SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements of Harmonic include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company’s fiscal quarters are based on 13-week periods, except for the fourth quarter which ends on December 31. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (“US GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The Company’s reported financial positions or results of operations may be materially different under changed conditions or when using different estimates and assumptions, particularly with respect to significant accounting policies. If estimates or assumptions differ from actual results, subsequent periods are adjusted to reflect more current information. Reclassifications Certain prior period balances have been reclassified to conform to the current year presentation. These reclassifications did not have a material impact on previously reported financial statements. Cash and Cash Equivalents All highly liquid investments with an original maturity of three months or less at the date of purchase are considered cash equivalents. The carrying amount of cash and cash equivalents approximates fair value because of the short maturity of those instruments. Credit Risk and Major Customers/Supplier Concentration Financial instruments which subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, and accounts receivable. Cash and cash equivalents are invested in short-term, highly liquid, investment-grade instruments, in accordance with the Company’s investment policy. The investment policy limits the amount of credit exposure to any one financial institution, commercial or governmental issuer. The Company’s accounts receivable are derived from sales to worldwide cable, satellite, telco, and broadcast and media companies. The Company generally does not require collateral from its customers, and performs ongoing credit evaluations of its customers and provides for expected losses. The Company maintains an allowance for doubtful accounts based upon the expected collectability of its accounts receivable. One customer had a balance greater than 10% of the Company’s net accounts receivable balance as of December 31, 2021 and 2020. During the year ended December 31, 2021, 2020 and 2019, Comcast is the only customer accounted for more than 10% of the Company’s revenue. Certain of the components and subassemblies included in the Company’s products are obtained from a single source or a limited group of suppliers. Although the Company seeks to reduce dependence on those sole source and limited source suppliers, the partial or complete loss of certain of these sources could have at least a temporary adverse effect on the Company’s results of operations and damage customer relationships. Revenue Recognition The Company’s principal sources of revenue are from the sale of hardware, software, hardware and software maintenance contracts, and end-to-end solutions, encompassing design, manufacture, test, integration and installation of products. The Company also derives recurring revenue from subscriptions, which are comprised of subscription fees from customers utilizing the Company’s cloud-based video processing solutions. Revenue from contracts with customers is recognized using the following five steps: a) Identify the contract(s) with a customer; b) Identify the performance obligations in the contract; c) Determine the transaction price; d) Allocate the transaction price to the performance obligations in the contract; and e) Recognize revenue when (or as) the Company satisfies a performance obligation. A contract contains a promise (or promises) to transfer goods or services to a customer. A performance obligation is a promise (or a group of promises) that is distinct. The transaction price is the amount of consideration a Company expects to be entitled to from a customer in exchange for providing the goods or services. The unit of account for revenue recognition is a performance obligation. A contract may contain one or more performance obligations, including hardware, software, professional services and support and maintenance. Performance obligations are accounted for separately if they are distinct. A good or service is distinct if the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer, and the good or service is distinct in the context of the contract. Otherwise performance obligations will be combined with other promised goods or services until the Company identifies a bundle of goods or services that is distinct. The transaction price is allocated to all the separate performance obligations in an arrangement. It reflects the amount of consideration to which the Company expects to be entitled to in exchange for transferring goods or services, which may include an estimate of variable consideration to the extent that it is probable of not being subject to significant reversals in the future based on the Company’s experience with similar arrangements. The transaction price also reflects the impact of the time value of money if there is a significant financing component present in an arrangement. The transaction price excludes amounts collected on behalf of third parties, such as sales taxes. Revenue is recognized when the Company satisfies each performance obligation by transferring control of the promised goods or services to the customer. Goods or services can transfer at a point in time or over time depending on the nature of the arrangement. Refer to Note 3, “Revenue,” for additional information. Inventories Inventories are stated at the lower of cost (determined on first-in, first-out basis) or net realizable value. The cost of