us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
Employee Stock Option [Member]
Document And Entity Information
Customer Concentration Risk [Member]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized
Note To Financial Statement Details Textual
Restricted Stock [Member]
statementsignificantaccountingpoliciespolicies
statementnoteasummaryofsignificantaccountingpoliciestables
statementnotebcommitmentsandfacilitiestables
statementnotecshareholdersequitytables
statementnotedincometaxestables
statementnoteemajorcustomerconcentrationtables
Sales [Member]
statementnoteamaturitydateofcdsdetails
Amendment Flag
Concentration Risk Benchmark [Axis]
Diluted (in shares)
The NET number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.
statementnoteaallowancefordoubtfulaccountsdetails
statementnoteacomponentsofinventorydetails
Income Tax Disclosure [Text Block]
Concentration Risk Type [Axis]
statementnoteaestimatedusefullivesofassetsdetails
Concentration Risk Benchmark [Domain]
statementnoteapropertyplantandequipmentdetails
Plan Name [Domain]
us-gaap_AllocatedShareBasedCompensationExpense
Allocated Share-based Compensation Expense
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchase of common stock
statementnoteaweightedaveragecommonsharesoutstandingdetails
Plan Name [Axis]
Concentration Risk Type [Domain]
statementnotebfutureminimumleasepaymentsdetails
Minimum [Member]
statementnotecoptiontransactionsummarydetails
Maximum [Member]
Accounts Receivable [Member]
Supplemental cash flow information
statementnotecoptionscurrentlyoutstandingdetails
Range [Axis]
Useful Lives [Member]
Useful lives [member]
statementnotecoptionsexercisabledetails
Range [Domain]
statementnotedvaluationallowanceactivitydetails
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
Document Fiscal Year Focus
Customer [Axis]
statementnotecrestrictedstocktransactionsdetails
Document Fiscal Period Focus
Customer [Domain]
Net income
Net income
Net income
Proceeds from issuance of common stock under employee stock purchase plan
statementnotedreconciliationofthefederalstatutoryincometaxratedetails
Allowance for Credit Losses on Financing Receivables [Table Text Block]
statementnotedsignificantcomponentsofdeferredincometaxassetsandliabilitiesdetails
us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
Accounts payable and accrued expenses
Proceeds from issuance of common stock
statementnoteemajorcustomerconcentrationsmajorcustomersdetails
statementnotedincometaxexpensebenefitcomponentsdetails
Document Period End Date
Notes To Financial Statements [Abstract]
Notes To Financial Statements
Current Fiscal Year End Date
Award Type [Axis]
Office Equipment [Member]
Entity Current Reporting Status
Entity Voluntary Filers
Entity Public Float
Equipment [Member]
Entity Filer Category
Machinery and Equipment [Member]
Document Type
Deferred rent
Equity Award [Domain]
us-gaap_AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits
Dilutive potential common shares
Pension and Other Postretirement Benefits Disclosure [Text Block]
us-gaap_GoodwillImpairmentLoss
Goodwill, Impairment Loss
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]
Cash flows from investing activities:
Entity Well-known Seasoned Issuer
us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Impairment of Long-Lived Assets Held-for-use
us-gaap_HeldToMaturitySecurities
Total
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Weighted Average Exercise Price, Exercised (in dollars per share)
Other Assets
Accounts receivable, net
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Weighted Average Exercise Price, Cancelled or Forfeited (in dollars per share)
Statement [Table]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Weighted Average Exercise Price, Outstanding (in dollars per share)
Weighted Average Exercise Price, Outstanding (in dollars per share)
September 30, 2015 (in dollars per share)
First Level of Matching [Member]
First level f matching [member]
Second Level Of Matching [Member]
Second level of matching [member]
Cash and cash equivalents
Cash and cash equivalents at beginning of year
Cash and cash equivalents at end of year
Short-term investments
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
September 30, 2015
Non-cash financing activities
Current Assets
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
September 30, 2015
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
