Document And Entity Information
Dividend yield
Finite-lived intangible assets
Note To Financial Statement Details Textual
Note 2 - Net Income Per Share
Note 3 - Cash, Cash Equivalents and Investments
Note 4 - Stock-based Compensation
Average risk-free interest rate
Note 6 - Inventories
Note 7 - Major Customer Concentration
Note 11 - Acquisition
Note 2 - Net Income Per Share - Net Income Per Common Share (Details)
Note 3 - Cash, Cash Equivalents and Investments - CD Maturity Dates (Details)
Note 4 - Stock-based Compensation - Valuation Assumption (Details)
Income Tax Disclosure [Text Block]
Note 4 - Stock-based Compensation - Stock Option Activity (Details)
Note 4 - Stock-based Compensation - Restricted Stock Transactions (Details)
Note 6 - Inventories - Components of Inventory (Details)
Average expected volatility
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory
Inventories
Other
Stock-based compensation
Note 7 - Major Customer Concentration - Customers Comprising 10% or More of Net Sales (Details)
Note 11 - Acquisition - Summary of Estimated Fair Values of Acquired Assets (Details)
us-gaap_LiabilitiesCurrent
Total current liabilities
Note 11 - Acquisition - Pro Forma Information (Details)
Title of Individual [Axis]
Notes To Financial Statements
Relationship to Entity [Domain]
us-gaap_FiniteLivedIntangibleAssetUsefulLife
Finite-Lived Intangible Asset, Useful Life
Notes To Financial Statements [Abstract]
Expected life (Year)
us-gaap_BusinessCombinationConsiderationTransferred1
Business Combination, Consideration Transferred, Total
Net sales
us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
Operating expenses
Deferred taxes
Share-based Compensation, Stock Options, Activity [Table Text Block]
Granted (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value
Proceeds from maturities of investments
Vested (in dollars per share)
Forfeited (in dollars per share)
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Balance, weighted-average grant date fair value (in dollars per share)
Balance, weighted-average grant date fair value (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited (in shares)
us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic
Basic (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Balance, unvested shares (in shares)
Balance, unvested shares (in shares)
Long-term investments
Granted (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested (in shares)
us-gaap_DepreciationDepletionAndAmortization
Depreciation and amortization
us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted
Diluted (in dollars per share)
us-gaap_AssetsCurrent
Total current assets
Income from operations
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term
us-gaap_PaymentsToAcquireInvestments
Purchases of investments
us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Net income
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Business Acquisition, Pro Forma Information [Table Text Block]
us-gaap_BusinessAcquisitionsProFormaRevenue
Net sales
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value
Common stock, authorized 50,000,000, $.01 par value; 13,693,943 and 13,812,821, shares issued and outstanding as of June 30, 2018 and September 30, 2017
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Weighted-average exercise price, outstanding (in dollars per share)
Weighted-average exercise price, outstanding (in dollars per share)
Common stock, shares authorized (in shares)
Common stock, shares issued (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
Cancelled or Forfeited (in dollars per share)
Common stock, par value (in dollars per share)
Goodwill and Intangible Assets Disclosure [Text Block]
us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Exercised (in dollars per share)
Deferred Tax Asset [Domain]
Deferred Tax Assets Related to Operating Loss Carryforwards [Member]
Represents the information pertaining to the deferred tax assets related to operating loss carryforwards.
Accrued expenses
Range [Domain]
Maximum [Member]
Non-cash financing activities
Minimum [Member]
Valuation Allowance by Deferred Tax Asset [Axis]
Accounts payable
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Options, outstanding (in shares)
Options, outstanding (in shares)
Other current assets
Proceeds from sale of property, plant and equipment
Range [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
Cancelled or Forfeited (in shares)
Preferred stock, $.01 par value; 500,000 shares; no shares issued or outstanding
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
Trademarks [Member]
Preferred stock, shares issued (in shares)
Accrued compensation
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Cash paid during the year for income taxes
Preferred stock, authorized shares (in shares)
Inventories, net
Inventories, net
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
Preferred stock, par value (in dollars per share)
Work-in-progress
us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Purchases of property, plant and equipment and intangible assets
Finished goods
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period
Customer [Axis]
Customer [Domain]
Vesting period (Year)
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
Current Liabilities
Raw materials
us-gaap_Assets
Total Assets
Supplemental disclosures for cash flow information
Patents [Member]
Plan Name [Axis]
Plan Name [Domain]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total
Cash flows from operating activities
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
Customer Relationships [Member]
Statement [Line Items]
Employee and Non-Employee Directors [Member]
Represents key employees and non-employee directors.
us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Allowance for Doubtful Accounts Receivable, Current, Ending Balance
Accounts receivables, net
Certification Marks [Member]
Additional paid-in capital
Calix, Inc. [Member]
Represents information about Calix, Inc.
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]
Finite-Lived Intangible Assets by Major Class [Axis]
Stock Compensation Plan 2007 [Member]
Name of the Company's equity-based compensation arrangement plan.
Finite-Lived Intangible Assets, Major Class Name [Domain]
Short-term investments
Shareholders’ Equity
Non Employee Directors [Member]
Represents information pertaining to non-employee directors of the Company.
Employees [Member]
Represents information about the Company's employees.
Equity Award [Domain]
Weighted average shares outstanding:
The weighted average shares outstanding.
Current Assets
Award Type [Axis]
Net income
Net income
Intangible assets, net
clfd_NumberOfPatentsGranted
Number of Patents Granted
Represents the number of patents granted in the United States.