inventories is comprised of material and manufacturing labor and overheads. The Company establishes provisions for excess and obsolete inventories to reduce such inventories to their estimated net realizable value after evaluation of historical sales, future demand and market conditions, expected product life cycles and current inventory levels. Such provisions are charged to cost of revenue in the Company’s Consolidated Statements of Operations. Property and Equipment Property and equipment are recorded at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Estimated useful lives are generally five years for furniture and fixtures, three years for software and four years for machinery and equipment. Depreciation for leasehold improvements are computed using the shorter of estimated useful lives or the terms of the related leases. Long-Lived Assets including Purchased Intangible Assets The Company reviews property and equipment, intangible assets and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (or asset group) may not be recoverable. Recoverability is measured by comparing the carrying amount to the future undiscounted cash flows that the asset is expected to generate. If the asset is not recoverable, its carrying amount would be adjusted down to its fair value. For the years ended December 31, 2021, 2020 and 2019, there were no impairment charges for long-lived assets. Goodwill The Company assesses goodwill for impairment on an annual basis (in the fourth quarter), or more frequently if events or changes in circumstances indicate that it might be impaired, by comparing its carrying value to the reporting unit’s fair value. For the years ended December 31, 2021, 2020 and 2019, there were no impairment charges for goodwill. Refer to Note 7, “Goodwill,” for additional information. Leases On January 1, 2019, the Company adopted ASC 842, Leases (“Topic 842”), using the modified retrospective method, applying Topic 842 to all leases existing at the date of initial application. The Company elected to use the effective date as the date of initial application. Consequently, prior period balances and disclosures have not been restated. The Company elected certain practical expedients, which among other things, allowed the Company to carry forward prior conclusions about lease identification and classification. Under Topic 842, operating lease expense is generally recognized evenly over the term of the lease. The Company has operating leases primarily consisting of facilities with remaining lease terms of 1 year to 11 years. The lease term represents the non-cancelable period of the lease. For certain leases, the Company has an option to extend the lease term. These renewal options are not considered in the remaining lease term unless it is reasonably certain that the Company will exercise such options. Refer to Note 4, “Leases,” for additional information. Foreign Currency The functional currency of the Company’s Israeli and Swiss subsidiaries is the U.S. dollar. All other foreign subsidiaries use the respective local currency as the functional currency. When the local currency is the functional currency, gains and losses from translation of these foreign currency financial statements into U.S. dollars are recorded as a separate component of other comprehensive income (loss) in stockholders’ equity. The Company’s foreign currency exposure is also related to its net position of monetary assets and monetary liabilities held by its foreign subsidiaries in their nonfunctional currencies. These monetary assets and liabilities are being remeasured into the subsidiaries’ respective functional currencies using exchange rates as of the balance sheet date. Such remeasurement gains and losses are included in “Other income (expense), net” in the Company’s Consolidated Statements of Operations. During the year ended December 31, 2021, the Company recorded remeasurement gain of approximately $0.6 million. During the years ended December 31, 2020 and 2019, the Company recorded remeasurement loss of $1.0 million and $1.5 million, respectively. Derivative Instruments The Company enters into derivative instruments, primarily foreign currency forward contracts, to minimize the short-term impact of foreign currency exchange rate fluctuations on certain foreign currency denominated assets and liabilities as well as certain foreign currencies denominated expenses. The Company does not enter into derivative instruments for trading purposes and these derivatives generally have maturities within three months. The derivative instruments are recorded at fair value in prepaid expenses and other current assets or accrued and other current liabilities in the Company’s Consolidated Balance Sheets. The Company enters into derivative instruments to hedge existing foreign currency denominated assets or liabilities, the gains or losses on these hedges are recorded immediately in earnings to offset the changes in the fair value of the assets or liabilities being hedged. Research and Development Research and development (“R&D”) costs are expensed as incurred and consists primarily of employee salaries and related expenses, contractors and outside consultants, supplies and materials, equipment depreciation and facilities costs, all associated with the design and development of new products and enhancements of existing products. The Company’s French subsidiary participates in the French Crédit d’Impôt Recherche (“CIR”) program which allows companies to monetize eligible research expenses. The R&D credits receivable from the French government for spending on innovative R&D under the CIR program is recorded as an offset