September 30, 2015 (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
(Decrease) increase in cash and cash equivalents
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value
Income Statement [Abstract]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
September 30, 2015 (in dollars per share)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term
us-gaap_DeferredTaxAssetsGross
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
us-gaap_DeferredTaxAssetsValuationAllowanceCurrent
Deferred Tax Assets, Valuation Allowance, Current
Valuation allowance
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash (used in) provided by financing activities
us-gaap_DeferredTaxAssetsValuationAllowanceNoncurrent
Deferred Tax Assets, Valuation Allowance, Noncurrent
Valuation allowance
Cashless Method Stock Option Exercised [Member]
Cashless method stock option exercised [member]
us-gaap_GainLossOnDispositionOfAssets1
Loss on disposal of assets
Excess tax benefit from exercise of stock options
us-gaap_DeferredTaxAssetsNetNoncurrent
Deferred taxes
us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
Tax withholding related to vesting of restricted stock grants and exercise of stock options
Payments Related to Tax Withholding for Share-based Compensation
Valuation Allowance by Deferred Tax Asset [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Outstanding (in shares)
Outstanding (in shares)
September 30, 2015 (in shares)
Deferred Tax Asset [Domain]
Summary of Valuation Allowance [Table Text Block]
us-gaap_StockholdersEquity
Balance
Balance
Total shareholders’ equity
us-gaap_DeferredTaxAssetsValuationAllowance
Balance at Beginning of Year
Balance at End of Year
Deferred Tax Assets, Valuation Allowance
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable [Table Text Block]
Short Term [Member]
Short term [member]
Fair Value of Financial Instruments, Policy [Policy Text Block]
Equity Compensation [Member]
Equity compensation [member]
us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs
Less Write-offs
Long-term [Member]
Long term [member]
Additions Charged to Costs and Expenses
Selling, general and administrative
us-gaap_TableTextBlock
Notes Tables
us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals
Accrued expenses and reserves
Preferred stock, shares issued (in shares)
us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Tax withholding related to vesting of restricted stock grants and exercise of stock options (in shares)
Preferred stock, shares authorized (in shares)
Preferred Stock, Shares Authorized
Earnings Per Share, Policy [Policy Text Block]
clfd_NumberOfPatentsPending
Number of Patents Pending
Represents the number of patents pending.
clfd_NumberOfPatentsGranted
Number of Patents Granted
Represents the number of patents granted in the United States.
Preferred stock, par value (in dollars per share)
us-gaap_StockRepurchaseProgramAuthorizedAmount1
Stock Repurchase Program, Authorized Amount
Leases of Lessee Disclosure [Text Block]
us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Stock Repurchase Program, Remaining Authorized Repurchase Amount
Customer A [Member]
Disclosure for customer A.
us-gaap_TreasuryStockAcquiredAverageCostPerShare
Treasury Stock Acquired, Average Cost Per Share
Inventories
Total
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]
Other current assets
us-gaap_DeferredTaxAssetsInventory
Inventories
Preferred stock, shares outstanding (in shares)
us-gaap_SharesIssued
Balance (in shares)
Balance (in shares)
Common stock, shares outstanding (in shares)
Operating expenses
us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets
Intangibles
Director [Member]
Non Employee Directors [Member]
Represents information pertaining to non-employee directors of the Company.
Relationship to Entity [Domain]
us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment
Property and equipment depreciation
Title of Individual [Axis]
Income Tax, Policy [Policy Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Unvested shares at September 30, 2013 (in shares)
Unvested shares at September 30, 2014 (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Granted (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number
us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
Net operating loss carry forwards and credits
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]
Customer C [Member]
Disclosure for customer C.
Customer B [Member]
Disclosure for customer B.
