| Significant Accounting Policies | Significant Accounting Policies Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates, assumptions and judgments that can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the reporting periods. Significant estimates, assumptions and judgements made by management include revenue recognition, inventory valuation, and accounting for income taxes. Other less significant estimates, assumptions and judgments made by management include stock-based compensation, employee benefit and pension plans, manufacturing partner and supplier liabilities, allowances for sales returns, allowances for credit losses, useful life of intangibles and property, plant and equipment, impairment loss related to lease abandonment, accrued warranty, operating and finance lease liabilities, restructuring and other related costs, fair value measurement of the debt component of the convertible senior notes, and loss contingencies. The Company bases its assumptions on historical experience and also on assumptions that it believes are reasonable. Actual results could differ materially from those estimates. The Company expects uncertainties around its key accounting estimates to continue to evolve depending on the duration and degree of impact associated with the outbreak of a novel strain of the coronavirus (“COVID-19”). These estimates may change as new events occur and additional information emerges, and such changes are recognized or disclosed in the Company's consolidated financial statements. Revenue Recognition The Company recognizes revenue when control of the promised goods or services is transferred to its customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. The Company determines revenue recognition by applying the following five-step approach: • identification of the contract, or contracts, with a customer; • identification of the performance obligations in the contract; • determination of the transaction price; • allocation of the transaction price to the performance obligations in the contract; and • recognition of revenue when, or as, the Company satisfies a performance obligation. Many of the Company's product sales are sold in combination with installation and deployment services along with initial hardware and software support. The Company's product sales are also sold at times with spares management, on-site hardware replacement services, network operations management, software subscription services, extended hardware warranty and training. Initial software and hardware support services are generally delivered over a one-year period in connection with the initial purchase. Software warranty provides customers with maintenance releases during the warranty support period and hardware warranty provides replacement or repair of equipment that fails to perform in line with specifications. Software subscription services include software warranty and additionally provides customers with rights to receive unspecified software product upgrades released during the support period. Spares management and on-site hardware replacement services include the replacement of defective units at customer sites in accordance with specified service level agreements. Network operations management includes the day-to-day operation of a customer's network. These services are generally delivered on an annual basis. The Company evaluates each promised good and service in a contract to determine whether it represents a distinct performance obligation or should be accounted for as a combined performance obligation. Services revenue includes software subscription services, installation and deployment services, spares management, on-site hardware replacement services, network operations management, extended hardware warranty and training. Revenue from software subscription services, spares management, on-site hardware replacement services, network operations management and extended hardware warranty contracts is deferred and is recognized ratably over the contractual support period, which is generally one year, as services are provided over the course of the entire period. Revenue related to training and installation and deployment services is recognized upon completion of the services. Contracts and customer purchase orders are generally used to determine the existence of an arrangement. In addition, shipping documents and customer acceptances, when applicable, are used to verify delivery and transfer of title. The Company typically satisfies its performance obligations upon shipment or delivery of product depending on the contractual terms. Payment terms to customers generally range from net 30 to 120 days from invoice, which are considered to be standard payment terms. The Company assesses its ability to collect from its customers based primarily on the creditworthiness and past payment history of the customer. For sales to resellers, the same revenue recognition criteria apply. It is the Company’s practice to identify an end-user prior to shipment to a reseller. The Company does not offer rights of return or price protection to its resellers. The Company reports revenue net of any required taxes collected from customers and remitted to government authorities, with the collected taxes recorded as current liabilities until remitted to the relevant government authority. Customer Purchase Commitments The Company sells software licenses that provide customers the ability to purchase incremental bandwidth capacity on an already-deployed piece of hardware. Infinera Instant Bandwidth-enabled systems generally include a specific initial capacity and incremental capacity can be added by the purchase of Instant Bandwidth licenses. Instant Bandwidth licenses are considered distinct performance obligations because customers can provision additional transmission capacity on demand without the deployment of any incremental equipment. Some contracts commit the customer to purchase incremental Instant Bandwidth licenses within a specified time frame from the initial shipment of the Instant Bandwidth-enabled hardware. The time frame varies by customer and generally ranges between 12 to 24 