Interest income
Restricted Stock [Member]
Other Assets
us-gaap_Liabilities
Total Liabilities
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash used in financing activities
Commitments and Contingencies
Cashless exercise of stock options
The issuance of common stock funded through shares sold to the company.
us-gaap_OperatingIncomeLoss
Income from operations
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash used in investing activities
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Decrease in cash and cash equivalents
Cost of sales
us-gaap_GrossProfit
Gross profit
us-gaap_GoodwillAcquiredDuringPeriod
Goodwill, Acquired During Period
Financing Receivables [Text Block]
Business Combination Disclosure [Text Block]
Property, plant and equipment, net
Goodwill
Goodwill
Other Liabilities
us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
Tax withholding related to exercise of stock options and restricted stock vestings
Cash flows from investing activities
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchase of common stock
us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability
us-gaap_HeldToMaturitySecurities
Total
Employee Stock Purchase Plan [Member]
The employee stock purchase plan.
Net income per common share:
Earnings Per Share [Text Block]
clfd_HeldtomaturitySecuritiesInvestmentTerm
Held-to-maturity Securities, Investment Term
Represents information about the Company's investment term in money market accounts and bank certificates of deposit.
Proceeds from issuance of common stock upon exercise of stock options
Proceeds from Stock Options Exercised
Proceeds from issuance of common stock under employee stock purchase plan
Accounts payable and accrued expenses
Deferred rent
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Income before income taxes
Income tax expense
Income Tax Expense (Benefit), Total
Equity Components [Axis]
Equity Component [Domain]
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.
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.
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.
Less than one year
1-5 years
Cash and cash equivalents
Cash and cash equivalents, beginning of period
Cash and cash equivalents, end of period
State and Local Jurisdiction [Member]
Income Tax Authority [Axis]
Income Tax Authority [Domain]
us-gaap_AllocatedShareBasedCompensationExpense
Allocated Share-based Compensation Expense, Total
Amendment Flag
us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits, Ending Balance
Accounting Policies [Abstract]
Concentration Risk Disclosure [Text Block]
Selling, General and Administrative Expenses [Member]
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]
Common stock, shares outstanding (in shares)
Preferred stock, shares outstanding (in shares)
Current Fiscal Year End Date
Cost of Sales [Member]
us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
Prepaid expenses and other
Basis of Accounting [Text Block]
Document Fiscal Period Focus
Document Fiscal Year Focus
Document Period End Date
Income Statement Location [Axis]
Income Statement Location [Domain]
Document Type
Document Information [Line Items]
Document Information [Table]
Entity Filer Category
Entity Current Reporting Status
Entity Voluntary Filers
Entity Well-known Seasoned Issuer
Dilutive potential common shares (in shares)
Impairment of long-lived assets
Impairment of Long-Lived Assets Held-for-use
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
us-gaap_GoodwillImpairmentLoss
Goodwill, Impairment Loss
Diluted (in shares)
Weighted average dilutive common shares outstanding (in shares)
Customer
Concentration Risk, Percentage
us-gaap_PurchaseObligation
Purchase Obligation, Total
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable, net
Entity Central Index Key
Entity Registrant Name
us-gaap_OperatingLossCarryforwardsValuationAllowance
Operating Loss Carryforwards, Valuation Allowance, Total
Entity [Domain]
Customer Concentration Risk [Member]
Legal Entity [Axis]
Statement [Table]
Scenario [Axis]
Statement of Financial Position [Abstract]
Diluted (in dollars per share)
Scenario, Unspecified [Domain]
Basic (in shares)
Weighted average common shares (in shares)
us-gaap_EffectiveIncomeTaxRateContinuingOperations
Effective Income Tax Rate Reconciliation, Percent, Total
Business Acquisition [Axis]
Basic (in dollars per share)
Concentration Risk Type [Axis]
Business Acquisition, Acquiree [Domain]
Concentration Risk Type [Domain]
Statement of Cash Flows [Abstract]
Entity Common Stock, Shares Outstanding (in shares)
Income Statement [Abstract]
Sales Revenue, Net [Member]
Accounts Receivable [Member]
us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts
Business Acquisition, Transaction Costs
us-gaap_IncreaseDecreaseInInventories
Inventories
Trading Symbol
Concentration Risk Benchmark [Axis]
Concentration Risk Benchmark [Domain]
Impairment of Long-lived Assets [Text Block]
The entire disclosure of impairments on long-lived assets.
us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Stock Issued During Period, Shares, Employee Stock Purchase Plans
Investments Classified by Contractual Maturity Date [Table Text Block]
us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Exercised (in shares)
us-gaap_TableTextBlock
Notes Tables
us-gaap_GainLossOnDispositionOfAssets1
Gain on disposal of assets
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]
Selling, general and administrative
us-gaap_LiabilitiesNoncurrent
Total other liabilities
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
Cash flows from financing activities
us-gaap_LiabilitiesAndStockholdersEquity
Total Liabilities and Shareholders’ Equity
Retained earnings
Customer A [Member]
Disclosure for customer A.
Customer B [Member]
Disclosure for customer B.
Total Assets
Customer C [Member]
Disclosure for customer C.
Changes in operating assets and liabilities, net of business acquisition:
us-gaap_StockholdersEquity
Total Shareholders’ Equity
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Total
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
Inventory Disclosure [Text Block]
Schedule of Inventory, Current [Table Text Block]
Class of Stock [Axis]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
us-gaap_PaymentsToAcquireBusinessesGross
Payments to Acquire Businesses, Gross
Business acquisition
Cash and Cash Equivalents Disclosure [Text Block]
Deferred taxes
us-gaap_DeferredIncomeTaxExpenseBenefit
Property, plant and equipment