Proceeds from sale of property and equipment
us-gaap_PaymentsToAcquireIntangibleAssets
Patent additions
Additional paid-in capital
us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Purchases of property and equipment
us-gaap_Assets
Total Assets
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
Stock-based compensation
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Vested (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Granted (in dollars per share)
Current Liabilities
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Unvested shares at September 30, 2013 (in dollars per share)
Unvested shares at September 30, 2014 (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
Forfeited (in dollars per share)
Property, plant and equipment, net
Net
us-gaap_TemporaryEquitySharesSubscribedButUnissued
Temporary Equity, Shares Subscribed but Unissued
Entity Registrant Name
Goodwill
us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill
Goodwill
Entity Central Index Key
us-gaap_NumberOfReportableSegments
Number of Reportable Segments
us-gaap_PropertyPlantAndEquipmentGross
Fixed Assets
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less accumulated depreciation
Net sales
Other
Entity Common Stock, Shares Outstanding (in shares)
Commitment and Contingencies
Long-term investments
us-gaap_Liabilities
Total Liabilities
Current deferred income tax assets (liabilities):
Earnings per share:
Valuation Allowance, Operating Loss Carryforwards [Member]
us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent
Deferred taxes
Net current deferred tax asset
Trading Symbol
Scenario [Axis]
Scenario, Unspecified [Domain]
us-gaap_AssetsCurrent
Total current assets
us-gaap_PaymentsToAcquireInvestments
Purchase of investments
us-gaap_DeferredTaxLiabilitiesPrepaidExpenses
Prepaid expenses
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
Valuation Allowances and Reserves [Domain]
Valuation Allowances and Reserves Type [Axis]
us-gaap_IncomeTaxesReceivable
Income Taxes Receivable, Current
Deferred income taxes
us-gaap_LiabilitiesCurrent
Total current liabilities
us-gaap_CurrentStateAndLocalTaxExpenseBenefit
State
us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit
State
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense
Property, Plant and Equipment [Table Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Cancelled or Forfeited (in shares)
Adjustments to reconcile net income to cash provided by operating activities:
Deferred:
Inventory, Policy [Policy Text Block]
Changes in operating assets and liabilities:
us-gaap_CurrentIncomeTaxExpenseBenefit
Current:
us-gaap_DepreciationDepletionAndAmortization
Depreciation and amortization
us-gaap_LiabilitiesAndStockholdersEquity
Total Liabilities and Shareholders’ Equity
us-gaap_Depreciation
Depreciation
us-gaap_DeferredFederalIncomeTaxExpenseBenefit
Federal
Property, Plant and Equipment, Policy [Policy Text Block]
us-gaap_CurrentFederalTaxExpenseBenefit
Federal
Accumulated deficit
Property, Plant and Equipment, Type [Axis]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
2019
Property, Plant and Equipment, Type [Domain]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
2020
us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
Thereafter
Employee stock purchase plan
us-gaap_OperatingLeasesFutureMinimumPaymentsDue
Total minimum lease payments
Leasehold Improvements [Member]
us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Stock Issued During Period, Shares, Employee Stock Purchase Plans
Income Tax Authority [Axis]
us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Defined Contribution Plan, Employer Discretionary Contribution Amount
Income Tax Authority [Domain]
Sale of investments
us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent
2016
State and Local Jurisdiction [Member]
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Defined Contribution Plan, Employer Matching Contribution, Percent of Match
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
2017
Domestic Tax Authority [Member]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
2018
us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross
Exercise of stock options, net of shares exchanged for payment (in shares)
Statement of Financial Position [Abstract]
us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities
Excess Tax Benefit from Share-based Compensation, Operating Activities
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]
us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation
Tax withholding related to vesting of restricted stock grants and exercise of stock options
Stock-based compensation expense
us-gaap_ShareBasedCompensation
Stock-based compensation expense
Restricted stock forfeiture, net (in shares)
Restricted stock issuance, net (in shares)
us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Exercised (in shares)
Exercise of stock options, net of shares exchanged for payment
Restricted stock issuance, net
us-gaap_PropertyPlantAndEquipmentUsefulLife
Property, plant and equipment useful life
Statement of Cash Flows [Abstract]
Statement of Stockholders' Equity [Abstract]
Cash flows from operating activities:
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]
us-gaap_StockRepurchasedDuringPeriodShares
Stock Repurchased During Period, Shares
us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Repurchase of common stock (in shares)
us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Repurchase of common stock
us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent
Net long-term deferred tax (liability) asset
us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]
Concentration Risk Disclosure [Text Block]
