plan and the 2004 Plan prior to vesting. Upon an "early exercise" of these options, the unvested shares acquired through the exercise become options subject to our repurchase right that lapse in accordance with the original option vesting schedule. Upon termination of employment prior to our repurchase rights lapsing in full, we have a right to repurchase the unvested shares at the original purchase price (or the then-current fair market value, if lower). The proceeds initially are recorded in other liabilities from the early exercise of stock options and are reclassified to common stock and paid-in capital as our repurchase right lapse. For the year ended December 31, 2014, we repurchased 29,803 shares of common stock at the original exercise price due to the termination of the holders of the unvested shares. As of December 31, 2014, shares held by employees and directors that were subject to repurchase were 1.4 million with an aggregate price of $4.6 million.

Net_Income_Per_Share_Available

Net Income Per Share Available to Common Stock	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Per Share Available to Common Stock	Net Income Per Share Available to Common Stock
	The following table sets forth the computation of our basic and diluted net income per share available to common stock (in thousands, except per share amounts):
		Year Ended December 31,
		2014				2013			2012
	Numerator:
	Basic:
	Net income	$	86,850			$	42,460		$	21,349
	Less: undistributed earnings allocated to participating securities	(17,961		)		(21,683		)	(11,727		)
	Net income available to common stockholders, basic	$	68,889			$	20,777		$	9,622
	Diluted:
	Net income attributable to common stockholders, basic	$	68,889			$	20,777		$	9,622
	Add: undistributed earnings allocated to participating securities	1,635				1,003			40
	Net income attributable to common stockholders, diluted	$	70,524			$	21,780		$	9,662
	Denominator:
	Basic:
	Weighted-average shares used in computing net income per share available to common stockholders, basic	48,427				27,320			24,711
	Diluted:
	Weighted-average shares used in computing net income per share available to common stockholders, basic	48,427				27,320			24,711
	Add weighted-average effect of dilutive securities:
	Stock options, RSUs and RSAs	6,059				2,726			187
	Employee stock purchase plan	104				—			—
	Stock purchase rights	—				5			3
	Weighted-average shares used in computing net income per share available to common stockholders, diluted	54,590				30,051			24,901
	Net income per share attributable to common stockholders:
	Basic	$	1.42			$	0.76		$	0.39
	Diluted	$	1.29			$	0.72		$	0.39
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net income per share available to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Stock options and RSUs	1,263			3,599			169

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The geographical breakdown of income before provision for income taxes is as follows (in thousands):
		Year Ended December 31,
		2014				2013				2012
	Domestic	$	120,838			$	50,455			$	26,837
	Foreign	670				7,820				6,138
	Income before provision for income taxes	$	121,508			$	58,275			$	32,975
	The components of the provision for income taxes are as follows (in thousands):
		Year Ended December 31,
		2014				2013				2012
	Current provision for income taxes:
	Federal	$	36,091			$	19,708			$	13,037
	State	2,716				4,525				2,003
	Foreign	3,306				413				308
	Total current	42,113				24,646				15,348
	Deferred tax benefit:
	Federal	(7,028		)		(8,059		)		(3,525		)
	State	153				(938		)		(342		)
	Foreign	(580		)		166				145
	Total deferred	(7,455		)		(8,831		)		(3,722		)
	Total provision for income taxes	$	34,658			$	15,815			$	11,626
	The reconciliation of the statutory federal income tax and our effective income tax is as follows:
		Year Ended December 31,
		2014			2013			2012
	U.S. federal statutory income tax	35	%		35	%		35	%
	State tax, net of federal benefit	1.19			0.89			0.26
	Foreign tax differential	0.68			(2.61	)		(3.21	)
	Tax credits	(5.26	)		(10.64	)		(0.96	)
	Change in valuation allowance	1.92			3.87			3.04
	Permanent items	(0.86	)		(2.54	)		(2.55	)
	Uncertain tax positions and associated interest	0.37			0.58			0.44
	Stock-based compensation	(4.01	)		2.47			3.21
	Other, net	(0.51	)		0.12			0.03
	Total provision for income taxes	28.52	%		27.14	%		35.26	%
	We have operations and a taxable presence in numerous jurisdictions outside the U.S. All of these countries except one jurisdiction have a lower tax rate than the U.S. The significant jurisdictions in which we have a presence include Cayman Islands, Ireland, and the United Kingdom.
	The tax effects of temporary differences that give rise to significant portions of deferred tax assets (liabilities) are as follows (in thousands):
		December 31,
		2014				2013
	Deferred tax assets:
	Property and equipment	$	504			$	1,020
	Stock-based compensation	6,365				1,738
	Reserves and accruals not currently deductible	16,160				13,351
	Net operating losses	721				1,143
	Tax credits	9,923				5,156
	State taxes	342				514
	Other	1,142				375
	Gross deferred tax assets	35,157				23,297
	Valuation allowance	(8,954		)		(6,288		)
	Total deferred tax assets	26,203				17,009
	Deferred tax liabilities:
	Property and equipment	(2,001		)		(47		)
	Accrued liabilities	(558		)		(173		)
	Other	(2		)		—
	Total deferred tax liabilities	(2,561		)		(220		)
	Net deferred tax assets	$	23,642			$	16,789
	The following table presents the breakdown between current and non-current deferred tax assets and liabilities (in thousands):
		December 31,
		2014				2013
	Deferred tax assets	$	12,252			$	12,356
	Deferred tax assets, non-current	11,510				4,541
	Deferred tax liabilities, non-current	(120		)		(108		)
	Total net deferred tax assets	$	23,642				$16,789
	Recognition of deferred tax assets is appropriate when realization of these assets is more likely than not. We believe that all of the deferred tax assets were realizable with the exception of California and Canada deferred tax assets. Therefore, a valuation allowance of $9.0 million and $6.3 million was recorded as of December 31, 2014 and 2013, respectively, against the California and Canadian deferred tax assets as it was not more likely than not that these assets will be recognized. The net valuation allowance increased by $2.7 million, $2.4 million and $1.0 million as of December 31, 2014, 2013 and 2012, respectively.
	As of December 31, 2014 and 2013, we had no net operating loss carryforwards for federal income tax purposes. As of December 31, 2014 and 2013, we had no state net operating loss carryforwards and approximately $13.1 million of carryforward, respectively, which has been fully utilized. As of December 31, 2014 and 2013, we had combined foreign net operating loss carryforwards of $7.5 million and $4.2 million, respectively, that do not expire.
As of December 31, 2014 and 2013, we had $1.9 million and zero, respectively, U.S. federal credit carryforwards which begin to expire in 2025. As of December 31, 2014 and 2013, we had state credit carryforwards of approximately $16.4 million and $9.6 million which can be carried over indefinitely. As of December 31, 2014 and 2013, we had $2.1 million and $1.3 million of Canadian scientific research and experimental development tax credit carry-forwards, respectively, which begin to expire in 2033.
Utilization of the net operating losses and tax credit carryforwards may be subject to limitations due to ownership changes limitations provided in the Internal Revenue code and similar state or foreign provisions. In all years up to December 31, 2014, such limitations had no impact to our deferred tax assets.
Our policy with respect to our undistributed foreign subsidiaries earnings is to consider those earnings to be indefinitely reinvested and, accordingly, no related provision for U.S. federal and state income taxes has been provided. Upon distribution of those earnings’ in the form of dividends or otherwise, we may be subject to both U.S. income taxes (subject to an adjustment for foreign tax credits) and withholding taxes in the various countries. As of December 31, 2014, 2013 and 2012, the undistributed earnings approximated $4.9 million, $4.9 million and $1.0 million, respectively. The determination of the future tax consequences of the remittance of these earnings is not practicable.
Uncertain Tax Positions
We recognize uncertain tax positions only to the extent that management believes that it is more likely than not the position will be sustained. The reconciliation of the beginning and ending amount of gross unrecognized tax benefits as of December 31, 2014, 2013 and 2012 was as follows (in thousands):
	Year Ended December 31,
	2014				2013				2012
Gross unrecognized tax benefits—beginning balance	$	16,973			$	13,960			$	13,326
Increases related to tax positions taken in a prior year	425				70				—
Increases related to tax positions taken during current year	4,355				2,975				634
Decreases related to tax positions taken in a prior year	(431		)		(32		)		—
Decreases related to settlements with taxing authorities	—				—				—
Decreases related to lapse of statute of limitations	—				—				—
Gross unrecognized tax benefits—ending balance	$	21,322			$	16,973			$	13,960
As of December 31, 2014, 2013 and 2012 the total amount of gross unrecognized tax benefits was $21.3 million, $17.0 million and $14.0 million of which $15.8 million, $13.9 million and $12.2 million would affect our effective tax rate if recognized, respectively.
Our policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. We accrued interest and penalties of $0.7 million and $0.5 million in the years ended December 31, 2014 and 2013, respectively. As of December 31, 2014 and 2013, we recognized a liability for interest and penalties of $1.5 million and $0.8 million, respectively.
We do not anticipate that the amount of existing unrecognized tax benefits would significantly increase or decrease within the next 12 months. Because of the net operating loss and tax credit carryforwards, substantially all of our tax years remain open to federal and state tax examination. The majority of our foreign tax returns are open to audit under the statute of limitations of the respective foreign countries, in which the subsidiaries are located.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Information	Segment Information
	We have determined that we operate as one reportable segment. The following table represents revenue based on the customer’s location, as determined by the customer’s shipping address (in thousands):
		Year Ended December 31,
		2014		2013		2012
	United States	$	456,691	$	293,579	$	149,537
	Other Americas	8,853		6,040		5,056
	Europe, Middle East and Africa	74,555		40,577		23,012
	Asia Pacific	44,007		21,028		15,803
	Total revenue	$	584,106	$	361,224	$	193,408
	Long lived assets, excluding intercompany receivables, investments in subsidiaries, privately-held equity investments
	and deferred tax assets, net by location are summarized as follows (in thousands):
		December 31,
		2014		2013
	United States	$	67,727	$	63,557
	International	3,831		3,647
	Total	$	71,558	$	67,204

Other_Related_Party_Transactio

Other Related Party Transactions and Balances	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Other Related Party Transactions and Balances	Other Related Party Transactions and Balances
	Certain members of our board of directors serve on the boards of our customers. During the years ended December 31, 2014, 2013 and 2012, we recognized revenue of $29.6 million, $11.1 million and $1.1 million, respectively, from sales transactions with these related party customers. Amounts due from these related party customers were $6.4 million and $3.8 million as of December 31, 2014 and 2013, respectively.

