Document And Entity Information
Dividend yield
Note To Financial Statement Details Textual
Equity-based Performance Stock Units Granted in 2019 [Member]
Represents equity-based performance stock units granted in 2019.
Significant Accounting Policies
Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]
Note 1 - Summary of Significant Accounting Policies
Note 2 - Business Acquisitions
Risk-free interest rate
Note 3 - Goodwill and Purchased Intangible Assets
Note 4 - Borrowings and Credit Agreements
Equity Based Performance Stock Units Granted in 2019, 2018, 2017, and 2016 [Member]
Represents equity based performance stock unites granted in 2019, 2018, 2017 and 2016.
Note 5 - Restructuring Charges
Note 6 - Employee Benefit Plans
Note 7 - Financial Instruments Measured at Fair Value
Note 8 - Income Taxes
Note 9 - Segment and Geographic Information
Note 10 - Leases
Changes in unrealized gains and losses on investments, net of tax
Change in unrealized gain/loss on investments, net of tax
Note 12 - Guarantees
Note 13 - Discontinued Operations
Expected volatility
Note 14 - Accumulated Other Comprehensive Loss
us-gaap_LiabilitiesCurrent
Total current liabilities
Note 16 - Quarterly Financial Data (Unaudited)
Schedule II - Valuation and Qualifying Accounts
Current liabilities of discontinued operations (Note 13)
Total current liabilities
Note 1 - Summary of Significant Accounting Policies - Computation of Basic and Diluted Income (Loss) Per Share (Details)
Expected term (Year)
Note 1 - Summary of Significant Accounting Policies - Inventories (Details)
Note 1 - Summary of Significant Accounting Policies - Property, Plant and Equipment (Details)
Note 1 - Summary of Significant Accounting Policies - Disaggregation of Revenue (Details)
us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax
Adjustments related to postretirement benefits, net of tax
Adjustments related to postretirement benefits
Note 2 - Business Acquisitions - Purchase Price Allocation, Xcerra Acquisition (Details)
Note 2 - Business Acquisitions - Preliminary Allocation of Intangible Assets, Xcerra Acquisition (Details)
Note 3 - Goodwill and Purchased Intangible Assets - Changes in Carrying Value of Goodwill (Details)
Note 3 - Goodwill and Purchased Intangible Assets - Purchased Intangible Assets (Details)
Note 4 - Borrowings and Credit Agreements - Summary of Borrowings (Details)
Note 4 - Borrowings and Credit Agreements - Debt Principal Payments for the Next Five Years and Thereafter (Details)
Swiss Plan [Member]
Information about the Swiss Plan.
Note 5 - Restructuring Charges - Charges Related to the Wind Down Plan (Details)
Debt Security, Government, Non-US [Member]
Note 6 - Employee Benefit Plans - Net Periodic Benefit Cost of Swiss Plan (Details)
Note 6 - Employee Benefit Plans - Benefit Obligation, Fair Value of Plan Assets, Funded Status and Liability of Swiss Plan (Details)
Note 6 - Employee Benefit Plans - Weighted-average Actuarial Assumptions to Determine Benefit Obligation and Net Periodic Benefit Cost (Details)
Note 6 - Employee Benefit Plans - Post-retirement Benefit Obligation to Funded Status and Liability (Details)
us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent
Foreign currency translation adjustments, net of tax
Granted, wt. avg. (in dollars per share)
Note 6 - Employee Benefit Plans - Stock Option Activity Under Share-based Compensation Plans (Details)
Released, wt. avg. (in dollars per share)
Cancelled, wt. avg. (in dollars per share)
Note 6 - Employee Benefit Plans - Stock Options Outstanding and Exercisable (Details)
Note 6 - Employee Benefit Plans - Restricted Stock Unit Activity Under Share-based Compensation Plans (Details)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Outstanding, beginning of year, wt. avg. (in dollars per share)
Outstanding, end of year, wt. avg. (in dollars per share)
us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax
Note 6 - Employee Benefit Plans - Equity-based Performance Stock Units (Details)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Cancelled, units (in shares)
Note 6 - Employee Benefit Plans - Performance Based Stock Unit Activity Under Share-based Compensation Plans (Details)
us-gaap_DeferredCompensationLiabilityCurrent
Deferred Compensation Liability, Current, Total
Note 6 - Employee Benefit Plans - Weighted-average Assumptions to Value Share-based Awards Granted (Details)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Outstanding, beginning of year, units (in shares)
Outstanding, end of year, units (in shares)
Changes in cumulative translation adjustment
Note 6 - Employee Benefit Plans - Reported Share-based Compensation in Consolidated Financial Statements (Details)
Note 7 - Financial Instruments Measured at Fair Value - Short-term Investments by Security Type (Details)
Real Estate Investments [Member]
This element represents direct equity investments in real estate projects
Note 7 - Financial Instruments Measured at Fair Value - Effective Maturities of Short-term Investments (Details)
Granted, units (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
Note 7 - Financial Instruments Measured at Fair Value - Assets Measured at Fair Value on Recurring Basis (Details)
Alternative Investments [Member]
Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds.
Note 8 - Income Taxes - Components of Provision (Benefit) for Income Taxes for Continuing Operations (Details)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Released, units (in shares)
Note 8 - Income Taxes - Income (Loss) Before Income Taxes From Continuing Operations (Details)
Note 8 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details)
us-gaap_LongTermDebtCurrent
Long-term Debt, Current Maturities, Total
Less: current portion
Note 8 - Income Taxes - Reconciliation of Income Tax Computed at U.S. Federal Statutory Tax Rate to Provision (Benefit) (Details)
Note 8 - Income Taxes - Reconciliation of Income Tax Computed at U.S. Federal Statutory Tax Rate to Provision (Benefit) (Details) (Parentheticals)
Note 8 - Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details)
Current installments of long-term debt
Note 9 - Segment and Geographic Information - Summary of Current Segments (Details)
Note 9 - Segment and Geographic Information - Customers Comprising 10% of Consolidated Sales (Details)
Other comprehensive income (loss), net of tax
Other comprehensive income (loss), net of tax
Note 9 - Segment and Geographic Information - Summary of Net Sales to Customers, Attributed to Countries (Details)
Note 9 - Segment and Geographic Information - Summary of Property, Plant and Equipment and Other Long Lived Assets in Geographical Area (Details)
Options Exercisable, Weighted Average Exercise Price (in dollars per share)
Options exercisable at year end, weighted average exercise price (in dollars per share)
Note 10 - Leases - Balance Sheet Information (Details)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Note 10 - Leases - Lease Expense (Details)
Note 10 - Leases - Future Minimum Lease Payments (Details)
cohu_AmortizationOfInventoryStepup
Amortization of Inventory, Step-up
The amortization expense related to the stepped-up basis of inventory.