to R&D expenses. In the years ended December 31, 2021, 2020 and 2019, the Company had R&D credits of $5.7 million, $4.5 million and $4.7 million, respectively. Restructuring and Related Charges The Company’s restructuring charges consist primarily of employee severance, one-time termination benefits related to the reduction of its workforce, and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the entity notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period. Termination benefits are calculated based on regional benefit practices and local statutory requirements. Refer to Note 10, “Restructuring and Related Charges,” for additional information. Warranty The Company accrues for estimated warranty costs at the time of revenue recognition and records such accrued liabilities as part of cost of revenue. Management periodically reviews its warranty liability and adjusts the accrued liability based on the terms of warranties provided to customers, historical and anticipated warranty claims experience, and estimates of the timing and cost of warranty claims. Advertising Expenses All advertising costs are expensed as incurred and included in “Selling, general and administrative expenses” in the Company’s Consolidated Statements of Operations. Advertising expense was $1.0 million, $1.1 million and $0.7 million for the years ended December 31, 2021, 2020 and 2019, respectively. Stock-based Compensation The Company measures and recognizes compensation expense for all stock-based compensation awards made to employees, including stock options, restricted stock units (“RSUs”) and stock purchase rights under the Company’s Employee Stock Purchase Plan (“ESPP”), based upon the grant-date fair value of those awards. The Company recognizes the impact of forfeitures as they occur. The fair value of the Company’s stock options and stock purchase rights under ESPP is estimated at grant date using the Black-Scholes option pricing model. The fair value of the Company’s RSUs and performance-based RSUs (“PRSUs”) is calculated based on the market value of the Company’s stock at the grant date. The fair value of the Company’s market-based RSUs (“MRSUs”) is estimated using the Monte-Carlo valuation model with market vesting conditions. The Company recognizes the stock-based compensation for options, RSUs, MRSUs and stock purchase rights under ESPP on straight-line basis over the requisite service period, which is generally the vesting period. The Company recognizes the stock-based compensation for PRSUs based on the probability of achieving performance criteria defined in the PRSU agreements. The Company estimates the number of PRSUs ultimately expected to vest and recognizes expense using the graded vesting attribution method over the requisite service period. Changes in the estimates related to probability of achieving certain performance criteria and number of PRSUs expected to vest could significantly affect the related stock-based compensation expense from one period to the next. Pension Plan Under French law, the Company’s subsidiary in France is obligated to provide for a defined benefit plan to its employees upon their retirement from the Company. The Company’s defined benefit pension plan in France is unfunded. The Company records its obligations relating to the pension plans based on calculations which include various actuarial assumptions including employees’ age and period of service with the company; projected mortality rates, mobility rates and increases in salaries; and a discount rate. The Company reviews its actuarial assumptions on an annual basis as of December 31 (or more frequently if a significant event requiring remeasurement occurs) and modifies the assumptions based on current rates and trends when it is appropriate to do so. The Company believes that the assumptions utilized in recording its obligations under its pension plan are reasonable based on its experience, market conditions and input from its actuaries. The Company accounts for the actuarial gains (losses) in accordance with ASC 715, “Compensation - Retirement Benefits.” If the net accumulated gain or loss exceeds 10% of the projected plan benefit obligation, a portion of the net gain or loss is amortized and included in expense for the following year based upon the average remaining service period of active plan participants, unless the Company’s policy is to recognize all actuarial gains (losses) when they occur. The Company elected to defer actuarial gains (losses) in accumulated other comprehensive income (loss). As of December 31, 2021, the Company did not meet the 10% threshold, and therefore no amortization of 2021 actuarial gain would be recorded in 2022. Refer to Note 12, “Employee Benefit Plans” for additional information. Income Taxes In preparing the Company’s consolidated financial statements, the Company estimates the income taxes for each of the jurisdictions in which the Company operates. This involves estimating the Company’s current tax expense and assessing temporary and permanent differences resulting from differing treatment of items, such as reserves and accruals, for tax and accounting purposes. These temporary differences result in deferred tax assets and liabilities, which are included within the Company’s Consolidated Balance Sheets. The Company’s income tax policy is to record the estimated future tax effects of temporary differences between the tax bases of assets and liabilities and amounts reported in the Company’s accompanying Consolidated Balance Sheets, as well as operating loss and tax credit carryforwards. The Company follows the guidelines set forth in the applicable