us-gaap_IncreaseDecreaseInOtherCurrentAssets
Other current assets
Accrued compensation
Tax Credit Carryforward [Axis]
Tax Credit Carryforward, Name [Domain]
us-gaap_IncomeTaxesPaid
Cash paid during the year for income taxes
Net income per share Diluted (in dollars per share)
Diluted (in dollars per share)
us-gaap_OperatingLossCarryforwardsValuationAllowance
Operating Loss Carryforwards, Valuation Allowance
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding
Weighted average dilutive common shares outstanding (in shares)
Accrued expenses
us-gaap_IncreaseDecreaseInInventories
Inventories
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Income before income taxes
Accounts payable
Income tax expense
Income tax expense
Cash flows from financing activities:
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash used in investing activities
Basic (in shares)
Weighted average common shares (in shares)
us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount
1-3 years
Net income per share Basic (in dollars per share)
Basic (in dollars per share)
us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount
Less than one year
Excess tax benefit of stock options exercised
Revenue Recognition, Policy [Policy Text Block]
Common stock, $ .01 par value; 50,000,000 shares authorized; 13,705,658 and 13,742,964 shares issued and outstanding at September 30, 2015 and 2014, respectively
Receivables, Policy [Policy Text Block]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Class of Stock [Axis]
Common stock, shares issued (in shares)
Significant Accounting Policies [Text Block]
Common stock, shares authorized (in shares)
Common Stock, Shares Authorized
Accounting Policies [Abstract]
Cash and Cash Equivalents, Policy [Policy Text Block]
Other Liabilities
Common stock, par value (in dollars per share)
Common Stock, Par or Stated Value Per Share
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable, net
us-gaap_OperatingLossCarryforwards
Operating Loss Carryforwards
us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate
Tax rate
Schedule of Inventory, Current [Table Text Block]
Preferred stock, $.01 par value; 500 shares; no shares issued or outstanding
Preferred Stock, Value, Issued
us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance
Change in valuation allowance
Use of Estimates, Policy [Policy Text Block]
us-gaap_InventoryWorkInProcessNetOfReserves
Work-in-process
us-gaap_InventoryFinishedGoodsNetOfReserves
Finished goods
New Accounting Pronouncements, Policy [Policy Text Block]
Employee Stock Purchase Plan [Member]
The employee stock purchase plan.
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]
Statement [Line Items]
Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]
us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense
Permanent differences
us-gaap_InventoryRawMaterialsNetOfReserves
Raw materials
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding [Table Text Block]
clfd_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePrice
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price
Represents information about the purchase price of each share under the employee stock purchase plan.
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
Investments Classified by Contractual Maturity Date [Table Text Block]
clfd_SharebasedCompensationArrangementBySharebasedPaymentAwardMarketPricePercentageOfferingDate
Share-based Compensation Arrangement by Share-based Payment Award, Market Price Percentage, Offering Date
Percentage of market price of one share of common stock on offering date that participants pay for shares.
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
clfd_AssetsNoncurrentExcludingPropertyPlantAndEquipment
Total other assets
Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer excluding property, plant and equipment.
Vehicles [Member]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
clfd_EffectiveIncomeTaxRateReconciliationExpirationOfStateNetOperatingLossPercent
Expiration of state NOL’s
Percentage 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 expiration of state NOL's.
us-gaap_LeaseAndRentalExpense
Operating Leases, Rent Expense
us-gaap_GrossProfit
Gross profit
Cost of sales
Deferred taxes
Shareholders’ Equity
us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Federal statutory rate
us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
State income taxes
us-gaap_LiabilitiesNoncurrent
Total other liabilities
us-gaap_AllowanceForDoubtfulAccountsReceivable
Balance at Beginning of Year
Balance at End of Year
Cashless exercise of stock options
The issuance of common stock funded through shares sold to the company.
us-gaap_FiniteLivedIntangibleAssetUsefulLife
Finite-Lived Intangible Asset, Useful Life
Equity Component [Domain]
Equity Components [Axis]
Investment, Policy [Policy Text Block]
Patents [Member]
us-gaap_ConcentrationRiskPercentage1
Concentration Risk, Percentage
Common Stock [Member]
Additional Paid-in Capital [Member]
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Retained Earnings [Member]
us-gaap_OperatingIncomeLoss
Income from operations
Interest income
clfd_DeferredTaxAssetValuationAllowanceIncomeTaxBenefitAdjustment
Income Tax Benefit
Amount of adjustment to the deferred tax asset's valuation allowance pertaining to income tax benefits.
clfd_DeferredTaxAssetValuationAllowanceStateNolExpirationReversal
Reversal for State NOL Expiration
Amount of the adjustment to the valuation allowance of deferred tax assets to enclose the information pertaining about the State NOL expiration.
Finite-Lived Intangible Assets by Major Class [Axis]
Finite-Lived Intangible Assets, Major Class Name [Domain]