Note 10 - Leases - Cash Flow Information (Details)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value
Note 12 - Guarantees - Changes in Accrued Warranty (Details)
Note 13 - Discontinued Operations - Balance Sheet Information for Fixture Services Business (Details)
Note 13 - Discontinued Operations - Summary of Operating Results (Details)
us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
Total equity
Balance
Balance
Options Exercisable (in shares)
Options exercisable at year end (in shares)
Note 14 - Accumulated Other Comprehensive Loss - Components of Other Comprehensive Loss (Details)
Note 14 - Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss, Net of Tax (Details)
Options Outstanding, Weighted Average Remaining Life (Year)
Note 16 - Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Data (Details)
Weighted-average grant date fair value per share (in dollars per share)
Schedule II - Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Details)
cohu_RepaymentsOfLongTermDebtCurrentMaturities
Repayments of Long-term Debt, Current Maturities
The cash outflow for the current portion of long-term debt.
Notes To Financial Statements
Notes To Financial Statements [Abstract]
Fixtures Services Business FSG [Member]
Represents information about Fixtures Services Business ("FSG").
Options Outstanding, Weighted Average Exercise Price (in dollars per share)
Outstanding, weighted average exercise price, beginning of year (in dollars per share)
Outstanding, weighted average exercise price, end of year (in dollars per share)
Cancelled, weighted average exercise price (in dollars per share)
us-gaap_ContractWithCustomerLiabilityCurrent
Contract with Customer, Liability, Current
cohu_PercentageOfFairValueToDeterminePriceOfCommonStock
Percentage of Fair Value to Determine Price of Common Stock
Percentage of the Fair Value to Determine the price of common stock.
cohu_EmployeeStockPurchasePlanSharesReservedforFutureIssuance
Employee Stock Purchase Plan, Shares Reserved for Future Issuance
The shares reserved for future issuance under the employee stock purchase plan.
Exercised, weighted average exercise price (in dollars per share)
Accrued compensation and benefits
Income taxes payable
Accounts payable
Unvested Restricted Stock Units [Member]
The unvested restricted stock units.
Number Outstanding (in shares)
Outstanding, beginning of year (in shares)
Outstanding, end of year (in shares)
Other accrued liabilities
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Accrued warranty
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage
Current liabilities:
Vesting [Axis]
Vesting [Domain]
Total assets for reportable segments
Assets, Total
us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
Discontinued operations
Plan Name [Axis]
Plan Name [Domain]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition
us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Income tax benefit
Commitments Contingencies and Guarantees [Text Block]
us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet
Accounts receivable, net
Share-based Payment Arrangement [Text Block]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]
Award Type [Domain]
Award Type [Axis]
Other comprehensive income (loss) attributable to noncontrolling interest
Accumulated Amortization
Intangible assets, net
Gross Carrying Amount, finite-lived intangible assets
Net income (loss) from noncontrolling interest
Net income (loss) attributable to noncontrolling interest
us-gaap_CapitalizedComputerSoftwareGross
Capitalized Computer Software, Gross
us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Indefinite-lived Intangible Assets (Excluding Goodwill), Ending Balance
Comprehensive income (loss) attributable to noncontrolling interest
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less accumulated depreciation and amortization
us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation
Divestiture of interest in consolidated entity
cohu_CollectionTermRange
Collection Term Range
The collection term range.
Property plant and equipment, net
Property, plant and equipment, net
Contingencies Disclosure [Text Block]
Goodwill
Goodwill
Beginning balance
Ending balance
Inventory, receivable and warranty reserves
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from inventory and warranty reserves.
us-gaap_CapitalLeasedAssetsGross
Capital Leased Assets, Gross, Total
Intangible assets and other acquisition basis differences
Amount of deferred tax liability attributable to taxable temporary differences from acquisition basis differences.
Settlements, adjustments and releases from statute expirations
Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax settlements adjustments and releases from statute expiration.
Property, plant and equipment
Intel [Member]
Information about Intel.
Rest of the World [Member]
The rest of the world.
Malaysia [Member]
Information about Malaysia.
Accrued retiree benefits
Net income (loss)
Net income (loss)
Net income (loss)
us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
Comprehensive income (loss)
us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax
Income (loss) before taxes
us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation
Income tax provision
us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest
Net income (loss)
us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax
Loss from sale of BMS
us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
Loss on impairment and disposal of segments held for sale (Note 13)
Additions (reductions) not charged to expense
Amount of increase (decrease) in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, not charged (credited) to costs and expenses.
Income (loss) from continuing operations before taxes
Income (loss) from continuing operations before taxes
Income tax provision (benefit)
Consolidation, Variable Interest Entity, Policy [Policy Text Block]
Additions (reduction) charged (credited) to expense
Amount of increase (decrease) in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from charges (credits) to costs and expenses.
cohu_CumulativeEffectsOfNewAccountingPrincipleInPeriodOfAdoption
Cumulative effect of accounting change, a
Represents cumulative effect of new accounting principle in period of adoption.
us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Defined Contribution Plan, Employer Discretionary Contribution Amount
us-gaap_GeneralAndAdministrativeExpense
Corporate expenses
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay
cohu_DefinedBenefitPlanExpectedFutureEmployeeAndEmployerContributionsNextTwelveMonths
Defined Benefit Plan, Expected Future Employee and Employer Contributions, Next Twelve Months
Represents the expected future employee and employer contributions, next twelve months.
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Defined Contribution Plan, Employer Matching Contribution, Percent of Match
us-gaap_LeaseAndRentalExpense
Operating Leases, Rent Expense, Total
Cash and cash equivalents
Cash and cash equivalents at end of year from continuing operations
us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Plan assets at end of year
Fair value of plan assets at beginning of year
Fair value of plan assets at end of year
Funded status
Net liability at end of year
Benefit obligation at beginning of year
Benefit obligation at end of year
us-gaap_DefinedBenefitPlanBenefitObligation
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter
Employer contributions
us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
Defined Benefit Plan, Expected Future Benefit Payment, Year Two
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
Defined Benefit Plan, Expected Future Benefit Payment, Year Three
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
Defined Benefit Plan, Expected Future Benefit Payment, Year Four
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
Defined Benefit Plan, Expected Future Benefit Payment, Year Five
Amendment Flag
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months
us-gaap_GainLossOnSaleOfBusiness
Gain (Loss) on Disposition of Business
us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components
New Accounting Pronouncements, Policy [Policy Text Block]
us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components
us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation
us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation
us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year
us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate
us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate
Rate of return on assets
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Compensation increase
Compensation increase
Current Fiscal Year End Date
cohu_TransferFromInProcessTechnologyToDevelopedTechnology
Transfer From In-Process Technology to Developed Technology
The value of technology transferred to "Developed Technology" which was previously classified as "In-Process Technology" in the period.