months. If the customer does not purchase the additional capacity within the time frame as stated in the contract, the Company has the right to deliver and invoice such Instant Bandwidth licenses to the customer. Future committed licenses are considered to be additional performance obligations when a minimum purchase obligation is present, as evidenced by enforceable rights and obligations. As such, the Company is required to estimate the variable consideration for future Instant Bandwidth licenses as part of determining the contract transaction price. Contract Termination Rights The contract term is determined on the basis of the period over which the parties to the contract have present enforceable rights and obligations. Certain customer contracts include a termination for convenience clause that allows the customer to terminate services without penalty, upon advance notification. For such contracts, the service duration is limited to the non-cancelable portion of the contract. Variable Consideration The consideration associated with customer contracts is generally fixed. Variable consideration includes discounts, rebates, refunds, credits, incentives, penalties, or other similar items. The amount of consideration that can vary is not a substantial portion of total consideration. Variable consideration estimates are re-assessed at each reporting period until a final outcome is determined. The changes to the original transaction price due to a change in estimated variable consideration will be applied on a retrospective basis, with the adjustment recorded in the period in which the change occurs. Stand-alone Selling Price Stand-alone selling price is the price at which an entity would sell a good or service on a stand-alone (or separate) basis at contract inception. Under this model, the observable price of a good or service sold separately provides the best evidence of stand-alone selling price. However, in certain situations, stand-alone selling prices will not be readily observable and the entity must estimate the stand-alone selling price. When allocating on a relative stand-alone selling price basis, any discount provided in the contract is generally allocated proportionately to all of the performance obligations in the contract. The majority of products and services offered by the Company have readily observable selling prices. For products and services that do not, the Company generally estimates stand-alone selling price using the market assessment approach based on expected selling price and adjust those prices as necessary to reflect the Company’s costs and margins. As part of its stand-alone selling price policy, the Company reviews product pricing on a periodic basis to identify any significant changes and revise its expected stand-alone selling price assumptions as appropriate. Shipping and Handling The Company treats shipping and handling activities as costs to fulfill the Company's promise to transfer products. Shipping and handling fees billed to customers are recorded as a reduction to cost of product. Capitalization of Costs to Obtain a Contract The Company has assessed the treatment of costs to obtain or fulfill a contract with a customer. Sales commissions have historically been expensed as incurred. Under Topic 606, the Company capitalizes sales commissions related to multi-year service contracts, which are paid for upfront, and amortizes the asset over the period of benefit, which is the service period. Sales commissions paid on service contract renewals, are commensurate with the sales commissions paid on the initial contracts. Transaction Price Allocated to the Remaining Performance Obligation The Company’s remaining performance obligations represent the transaction price allocated to performance obligations that are unsatisfied or partially satisfied as of period end, consisting of deferred revenue and backlog. The Company’s backlog represents purchase orders received from customers for future product shipments and services that are unsatisfied or partially satisfied as of period end. The Company’s backlog is subject to future events that could cause the amount or timing of the related revenue to change, and, in certain cases, may be canceled without penalty. Orders in backlog may be fulfilled several quarters following receipt or may relate to multi-year support service obligations. Stock-Based Compensation Stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period (generally the vesting period) under the straight-line amortization method. The Company accounts for forfeitures as they occur. The Company estimates the fair value of the rights to acquire stock under its 2007 Employee Stock Purchase Plan (the “ESPP”) using the Black-Scholes option pricing formula. The ESPP provides for consecutive six-month offering periods and the Company's historical volatility data in the valuation of shares that are purchased under the ESPP. The Company accounts for the fair value of restricted stock units (“RSUs”) using the closing market price of the Company’s common stock on the date of grant. For new-hire grants, RSUs typically vest ratably on an annual basis over four years. For annual refresh grants, RSUs typically vest ratably over 18 months to three years. The Company granted performance shares (“PSUs”) to its executive officers and senior management. The PSUs granted during 2018 to the Company’s executive officers and senior management are based on the Total Shareholder Return ("TSR") of the Company’s common stock price relative to the TSR of the individual companies listed in the S&P North American Technology Multimedia Networking Index (the "SPGIIPTR") over the span of one year, two years and three years. The number of shares to be issued upon vesting of these PSUs range from zero to two times the target number of PSUs granted depending on the Company’s performance against the individual companies listed in the SPGIIPTR. This performance metric is classified as a market condition. PSUs granted to the Company's executive officers and senior management during 2019, 2020 and 2021 are based on performance criteria related to a specific financial target over the