accounting guidance regarding the recoverability of any tax assets recorded on the Consolidated Balance Sheets and provides any necessary allowances as required. Determining necessary allowances requires the Company to make assessments about the timing of future events, including the probability of expected future taxable income and available tax planning opportunities. A history of operating losses in recent years has led to uncertainty with respect to our ability to realize certain of our net deferred tax assets, and as a result we applied a full valuation allowance against our U.S. net deferred tax assets as of December 31, 2021. In the event that actual results differ from these estimates or the Company adjusts these estimates in future periods, the Company’s operating results, and financial position could be materially affected. The Company is subject to examination of its income tax returns by various tax authorities on a periodic basis. The Company regularly assesses the likelihood of adverse outcomes resulting from such examinations to determine the adequacy of its provision for income taxes. The Company has applied the provisions of the applicable accounting guidance on accounting for uncertainty in income taxes, which requires application of a more-likely-than-not threshold to the recognition and de-recognition of uncertain tax positions. If the recognition threshold is met, the applicable accounting guidance permits the Company to recognize a tax benefit measured at the largest amount of tax benefit that, in the Company’s judgment, is more than 50% likely to be realized upon settlement. It further requires that a change in judgment related to the expected ultimate resolution of uncertain tax positions be recognized in earnings in the period of such change. The Company files annual income tax returns in multiple taxing jurisdictions around the world. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves and penalties, as well as the related interest, in light of changing facts and circumstances. Changes in the Company’s assessment of its uncertain tax positions or settlement of any particular position could materially and adversely impact the Company’s income tax rate, operating results, financial position and cash flows. Segment Reporting Operating segments are defined as components of an enterprise that engage in business activities for which separate financial information is available and is evaluated by the Chief Operating Decision Maker (“CODM”), which for the Company is its Chief Executive Officer, in deciding how to allocate resources and assess performance. The Company has two operating segments: Video and Cable Access. Recently Issued Accounting Pronouncements In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which simplifies the accounting for convertible instruments and contracts on an entity’s own equity. Among other changes, ASU No. 2020-06 removes from U.S. GAAP the liability and equity separation model for convertible instruments with a cash conversion feature, and as a result, after adoption, entities will no longer separately present in equity an embedded conversion feature for such debt. Similarly, the embedded conversion feature will no longer be amortized into income as interest expense over the life of the instrument. Instead, entities will account for a convertible debt instrument wholly as debt unless (1) a convertible instrument contains features that require bifurcation as a derivative under ASC Topic 815, Derivatives and Hedging, or (2) a convertible debt instrument was issued at a substantial premium. The new ASU is effective for interim and annual periods beginning after December 15, 2021, with early adoption permitted after December 15, 2020, and can be adopted either be on a modified retrospective or full retrospective basis. The Company will adopt this ASU on January 1, 2022 on a modified retrospective basis. The adoption is expected to reduce additional paid-in capital and convertible debt (mezzanine equity) by approximately $32.2 million and $0.9 million, respectively, due to the recombination of the equity conversion component of outstanding convertible debt, which was initially separated and recorded in stockholders’ equity, and to remove the remaining debt discount of approximately $15.2 million related to this previous separation. The net effect of these adjustments will be recorded as a reduction in the balance of the opening accumulated deficit as of January 1, 2022. The Company currently expects that the adoption of this ASU will result in the reduction of non-cash interest expense for the year ending December 31, 2022 and future periods until the settlement of the remaining outstanding Notes. The required use of if-converted method to calculate the impact of convertible notes on diluted earnings per share is not expected to have a material impact. During the fourth quarter of fiscal 2021, the Company and the trustee for 2022 Notes and 2024 Notes entered into supplemental indentures for both the 2022 Notes and 2024 Notes. Pursuant to the supplemental indentures, the Company eliminated its option to settle the principal amount of the Notes in shares of the Company's common stock upon conversion. Accordingly, the dilutive effect of the Company's 2022 Notes and 2024 Notes will be limited to the conversion premium. The adoption of this ASU will have no impact on the consolidated statement of cash flows. From time to time, new accounting pronouncements are issued by the FASB, or other standards setting bodies, that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position, results of operations and cash flows upon adoption.