Discount rate
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Discount rate
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate
Valuation and Qualifying Accounts Disclosure [Table Text Block]
The tabular disclosure of valuation and qualifying accounts and reserves.
us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
Accumulated benefit obligation at beginning of year
Accumulated benefit obligation at end of year
Document Fiscal Period Focus
Document Fiscal Year Focus
Document Period End Date
Entity Emerging Growth Company
Document Type
Entity Small Business
Return on assets, net of actuarial loss
Entity Shell Company
Participant contributions
Document Information [Line Items]
Document Information [Table]
us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss
Foreign currency exchange adjustment
Entity Public Float
us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid
Benefits paid
Entity Filer Category
Entity Current Reporting Status
Restructuring charges (Note 5)
Restructuring Charges, Total
Entity Voluntary Filers
us-gaap_BusinessCombinationAcquisitionRelatedCosts
Business Combination, Acquisition Related Costs
Entity Well-known Seasoned Issuer
us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant
Participant contributions
Actuarial gain (loss)
Actuarial gain
Foreign currency exchange adjustment
Plan change
us-gaap_GoodwillImpairmentLoss
Impairments (1)
Net sales percentage
Statement of Comprehensive Income [Abstract]
Entity Central Index Key
Entity Registrant Name
Entity [Domain]
Legal Entity [Axis]
Customer Concentration Risk [Member]
Amortization of purchased intangible assets
Amortization of Intangible Assets, Total
Concentration Risk Type [Axis]
Concentration Risk Type [Domain]
Entity Common Stock, Shares Outstanding (in shares)
Revenue Benchmark [Member]
us-gaap_CashSurrenderValueOfLifeInsurance
Cash Surrender Value of Life Insurance
Investments [Domain]
Trading Symbol
Concentration Risk Benchmark [Axis]
Concentration Risk Benchmark [Domain]
Investment Type [Axis]
us-gaap_TableTextBlock
Notes Tables
us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage
Selling, general and administrative
us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesAfterTax
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax
ALBS [Member]
Represents information pertaining to ALBS Solutions Sdn Bhd.
cohu_NumberOfVIEsConsolidated
Number of VIEs Consolidated
Represents the number of variable interest entities consolidated as of the balance sheet date.
Raw materials and purchased parts
Finished goods
Work in process
cohu_IncreaseDecreaseOfEarningPerShareDueToImpactOfTaxHolidays
Increase (Decrease) of Earning Per Share Due To Impact Of Tax Holidays
The increase or decrease of earning per share due to impact of tax holidays.
Xcerra [Member]
Related to the entity Xcerra.
Noncurrent assets of discontinued operations (Note 13)
Research and development
cohu_IncreaseDecreaseInAccruedCompensationWarrantyAndOtherLiabilities
Accrued compensation, warranty and other liabilities
The increase (decrease) during the period in accrued salaries, warranty, and other liabilities.
us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent
Property, plant and equipment, net
us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets
Other noncurrent assets
us-gaap_InterestExpense
Interest expense
us-gaap_AmortizationOfFinancingCosts
Amortization of Debt Issuance Costs
Defined Benefit Plan, Equity Securities [Member]
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
Subsequent Event [Member]
Defined Benefit Plan, Plan Assets, Category [Axis]
Defined Benefit Plan, Plan Assets, Category [Domain]
Schedule of Inventory, Current [Table Text Block]
Goodwill and other intangible assets
Subsequent Event Type [Axis]
Subsequent Event Type [Domain]
Gross Carrying Amount, finite-lived and indefinite-lived intangible assets
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Finite-Lived Intangible Assets, Amortization Expense, after Year Five
Fair Value Measurement, Policy [Policy Text Block]
cohu_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssignedAttributedToPreMergerServices
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned, Attributed to Pre-Merger Services
Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity, attributable to pre-Merger services.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
Finite-Lived Intangible Assets, Amortization Expense, Year Two
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
Finite-Lived Intangible Assets, Amortization Expense, Year Three
cohu_BusinessCombinationNumberOfBrandsAcquired
Business Combination, Number of Brands Acquired
Represents the number of brands acquired in a business combination.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
Finite-Lived Intangible Assets, Amortization Expense, Year Four
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
Finite-Lived Intangible Assets, Amortization Expense, Year Five
Segment Reporting, Policy [Policy Text Block]
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months
SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain]
Equity-based Performance Stock Units Granted in 2017 [Member]
Represents equity-based performance stock units granted in fiscal year 2017.
Foreign Currency Transactions and Translations Policy [Policy Text Block]
In-process Technology [Member]
Represents information pertaining to in-process technology.
Other assets
Equity-based Performance Stock Units Granted in 2016 [Member]
Represents equity-based performance stock units granted in fiscal year 2016.
SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis]
Remaining Useful Life (Year)
Earnings Per Share, Policy [Policy Text Block]
Intangible assets, estimated fair value
Amount of increase in assets, excluding financial assets and goodwill, lacking physical substance with a finite or indefinite life, from an acquisition.
Comprehensive Income, Policy [Policy Text Block]
Discontinued Operations, Policy [Policy Text Block]
Income Tax, Policy [Policy Text Block]
Internal Use Software, Policy [Policy Text Block]
us-gaap_LesseeOperatingLeaseRenewalTerm
Lessee, Operating Lease, Renewal Term
Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block]
us-gaap_AssetsCurrent
Total current assets
Share-based Payment Arrangement [Policy Text Block]
Kita Term Loans [Member]
Represents information pertaining to term loans related to the Kita acquisition.
Current assets of discontinued operations (Note 13)
Total current assets
Advertising Cost [Policy Text Block]
Xcerra Term Loan [Member]
Represents information pertaining to a term loan related to the Xcerra acquisition.
Assets held for sale
us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent
Inventories
Ismeca [Member]
Represents information pertaining to Ismeca, a wholly-owned subsidiary of Cohu.
us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets
Other current assets
cohu_NumberOfAvailableLinesOfCredit
Number of Available Lines of Credit
Represents the number of available lines of credit as of the balance sheet date.