Organization_and_Summary_of_Si1

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation
	The accompanying consolidated financial statements include the accounts of Arista Networks, Inc. and our wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated. Our consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP).
Use of Estimates	Use of Estimates
	The preparation of the accompanying consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes. Those estimates and assumptions include, but are not limited to, revenue recognition and deferred revenue; allowance for doubtful accounts and sales return reserve; 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 consolidated financial statements.
Consolidation of Variable Interest Entities	Consolidation of Variable Interest Entities
	We use a qualitative approach in assessing the consolidation requirement for variable interest entities (VIEs). This approach focuses on determining whether we have the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance and whether we have the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the VIE. For all periods presented in the accompanying consolidated financial statements, we have determined that we are not the primary beneficiary of any VIEs. However, in the event that we are the primary beneficiary of a VIE entity, the assets, liabilities, and results of operations of the VIE will be included in our consolidated financial statements.
Business Concentrations	Business Concentrations
	We work closely with third parties to manufacture and deliver our products. As of December 31, 2014 and 2013, two suppliers provided all of our electronic manufacturing services. 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	Concentrations of Credit Risk
	Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, restricted cash, accounts receivable and notes receivable. Our cash, cash equivalents and restricted cash 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. Our notes receivable are secured and represent amounts due to us from a private company. We mitigate credit risk in respect to the notes receivable by performing ongoing credit evaluations of the borrower to assess the probability of collecting all amounts due to us under the existing contractual terms.
	We market and sell our products through both our direct sales force and our channel partners, including distributors, value-added resellers, system integrators and original equipment manufacturer (“OEM”) partners. Significant customers are those which represent more than 10% of our total net revenue during the period or net accounts receivable balance at each respective balance sheet date.
Reclassifications	Reclassifications
	As a result of a change in classification, we have reclassified our spare parts inventory from inventory to other current and non-current assets as of December 31, 2014. Spare parts inventory are used to satisfy our warranty obligations, and are not available for sale or used in the production process. Prior year balances have been adjusted to conform to this new classification for comparability purposes.
Comprehensive Income	Comprehensive Income
	Comprehensive income is comprised of net income and other comprehensive income. Unrealized gains and losses on available-for-sale investments and foreign currency translation adjustments are included in our other comprehensive income or loss.
Cash and Cash Equivalents	Cash and Cash Equivalents
	We consider all highly liquid investments with stated maturity of three months or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of cash on deposit with various financial institutions and highly liquid investments in money market funds. Interest is accrued as earned.
Marketable Securities	Marketable Securities
	We invest our excess cash primarily in money market and highly liquid debt instruments of the U.S. government. We classify all highly liquid investments with stated maturities of greater than three months as marketable securities. We determine the appropriate classification of our investments in marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified and accounted for our marketable securities as available-for-sale. We may or may not hold securities with stated maturities greater than 12 months until maturity. After consideration of our risk versus reward objectives, as well as our liquidity requirements, we may sell these securities prior to their stated maturities. As we view these securities as available to support current operations, we classify securities with maturities beyond 12 months as current assets under the caption marketable securities in the accompanying consolidated balance sheets. We carry these securities at fair value, and report the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be other-than-temporary, which we record as other income (expense), net. We determine any realized gains or losses on the sale of marketable securities on a specific identification method, and we record such gains and losses as a component of interest and other income, net.
Fair Value Measurements	Fair Value Measurements
	Our assets and liabilities which require fair value measurement consist of cash and cash equivalents, restricted cash, marketable securities, accounts receivable, investments, accounts payable, accrued liabilities and convertible notes payable. Cash equivalents, restricted cash, accounts receivable, accounts payable and accrued liabilities are stated at carrying amounts as reported in the consolidated financial statements, which approximates fair value due to their short term nature. For certain investments where we have elected the fair value option, these investments are stated at fair value. The carrying amounts of our convertible notes payable approximate fair value as the stated interest rates approximate market rates currently available to us.
	Assets and liabilities recorded at fair value on a recurring basis in the accompanying consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of the inputs used to measure fair value instruments as follows:
	Level I—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;
	Level II—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and
	Level III—Unobservable inputs that are supported by little or no market data for the related assets or liabilities and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.
	Our financial instruments consist of Level I and Level III assets. Level I assets include highly liquid money market funds that are included in cash and cash equivalents and U.S. government notes classified as marketable securities. Level III assets that were measured on a recurring basis consisted solely of our notes receivable. We classified the notes receivable as Level III, as we used unobservable inputs to the valuation methodology that were significant to the fair value measurement, and the valuation required management judgment due to the absence of quoted market prices. We measured the fair value for certain investments based upon the probability-weighted present value of expected future investment returns, considering each of the possible future outcomes available to us. The significant unobservable inputs used in the fair value measurement of the convertible notes are the scenario probabilities and the discount rate estimated at the valuation date. Generally, increases (decreases) in the discount rate would result in a directionally opposite impact to the fair value measurement of the notes. Also, changes in the probability scenarios would have had varying impacts depending on the weighting of each specific scenario. More weighting towards a change in control or an equity financing by the investee would result in an increase in fair value of the notes receivable.
Restricted Cash	Restricted Cash
	We had restricted cash pledged as collateral representing a security deposit required for a facility lease.
Foreign Currency	Foreign Currency
	The functional currency of our foreign subsidiaries is either the U.S. dollar or their local currency.
	Transaction re-measurement-Assets and liabilities denominated in a currency other than the foreign subsidiaries’ functional currency are re-measured into the functional currency using exchange rates in effect at the end of the reporting period, with gains and losses recorded in other income (expense), net in the consolidated statements of income. We recognized $0.6 million, $0.1 million and $0.2 million in transaction losses for the years ended December 31, 2014, 2013 and 2012, respectively.
	Translation-Assets and liabilities of subsidiaries denominated in foreign functional currencies are translated into U.S. dollars at the closing exchange rate on the balance sheet date and equity related balances are translated at historical exchange rates. Revenues, costs and expenses in foreign functional currencies are translated using average exchange rates that approximate those in effect during the period. Translation adjustments are accumulated as a separate component of accumulated other comprehensive income within stockholders’ equity (deficit).
Accounts Receivable, Allowance for Doubtful Accounts, and Sales Return Reserves	Accounts Receivable, Allowance for Doubtful Accounts, and Sales Return Reserves
	Accounts receivable are recorded at the invoiced amount, net of allowances for doubtful accounts, and sales return reserves. We estimate our allowance for doubtful accounts based upon the collectability of the receivables in light of historical trends, adverse situations that may affect our customers’ ability to pay and prevailing economic conditions. This evaluation is done in order to identify issues which may impact the collectability of receivables and related estimated required allowance. Revisions to the allowance are recorded as an adjustment to bad debt expense. After appropriate collection efforts are exhausted, specific accounts receivable deemed to be uncollectible are charged against the allowance in the period they are deemed uncollectible. Recoveries of accounts receivable previously written-off are recorded as credits to bad debt expense. We estimate our sales return reserves based on historical return rates applied against current period gross revenues. Specific customer returns and allowances are considered when determining our sales return reserve estimate. Revisions to the reserve are recorded as adjustments to revenue and the sales return reserves.
	We mitigate credit risk in respect to accounts receivable by performing ongoing credit evaluations of our customers and channel partners to assess the probability of accounts receivable collection based on a number of factors, including past transaction experience with the customer or channel partner, evaluation of credit history, the credit limits extended and review of the invoicing terms of the arrangement. In situations where a partner or customer may be thinly capitalized and we have limited payment history with it, we will either establish a small credit limit or require it to prepay their purchases.
Inventories	Inventories
	Inventories primarily consist finished goods purchased from third party contract manufacturers and are stated at the lower of cost (computed using the first-in, first-out method) or market value. Manufacturing overhead costs and inbound shipping costs are included in the cost of inventory. In addition, we also purchase certain strategic component inventory, including integrated circuits which are consigned to our contract manufacturers. We record a provision when inventory is determined to be in excess of anticipated demand, or obsolete, to adjust inventory to its estimated realizable value. For the years ended December 31, 2014, 2013 and 2012, we incurred inventory write-downs of $2.8 million, $5.3 million and $3.2 million, respectively.
	We outsource most of our manufacturing and supply chain management operations to two third-party contract manufacturers and as a result, a significant portion of our cost of revenue consists of payments to them. Our third-party contract manufacturers purchase and own a portion of the material used to build our switch products until they are shipped to us, at which time our third-party contract manufacturers invoice us. In addition, we also purchase certain strategic component inventory, including integrated circuits which are consigned to our third-party contract manufacturers. As of December 31, 2014 and 2013, our strategic component inventory consigned to others was $17.1 million and $18.3 million, respectively, and are included in raw materials.
	Our finished goods inventory consists of our finished switch products and accessories. This inventory is located principally at third-party direct fulfillment facilities in California, the Netherlands and Singapore.
Property and Equipment	Property and Equipment
	Property and equipment are stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method over the shorter of the estimated useful lives of the related assets, generally from one to five years, 30 years for buildings or the lease term for leasehold improvements. The leased building under our build to suit lease is capitalized and included in property and equipment as we were involved in the construction funding and did not meet the “sale-leaseback” criteria.
Investments	Investments in Privately-held Companies
	In 2014, we have equity investments in privately-held companies. Our investments are accounted for under the cost method and are included in investments, non-current in the accompanying consolidated balance sheets. Initial measurement of our investments under the cost method were recorded at historical cost which represents our initial investment in the privately-held companies.  We will periodically assess and evaluate our cost method investments for impairment and perform an assessment based on evaluation of overall financial performance, industry and market conditions, and other relevant events or factors deemed necessary that may affect carrying value. If we determine that a decrease in the equity investments should be recognized given impairment that is considered “other-than-temporary” in nature, we will write-down the carrying amount to its revised new fair value.