The accompanying consolidated financial statements of Harmonic include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company’s fiscal quarters are based on 13-week periods, except for the fourth quarter which ends on December 31.

The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (“US GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The Company’s reported financial positions or results of operations may be materially different under changed conditions or when using different estimates and assumptions, particularly with respect to significant accounting policies. If estimates or assumptions differ from actual results, subsequent periods are adjusted to reflect more current information.

All highly liquid investments with an original maturity of three months or less at the date of purchase are considered cash equivalents. The carrying amount of cash and cash equivalents approximates fair value because of the short maturity of those instruments.

Financial instruments which subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, and accounts receivable. Cash and cash equivalents are invested in short-term, highly liquid, investment-grade instruments, in accordance with the Company’s investment policy. The investment policy limits the amount of credit exposure to any one financial institution, commercial or governmental issuer.

The Company’s accounts receivable are derived from sales to worldwide cable, satellite, telco, and broadcast and media companies. The Company generally does not require collateral from its customers, and performs ongoing credit evaluations of its customers and provides for expected losses. The Company maintains an allowance for doubtful accounts based upon the expected collectability of its accounts receivable. One customer had a balance greater than 10% of the Company’s net accounts receivable balance as of December 31, 2021 and 2020. During the year ended December 31, 2021, 2020 and 2019, Comcast is the only customer accounted for more than 10% of the Company’s revenue.

Certain of the components and subassemblies included in the Company’s products are obtained from a single source or a limited group of suppliers. Although the Company seeks to reduce dependence on those sole source and limited source suppliers, the partial or complete loss of certain of these sources could have at least a temporary adverse effect on the Company’s results of operations and damage customer relationships.

The Company’s principal sources of revenue are from the sale of hardware, software, hardware and software maintenance contracts, and end-to-end solutions, encompassing design, manufacture, test, integration and installation of products. The Company also derives recurring revenue from subscriptions, which are comprised of subscription fees from customers utilizing the Company’s cloud-based video processing solutions.

A contract contains a promise (or promises) to transfer goods or services to a customer. A performance obligation is a promise (or a group of promises) that is distinct. The transaction price is the amount of consideration a Company expects to be entitled to from a customer in exchange for providing the goods or services.

The unit of account for revenue recognition is a performance obligation. A contract may contain one or more performance obligations, including hardware, software, professional services and support and maintenance. Performance obligations are accounted for separately if they are distinct. A good or service is distinct if the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer, and the good or service is distinct in the context of the contract. Otherwise performance obligations will be combined with other promised goods or services until the Company identifies a bundle of goods or services that is distinct.

The transaction price is allocated to all the separate performance obligations in an arrangement. It reflects the amount of consideration to which the Company expects to be entitled to in exchange for transferring goods or services, which may include an estimate of variable consideration to the extent that it is probable of not being subject to significant reversals in the future based on the Company’s experience with similar arrangements. The transaction price also reflects the impact of the time value of money if there is a significant financing component present in an arrangement. The transaction price excludes amounts collected on behalf of third parties, such as sales taxes.

Revenue is recognized when the Company satisfies each performance obligation by transferring control of the promised goods or services to the customer. Goods or services can transfer at a point in time or over time depending on the nature of the arrangement.

Inventories are stated at the lower of cost (determined on first-in, first-out basis) or net realizable value. The cost of inventories is comprised of material and manufacturing labor and overheads. The Company establishes provisions for excess and obsolete inventories to reduce such inventories to their estimated net realizable value after evaluation of historical sales, future demand and market conditions, expected product life cycles and current inventory levels. Such provisions are charged to cost of revenue in the Company’s Consolidated Statements of Operations.