Standard Product Warranty, Policy [Policy Text Block]
us-gaap_DeferredTaxAssetsValuationAllowance
Deferred Tax Assets, Valuation Allowance, Total
Less valuation allowance
Commitments and Contingencies, Policy [Policy Text Block]
Other current assets
us-gaap_DeferredTaxAssetsNet
Total deferred tax assets
Total debt
Represents the aggregate of total long-term debt, including current maturities and short-term debt, before financing fees and discount.
Debt, Policy [Policy Text Block]
Prepaid expenses
Other
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]
Goodwill and Intangible Assets, Policy [Policy Text Block]
us-gaap_DeferredTaxAssetsGross
Gross deferred tax assets
us-gaap_DeferredIncomeTaxLiabilities
Total deferred tax liabilities
Inventories
Total inventories
Net sales
Net sales
Foreign transaction gain (loss) and other
us-gaap_PropertyPlantAndEquipmentUsefulLife
Property, Plant and Equipment, Useful Life
Segment profit (loss) before tax:
Net sales by segment:
Accounts receivable, net
Schedule of Segment Reporting Information, by Segment [Table Text Block]
Equity-based Performance Stock Units Granted in 2018 [Member]
Represents equity-based performance stock units granted in fiscal year 2018.
Accrued employee benefits
us-gaap_NumberOfOperatingSegments
Number of Operating Segments
PCB Test [Member]
Relating to the segment, PCB Test.
us-gaap_NumberOfReportableSegments
Number of Reportable Segments
Semiconductor Test and Inspection [Member]
Relating to the segment, Semiconductor Test & Inspection.
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
Stock-based compensation
Building and Building Improvements [Member]
Building [Member]
Building Improvements [Member]
Semiconductor Test and Inspection and PCB Test [Member]
Relating to the segments, Semiconductor Test and Inspection and PCB Test.
Land and Land Improvements [Member]
Property, Plant and Equipment, Policy [Policy Text Block]
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table Text Block]
Tabular disclosure of assets, excluding financial assets and goodwill, lacking physical substance with a finite or indefinite life, by either major class or business segment.
Property, Plant and Equipment, Type [Axis]
Property, Plant and Equipment, Type [Domain]
Segment Reporting Disclosure [Text Block]
Tax credit carryforwards
Net operating loss carryforwards
Current assets:
us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
Cash and cash equivalents at beginning of year
Cash and cash equivalents at end of year
Inventory, Policy [Policy Text Block]
Total assets by segment:
Interest income
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash provided by (used in) financing activities
us-gaap_OperatingIncomeLoss
Income (loss) from operations
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
Other (expense) income:
us-gaap_DeferredTaxLiabilities
Net deferred tax liabilities
Effect of exchange rate changes on cash and cash equivalents
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Net increase (decrease) in cash and cash equivalents
us-gaap_CostOfGoodsAndServicesSold
Cost of sales:
us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations
Net cash used in investing activities
us-gaap_InventoryWriteDown
Inventory Write-down
us-gaap_SaleLeasebackTransactionDeferredGainGross
Sale Leaseback Transaction, Deferred Gain, Gross
Cost of sales, Amortization
Unremitted earnings of foreign subsidiaries
us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities
Payment of contingent consideration
Concentration Risk, Credit Risk, Policy [Policy Text Block]
Depreciation and fixed asset related
us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment
us-gaap_PaymentsOfDividendsCommonStock
Cash dividends paid
Issuance (repurchases) of common stock, net including awards settled in cash
us-gaap_CostsAndExpenses
Cost and expenses:
us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability
cohu_DefinedBenefitPlanBenefitObligationBenefitsPaidRecovered
Benefits paid
Amount of the payment (recovery) to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, life insurance benefits, and legal, educational and advisory services.
Title of Individual [Domain]
U.S. State
Title of Individual [Axis]
us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit
U.S. State
Foreign
cohu_DefinedBenefitPlanPlanAssetsBenefitsPaidRecovered
Benefits paid
Amount of payment (recovery) to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.
us-gaap_DeferredForeignIncomeTaxExpenseBenefit
Foreign
U.S. Federal
us-gaap_DeferredFederalIncomeTaxExpenseBenefit
U.S. Federal
cohu_LesseeLeaseRemainingTermOfContract
Lessee, Lease, Remaining Term of Contract
Remaining term of lessee's operating and finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.
Lessee, Leases [Text Block]
The entire disclosure for operating and finance leases of lessee.
us-gaap_CurrentIncomeTaxExpenseBenefit
Total current
cohu_LesseeSubleaseIncomeReceivableYearTwo
Lessee, Sublease Income, Receivable, Year Two
Amount of sublease income receivable for the second fiscal year following the latest year.
Construction Loans [Member]
cohu_LesseeSubleaseIncomeReceivableRemainderOfFiscalYear
Lessee, Sublease Income, Receivable, Remainder of Fiscal Year
Amount of sublease income receivable for the remainder of the fiscal year.
us-gaap_RevenueRemainingPerformanceObligation
Revenue, Remaining Performance Obligation, Amount
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign
Income from continuing operations, Foreign
cohu_LeaseRightofuseAsset
Total lease assets
Amount of lessee's right to use underlying asset under finance and operating lease.
Other Accrued Liabilities [Member]
Related to other accrued liabilities.
Leases, Balance Sheet Information [Table Text Block]
Tabular disclosure of balance sheet information for leases.
2021, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due in second fiscal year following latest fiscal year.
Lessee, Lease, Liability, Maturity [Table Text Block]
Tabular disclosure of undiscounted cash flows of lessee's operating and finance lease liability.
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic
Income (loss) from continuing operations, U.S.
Present value of lease liabilities, total
cohu_LeaseLiability
Total lease liabilities
Present value of lessee's discounted obligation for lease payments from finance and operating lease.
Thereafter, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due after fifth fiscal year following latest fiscal year.
2024, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due in fifth fiscal year following latest fiscal year.
2023, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due in fourth fiscal year following latest fiscal year.
2022, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due in third fiscal year following latest fiscal year.
Lease, Cash Flow Information [Table Text Block]
Tabular disclosure of the cash flow information for leases.
cohu_LesseeLeaseLiabilityUndiscountedExcessAmount
Less: Interest, total
Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating and finance lease.
cohu_LesseeLeaseLiabilityPaymentsDue
Total lease payments, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease.