Notes Receivable	Notes Receivable
	In 2014, we also entered into an unsecured promissory note with a privately held company which was recorded at cost.
	In 2012, we entered into secured note purchase agreements with a private company to provide them with cash advances. We elected the fair value option to account for these investments and recorded unrealized gains and losses in earnings at each subsequent reporting date. Accordingly, these notes receivable were remeasured to fair value at the end of each reporting period. Upfront costs and fees incurred in conjunction with entering into notes receivable were expensed and recognized in earnings as incurred. Gains and losses from the change in fair value, as well as interest income, were recorded in other income (expense), net in the accompanying consolidated statements of income at each reporting period.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets and Investments
	The carrying amounts of our long-lived assets, including property and equipment and investments in privately-held companies, are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows the asset is expected to generate over their remaining lives. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired asset. No impairment of any long-lived assets was identified for any of the periods presented.
Revenue Recognition	Revenue Recognition
	We generate revenue from sales of switching products which incorporate our EOS software and accessories such as cables and optics to direct customers and channel partners together with post contract customer support (“PCS”). We typically sell products and PCS in a single transaction. We recognize revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery or performance has occurred; the sales price is fixed or determinable; and collectability is reasonably assured.
	We define each of the four criteria above as follows:
	•	Persuasive evidence of an arrangement exists. Evidence of an arrangement consists of stand-alone purchase orders or purchase orders issued pursuant to the terms and conditions of a master sales agreement. It is our practice to identify an end customer prior to shipment to a reseller or distributor.
	•	Delivery or performance has occurred. We use shipping documents or written evidence of customer acceptance, when applicable, to verify delivery or performance. We recognize product revenue upon transfer of title and risk of loss, which primarily is upon shipment to customers. We do not have significant obligations for future performance, such as customer acceptance provisions, rights of return or pricing credits, associated with our product sales. In instances where substantive acceptance provisions are specified in the customer arrangement, revenue is deferred until all acceptance criteria have been met.
	•	The sales price is fixed or determinable. We assess whether the sales price is fixed or determinable based on payment terms and whether the sales price is subject to refund or adjustment.
	•	Collectability is reasonably assured. We assess probability of collectability on a customer-by-customer basis. Our customers and channel partners are subjected to a credit review process that evaluates their financial condition and ability to pay for products and services.
	PCS is offered under renewable, fee-based contracts, which includes technical support, hardware repair and replacement parts beyond standard warranty, bug fixes, patches and unspecified upgrades on a when-and-if-available basis. We initially defer PCS revenue and recognize it ratably over the life of the PCS contract, with the related expenses recognized as incurred. PCS contracts usually have a term of one to three years. We include billed but unearned PCS revenue in deferred revenue.
	We report revenue net of sales taxes. We include shipping charges billed to customers in revenue and the related shipping costs are included in cost of goods sold.
Multiple-Element Arrangements	Multiple-Element Arrangements
	Most of our arrangements, other than renewals of PCS, are multiple element arrangements with a combination of products and PCS. Products and PCS generally qualify as separate units of accounting. Our hardware deliverables include EOS software, which together deliver the essential functionality of our products. For multiple element arrangements, we allocate revenue to each unit of accounting based on the relative selling price. The relative selling price for each element is based upon the following hierarchy: vendor-specific objective evidence (“VSOE”), if available; third-party evidence (“TPE”), if VSOE is not available; and best estimate of selling price (“BESP”), if neither VSOE nor TPE is available. As we have not been able to establish VSOE or TPE for our products and most of our services, we generally utilize BESP for the purposes of allocating revenue to each unit of accounting.
	•	VSOE—We determine VSOE based on our historical pricing and discounting practices for the specific products and services when sold separately. In determining VSOE, we require that a substantial majority of the stand-alone selling prices fall within a reasonably narrow pricing range.
	•	TPE—When VSOE cannot be established for deliverables in multiple-element arrangements, we apply judgment with respect to whether we can establish a selling price based on TPE. TPE is determined based on competitor prices for interchangeable products or services when sold separately to similarly situated customers. However, as our products contain a significant element of proprietary technology and offer substantially different features and functionality, the comparable pricing of products with similar functionality typically cannot be obtained. Additionally, as we are unable to reliably determine what competitors products’ selling prices are on a stand-alone basis, we are not able to obtain reliable evidence of TPE of selling price.
	•	BESP—When we are unable to establish selling price using VSOE or TPE, we use BESP in our allocation of arrangement consideration. The objective of BESP is to determine the price at which we would transact a sale if the product or service was sold regularly on a stand-alone basis. BESP is based on considering multiple factors including, but not limited to the sales channel (reseller, distributor or end customer), the geographies in which our products and services were sold (domestic or international) and size of the end customer.
	We limit the amount of revenue recognition for delivered elements to the amount that is not contingent on the future delivery of products or services, future performance obligations, or subject to customer-specific return, acceptance or refund privileges.
	We account for multiple agreements with a single partner as one arrangement if the contractual terms and/or substance of those agreements indicate that they may be so closely related that they are, in effect, parts of a single arrangement.
	We may occasionally accept returns to address customer satisfaction issues even though there is no contractual provision for such returns. We estimate returns for sales to customers based on historical returns rates applied against current-period gross revenues. Specific customer returns and allowances are considered when determining our sales return reserve estimate.
Research and Development Expenses	Research and Development Expenses
	Costs related to the research, design and development of our products are charged to research and development expenses as incurred. Software development costs are capitalized beginning when a product’s technological feasibility has been established and ending when the product is available for general release to customers. Generally, our products are released soon after technological feasibility has been established. As a result, costs incurred subsequent to achieving technological feasibility have not been significant and accordingly, all software development costs have been expensed as incurred.
Warranty	Warranty
	We offer a one-year warranty on all of our hardware products and a 90-day warranty against defects in the software embedded in the products. We accrue for potential warranty claims at the time of shipment as a component of cost of revenues based on historical experience and other relevant information. We accrue specifically identified reserves if and when we determine we have a systemic product failure. The accrued warranty liability is recorded in accrued liabilities in the accompanying consolidated balance sheets.
Post-Employment Benefits	Post-Employment Benefits
	We have a 401(k) Plan that covers substantially all of our employees in the U.S.
Segment Reporting	Segment Reporting
	Our chief operating decision maker is our Chief Executive Officer. Our Chief Executive Officer reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. We have one business activity and there are no segment managers who are held accountable for operations or operating results. Accordingly, we have determined that we operate as one reportable segment.
Stock-Based Compensation	Stock-Based Compensation
	We recognize stock-based compensation for stock-based awards, including stock options, restricted stock units (RSUs), restricted stock awards (“RSAs”), stock purchase rights from our employee stock purchase program based on the estimated fair value of the awards, net of estimated forfeitures. The fair value of each stock-based award and option is estimated on the grant date using the Black-Scholes option-pricing model. This model requires that at the date of grant we determine the fair value of the underlying common stock, the expected term of the award, the expected volatility of the price of our common stock, risk-free interest rates, and expected dividend yield of our common stock. RSUs are measured based on the fair market values of the underlying stock on the dates of grant.
	The stock-based compensation expense, net of forfeitures, is recognized on a straight-line basis over the requisite service periods of the awards, which is generally two to five years. We estimate a forfeiture rate to calculate the stock-based compensation for our awards. Our forfeiture rate is based on an analysis of our actual historical forfeitures.
	Excess tax benefits associated with stock option exercises and other equity awards are recognized in additional paid in capital.
Income Taxes	Income Taxes
	We account for income taxes under the liability approach for deferred income taxes, which requires recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been recognized in our consolidated financial statements, but have not been reflected in our taxable income. Estimates and judgments occur in the calculation of certain tax liabilities and in the determination of the recoverability of certain deferred income tax assets, which arise from temporary differences and carryforwards. Deferred income tax assets and liabilities are measured using the currently enacted tax rates that apply to taxable income in effect for the years in which those tax assets are expected to be realized or settled. We regularly assess the likelihood that our deferred income tax assets will be realized based on the positive and negative evidence available. We record a valuation allowance to reduce the deferred tax assets to the amount that we are more likely than not to realize.
	We regularly review our tax positions and benefits to be realized. We recognize tax liabilities based upon our estimate of whether, and to the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. We recognize interest and penalties related to income tax matters as income tax expense.
Net Income per Share of Common Stock	Net Income per Share of Common Stock
	Basic and diluted net income per share attributable to common stockholders is calculated in conformity with the two-class method required for participating securities. We considered our Series A convertible preferred stock to be participating securities. Under the two-class method, net income attributable to common stockholders is determined by allocating undistributed earnings, calculated as net income less current period convertible preferred stock non-cumulative dividends, among our common stock and convertible preferred stock. In computing diluted net income attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Shares of common stock subject to repurchase resulting from the early exercise of employee stock options are considered participating securities. Diluted net income per share attributable to common stockholders is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding, including potential dilutive common shares assuming the dilutive effect of outstanding stock options using the treasury stock method. For purposes of this calculation, convertible preferred stock and options to purchase shares of common stock are considered to be common stock equivalents and are excluded from the calculation of diluted net income per share of common stock if their effect is antidilutive. Convertible notes payable were excluded from the calculation of diluted net income per share since such notes were convertible to common stock at the option of the holder only upon the occurrence of a contingent event, including change in control, initial public offering or prepayment of the convertible notes.
Recent Accounting Pronouncements	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 standard is effective for fiscal years (and interim reporting periods within those years) beginning after December 15, 2016. Early application is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. 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.