span of a three-year performance period. These PSUs may become eligible for vesting to begin before the end of the three year performance period, if the applicable financial target is met. The number of shares to be issued upon vesting of these PSUs is capped at the target number of PSUs granted. The Company assesses the achievement status of these PSUs on a quarterly basis and records the related stock-based compensation expenses based on the estimated achievement payout. The Company uses a Monte Carlo simulation model to determine the fair value of PSUs with market conditions. The Monte Carlo simulation model is based on a discounted cash flow approach, with the simulation of a large number of possible stock price outcomes for the Company's stock and the target composite index. The use of the Monte Carlo simulation model requires the input of a number of assumptions including expected volatility of the Company's stock price, expected volatility of a target composite index, correlation between changes in the Company's stock price and changes in the target composite index, risk-free interest rate, and expected dividends as applicable. Expected volatility of the Company's stock is based on the weighted-average historical volatility of its stock. Expected volatility of the target composite index is based on the historical and implied data. Correlation is based on the historical relationship between the Company's stock price and the target composite index average. The risk-free interest rate is based upon the treasury zero-coupon yield appropriate for the term of the PSU as of the grant date. The expected dividend yield is zero for the Company as it does not expect to pay dividends in the future. The expected dividend yield for the target composite index is the annual dividend yield expressed as a percentage of the composite average of the target composite index on the grant date. In addition, the Company granted other PSUs to certain employees that only vest upon the achievement of specific operational performance criteria. The Company assesses the achievement status of these PSUs on a quarterly basis and records the related stock-based compensation expenses based on the estimated achievement payout. Employee Benefit and Pension Plans The Company operates a number of post-employment plans in Germany, as well as smaller post-employment plans in other countries, including both defined contribution and defined benefit plans. Benefit cost and obligations pertaining to these plans are based on assumptions for the discount rate, expected return on plan assets, mortality rates, expected salary increases, health care cost trend rates and attrition rates. The discount rate assumption is based on current investment yields of high-quality fixed-income securities with maturities similar to the expected benefits payment period. Mortality rates help predict the expected life of plan participants. The expected increase in the compensation levels assumption reflects the Company's actual experience and future expectations. The expected long-term return on plan assets is determined based on asset allocations, historical portfolio results, historical asset correlations and management’s expected returns for each asset class. The Company evaluates its expected return assumptions annually including reviewing current capital market assumptions to assess the reasonableness of the expected long-term return on plan assets. The Company updates the expected long-term return on assets when the Company observes a sufficient level of evidence that would suggest the long-term expected return has changed. Research and Development All costs to develop the Company’s hardware products are expensed as incurred. Software development costs are capitalized beginning when a product’s technological feasibility has been established and ending when a product is available for general release to customers. Generally, the Company’s software products are released soon after technological feasibility has been established. As a result, costs subsequent to achieving technological feasibility have not been significant and all software development costs have been expensed as incurred. Advertising All advertising costs are expensed as incurred. Advertising expenses in 2021, 2020 and 2019 were $1.6 million, $1.3 million, and $1.5 million, respectively. Accounting for Income Taxes As part of the process of preparing its consolidated financial statements, the Company is required to estimate its taxes in each of the jurisdictions in which it operates. The Company estimates actual current tax expense together with assessing temporary differences resulting from different treatment of items, such as accruals and allowances not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities, which are included in consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in consolidated statements of operations become deductible expenses under applicable income tax laws or loss, or credit carryforwards are utilized. Accordingly, realization of deferred tax assets is dependent on future taxable income within the respective jurisdictions against which these deductions, losses and credits can be utilized within the applicable future periods. The Company must assess the likelihood that some portion or all of its deferred tax assets will be recovered from future taxable income within the respective jurisdictions, and to the extent the Company believes that recovery does not meet the “more-likely-than-not” standard, it must establish a valuation allowance. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management judgment is required in determining its provision for income taxes, its deferred tax assets and liabilities and any valuation allowance recorded against our net deferred tax assets. In evaluating the need for a full or partial valuation allowance, all positive and negative evidence must be considered, including the Company's forecast of taxable income over the applicable carryforward periods, its current financial performance, its market environment, and other factors. Accordingly, the domestic net deferred tax assets are subject to a full valuation allowance. To the extent that the Company determines that deferred tax assets are realizable on a more likely than not basis, and an adjustment is needed, that adjustment will be recorded in the period that the determination is made. Foreign Currency Translation and Transactions The Company considers the functional currencies of its foreign subsidiaries to be the local currency. Assets and liabilities recorded in foreign currencies are translated at the exchange rate as of the balance sheet date, revenue, costs and expenses are translated at average exchange rates in effect during the period. Equity transactions are translated using historical exchange rates. The effects of foreign currency translation adjustments are recorded as a separate component of accumulated other comprehensive income (loss) in the accompanying consolidated balance sheets and consolidated statements of comprehensive income (loss). For all non-functional currency account balances, the re-measurement of such balances to the functional currency will result in either a foreign exchange transaction gain or loss, which is recorded to other income (loss), net, in the Company's consolidated statement of operations, in the same period that the re-measurement occurred. Aggregate foreign exchange transactions recorded in 2021, 2020 and 2019 were losses of $17.2 million, $0.2 million, and $3.7 million, respectively. The Company enters into foreign currency exchange forward contracts to reduce the impact of foreign exchange fluctuations on earnings from certain non-functional currency account balances denominated primarily in euros and British pounds. Cash Cash consists primarily of cash in bank deposit accounts which, at times, a portion may exceed federally insured limits. The Company has not experienced any losses in such accounts. Fair Value Measurement Pursuant to the accounting guidance for fair value measurements and its subsequent updates, fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and it considers assumptions that market participants would use when pricing the asset or liability. Valuation techniques used by the Company are based upon observable and unobservable inputs. Observable or market inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about market participant assumptions based on the best information available. Observable inputs are the preferred source of values. These two types of inputs create the following fair value hierarchy: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Prices or valuations that require management inputs that are both significant to the fair value measurement and unobservable. The Company measures its foreign currency exchange forward contracts and debt securities at fair value and classifies them in accordance with the fair value hierarchy on a recurring basis. Foreign Currency Exchange Forward Contracts As discussed in Note 6, “Derivative Instruments" to the Notes to Consolidated Financial Statements, the Company mainly holds non-speculative foreign exchange forward contracts to hedge certain foreign currency exchange exposures. The Company estimates the fair values of derivatives based on quoted market prices or pricing models using current market rates. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, credit risk, foreign exchange rates, and forward and spot prices for currencies. Facilities-related Charges The Company estimates the fair value of its facilities-related charges associated with its restructuring plans, based on estimated future discounted cash flows and unobservable inputs, which includes the amount and timing of estimated sublease rental receipts that the Company can reasonably obtain over the remaining lease term and the discount rate. Pension As a result of the Acquisition, the Company acquired a number of post-employment plans in Germany, as well as a number of smaller post-employment plans in other countries, including both defined contribution and defined benefit plans. The defined benefit plans expose the Company to actuarial risks such as investment risk, interest rate risk, life expectancy risk and salary risk. The characteristics of the defined benefit plans and the risks associated with them vary depending on legal, fiscal, and economic requirements. Refer to Note 18, "Employee Benefit and Pension Plans" to the Notes to Consolidated Financial Statements, for more information on fair value of plan assets by major asset category. Accounts Receivable and Allowances for Credit Losses Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company maintains an allowance for estimated credit losses resulting from the inability of its customers to make required payments and reviewed the allowance quarterly. The Company determines expected credit losses by performing credit evaluations of its customers' financial condition, establishing both a general reserve and specific reserve for customers in adverse financial condition and adjusting for its expectations of changes in conditions that may impact the collectability of outstanding receivables. The Company considers a customer's receivable balance past due when the amount is due beyond the credit terms extended, The Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, and geographic or country-specific risks. Amounts are written off when receivables are determined to be uncollectible. Allowances for Sales Returns Customer product returns are approved on a case by case basis. Specific reserve provisions are made based upon a specific review of all the approved product returns where the customer has yet to return the products to generate the related sales return credit at the end of a period. Estimated sales returns are provided for as a reduction to revenue. At December 25, 2021, December 26, 2020 and December 28, 2019, revenue was reduced for estimated sales returns by $0.8 million, $2.4 million, and $3.5 million, respectively. Concentration of Risk Financial instruments that are potentially subject to concentrations of credit risk consist primarily of cash, restricted cash, foreign exchange contracts and accounts receivable. The risk with respect to foreign exchange contracts is