Comprehensive Income (Loss) Note [Text Block]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Debt Securities and Cash [Member]
Information related to debt securities and cash.
cohu_FinanceLeaseRightofuseAssetAccumulatedAmortization
Finance Lease Right-of-use Asset, Accumulated Amortization
The amount of accumulated amortization of finance lease right-of-use asset.
us-gaap_PaymentsOfDebtIssuanceCosts
Payment of debt issuance costs
State and Local Jurisdiction [Member]
Income Tax Authority [Axis]
Income Tax Authority [Domain]
Disaggregation of Revenue [Table Text Block]
Domestic Tax Authority [Member]
Foreign Tax Authority [Member]
Cash and Cash Equivalents, Policy [Policy Text Block]
Kita Manufacturing Co. LTD. and Kita USA, Inc. [Member]
Represents a business acquired by the reporting entity.
us-gaap_UnrecognizedTaxBenefits
Balance at beginning of year
Balance at end of year
us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Unrecognized Tax Benefits that Would Impact Effective Tax Rate
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]
us-gaap_OpenTaxYear
Open Tax Year
Basis of Accounting, Policy [Policy Text Block]
us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations
Reductions due to lapse of the statute of limitations
us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromForeignCurrencyTranslation
Foreign exchange rate impact
Foreign exchange rate impact
Cash dividend, per share (in dollars per share)
us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities
Reductions due to settlements
Additions related to Xcerra and Kita acquisitions
us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Cumulative Effect of New Accounting Principle in Period of Adoption
Additions (reductions) for tax positions of prior years
us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions
Additions (reductions) for tax positions of prior years
Additions for tax positions of current year
Vesting Over One Year Period [Member]
Represent a year vesting period.
Vesting Over Two Year Period [Member]
Represent two year vesting period.
Proceeds from Term B Loan
Proceeds from Issuance of Long-term Debt, Total
Vesting Over Four Year Period [Member]
Represent four year vesting period.
Vest on the Third Anniversary of Awards Grant [Member]
Represent awards that are versing on the third anniversary of grant.
Schedule of Share-based Compensation, Equity-based Performance Stock Units [Table Text Block]
Tabular disclosure of equity-based performance stock units.
Range of Award
The percent of the original grant of equity-based compensation awards that may be granted as part of a performance-based equity compensation program.
Performance Criteria Period (Year)
In a performance-based equity compensation plan, the timing in which performance goals are set relative to the grant date.
Effect of dilutive stock options and restricted stock units (in shares)
us-gaap_TaxCreditCarryforwardAmount
Tax Credit Carryforward, Amount
us-gaap_ProductWarrantyAccrualNoncurrent
Product Warranty Accrual, Noncurrent
Range 1 [Member]
Information by range of option prices pertaining to options granted.
us-gaap_OtherAccruedLiabilitiesNoncurrent
Other accrued liabilities
Range 3 [Member]
Information by range of option prices pertaining to options granted.
us-gaap_SharePrice
Share Price
Range 2 [Member]
Information by range of option prices pertaining to options granted.
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
cohu_OwnershipPercentageOfTheCompany
Ownership Percentage of the Company
The percentage of ownership of common stock or equity of the company.
Blackrock [Member]
Represents the entity of Blackrock, a related party of the company.
us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding
(in shares)
Diluted (in shares)
us-gaap_OperatingLossCarryforwards
Operating Loss Carryforwards, Total
Proceeds from construction loan
us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare
Income (loss) from discontinued operations (in dollars per share)
Statement of Financial Position [Abstract]
us-gaap_EarningsPerShareDiluted
Net income (loss) attributable to Cohu (in dollars per share)
Net income (loss) (in dollars per share)
Weighted average common shares outstanding (in shares)
Basic (in shares)
Diluted:
Cost of sales (1)
us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare
Income (loss) from continuing operations before non-controlling interest (in dollars per share)
Income (loss) from discontinued operations (in dollars per share)
Business Acquisition [Axis]
us-gaap_EarningsPerShareBasic
Net income (loss) attributable to Cohu (in dollars per share)
Net income (loss) (in dollars per share)
Business Acquisition, Acquiree [Domain]
Income (loss) from continuing operations before non-controlling interest (in dollars per share)
Income (loss) from continuing operations (in dollars per share)
Basic:
Statement of Cash Flows [Abstract]
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]
Statement of Stockholders' Equity [Abstract]
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]
Impact of currency exchange
Impact of currency exchange
Quarterly Financial Information [Table Text Block]
Interest on lease liabilities
us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]
us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentFinancialLiabilities
Liabilities assumed, measurement period adjustments
us-gaap_FinanceLeaseLiabilityPaymentsDue
Total lease payments, finance leases
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]
Amortization of leased assets
Investments Classified by Contractual Maturity Date [Table Text Block]
us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentFinancialAssets
Other assets, measurement period adjustments
2024, finance leases
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
Thereafter, finance leases
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount
Less: Interest, finance leases
2020, finance leases
2021, finance leases
2022, finance leases
2023, finance leases
Restructuring Plan [Axis]
Restructuring Plan [Domain]
Other Restructuring [Member]
Type of Restructuring [Domain]
us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent
Finance leases
us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value
Employee Severance [Member]
Restructuring and Related Activities Disclosure [Text Block]
Restructuring and Related Costs [Table Text Block]
Fair Value, Assets Measured on Recurring Basis [Table Text Block]
Restructuring Type [Axis]
us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1
Finance leases (Year)
Other, net
Cash flows from financing activities:
U.S. statutory rate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
Impact of Tax Act, before reduction in valuation allowance
Change in valuation allowance
us-gaap_DividendsPayableCurrentAndNoncurrent
Dividends declared but not yet paid
us-gaap_IncomeTaxReconciliationRepatriationOfForeignEarnings
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount
Corporate, Non-Segment [Member]
Deferred profit
The carrying value of deferred revenue, net of expenses, as of the balance sheet date that is expected to be recognized as such within one year or the normal operating cycle, if longer.
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet
Net assets acquired
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
Liabilities assumed
us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired
Payment for purchase of business, net of cash received
Non-deductible transaction related costs
Class of Stock [Axis]
Stock-based compensation
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
us-gaap_PaymentsToAcquireBusinessesGross
Payments to Acquire Businesses, Gross
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Total assets acquired
State income taxes, net of federal tax benefit
Foreign rate differential
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
Property, plant and equipment
us-gaap_IncomeTaxReconciliationTaxCreditsResearch
Federal tax credits
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets
Other assets
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
Intangible assets
Tax provision at U.S. 21% statutory rate (35% in 2017)
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets
Current assets, including cash received
cohu_UnrecognizedTaxBenefitsInterestExpenseNetOfAccruedInterestReversed
Unrecognized Tax Benefits, Interest Expense, Net of Accrued Interest Reversed
Amount of interest expense net of accrued interest reversed for an underpayment of income taxes.