Organization_and_Summary_of_Si2

Organization and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedules of Concentration of Risk, by Risk Factor	For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:
		Revenue						Accounts Receivable
		Year Ended December 31,						December 31,
	Customers	2014		2013		2012		2014		2013
	Customer A	15	%	22	%	15	%	15	%	17	%
	Customer B	*		*		*		*		11	%
	*less than 10%

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair value of financial assets by level	We measure and report our cash equivalents, restricted cash, available-for-sale marketable securities and notes receivable at fair value. The following table set forth the fair value of our financial assets by level within the fair value hierarchy (in thousands):
		December 31, 2014
		Level I		Level II		Level III		Total
	Financial Assets
	Cash and cash equivalents:
	Money market funds	$	104,216	$	—	$	—	$	104,216
	Marketable securities:
	U.S. government notes	209,426		—		—		209,426
	Total financial assets	$	313,642	$	—	$	—	$	313,642
		December 31, 2013
		Level I		Level II		Level III		Total
	Financial Assets
	Cash and cash equivalents:
	Money market funds	$	47,036	$	—	$	—	$	47,036
	Other assets—Restricted cash:
	Money market funds	4,040		—		—		4,040
	Investments:
	Notes receivable(1)	—		—		4,000		4,000
	Total financial assets	$	51,076	$	—	$	4,000	$	55,076
	(1) There were no changes in the fair value of the Level III assets during the year ended December 31, 2013. In 2014, we increased the fair value of our Notes receivable by $4.0 million (See “Note 4 – Investments”). During the year ended December 31, 2014 and 2013, we had no transfers between levels of the fair value hierarchy of its assets measured at fair value. In October 2014, we received payment in full from the borrower equal to two times our outstanding principal balance as well as the unpaid accrued interest through the payment date.

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2014
Balance Sheet Components [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following table summarizes the unrealized gains and losses and fair value of our available-for-sale marketable securities (in thousands):
		December 31, 2014
		Amortized Cost			Unrealized Gains			Unrealized Losses			Fair Value
	U.S. government notes	$	209,671		$	—		$	(245	)	$	209,426
Schedule of Investments by Contractual Years-to-Maturity	The following table summarizes the amortized cost and fair value of our marketable securities as of December 31, 2014, by contractual years-to-maturity (in thousands):
		Amortized Cost			Fair Value
	Due within one year	$	209,671		$	209,426
Schedule of Accounts Receivable	Accounts Receivable, net
	Accounts receivable, net consists of the following (in thousands):
		December 31,
		2014			2013
	Accounts receivable	$	100,076		$	80,338
	Allowance for doubtful accounts	(1,063		)	(810		)
	Product sales return reserve	(2,031		)	(1,529		)
	Accounts receivable, net	$	96,982		$	77,999
	Allowance for Doubtful Accounts
	Activity in the allowance for doubtful accounts consists of the following (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Balance at the beginning of year	$	810		$	1,284		$	1,169
	Charged to expenses	860			191			326
	Deductions (write-offs)	(607		)	(665		)	(211		)
	Balance at the end of year	$	1,063		$	810		$	1,284
	Sales Return Reserve
	Activity in the sales return reserve consists of the following (in thousands):
		Year Ended December 31,
		2014			2013
	Balance at the beginning of year	$	1,529		$	—
	Charged against revenue	4,063			1,627
	Sales returns	(3,561		)	(98		)
	Balance at the end of year	$	2,031		$	1,529
Schedule of Inventories	Inventories consist of the following (in thousands):
		December 31,
		2014			2013
	Raw materials	$	17,094		$	18,286
	Finished goods	63,425			48,808
	Total inventories	$	80,519		$	67,094
Schedule of Other Current Assets	Prepaid Expenses and Other Current Assets
	Prepaid expenses and other current assets consists of the following (in thousands):
		December 31,
		2014			2013
	Prepaid income taxes	$	25,212		$	134
	Other current assets	9,820			5,137
	Other prepaid and deposits	5,237			2,382
	Total prepaid expenses and other current assets	$	40,269		$	7,653
Schedule of Property and Equipment, net	Property and equipment, net consists of the following (in thousands):
		December 31,
		2014			2013
	Equipment and machinery	$	18,265		$	13,733
	Computer hardware and software	7,772			3,688
	Furniture and fixtures	1,373			1,352
	Leasehold improvements	19,420			19,407
	Building	35,154			35,154
	Construction-in-process	6,532			1,056
	Property and equipment, gross	88,516			74,390
	Less: accumulated depreciation	(16,958		)	(7,186		)
	Property and equipment, net	$	71,558		$	67,204
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands):
		December 31,
		2014			2013
	Accrued payroll related costs	$	30,749		$	9,103
	Accrued warranty costs	3,204			5,075
	Accrued manufacturing costs	1,089			3,835
	Accrued professional fees	2,354			1,220
	Accrued taxes	1,577			927
	Other	1,396			1,379
	Total accrued liabilities	$	40,369		$	21,539
Schedule of Warranty Accrual	The following table summarizes the activity related to our accrued liability for estimated future warranty costs (in thousands):
		Year Ended December 31,
		2014			2013
	Warranty accrual, beginning of period	$	5,075		$	5,314
	Liabilities accrued for warranties issued during the period	2,611			4,290
	Warranty costs incurred during the period	(2,163		)	(4,529		)
	Adjustments related to change in estimate	(2,319		)	—
	Warranty accrual, end of period	$	3,204		$	5,075
Other Current Liabilities	Other current liabilities consist of the following (in thousands):
		December 31,
		2014			2013
	Liability for early exercised shares subject to repurchase	$	4,616		$	7,520
	Sales tax payable	3,101			1,359
	Lease financing obligations, current portion	1,087			818
	Other	2,445			447
	Total other current liabilities	$	11,249		$	10,144

Debt_Obligations_Tables

Debt Obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Debt Obligations	Our debt obligations consist of the following (in thousands):
		December 31,
		2013
	Convertible notes payable—related party	$	25,000
	Convertible notes payable	75,000
	Total	100,000
	Less: Unamortized discount on notes payable	1,207
	Less: Current portion	98,793
	Total long-term portion of debt	$	—

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Operating Leases	As of December 31, 2014, the aggregate future minimum payments under non-cancelable operating leases consist of the following (in thousands):
	Years Ending December 31,
	2015	$	2,583
	2016	4,297
	2017	5,155
	2018	5,378
	2019	5,369
	Thereafter	22,407
	Total minimum future lease payments	$	45,189
Schedule of Lease Financing Obligations	As of December 31, 2014, the future minimum payments due under the lease financing obligation were as follows (in thousands):
	Years Ending December 31,
	2015	$	5,588
	2016	5,754
	2017	5,933
	2018	6,113
	2019	6,293
	Thereafter	25,287
	Total payments	54,968
	Less: interest and land lease expense	(34,770		)
	Total payments under facility financing obligations	20,198
	Property reverting to landlord	23,436
	Present value of obligation	43,634
	Less current portion	(1,087		)
	Long-term portion of obligation	$	42,547