Property and equipment are recorded at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Estimated useful lives are generally five years for furniture and fixtures, three years for software and four years for machinery and equipment. Depreciation for leasehold improvements are computed using the shorter of estimated useful lives or the terms of the related leases.

Recoverability is measured by comparing the carrying amount to the future undiscounted cash flows that the asset is expected to generate. If the asset is not recoverable, its carrying amount would be adjusted down to its fair value. For the years ended December 31, 2021, 2020 and 2019, there were no impairment charges for long-lived assets.

The Company assesses goodwill for impairment on an annual basis (in the fourth quarter), or more frequently if events or changes in circumstances indicate that it might be impaired, by comparing its carrying value to the reporting unit’s fair value. For the years ended December 31, 2021, 2020 and 2019, there were no impairment charges for goodwill.

On January 1, 2019, the Company adopted ASC 842, Leases (“Topic 842”), using the modified retrospective method, applying Topic 842 to all leases existing at the date of initial application. The Company elected to use the effective date as the date of initial application. Consequently, prior period balances and disclosures have not been restated. The Company elected certain practical expedients, which among other things, allowed the Company to carry forward prior conclusions about lease identification and classification.

Under Topic 842, operating lease expense is generally recognized evenly over the term of the lease. The Company has operating leases primarily consisting of facilities with remaining lease terms of 1 year to 11 years. The lease term represents the non-cancelable period of the lease. For certain leases, the Company has an option to extend the lease term. These renewal options are not considered in the remaining lease term unless it is reasonably certain that the Company will exercise such options.

The functional currency of the Company’s Israeli and Swiss subsidiaries is the U.S. dollar. All other foreign subsidiaries use the respective local currency as the functional currency. When the local currency is the functional currency, gains and losses from translation of these foreign currency financial statements into U.S. dollars are recorded as a separate component of other comprehensive income (loss) in stockholders’ equity.

The Company’s foreign currency exposure is also related to its net position of monetary assets and monetary liabilities held by its foreign subsidiaries in their nonfunctional currencies. These monetary assets and liabilities are being remeasured into the subsidiaries’ respective functional currencies using exchange rates as of the balance sheet date. Such remeasurement gains and losses are included in “Other income (expense), net” in the Company’s Consolidated Statements of Operations. During the year ended December 31, 2021, the Company recorded remeasurement gain of approximately $0.6 million. During the years ended December 31, 2020 and 2019, the Company recorded remeasurement loss of $1.0 million and $1.5 million, respectively.

The Company enters into derivative instruments, primarily foreign currency forward contracts, to minimize the short-term impact of foreign currency exchange rate fluctuations on certain foreign currency denominated assets and liabilities as well as certain foreign currencies denominated expenses. The Company does not enter into derivative instruments for trading purposes and these derivatives generally have maturities within three months.

The derivative instruments are recorded at fair value in prepaid expenses and other current assets or accrued and other current liabilities in the Company’s Consolidated Balance Sheets. The Company enters into derivative instruments to hedge existing foreign currency denominated assets or liabilities, the gains or losses on these hedges are recorded immediately in earnings to offset the changes in the fair value of the assets or liabilities being hedged.

Research and development (“R&D”) costs are expensed as incurred and consists primarily of employee salaries and related expenses, contractors and outside consultants, supplies and materials, equipment depreciation and facilities costs, all associated with the design and development of new products and enhancements of existing products.

The Company’s French subsidiary participates in the French Crédit d’Impôt Recherche (“CIR”) program which allows companies to monetize eligible research expenses. The R&D credits receivable from the French government for spending on innovative R&D under the CIR program is recorded as an offset to R&D expenses. In the years ended December 31, 2021, 2020 and 2019, the Company had R&D credits of $5.7 million, $4.5 million and $4.7 million, respectively.

The Company’s restructuring charges consist primarily of employee severance, one-time termination benefits related to the reduction of its workforce, and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the entity notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period. Termination benefits are calculated based on regional benefit practices and local statutory requirements.