Income Tax Disclosure [Text Block]
Schedule of Maturities of Long-term Debt [Table Text Block]
Schedule of Debt [Table Text Block]
us-gaap_BusinessCombinationConsiderationTransferred1
Business Combination, Consideration Transferred, Total
Inventory capitalized as capital assets
Represents information about inventory capitalized as property, plant and equipment.
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]
Finite-lived intangible assets, estimated fair value
Finite-lived intangible assets, average useful life (Year)
Share-based Payment Arrangement, Option, Activity [Table Text Block]
Indefinite-lived intangible assets, estimated fair value
Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]
Sales and maturities of short-term investments
us-gaap_DisposalGroupIncludingDiscontinuedOperationCash
Cash held by discontinued operations (Note 13)
Cash
Semiconductor Equipment [Member]
Semiconductor equipment as a business segment.
us-gaap_GoodwillAndIntangibleAssetImpairment
Goodwill and Intangible Asset Impairment, Total
Nonrecurring Adjustment [Axis]
Nonrecurring Adjustment [Domain]
Schedule of Nonvested Performance-based Units Activity [Table Text Block]
Fair Value Adjustment to Inventory [Member]
Schedule of Net Benefit Costs [Table Text Block]
Schedule of Net Funded Status [Table Text Block]
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]
Defined Benefit Plan, Assumptions [Table Text Block]
Equity Based Performance Stock Units [Member]
Equity based performance stock units.
us-gaap_PaymentsToAcquireShortTermInvestments
Purchases of short-term investments
Employee Stock Purchase Plan [Member]
Employee stock purchase plan.
Retirement Plan Name [Axis]
Retirement Plan Name [Domain]
Reporting Unit [Axis]
Reporting Unit [Domain]
Goodwill and Intangible Assets Disclosure [Text Block]
Schedule of Goodwill [Table Text Block]
Revolving Credit Facility [Member]
Postretirement Health Coverage [Member]
Retirement Plan Type [Axis]
Retirement Plan Type [Domain]
Property, plant and equipment purchases included in accounts payable
Credit Facility [Axis]
Credit Facility [Domain]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
Trademarks and Trade Names [Member]
Trade Names [Member]
Indefinite-lived Intangible Assets [Axis]
Indefinite-lived Intangible Assets, Major Class Name [Domain]
Capital expenditures
Purchases of property, plant and equipment
cohu_StandardProductWarrantyTerm
Standard Product Warranty Term
Describes the term of the product warranty.
Order or Production Backlog [Member]
Weighted average shares used in computing income (loss) per share:
Cash paid during the year for income taxes
Noncompete Agreements [Member]
Off-Market Favorable Lease [Member]
Developed Technology Rights [Member]
Supplemental disclosure of cash flow information:
cohu_DebtInstrumentAmortizationPercentageOfPrincipalAmount
Debt Instrument, Amortization, Percentage of Principal Amount
Percentage of quarterly installments of the original principal, with balance payable at maturity.
us-gaap_OperatingLeaseImpairmentLoss
Operating Lease, Impairment Loss
Secured Term Loan Facility [Member]
Represents the information pertaining to the secured term loan facility.
us-gaap_LongTermDebtFairValue
Long-term Debt, Fair Value
Cohu RSUs [Member]
Awarded as replacement awards as a result of the completed Merger.
us-gaap_SubleaseIncome
Sublease income
Customer Relationships [Member]
cohu_NetIncomeLossAttributableToNoncontrollingInterestPerBasicShare
Net income (loss) attributable to noncontrolling interest (in dollars per share)
The amount of net income (loss) attributable to noncontrolling interest per each share of common stock or unit outstanding during the reporting period.
cohu_NetIncomeLossAttributableToNoncontrollingInterestPerDilutedShare
Net income (loss) attributable to noncontrolling interest (in dollars per share)
The amount of net income (loss) attributable to the noncontrolling interest during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.
Finite-Lived Intangible Assets by Major Class [Axis]
Finite-Lived Intangible Assets, Major Class Name [Domain]
Contingent Consideration by Type [Axis]
Contingent Consideration Type [Domain]
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]
Equity Interest Type [Axis]
Equity Interest Issued or Issuable, Type [Domain]
us-gaap_IncomeLossFromContinuingOperations
Income (loss) from continuing operations
Income (loss) from continuing operations
Income (loss) from discontinued operations, net of tax
Income (loss), net of tax
Net income (loss) attributable to Cohu
Net income (loss) attributable to Cohu
Net income (loss) attributable to Cohu
Net cash received from sale of land, facility and assets
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Option [Member]
Impact of currency exchange
us-gaap_GoodwillForeignCurrencyTranslationGainLoss
Adjustments
us-gaap_GoodwillPurchaseAccountingAdjustments
Goodwill, measurement period adjustments
Additions
us-gaap_GoodwillAcquiredDuringPeriod
Business Combination Disclosure [Text Block]
Severance and Other Separation Payments [Member]
Related to severance and other separation payments.
Executive Officers and Board of Directors of Xcerra [Member]
Related to executive officers and members of the board of directors of Xcerra.
Long-term Debt, Type [Axis]
Xcerra Employees [Member]
Related to Xcerra employees.
Long-term Debt, Type [Domain]
Inventory Charges [Member]
Related to inventory charges.
Integration Program [Member]
Related to the Integration program
GILTI
Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to GILTI.
Executive compensation limited by Section 162(m)
Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to limited executive compensation.
Profit (loss) for reportable segments
The amount of profit (loss) from operating segments.
Repayments of long-term debt
The amount of cash inflow (outflow) from bank debt.