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Stock-Based Compensation Expense	Total stock-based compensation expense related to options, restricted stock awards, employee stock purchases, restricted stock units and stock purchase rights granted were charged to the department to which the associated employee reported as follow (in thousands):
		Year Ended December 31,
		2014			2013				2012
	Cost of revenue	$	1,535		$	408			$	270
	Research and development 1	14,986			5,464				2,590
	Sales and marketing 1	7,643			2,985				1,078
	General and administrative	3,455			1,302				765
	Total stock-based compensation	$	27,619		$	10,159			$	4,703
	_________________
	1Includes modification charge of $0.5 million in 2014 related to acceleration of shares upon termination for two employees.
Schedule of Stock Option Valuation Assumptions	For the years ended December 31, 2014, 2013 and 2012 the fair value of each stock option granted under our plans was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions and fair value per share:
		Year Ended December 31,
		2014		2013			2012
	Expected term (in years)	7.6		6.5			5.6
	Risk-free interest rate	2.2	%	1.7	%		0.9	%
	Expected volatility	47.7	%	51	%		51	%
	Dividend rate	—	%	—	%		—	%
Schedule of ESPP Valuation Assumptions	There were no stock purchases under the ESPP during the year ended December 31, 2014.  The following table summarizes the assumptions relating to our ESPP:
		Year Ended December 31,
		2014		2013		2012
	Expected term (in years)	1.4		N/A		N/A
	Risk-free interest rate	0.3	%	N/A		N/A
	Expected volatility	36.3	%	N/A		N/A
	Dividend rate	—	%	N/A		N/A
Schedule of Option and RSA Activity	The following table summarizes the option and RSA (Restricted Stock Award) activity under the 2004 Plan, 2011 Plan and 2014 Plan and related information:
				Options and RSAs Outstanding
		Shares		Number of			Weighted-				Weighted-	Aggregate
		Available for		Shares			Average				Average	Intrinsic
		Grant		Underlying			Exercise				Remaining	Value
		(in thousands)		Outstanding Options and RSAs			Price per Share				Contractual	of Stock
				(in thousands)							Term (Years) of	Options
											Stock Options	Outstanding
												(in thousands)
	Balance—December 31, 2013	8,941		11,245			$	6.82			8.8	$	254,319
	Authorized	6,510
	Options granted	(4,521	)	4,412			40.88
	Options exercised	—		(1,349	)		6.04
	Options canceled	654		(654	)		12.45
	Early exercised shares repurchased1	28		—			4.05
	Balance—December 31, 2014	11,612		13,654			$	17.63			8.3	$	598,775
	Vested and exercisable—December 31, 2014			3,397			$	5.36			7.4	$	188,223
	Vested and expected to vest—December 31, 2014			12,034			$	16.12			8.2	$	544,919
	_________________
	1Early exercised shares repurchased includes 2,000 shares that were originally granted out of our 2004 Plan and were subsequently retired.
Schedule of Stock Options Outstanding and Vested and Exercisable by Exercise Price	Under the 2004 Plan and 2011 Plan, the options outstanding and vested and exercisable by exercise price at December 31, 2014 are as follows:
		Options Outstanding and Exercisable								Options Vested and Exercisable
	Range of Exercise Price	Number of		Weighted-		Weighted-				Number of		Weighted-
		Shares Underlying		Average		Average				Shares		Average
		Outstanding		Remaining		Exercise Price				Underlying		Exercise Price
		Options		Contractual		per Share				Outstanding		per Share
		(in thousands)		Life (Years)						Options
										(in thousands)
	$3.33	2,116		6.8		$	3.33			1,457		$	3.33
	$4.16 - $4.18	2,272		7.6		4.17				875		4.17
	$4.92 - $7.76	1,868		8		6.3				618		5.81
	$8.77 - $10.18	2,624		8.6		9.73				313		9.5
	$22.49 -$30.67	2,652		9.1		27.58				127		22.59
	$34.12 - $68.34	1,888		9.6		50.84				7		36.38
	$75.00 - $76.80	224		9.7		75.71				—		—
	$84.00	10		9.7		84				—		—
		13,654		8.3		$	17.63			3,397		$	5.36
Schedule of Nonvested Restricted Stock Units Activity	A summary of the activity under our stock plans and changes during the reporting period and a summary of information related to RSUs are presented below (in thousands, except years and per share amounts):
		Number of		Weighted-				Weighted-Average		Aggregate Intrinsic Value
		Shares		Average Grant				Remaining
				Date Fair Value Per Share				Contractual Term (in years)
	Unvested balance—December 31, 2013	—		—				0		—
	RSUs granted	109		$	75.55
	RSUs vested	—		—
	RSUs forfeited/canceled	(1	)	75
	Unvested balance—December 31, 2014	108		$	75.56			2		$	6,557
	RSUs expected to vest—December 31, 2014	94		$	75.56			2		$	5,722
Nonvested Restricted Stock Shares Activity	A summary of our RSA activity and related information is as follows (in thousands, except per share amounts):
		Number of		Weighted-
		RSA’s		Average Grant
		Outstanding		Date Fair Value Per Share
	Unvested balance—December 31, 2013	142		$	2.42
	Vested	(57	)	2.5
	Unvested balance—December 31, 2014	85		$	2.5

Net_Income_Per_Share_Available1

Net Income Per Share Available to Common Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Income Per Share Available to Common Stock	The following table sets forth the computation of our basic and diluted net income per share available to common stock (in thousands, except per share amounts):
		Year Ended December 31,
		2014				2013			2012
	Numerator:
	Basic:
	Net income	$	86,850			$	42,460		$	21,349
	Less: undistributed earnings allocated to participating securities	(17,961		)		(21,683		)	(11,727		)
	Net income available to common stockholders, basic	$	68,889			$	20,777		$	9,622
	Diluted:
	Net income attributable to common stockholders, basic	$	68,889			$	20,777		$	9,622
	Add: undistributed earnings allocated to participating securities	1,635				1,003			40
	Net income attributable to common stockholders, diluted	$	70,524			$	21,780		$	9,662
	Denominator:
	Basic:
	Weighted-average shares used in computing net income per share available to common stockholders, basic	48,427				27,320			24,711
	Diluted:
	Weighted-average shares used in computing net income per share available to common stockholders, basic	48,427				27,320			24,711
	Add weighted-average effect of dilutive securities:
	Stock options, RSUs and RSAs	6,059				2,726			187
	Employee stock purchase plan	104				—			—
	Stock purchase rights	—				5			3
	Weighted-average shares used in computing net income per share available to common stockholders, diluted	54,590				30,051			24,901
	Net income per share attributable to common stockholders:
	Basic	$	1.42			$	0.76		$	0.39
	Diluted	$	1.29			$	0.72		$	0.39
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net income per share available to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Stock options and RSUs	1,263			3,599			169

Income_Taxes_Income_Taxes_Tabl

Income Taxes Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax	The geographical breakdown of income before provision for income taxes is as follows (in thousands):
		Year Ended December 31,
		2014				2013				2012
	Domestic	$	120,838			$	50,455			$	26,837
	Foreign	670				7,820				6,138
	Income before provision for income taxes	$	121,508			$	58,275			$	32,975
Schedule of Components of Income Tax Expense (Benefit)	The components of the provision for income taxes are as follows (in thousands):
		Year Ended December 31,
		2014				2013				2012
	Current provision for income taxes:
	Federal	$	36,091			$	19,708			$	13,037
	State	2,716				4,525				2,003
	Foreign	3,306				413				308
	Total current	42,113				24,646				15,348
	Deferred tax benefit:
	Federal	(7,028		)		(8,059		)		(3,525		)
	State	153				(938		)		(342		)
	Foreign	(580		)		166				145
	Total deferred	(7,455		)		(8,831		)		(3,722		)
	Total provision for income taxes	$	34,658			$	15,815			$	11,626
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the statutory federal income tax and our effective income tax is as follows:
		Year Ended December 31,
		2014			2013			2012
	U.S. federal statutory income tax	35	%		35	%		35	%
	State tax, net of federal benefit	1.19			0.89			0.26
	Foreign tax differential	0.68			(2.61	)		(3.21	)
	Tax credits	(5.26	)		(10.64	)		(0.96	)
	Change in valuation allowance	1.92			3.87			3.04
	Permanent items	(0.86	)		(2.54	)		(2.55	)
	Uncertain tax positions and associated interest	0.37			0.58			0.44
	Stock-based compensation	(4.01	)		2.47			3.21
	Other, net	(0.51	)		0.12			0.03
	Total provision for income taxes	28.52	%		27.14	%		35.26	%
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences that give rise to significant portions of deferred tax assets (liabilities) are as follows (in thousands):
		December 31,
		2014				2013
	Deferred tax assets:
	Property and equipment	$	504			$	1,020
	Stock-based compensation	6,365				1,738
	Reserves and accruals not currently deductible	16,160				13,351
	Net operating losses	721				1,143
	Tax credits	9,923				5,156
	State taxes	342				514
	Other	1,142				375
	Gross deferred tax assets	35,157				23,297
	Valuation allowance	(8,954		)		(6,288		)
	Total deferred tax assets	26,203				17,009
	Deferred tax liabilities:
	Property and equipment	(2,001		)		(47		)
	Accrued liabilities	(558		)		(173		)
	Other	(2		)		—
	Total deferred tax liabilities	(2,561		)		(220		)
	Net deferred tax assets	$	23,642			$	16,789
	The following table presents the breakdown between current and non-current deferred tax assets and liabilities (in thousands):
		December 31,
		2014				2013
	Deferred tax assets	$	12,252			$	12,356
	Deferred tax assets, non-current	11,510				4,541
	Deferred tax liabilities, non-current	(120		)		(108		)
	Total net deferred tax assets	$	23,642				$16,789
Schedule of Unrecognized Tax Benefits Roll Forward	The reconciliation of the beginning and ending amount of gross unrecognized tax benefits as of December 31, 2014, 2013 and 2012 was as follows (in thousands):
		Year Ended December 31,
		2014				2013				2012
	Gross unrecognized tax benefits—beginning balance	$	16,973			$	13,960			$	13,326
	Increases related to tax positions taken in a prior year	425				70				—
	Increases related to tax positions taken during current year	4,355				2,975				634
	Decreases related to tax positions taken in a prior year	(431		)		(32		)		—
	Decreases related to settlements with taxing authorities	—				—				—
	Decreases related to lapse of statute of limitations	—				—				—
	Gross unrecognized tax benefits—ending balance	$	21,322			$	16,973			$	13,960

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Schedule of Net Revenue and Long Lived Assets, by Location	The following table represents revenue based on the customer’s location, as determined by the customer’s shipping address (in thousands):
		Year Ended December 31,
		2014		2013		2012
	United States	$	456,691	$	293,579	$	149,537
	Other Americas	8,853		6,040		5,056
	Europe, Middle East and Africa	74,555		40,577		23,012
	Asia Pacific	44,007		21,028		15,803
	Total revenue	$	584,106	$	361,224	$	193,408
	Long lived assets, excluding intercompany receivables, investments in subsidiaries, privately-held equity investments
	and deferred tax assets, net by location are summarized as follows (in thousands):
		December 31,
		2014		2013
	United States	$	67,727	$	63,557
	International	3,831		3,647
	Total	$	71,558	$	67,204