mitigated by entering into these contracts with a large high-quality financial institution and the Company monitors the creditworthiness of the counterparty consistently. The risk with respect to accounts receivable is mitigated by ongoing credit evaluations that the Company performs on its customers. As the Company continues to expand its sales internationally, it may experience increased levels of customer credit risk associated with those regions. Collateral is generally not required for accounts receivable but may be used in the future to mitigate credit risk associated with customers located in certain geographical regions. As of December 25, 2021, no customer accounted for over 10% of the Company's accounts receivable balance, net on the consolidated balance sheets. As of December 26, 2020, one customer accounted for over 10% of the Company's accounts receivable balance, net on the consolidated balance sheets. One customer accounted for approximately 11% and 13% of the Company's revenue in 2020 and 2019, respectively. No other customers accounted for 10% or more of the Company's revenue in 2020 and 2019. No customer accounted for 10% or more of the Company's revenue in 2021. The Company depends on sole source or limited source suppliers for several key components and raw materials. The Company generally purchases these sole source or limited source components and raw materials through standard purchase orders and does not have long-term contracts with many of these limited-source suppliers. While the Company seeks to maintain sufficient reserve stock of such components and raw materials, the Company’s business and results of operations could be adversely affected if any of its sole source or limited source suppliers suffer from capacity constraints, lower than expected yields, deployment delays, work stoppages or any other reduction or disruption in output. Derivative Instruments The Company is exposed to foreign currency exchange rate fluctuations in the normal course of its business. As part of its risk management strategy, the Company uses derivative instruments, specifically forward contracts, to reduce the impact of foreign exchange fluctuations on earnings. The forward contracts are with high-quality institutions and the Company monitors the creditworthiness of the counterparties consistently. The Company’s objective is to offset gains and losses resulting from these exposures with gains and losses on the derivative contracts used to hedge them, thereby reducing volatility of earnings or protecting fair values of assets. The Company does not use derivative contracts for trading or speculative purposes. The Company enters into foreign currency exchange forward contracts to manage its exposure to fluctuations in foreign exchange rates that arise primarily from euro and British pounds. Gains and losses on these contracts are intended to offset the impact of foreign exchange rate changes on the underlying account balances, and therefore, do not subject the Company to material balance sheet risk. The Company has entered into factoring agreements, to sell certain receivables to unrelated third-party financial institutions. These transactions are accounted for in accordance with ASC Topic 860, “Transfers and Servicing” (“ASC 860”). ASC 860 and result in a reduction in accounts receivable because the agreements transfer effective control over and risk related to the receivables to the buyers. The Company's factoring agreements do not allow for recourse in the event of uncollectability, and the Company does not retain any interest in the underlying accounts receivable once sold. Inventory Valuation Inventories consist of raw materials, work-in-process and finished goods and are stated at standard cost adjusted to approximate the lower of actual cost or net realizable value. Costs are recognized utilizing the first-in, first-out method. Net realizable value is based upon an estimated selling price reduced by the estimated cost of disposal. The determination of market value involves numerous judgments including estimated average selling prices based upon recent sales volumes, industry trends, existing customer orders, current contract price, future demand and pricing and technological obsolescence of the Company’s products. Inventory that is obsolete or in excess of the Company’s forecasted demand or is anticipated to be sold at a loss is written down to its estimated net realizable value based on historical usage and expected demand. In valuing its inventory costs and deferred inventory costs, the Company considered whether the net realizable value of inventory delivered or expected to be delivered at less than cost, primarily comprised of common equipment, had declined. The Company concluded that, in the instances where the net realizable value of inventory delivered or expected to be delivered was less than cost, it was appropriate to value the inventory costs and deferred inventory costs at cost or net realizable value, whichever is lower, thereby recognizing the cost of the reduction in net realizable value of inventory in the period in which the reduction occurred or can be reasonably estimated. The Company has, therefore, recognized inventory write-downs as necessary in each period in order to reflect inventory at the lower of actual cost or net realizable value. The Company considers whether it should accrue losses on firm purchase commitments related to inventory items. Given that the net realizable value of common equipment is below contractual purchase price, the Company has also recorded losses on these firm purchase commitments in the period in which the commitment is made. When the inventory parts related to these firm purchase commitments are received, that inventory is recorded at the purchase price less the accrual for the loss on the purchase commitment. Property, Plant and Equipment Property, plant and equipment are stated at cost. This includes enterprise-level business software that the Company customizes to meet its specific operational needs and certain software licenses. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are amortized using the straig |