Cash flows from investing activities, excluding effects from acquisitions and divestitures:
us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable
Income taxes payable
Related Party Transactions Disclosure [Text Block]
Changes in other accrued liabilities
SWITZERLAND
SEC Schedule, 12-09, Reserve, Inventory [Member]
CHINA
us-gaap_IncreaseDecreaseInAccountsPayable
Accounts payable
GERMANY
Change in unrealized gain/loss on investments, tax
us-gaap_DebtInstrumentTerm
Debt Instrument, Term
us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Debt Instrument, Unused Borrowing Capacity, Amount
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax
Total share-based compensation, net of tax
Share-based compensation of continuing operations
Share-based Payment Arrangement, Expense
us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansTaxPortionAttributableToParent
Adjustments related to postretirement benefits, tax
Foreign currency translation adjustments, tax
us-gaap_ComprehensiveIncomeNetOfTax
Comprehensive income (loss) attributable to Cohu
Common stock, shares outstanding (in shares)
us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Debt Instrument, Basis Spread on Variable Rate
us-gaap_DebtInstrumentInterestRateStatedPercentage
Debt Instrument, Interest Rate, Stated Percentage
Variable lease expense
us-gaap_LeaseCost
Net lease cost
JAPAN
us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent
Operating leases
Operating leases (1)
Short-term operating leases
Lease, Cost [Table Text Block]
Leased assets obtained in exchange for new operating lease liabilities
us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Operating leases (Year)
us-gaap_DebtInstrumentFaceAmount
Debt Instrument, Face Amount
us-gaap_DividendsCommonStockCash
Cash dividends - $0.24 per share
us-gaap_DebtInstrumentCollateralAmount
Debt Instrument, Collateral Amount
Debt Instrument [Axis]
Debt Instrument, Name [Domain]
London Interbank Offered Rate (LIBOR) [Member]
Variable Rate [Domain]
Variable Rate [Axis]
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable
Share-based compensation expense
Quarterly Financial Information [Text Block]
Broadcast Microwave Services, Inc. (“BMS”) [Member]
Represents information about Broadcast Microwave Services,Inc., the Company's microwave communications equipment segment.
us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Repurchase and retirement of stock
PHILIPPINES
us-gaap_IncreaseDecreaseInOtherCurrentAssets
Other current assets
us-gaap_IncreaseDecreaseInOtherNoncurrentAssets
Changes in other assets
us-gaap_IncreaseDecreaseInInventories
Inventories
us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total
Net periodic costs
Service cost
Service cost
Interest cost
Interest cost
Interest cost
us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
Expected return on assets
us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Stock Issued During Period, Shares, Employee Stock Purchase Plans
SINGAPORE
Shares issued for acquisition of Xcerra
us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Exercised (in shares)
Shares issued under ESPP
us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Line of Credit Facility, Maximum Borrowing Capacity
Exercise of stock options
Shares issued for restricted stock units vested
Related Party [Axis]
Related Party [Domain]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Cancelled (in shares)
TAIWAN, PROVINCE OF CHINA
us-gaap_LiabilitiesAndStockholdersEquity
UNITED STATES
Retained earnings
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total
Total accumulated other comprehensive loss
Money Market Funds [Member]
Debt Disclosure [Text Block]
Cash and Cash Equivalents [Axis]
Cash and Cash Equivalents [Domain]
Cash [Member]
Changes in current assets and liabilities, excluding effects from acquisitions and divestitures:
us-gaap_ForeignCurrencyTransactionGainLossRealized
Foreign Currency Transaction Gain (Loss), Realized
Long-term lease liabilities
Operating
Present value of lease liabilities, operating leases
Operating Lease, Liability, Total
us-gaap_OperatingLeaseLiabilityCurrent
Operating
us-gaap_FinanceLeaseLiabilityCurrent
Finance
Operating lease right of use assets
Operating Lease, Right-of-Use Asset
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue
Total lease payments, operating leases
us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount
Less: Interest, operating leases
Present value of lease liabilities, finance leases
Financing cash flows from finance leases
us-gaap_DeferredIncomeTaxExpenseBenefit
Total deferred
Deferred income taxes
2022, operating leases
2023, operating leases
2024, operating leases
us-gaap_FinanceLeaseRightOfUseAsset
Finance lease assets
Thereafter, operating leases
us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
Accumulated net adjustments related to postretirement benefits
2020, operating leases
2021, operating leases
us-gaap_PaymentsForRestructuring
Amounts paid or charged
Amounts paid or charged
us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax
Accumulated net currency translation adjustments
Amortization of debt discounts and issuance costs
us-gaap_AssetsFairValueDisclosure
Depreciation
Depreciation, Total
Total depreciation and amortization for reportable segments
Depreciation and amortization
us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges
(Gain) loss on disposal of fixed assets
us-gaap_CashAndCashEquivalentsFairValueDisclosure
Cash and cash equivalents
Adjustment to contingent consideration liability
Common stock, $1 par value; 60,000 shares authorized, 41,395 shares issued and outstanding in 2019 and 40,763 shares in 2018
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Measurement Frequency [Axis]
cohu_DefinedBenefitPlanHealthCareCostTrendRateAnnualRateOfChange
Defined Benefit Plan, Health Care Cost Trend Rate, Annual Rate of Change
The annual rate of change (increase (decrease)) in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.
Measurement Frequency [Domain]
Fair Value, Recurring [Member]
Common stock, shares authorized (in shares)
Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block]
Common stock, shares issued (in shares)
Common stock, par value (in dollars per share)
us-gaap_DeconsolidationGainOrLossAmount
Gain on divestiture of consolidated entity
us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible
Decrease in Unrecognized Tax Benefits is Reasonably Possible
Statistical Measurement [Domain]
Operating cash flows from operating leases
Maximum [Member]
Minimum [Member]
Ownership [Domain]
Product and Service [Axis]
Product and Service [Domain]
Statistical Measurement [Axis]
Operating cash flows from finance leases
Ownership [Axis]
Preferred stock, $1 par value; 1,000 shares authorized, none issued
Preferred stock, shares issued (in shares)
Cash paid for interest
Geographical [Axis]
Property, Plant and Equipment [Table Text Block]
Geographical [Domain]
Preferred stock, shares authorized (in shares)
Preferred stock, par value (in dollars per share)
Fair Value, Inputs, Level 3 [Member]
Fair Value Hierarchy and NAV [Domain]
Customer [Axis]
Customer [Domain]
Fair Value, Inputs, Level 1 [Member]
Fair Value, Inputs, Level 2 [Member]
Fair Value Hierarchy and NAV [Axis]
us-gaap_ProductWarrantyAccrualPayments
Warranty payments
Warranty liability assumed
Warranty accruals
Noncontrolling interest
Cash flows from operating activities:
Revenue [Policy Text Block]
Statement [Line Items]
Paid-in capital
AOCI Attributable to Parent [Member]
Schedule of Product Warranty Liability [Table Text Block]
Stockholders' equity:
Adjustments for New Accounting Principle, Early Adoption [Member]
us-gaap_Liabilities
Liabilities, Total
us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
Total liabilities
Accounting Standards Update 2014-09 [Member]
Consolidation Items [Domain]
Deferred income taxes
us-gaap_ContractWithCustomerLiability
Contract with Customer, Liability, Total
Consolidation Items [Axis]
Accounting Standards Update 2016-02 [Member]
us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total
Type of Adoption [Domain]
Adjustments for New Accounting Pronouncements [Axis]
Condensed Statement of Comprehensive Income [Table Text Block]
Disposal Group Classification [Axis]
Disposal Group Classification [Domain]
us-gaap_ProductWarrantyAccrual
Beginning balance
Ending balance
Noncontrolling Interest [Member]
Retained Earnings [Member]
Additional Paid-in Capital [Member]
Noncurrent deferred gain on sale of facility
Common Stock [Member]
Non-current Other Accrued Liabilities [Member]
Represents non-current other accrued liabilities.