Organization_and_Summary_of_Si3

Organization and Summary of Significant Accounting Policies - Additional Information (Details) (USD $)	0 Months Ended	12 Months Ended
	Jun. 06, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 31, 2014	Jun. 06, 2014
		segment	supplier		multiplier	noteholder
		multiplier
		manufacturer
		supplier
Class of Stock [Line Items]
Proceeds from initial public offering, net of offering costs	$239,100,000	$239,055,000
Underwriting discounts and commissions	15,600,000
Issuance costs	5,000,000
Number of noteholders paid out upon closing of IPO	1					1
Repayment of notes payable and accrued interest	23,600,000
Withholding taxes	1,100,000
Converted debt amount	96,500,000
Number of suppliers		2	2
Foreign Currency [Abstract]
Foreign currency transaction losses		600,000	100,000	200,000
Inventory [Line Items]
Inventory write-down		2,800,000	5,300,000	3,200,000
Number of third-party contract manufacturers		2
Raw materials		17,094,000	18,286,000
Notes Receivable
Multiplier of payment received		2			2
Warranty
Warranty term on hardware products		1 year
Warranty term on software embedded in products		90 days
Segment Reporting [Abstract]
Number of business activities		1
Number of reportable segments		1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefits from stock awards		17,358,000	552,000	39,000
Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		1 year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of the awards		2 years
Minimum | Software Service, Support and Maintenance Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
PCS term of contract		1 year
Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of the awards		5 years
Maximum | Software Service, Support and Maintenance Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
PCS term of contract		3 years
Building
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		30 years
Consigned [Member]
Inventory [Line Items]
Raw materials		17,100,000	18,300,000
Other Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash		$4,000,000
Common Stock
Class of Stock [Line Items]
Issuance of common stock during IPO (in shares)	6,037,500
Issue price (in dollars per share)	$43					43
Common stock issued pursuant to exercise of over-allotment option by underwriters	787,500
Shares issued upon conversion (in shares)	24,000,000
Ratio of shares issued upon conversion	1					1
Convertible Debt [Member] | Common Stock
Class of Stock [Line Items]
Shares issued upon conversion (in shares)	2,200,000

Organization_and_Summary_of_Si4

Organization and Summary of Significant Accounting Policies - Concentrations of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Concentration Risk [Line Items]
Percentage of total per significant customer, revenue, accounts receivable	10.00%
Customer Concentration Risk [Member] | Revenue | Customer A
Concentration Risk [Line Items]
Percentage of total per significant customer, revenue, accounts receivable	15.00%	22.00%	15.00%
Credit Concentration Risk [Member] | Accounts Receivable | Customer A
Concentration Risk [Line Items]
Percentage of total per significant customer, revenue, accounts receivable	15.00%	17.00%
Credit Concentration Risk [Member] | Accounts Receivable | Customer B
Concentration Risk [Line Items]
Percentage of total per significant customer, revenue, accounts receivable		11.00%

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	0 Months Ended	12 Months Ended
	Jul. 30, 2014	Dec. 31, 2014	Oct. 31, 2014	Dec. 31, 2013
			multiplier
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in notes receivable	$4,000,000
Multiplier of payment received		2	2
U.S. government notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. government notes		209,426,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable				4,000,000	[1]
Total financial assets		313,642,000		55,076,000
Fair Value, Measurements, Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		104,216,000		47,036,000
Other assets - Restricted cash				4,040,000
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable				0	[1]
Total financial assets		313,642,000		51,076,000
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		104,216,000		47,036,000
Other assets - Restricted cash				4,040,000
Fair Value, Measurements, Recurring | Level 1 | U.S. government notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. government notes		209,426,000
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable				0	[1]
Total financial assets		0		0
Fair Value, Measurements, Recurring | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0		0
Other assets - Restricted cash				0
Fair Value, Measurements, Recurring | Level 2 | U.S. government notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. government notes		0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable				4,000,000	[1]
Total financial assets		0		4,000,000
Fair Value, Measurements, Recurring | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0		0
Other assets - Restricted cash				0
Fair Value, Measurements, Recurring | Level 3 | U.S. government notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. government notes		0
6% Convertible Notes Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in notes receivable		$4,000,000
[1]	There were no changes in the fair value of the Level III assets during the year ended December 31, 2013. In 2014, we increased the fair value of our Notes receivable by $4.0 million (See “Note 4 – Investments”). During the year ended December 31, 2014 and 2013, we had no transfers between levels of the fair value hierarchy of its assets measured at fair value. In October 2014, we received payment in full from the borrower equal to two times our outstanding principal balance as well as the unpaid accrued interest through the payment date.

Balance_Sheet_Components_Unrea

Balance Sheet Components - Unrealized Gains and Losses and Fair Value of Investments (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified	security
Schedule of Available-for-sale Securities [Line Items]
Marketable securities in continuous unrealized loss position, greater than twelve months	0
U.S. government notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	209,671
Unrealized Gains	0
Unrealized Losses	-245
Fair Value	209,426

Balance_Sheet_Components_Amort

Balance Sheet Components - Amortized Cost and Fair Value of Investments by Contractual Years-to-Maturity (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Balance Sheet Components [Abstract]
Maximum maturity of marketable securities	2 years
Weighted-average remaining duration of current marketable securities	9 months 26 days
Amortized Cost	$209,671
Fair Value	$209,426

Balance_Sheet_Components_Accou

Balance Sheet Components - Accounts Receivable, Net (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Balance Sheet Components [Abstract]
Accounts receivable	$100,076	$80,338
Allowance for doubtful accounts	-1,063	-810
Product sales return reserve	-2,031	-1,529	0
Accounts receivable, net	$96,982	$77,999

Balance_Sheet_Components_Allow

Balance Sheet Components - Allowance for Doubtful Accounts (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at the beginning of year	$810	$1,284	$1,169
Charged to expenses	860	191	326
Deductions (write-offs)	-607	-665	-211
Balance at the end of year	$1,063	$810	$1,284

Balance_Sheet_Components_Sales

Balance Sheet Components - Sales Return Reserve (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Sales Return Reserve [Roll Forward]
Balance at the beginning of year	$1,529	$0
Charged against revenue	4,063	1,627
Sales returns	-3,561	-98
Balance at the end of year	$2,031	$1,529

Balance_Sheet_Components_Inven

Balance Sheet Components - Inventories (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventories
Raw materials	$17,094	$18,286
Finished goods	63,425	48,808
Total inventories	$80,519	$67,094

Balance_Sheet_Components_Prepa

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Balance Sheet Components [Abstract]
Prepaid income taxes	$25,212	$134
Other current assets	9,820	5,137
Other prepaid and deposits	5,237	2,382
Total prepaid expenses and other current assets	$40,269	$7,653

Balance_Sheet_Components_Prope

Balance Sheet Components - Property and Equipment, net (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$88,516,000	$74,390,000
Less: accumulated depreciation	-16,958,000	-7,186,000
Property and equipment, net	71,558,000	67,204,000
Depreciation	10,000,000	5,000,000	1,800,000
Equipment and machinery
Property, Plant and Equipment [Line Items]
Property and equipment, gross	18,265,000	13,733,000
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,772,000	3,688,000
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,373,000	1,352,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	19,420,000	19,407,000
Building
Property, Plant and Equipment [Line Items]
Property and equipment, gross	35,154,000	35,154,000
Construction-in-process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,532,000	1,056,000
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	53,400,000	53,300,000
Line of Credit | Letter of Credit
Property, Plant and Equipment [Line Items]
Letter of credit	$4,000,000

Balance_Sheet_Components_Accru

Balance Sheet Components - Accrued Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Balance Sheet Components [Abstract]
Accrued payroll related costs	$30,749	$9,103
Accrued warranty costs	3,204	5,075	5,314
Accrued manufacturing costs	1,089	3,835
Accrued professional fees	2,354	1,220
Accrued taxes	1,577	927
Other	1,396	1,379
Total accrued liabilities	$40,369	$21,539

Balance_Sheet_Components_Warra

Balance Sheet Components - Warranty Accrual (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Warranty [Roll Forward]
Warranty accrual, beginning of period	$5,075,000	$5,314,000
Liabilities accrued for warranties issued during the period	2,611,000	4,290,000
Warranty costs incurred during the period	-2,163,000	-4,529,000
Adjustments related to change in estimate	-2,319,000	0
Warranty accrual, end of period	3,204,000	5,075,000
Specific product warranty reserves recorded	$0

Balance_Sheet_Components_Other

Balance Sheet Components - Other Current Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Balance Sheet Components [Abstract]
Liability for early exercised shares subject to repurchase	$4,616	$7,520
Sales tax payable	3,101	1,359
Lease financing obligations, current portion	1,087	818
Other	2,445	447
Total other current liabilities	$11,249	$10,144

Investments_Investments_in_Pri

Investments - Investments in Privately-held Companies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Cost method investments	$33,600,000
Cost-method investments impairment	$0

Investments_Notes_Receivable_D

Investments - Notes Receivable (Details) (USD $)	0 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jul. 30, 2014	Dec. 31, 2014	Oct. 31, 2014	Dec. 31, 2012
		multiplier	multiplier
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investments	$8
Minimum percentage of voting power transferred in corporate transaction	50.00%
Increase in notes receivable	4
Multiplier of payment received		2	2
Period borrower cannot sell exclusive features to other customers		24 months
8% Promissory Note Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investments		3
Interest rate on notes receivable				8.00%
6% Convertible Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investments				4
Interest rate on notes receivable				6.00%
Increase in notes receivable		4

Debt_Obligations_Schedule_of_D

Debt Obligations - Schedule of Debt Obligations (Details) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Long-term debt, gross	$100,000
Less: Unamortized discount on notes payable	1,207
Less: Current portion	98,793
Total long-term portion of debt	0
Convertible notes
Debt Instrument [Line Items]
Long-term debt, gross	75,000
Convertible notes payable—related party | Convertible notes
Debt Instrument [Line Items]
Long-term debt, gross	$25,000