The Company accrues for estimated warranty costs at the time of revenue recognition and records such accrued liabilities as part of cost of revenue. Management periodically reviews its warranty liability and adjusts the accrued liability based on the terms of warranties provided to customers, historical and anticipated warranty claims experience, and estimates of the timing and cost of warranty claims.

All advertising costs are expensed as incurred and included in “Selling, general and administrative expenses” in the Company’s Consolidated Statements of Operations. Advertising expense was $1.0 million, $1.1 million and $0.7 million for the years ended December 31, 2021, 2020 and 2019, respectively.

The Company measures and recognizes compensation expense for all stock-based compensation awards made to employees, including stock options, restricted stock units (“RSUs”) and stock purchase rights under the Company’s Employee Stock Purchase Plan (“ESPP”), based upon the grant-date fair value of those awards. The Company recognizes the impact of forfeitures as they occur.

The fair value of the Company’s stock options and stock purchase rights under ESPP is estimated at grant date using the Black-Scholes option pricing model. The fair value of the Company’s RSUs and performance-based RSUs (“PRSUs”) is calculated based on the market value of the Company’s stock at the grant date. The fair value of the Company’s market-based RSUs (“MRSUs”) is estimated using the Monte-Carlo valuation model with market vesting conditions.

The Company recognizes the stock-based compensation for options, RSUs, MRSUs and stock purchase rights under ESPP on straight-line basis over the requisite service period, which is generally the vesting period. The Company recognizes the stock-based compensation for PRSUs based on the probability of achieving performance criteria defined in the PRSU agreements. The Company estimates the number of PRSUs ultimately expected to vest and recognizes expense using the graded vesting attribution method over the requisite service period. Changes in the estimates related to probability of achieving certain performance criteria and number of PRSUs expected to vest could significantly affect the related stock-based compensation expense from one period to the next.

The Company records its obligations relating to the pension plans based on calculations which include various actuarial assumptions including employees’ age and period of service with the company; projected mortality rates, mobility rates and increases in salaries; and a discount rate. The Company reviews its actuarial assumptions on an annual basis as of December 31 (or more frequently if a significant event requiring remeasurement occurs) and modifies the assumptions based on current rates and trends when it is appropriate to do so. The Company believes that the assumptions utilized in recording its obligations under its pension plan are reasonable based on its experience, market conditions and input from its actuaries.

The Company accounts for the actuarial gains (losses) in accordance with ASC 715, “Compensation - Retirement Benefits.” If the net accumulated gain or loss exceeds 10% of the projected plan benefit obligation, a portion of the net gain or loss is amortized and included in expense for the following year based upon the average remaining service period of active plan participants, unless the Company’s policy is to recognize all actuarial gains (losses) when they occur. The Company elected to defer actuarial gains (losses) in accumulated other comprehensive income (loss). As of December 31, 2021, the Company did not meet the 10% threshold, and therefore no amortization of 2021 actuarial gain would be recorded in 2022.

In preparing the Company’s consolidated financial statements, the Company estimates the income taxes for each of the jurisdictions in which the Company operates. This involves estimating the Company’s current tax expense and assessing temporary and permanent differences resulting from differing treatment of items, such as reserves and accruals, for tax and accounting purposes. These temporary differences result in deferred tax assets and liabilities, which are included within the Company’s Consolidated Balance Sheets.

The Company’s income tax policy is to record the estimated future tax effects of temporary differences between the tax bases of assets and liabilities and amounts reported in the Company’s accompanying Consolidated Balance Sheets, as well as operating loss and tax credit carryforwards. The Company follows the guidelines set forth in the applicable accounting guidance regarding the recoverability of any tax assets recorded on the Consolidated Balance Sheets and provides any necessary allowances as required. Determining necessary allowances requires the Company to make assessments about the timing of future events, including the probability of expected future taxable income and available tax planning opportunities. A history of operating losses in recent years has led to uncertainty with respect to our ability to realize certain of our net deferred tax assets, and as a result we applied a full valuation allowance against our U.S. net deferred tax assets as of December 31, 2021. In the event that actual results differ from these estimates or the Company adjusts these estimates in future periods, the Company’s operating results, and financial position could be materially affected.