Equity Components [Axis]
Equity Component [Domain]
us-gaap_LongTermDebt
Long-term Debt, Total
Total
Lines of Credit
Long-term Line of Credit, Total
us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Less: financing fees and discount
Machinery and Equipment [Member]
Balance Sheet Location [Axis]
Balance Sheet Location [Domain]
Long term Debt
Selling, General and Administrative Expenses [Member]
Entity Interactive Data Current
Short-term borrowings
Title of 12(b) Security
Cost of Sales [Member]
Research and Development Expense [Member]
us-gaap_ValuationAllowancesAndReservesBalance
Balance, beginning of year
Balance, end of year
us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense
Income Statement Location [Axis]
Income Statement Location [Domain]
Deductions/write-offs
Discontinued Operations, Held-for-sale [Member]
Current and long-term operating lease liabilities
Amount of increase (decrease) in current and noncurrent operating lease liabilities.
cohu_IncreaseDecreaseInOperatingLeaseRightOfUseAssets
Operating lease right-of-use assets
Amount of increase (decrease) in operating lease right-of-use assetS.
2020, total
Amount of lessee's undiscounted obligation for lease payments for operating and finance lease, due in next twelve months following latest fiscal year.
Due after one year through three years, amortized cost
Amount after adjustments of available-for-sale debt securities at cost, maturing in the second fiscal year through the third fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
Due after one year through three years, fair value
The estimated fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through third fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.
Equity Incentive Plan 2005 [Member]
Information pertaining to the 2005 Equity Incentive Plan.
Operating lease right-of-use assets
Amount of deferred tax liability attributable to taxable temporary differences from operating lease right-of-use assets.
Lease liabilities
Amount before allocation of valuation allowances of deferred tax asset attributable to lease liabilities.
Segments [Axis]
Segments [Domain]
NXP Semiconductors N.V. [Member]
Information pertaining to NXP Semiconductors N.V.
cohu_IncreaseDecreaseOfNetIncomeDueToImpactOfTaxHolidays
Increase (Decrease) of Net Income Due to Impact of Tax Holidays
Increase (decrease) in net income due to the impact of tax holidays.
us-gaap_MinorityInterestPeriodIncreaseDecrease
Noncontrolling interest
Rasco Construction Loan [Member]
Represents Rasco construction loan.
us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent
Other accrued current liabilities
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]
Statement [Table]
us-gaap_AvailableForSaleSecurities
Short-term investments
us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss
Operating income
us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue
Net sales
Short-term investments
Estimated Fair Value
us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent
Other comprehensive income (loss), before tax
us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1
Other comprehensive income (loss), tax
Available-for-sale Securities [Table Text Block]
Income Statement [Abstract]
us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
Other comprehensive income (loss) attributable to Cohu
Disposal Groups, Including Discontinued Operations [Table Text Block]
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
2022
First Facility [Member]
Represents the first facility.
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
2023
Disposal Group Name [Axis]
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
2024
us-gaap_RestructuringReserve
Accrued restructuring, beginning balance
Accrued restructuring, ending balance
Adoption of New Accounting Standard [Policy Text Block]
Disclosure of accounting policy for the adoption of new accounting standards.
us-gaap_BusinessCombinationContingentConsiderationLiability
Business Combination, Contingent Consideration, Liability, Total
Disposal Group Name [Domain]
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive
Thereafter
Amortized Cost
cohu_DebtInstrumentPrincipalPaymentTerms
Debt Instrument, Principal Payment Terms
The period of principal payments pursuant to the debt agreement.
Second Facility [Member]
Represents the second facility.
Loan Facilities [Member]
Represents the loan facilities.
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
2020
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]
us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
2021
cohu_IncreaseDecreaseInDeferredProfit
Deferred profit
The amount of increase (decrease) in deferred profit during the period.
cohu_AmountCommittedToAcquireLeasedFacility
Amount Committed to Acquire Leased Facility
The amount that committed to exercise bargain purchase option to acquire lease facility.
cohu_VariableInterestEntityOwnershipPercentageSold
Variable Interest Entity, Ownership Percentage Sold
The percentage of interest in a variable interest entity sold during the period.
cohu_DisposalGroupIncludingDiscontinuedOperationImpairment
Disposal Group, Including Discontinued Operation, Impairment
Loss from impairment of FSG
Amount of impairment attributable to disposal group, including, but not limited to, discontinued operation.
Non-systems [Member]
The amount of revenue derived from all other sources that are not systems.
Systems [Member]
The amount of revenue derived from systems.
Assets Held-for-sale [Policy Text Block]
Disclosure of accounting policy for assets held-for-sale for fiscal year end.
Amortization of inventory step-up and inventory related charges
The adjustment related to the amortization of inventory step-up and inventory related charges.
Machinery, Equipment and Software [Member]
Tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment and collection of computer programs and related data that provide instructions to a computer.
Other Accrued Liabilities and Long-term Lease Liabilities [Member]
Primary financial statement caption encompassing other accrued liabilities and long-term lease liabilities.
cohu_InterestCapitalizedAssociatedWithCloudComputingImplementation
Interest capitalized associated with cloud computing implementation
Amount of interest capitalized associated with cloud computing implementation.
Employee Severance and Other Exit Costs [Member]
Represents employee severance and other exit costs.
cohu_SharebasedCompensationExpenseIncludingRestructuringCharges
Share-based compensation expense including restructuring charges
Amount of noncash expense for share-based payment arrangement, including restructuring charges.
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total
Gross Unrealized Gains
Gross Unrealized Losses
Change in unrealized gain/loss on investments, before tax
Noncurrent liabilities of discontinued operations (Note 13)
us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent
Adjustments related to postretirement benefits, before tax
Accrued retirement benefits
Foreign currency translation adjustments, before tax
us-gaap_ContractWithCustomerLiabilityNoncurrent
Contract with Customer, Liability, Noncurrent
us-gaap_StockholdersEquity
Total Cohu stockholders' equity
Noncurrent income tax liabilities
us-gaap_LongTermDebtNoncurrent
Total long-term debt
Long-term debt
Range of Exercise Prices, Upper (in dollars per share)
Exercise Price Range [Axis]
Exercise Price Range [Domain]
Range of Exercise Prices, Lower (in dollars per share)