Debt_Obligations_Additional_In

Debt Obligations - Additional Information (Details) (USD $)	0 Months Ended	12 Months Ended
	Jun. 06, 2014	Dec. 31, 2014	Jan. 31, 2011	Jun. 30, 2011
			trust
			related_party
Debt Instrument [Line Items]
Number of trusts related to two co-founders			2
Number of related co-founders			2
Prepay notice period		10 days
Repayment of notes payable and accrued interest	$23,600,000
Withholding taxes	1,100,000
Converted debt amount	96,500,000
Convertible notes
Debt Instrument [Line Items]
Interest rate		6.00%
Minimum amount of indebtedness not subject to acceleration of maturity after failure to make other payment obligations		10,000,000
Convertible notes | Convertible notes issued January 2011
Debt Instrument [Line Items]
Aggregate principal amount			55,000,000
Convertible notes | Convertible debt issued June 2011
Debt Instrument [Line Items]
Aggregate principal amount				20,000,000
Trusts related to two co-founders | Convertible notes | Related party convertible notes issued January 2011
Debt Instrument [Line Items]
Aggregate principal amount			25,000,000
Common Stock | Convertible notes payable
Debt Instrument [Line Items]
Shares issued upon conversion (in shares)		1,543,000
Common Stock
Debt Instrument [Line Items]
Issue price (in dollars per share)	$43
Shares issued upon conversion (in shares)	24,000,000
Common Stock | Convertible notes payable
Debt Instrument [Line Items]
Shares issued upon conversion (in shares)	2,200,000

Commitments_and_Contingencies_1

Commitments and Contingencies - Operating Leases (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2015	$2,583
2016	4,297
2017	5,155
2018	5,378
2019	5,369
Thereafter	22,407
Total minimum future lease payments	$45,189

Commitments_and_Contingencies_2

Commitments and Contingencies - Additional Information (Details) (USD $)	1 Months Ended	12 Months Ended
	Aug. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long-term Purchase Commitment [Line Items]
Rent expense		$3,300,000	$3,600,000	$2,000,000
Lease term	120 months
Recorded assets		88,516,000	74,390,000
Lease financing obligation		43,600,000	44,000,000
Lease financing obligation, current		1,100,000
Lease financing obligations, non-current		42,547,000	43,152,000
Contract manufacturer liability		300,000	1,800,000
Other Assets
Long-term Purchase Commitment [Line Items]
Restricted deposits		2,300,000	2,300,000
Line of Credit | Letter of Credit
Long-term Purchase Commitment [Line Items]
Letter of credit		4,000,000
Building and improvements
Long-term Purchase Commitment [Line Items]
Recorded assets		53,400,000	53,300,000
Building
Long-term Purchase Commitment [Line Items]
Recorded assets		$35,154,000	$35,154,000
Estimated useful life		30 years

Commitments_and_Contingencies_3

Commitments and Contingencies - Lease Financing Obligation (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Lease Financing Obligation, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2015	$5,588
2016	5,754
2017	5,933
2018	6,113
2019	6,293
Thereafter	25,287
Total payments	54,968
Less: interest and land lease expense	-34,770
Total payments under facility financing obligations	20,198
Property reverting to landlord	23,436
Present value of obligation	43,634
Less current portion	-1,087	-818
Long-term portion of obligation	$42,547	$43,152

StockBased_Compensation_StockB

Stock-Based Compensation - Stock-Based Compensation Expense (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
	employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$27,619,000		$10,159,000		$4,703,000
Modification charge related to acceleration of shares	500,000
Number of employees terminated	2
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,535,000		408,000		270,000
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	14,986,000	[1]	5,464,000	[1]	2,590,000	[1]
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	7,643,000	[1]	2,985,000	[1]	1,078,000	[1]
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$3,455,000		$1,302,000		$765,000
[1]	Includes modification charge of $0.5 million in 2014 related to acceleration of shares upon termination for two employees.

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 17, 2015	Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized	6,510,000
Number of shares available for grant (in shares)	11,612,000	8,941,000
Weighted-average grant-date fair value of options granted (in dollars per share)	$24.69
Aggregate intrinsic value of options exercised	$80,500,000
Unrecognized stock-based compensation expense	106,800,000
Fair value of options vested	16,500,000
Shares subject to repurchase (in shares)	1,400,000
Aggregate price of shares subject to repurchase	4,616,000	7,520,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchases under the ESPP (in shares)		21,250	20,000
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period	4 years 4 months 24 days
Stock Option | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchased shares of common stock (in shares)	29,803
Restricted Stock Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period	1 year 9 months 18 days
RSUs granted (in shares)	0
Unrecognized expense	200,000
Fair value unvested restricted stock awards (in dollars per share)	$60.76
Intrinsic value of unvested restricted stock awards	5,000,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchases under the ESPP (in shares)	0
Unrecognized stock-based compensation expense for unvested options, net of expected forfeitures	3,000,000
Weighted-average amortization period	1 year 7 months 6 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense for unvested options, net of expected forfeitures	$6,500,000
Weighted-average amortization period	3 years 9 months 26 days
RSUs granted (in shares)	109,000
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					6,510,000
Percent of shares outstanding to increase number of shares available for grant and issuance	3.00%
Maximum increase of number of shares available for grant	12,500,000
2014 Equity Incentive Plan | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of shares outstanding to increase number of shares available for grant and issuance				1.00%
2014 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares added to the 2014 Plan					20,025,189
2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					651,000
Percent of shares outstanding to increase number of shares available for grant and issuance	1.00%
2014 Employee Stock Purchase Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)	2,500,000
2014 Employee Stock Purchase Plan | Maximum | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized				655,139

StockBased_Compensation_Fair_V

Stock-Based Compensation - Fair Value Assumptions - Stock Options (Details) (Stock Option)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 years 7 months 6 days	6 years 6 months	5 years 7 months 6 days
Risk-free interest rate	2.20%	1.70%	0.90%
Expected volatility	47.70%	51.00%	51.00%
Expected dividend rate	0.00%	0.00%	0.00%

StockBased_Compensation_Fair_V1

Stock-Based Compensation - Fair Value Assumptions - ESPP (Details) (ESPP)	12 Months Ended
	Dec. 31, 2014
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	1 year 4 months 24 days
Risk-free interest rate	0.30%
Expected volatility	36.30%
Expected dividend rate	0.00%

StockBased_Compensation_Option

Stock-Based Compensation - Option and RSA Activity Rollforward (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Shares Available for Grant
Outstanding, beginning balance (in shares)	8,941,000
Authorized (in shares)	6,510,000
Options granted (in shares)	-4,521,000
Options canceled (in shares)	654,000
Early exercised shares repurchased (in shares)	28,000	[1]
Outstanding, ending balance (in shares)	11,612,000		8,941,000
Number of Shares Underlying Outstanding Options and RSAs (in thousands)
Outstanding, beginning balance (in shares)	11,245,000
Options granted (in shares)	4,412,000
Options exercised (in shares)	-1,349,000
Options canceled (in shares)	-654,000
Early exercised shares repurchased (in shares)	0	[1]
Outstanding, ending balance (in shares)	13,654,000		11,245,000
Vested and exercisable (in shares)	3,397,000
Vested and expected to vest (in shares)	12,034,000
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in dollars per share)	$6.82
Options granted (in dollars per share)	$40.88
Options exercised (in dollars per share)	$6.04
Options canceled (in dollars per share)	$12.45
Early exercised shares repurchased (in dollars per share)	$4.05	[1]
Outstanding, ending balance (in dollars per share)	$17.63		$6.82
Vested and exercisable (in dollars per share)	$5.36
Vested and expected to vest (in dollars per share)	$16.12
Weighted- Average Remaining Contractual Term (Years) of Stock Options
Weighted-average remaining contractual term of stock options outstanding	8 years 3 months 18 days		8 years 9 months 18 days
Weighted-average remaining contractual term of stock options vested and exercisable	7 years 4 months 28 days
Weighted-average remaining contractual term of stock options vested and expected to vest	8 years 2 months 27 days
Aggregate intrinsic value of stock options outstanding, beginning of period	$254,319
Aggregate intrinsic value of stock options outstanding, end of period	598,775		254,319
Aggregate intrinsic value of stock options outstanding vested and exercisable	188,223
Aggregate intrinsic value of stock options outstanding vested and expected to vest	$544,919
Early exercised shares repurchased and retired	2,000
[1]	Early exercised shares repurchased includes 2,000 shares that were originally granted out of our 2004 Plan and were subsequently retired.