The Company is subject to examination of its income tax returns by various tax authorities on a periodic basis. The Company regularly assesses the likelihood of adverse outcomes resulting from such examinations to determine the adequacy of its provision for income taxes. The Company has applied the provisions of the applicable accounting guidance on accounting for uncertainty in income taxes, which requires application of a more-likely-than-not threshold to the recognition and de-recognition of uncertain tax positions. If the recognition threshold is met, the applicable accounting guidance permits the Company to recognize a tax benefit measured at the largest amount of tax benefit that, in the Company’s judgment, is more than 50% likely to be realized upon settlement. It further requires that a change in judgment related to the expected ultimate resolution of uncertain tax positions be recognized in earnings in the period of such change.

The Company files annual income tax returns in multiple taxing jurisdictions around the world. A number of years may elapse before an uncertain tax position is audited and finally resolved. While it is often difficult to predict the final outcome or the timing of resolution of any particular uncertain tax position, the Company believes that its reserves for income taxes reflect the most likely outcome. The Company adjusts these reserves and penalties, as well as the related interest, in light of changing facts and circumstances. Changes in the Company’s assessment of its uncertain tax positions or settlement of any particular position could materially and adversely impact the Company’s income tax rate, operating results, financial position and cash flows.

Operating segments are defined as components of an enterprise that engage in business activities for which separate financial information is available and is evaluated by the Chief Operating Decision Maker (“CODM”), which for the Company is its Chief Executive Officer, in deciding how to allocate resources and assess performance. The Company has two operating segments: Video and Cable Access.

In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which simplifies the accounting for convertible instruments and contracts on an entity’s own equity. Among other changes, ASU No. 2020-06 removes from U.S. GAAP the liability and equity separation model for convertible instruments with a cash conversion feature, and as a result, after adoption, entities will no longer separately present in equity an embedded conversion feature for such debt. Similarly, the embedded conversion feature will no longer be amortized into income as interest expense over the life of the instrument. Instead, entities will account for a convertible debt instrument wholly as debt unless (1) a convertible instrument contains features that require bifurcation as a derivative under ASC Topic 815, Derivatives and Hedging, or (2) a convertible debt instrument was issued at a substantial premium. The new ASU is effective for interim and annual periods beginning after December 15, 2021, with early adoption permitted after December 15, 2020, and can be adopted either be on a modified retrospective or full retrospective basis.

The Company will adopt this ASU on January 1, 2022 on a modified retrospective basis. The adoption is expected to reduce additional paid-in capital and convertible debt (mezzanine equity) by approximately $32.2 million and $0.9 million, respectively, due to the recombination of the equity conversion component of outstanding convertible debt, which was initially separated and recorded in stockholders’ equity, and to remove the remaining debt discount of approximately $15.2 million related to this previous separation. The net effect of these adjustments will be recorded as a reduction in the balance of the opening accumulated deficit as of January 1, 2022.

The Company currently expects that the adoption of this ASU will result in the reduction of non-cash interest expense for the year ending December 31, 2022 and future periods until the settlement of the remaining outstanding Notes. The required use of if-converted method to calculate the impact of convertible notes on diluted earnings per share is not expected to have a material impact. During the fourth quarter of fiscal 2021, the Company and the trustee for 2022 Notes and 2024 Notes entered into supplemental indentures for both the 2022 Notes and 2024 Notes. Pursuant to the supplemental indentures, the Company eliminated its option to settle the principal amount of the Notes in shares of the Company's common stock upon conversion. Accordingly, the dilutive effect of the Company's 2022 Notes and 2024 Notes will be limited to the conversion premium. The adoption of this ASU will have no impact on the consolidated statement of cash flows.

From time to time, new accounting pronouncements are issued by the FASB, or other standards setting bodies, that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position, results of operations and cash flows upon adoption.