StockBased_Compensation_Stock_

Stock-Based Compensation - Stock Options by Exercise Price (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Underlying Outstanding Options (in shares)	13,654
Weighted- Average Remaining Contractual Life (Years)	8 years 3 months 18 days
Weighted- Average Exercise Price per Share (in dollars per share)	$17.63
Number of Shares Underlying Outstanding Options (in shares)	3,397
Weighted- Average Exercise Price per Share (in dollars per share)	$5.36
$3.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$3.33
Exercise price range, maximum (in dollars per share)	$3.33
Number of Shares Underlying Outstanding Options (in shares)	2,116
Weighted- Average Remaining Contractual Life (Years)	6 years 9 months 18 days
Weighted- Average Exercise Price per Share (in dollars per share)	$3.33
Number of Shares Underlying Outstanding Options (in shares)	1,457
Weighted- Average Exercise Price per Share (in dollars per share)	$3.33
$4.16 - $4.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$4.18
Exercise price range, maximum (in dollars per share)	$4.16
Number of Shares Underlying Outstanding Options (in shares)	2,272
Weighted- Average Remaining Contractual Life (Years)	7 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$4.17
Number of Shares Underlying Outstanding Options (in shares)	875
Weighted- Average Exercise Price per Share (in dollars per share)	$4.17
$4.92 - $7.76
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$7.76
Exercise price range, maximum (in dollars per share)	$4.92
Number of Shares Underlying Outstanding Options (in shares)	1,868
Weighted- Average Remaining Contractual Life (Years)	8 years
Weighted- Average Exercise Price per Share (in dollars per share)	$6.30
Number of Shares Underlying Outstanding Options (in shares)	618
Weighted- Average Exercise Price per Share (in dollars per share)	$5.81
$8.77 - $10.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$10.18
Exercise price range, maximum (in dollars per share)	$8.77
Number of Shares Underlying Outstanding Options (in shares)	2,624
Weighted- Average Remaining Contractual Life (Years)	8 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$9.73
Number of Shares Underlying Outstanding Options (in shares)	313
Weighted- Average Exercise Price per Share (in dollars per share)	$9.50
$22.49 -$30.67
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$30.67
Exercise price range, maximum (in dollars per share)	$22.49
Number of Shares Underlying Outstanding Options (in shares)	2,652
Weighted- Average Remaining Contractual Life (Years)	9 years 1 month 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$27.58
Number of Shares Underlying Outstanding Options (in shares)	127
Weighted- Average Exercise Price per Share (in dollars per share)	$22.59
$34.12 - $68.34
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$68.34
Exercise price range, maximum (in dollars per share)	$34.12
Number of Shares Underlying Outstanding Options (in shares)	1,888
Weighted- Average Remaining Contractual Life (Years)	9 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$50.84
Number of Shares Underlying Outstanding Options (in shares)	7
Weighted- Average Exercise Price per Share (in dollars per share)	$36.38
$75.00 - $76.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$76.80
Exercise price range, maximum (in dollars per share)	$75
Number of Shares Underlying Outstanding Options (in shares)	224
Weighted- Average Remaining Contractual Life (Years)	9 years 8 months 12 days
Weighted- Average Exercise Price per Share (in dollars per share)	$75.71
Number of Shares Underlying Outstanding Options (in shares)	0
Weighted- Average Exercise Price per Share (in dollars per share)	$0
$84.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$84
Exercise price range, maximum (in dollars per share)	$84
Number of Shares Underlying Outstanding Options (in shares)	10
Weighted- Average Remaining Contractual Life (Years)	9 years 8 months 12 days
Weighted- Average Exercise Price per Share (in dollars per share)	$84
Number of Shares Underlying Outstanding Options (in shares)	0
Weighted- Average Exercise Price per Share (in dollars per share)	$0

StockBased_Compensation_Restri

Stock-Based Compensation - Restricted Stock Unit (RSU) Activities (Details) (Restricted Stock Units (RSUs), USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock Units (RSUs)
Restricted Stock Awards, Number of Shares [Roll Forward]
Unvested beginning balance (in shares)	0
RSUs granted (in shares)	109,000
RSUs Vested (in shares)	0
RSUs forfeited/canceled (in shares)	-1,000
Unvested ending balance (in shares)	108,000	0
RSUs vested and expected to vest, (in shares)	94,000
Restricted Stock Unit Activities, Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share)	$0
RSUs granted (in dollars per share)	$75.55
RSUs Vested (in dollars per share)	$0
RSUs forfeited/canceled (in dollars per share)	$75
Unvested ending balance (in dollars per share)	$75.56	$0
RSUs vested and expected to vest, weighted average grant date fair value (in dollars per share)	$75.56
Restricted Stock Unit Activities, Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Unvested, weighted average remaining contractual term (in years)	2 years	0 years
RSUs vested and expected to vest, weighted average contractual term (in years)	2 years
Unvested, aggregate intrinsic value, beginning of period	$0
Unvested, aggregate intrinsic value, end of period	6,557	0
RSUs vested and expected to vest, aggregate intrinsic value	$5,722

StockBased_Compensation_Restri1

Stock-Based Compensation - Restricted Stock Award Activities (Details) (Restricted Stock Award, USD $)	12 Months Ended
	Dec. 31, 2014
Restricted Stock Award
Restricted Stock Award Activities, Number of RSA's Outstanding
Unvested beginning balance (in shares)	141,667
Vested (in shares)	-56,667
Unvested ending balance (in shares)	85,000
Restricted Stock Award Activities, Weighted-Average Grant Date Fair Value Per Share
Unvested beginning balance (in dollars per share)	$2.42
Vested (unaudited) (in dollars per share)	$2.50
Unvested ending balance (in dollars per share)	$2.50

Net_Income_Per_Share_Available2

Net Income Per Share Available to Common Stock - Basic and Diluted Net Income Per Share (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income	$86,850	$42,460	$21,349
Less: undistributed earnings allocated to participating securities	-17,961	-21,683	-11,727
Net income attributable to common stockholders, basic	68,889	20,777	9,622
Add: undistributed earnings allocated to participating securities	1,635	1,003	40
Net income attributable to common stockholders, diluted	$70,524	$21,780	$9,662
Weighted-average shares used in computing net income per share available to common stockholders, basic (in shares)	48,427	27,320	24,711
Add weighted-average effect of dilutive securities:
Stock options and RSAs (in shares)	6,059	2,726	187
Employee stock purchase plan (in shares)	104	0	0
Stock purchase rights (in shares)	0	5	3
Weighted-average shares used in computing net income per share available to common stockholders, diluted (in shares)	54,590	30,051	24,901
Net income per share attributable to common stockholders:
Basic (in dollars per share)	$1.42	$0.76	$0.39
Diluted (in dollars per share)	$1.29	$0.72	$0.39

Net_Income_Per_Share_Available3

Net Income Per Share Available to Common Stock - Antidilutive Securities Excluded from Earnings Per Share (Details) (Stock options and RSAs)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock options and RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	1,263	3,599	169

Income_Taxes_Geographical_Brea

Income Taxes - Geographical Breakdown Income before Taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
Domestic	$120,838	$50,455	$26,837
Foreign	670	7,820	6,138
Income before provision for income taxes	$121,508	$58,275	$32,975

Income_Taxes_Components_of_the

Income Taxes - Components of the Provision for Income Taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current provision for income taxes:
Federal	$36,091	$19,708	$13,037
State	2,716	4,525	2,003
Foreign	3,306	413	308
Total current	42,113	24,646	15,348
Deferred tax benefit:
Federal	-7,028	-8,059	-3,525
State	153	-938	-342
Foreign	-580	166	145
Total deferred	-7,455	-8,831	-3,722
Total provision for income taxes	$34,658	$15,815	$11,626

Income_Taxes_Effective_Income_

Income Taxes - Effective Income Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax	35.00%	35.00%	35.00%
State tax, net of federal benefit	1.19%	0.89%	0.26%
Foreign tax differential	0.68%	-2.61%	-3.21%
Tax credits	-5.26%	-10.64%	-0.96%
Change in valuation allowance	1.92%	3.87%	3.04%
Permanent items	-0.86%	-2.54%	-2.55%
Uncertain tax positions and associated interest	0.37%	0.58%	0.44%
Stock-based compensation	-4.01%	2.47%	3.21%
Other, net	-0.51%	0.12%	0.03%
Total provision for income taxes	28.52%	27.14%	35.26%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Line Items]
Valuation allowance	$8,954,000	$6,288,000
Increase in valuation allowance	2,700,000	2,400,000	1,000,000
Undistributed earnings	4,900,000	4,900,000	1,000,000
Unrecognized tax benefits	21,322,000	16,973,000	13,960,000	13,326,000
Unrecognized tax benefits that would affect effective tax rate	15,800,000	13,900,000	12,200,000
Accrued interest and penalties	700,000	500,000
Liability for interest and penalties	1,500,000	800,000
Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	0	0
Tax credit carryforward	1,900,000	0
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	0	13,100,000
Tax credit carryforward	16,400,000	9,600,000
Foreign Tax Authority [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	7,500,000	4,200,000
Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward	$2,100,000	$1,300,000

Income_Taxes_Deferred_Tax_Asse

Income Taxes - Deferred Tax Assets (Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Property and equipment	$504	$1,020
Stock-based compensation	6,365	1,738
Reserves and accruals not currently deductible	16,160	13,351
Net operating losses	721	1,143
Tax credits	9,923	5,156
State taxes	342	514
Other	1,142	375
Gross deferred tax assets	35,157	23,297
Valuation allowance	-8,954	-6,288
Total deferred tax assets	26,203	17,009
Deferred Tax Liabilities, Gross [Abstract]
Property and equipment	-2,001	-47
Accrued liabilities	-558	-173
Other	-2	0
Total deferred tax liabilities	-2,561	-220
Net deferred tax assets	23,642	16,789
Deferred Tax Assets, Net of Valuation Allowance, Classification [Abstract]
Deferred tax assets	12,252	12,356
Deferred tax assets, non-current	11,510	4,541
Deferred tax liabilities, non-current	($120)	($108)

Income_Taxes_Unrecognized_Tax_

Income Taxes - Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits—beginning balance	$21,322	$16,973	$13,960	$13,326
Increases related to tax positions taken in a prior year	425	70	0
Increases related to tax positions taken during current year	4,355	2,975	634
Decreases related to tax positions taken in a prior year	-431	-32	0
Decreases related to settlements with taxing authorities	0	0	0
Decreases related to lapse of statute of limitations	0	0	0
Gross unrecognized tax benefits—ending balance	$21,322	$16,973	$13,960	$13,326

Segment_Information_Details

Segment Information (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	segment
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reportable segments	1
Revenue	$584,106	$361,224	$193,408
Long lived assets	71,558	67,204
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	456,691	293,579	149,537
Long lived assets	67,727	63,557
Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	8,853	6,040	5,056
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	74,555	40,577	23,012
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	44,007	21,028	15,803
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long lived assets	$3,831	$3,647

Other_Related_Party_Transactio1

Other Related Party Transactions and Balances (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
Revenue from related parties	$29.60	$11.10	$1.10
Due from related parties	$6.40	$3.80