Document And Entity Information
us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment
Accumulated depreciation and amortization
us-gaap_ResearchAndDevelopmentExpense
Research and Development Expense
Note To Financial Statement Details Textual
statementsignificantaccountingpoliciespolicies
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]
statementnoteaorganizationandsummaryofsignificantaccountingpoliciestables
statementnotebinventoriestables
statementnotecpropertyandequipmenttables
statementnotedothercomprehensivelosstables
statementnotefincometaxestables
us-gaap_DeferredTaxAssetsInventory
Inventory capitalization
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
statementnotegemployeebenefitplanstables
statementnotehstockholdersequitytables
statementnoteicommitmentstables
statementnotejeconomicdependencytables
statementnotemsegmentinformationtables
statementnoteaorganizationandsummaryofsignificantaccountingpoliciescalculationofbasicanddilutednetincomepercommonsharedetails
statementnotebinventoriessummaryofinventoriesdetails
statementnotecpropertyandequipmentsummaryofpropertyandequipmentdetails
Derivative Instruments and Hedging Activities Disclosure [Text Block]
statementnotefincometaxesprovisionforincometaxesdetails
us-gaap_DeferredTaxAssetsOther
Other, net
statementnotedothercomprehensivelossothercomprehensivelossincomedetails
statementnotefincometaxesreconciliationofincometaxprovisiondetails
statementnotefincometaxesnetdeferredtaxassetsanddeferredtaxliabilitiesdetails
statementnotegemployeebenefitplanscomponentsincludedindefinedbenefitpensionplansnetperiodicbenefitexpensedetails
us-gaap_DeferredTaxAssetsLiabilitiesNet
Net deferred tax assets
statementnotegemployeebenefitplansdefinedbenefitpensionplansfundedstatusandamountrecognizeddetails
statementnotegemployeebenefitplansbenefitpaymentsexpectedtobepaiddetails
us-gaap_DeferredTaxAssetsGross
Total gross deferred tax assets
statementnotegemployeebenefitplanssummaryofchangesinplanassetsandbenefitobligationdetails
statementnotegemployeebenefitsplansdefinedbenefitpensionplansweightedaverageassetassociationandweightedaveragetargetallocationdetails
us-gaap_ForeignCurrencyContractAssetFairValueDisclosure
Foreign Currency Contract, Asset, Fair Value Disclosure
Provision for uncollectible accounts receivable
statementnotegemployeebenefitsplansweightedaverageratesusedindeterminingdefinedbenefitpensionplansnetpensioncostsdetails
Selling, general and administrative expenses
statementnotehstockholdersequitystockoptionactivitydetails
statementnotegemployeebenefitsplansfairvaluesbyassetcategoryofdefinedbenefitpensionplandetails
statementnoteicommitmentsminimumrentalcommitmentsdetails
statementnotehstockholdersequityrestrictedstockdetails
statementnotemsegmentinformationoperatingresultsbybusinesssegmentdetails
us-gaap_DeferredTaxAssetsNetCurrent
Deferred income taxes
statementnotejeconomicdependencysubstantialnetsalestocertaincustomersdetails
us-gaap_DeferredTaxAssetsNetNoncurrent
Deferred income taxes
statementnotemsegmentinformationassetsandcapitalexpendituresbygeographicalregiondetails
Notes To Financial Statements
statementnotemsegmentinformationassetsbybusinesssegmentdetails
statementnotemsegmentinformationnetsalesbygeographicregiondetails
us-gaap_PropertyPlantAndEquipmentUsefulLife
Property, Plant and Equipment, Useful Life
Notes To Financial Statements [Abstract]
us-gaap_DeferredTaxAssetsValuationAllowance
Valuation allowance
Credit Agreement [Member]
Name of the debt instrument.
us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount
us-gaap_GainLossOnDispositionOfAssets
Gain on disposal of assets
naii_RatioOfTotalCurrentAssetsToTotalCurrentLiabilities
Ratio of Total Current Assets to Total Current Liabilities
Total current assets divided by total current liabilities.
Building and Building Improvements [Member]
us-gaap_DerivativeInstrumentsGainRecognizedInOtherComprehensiveIncomeEffectivePortion
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion
us-gaap_DerivativeInstrumentsLossRecognizedInOtherComprehensiveIncomeEffectivePortion
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion
us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion
Cash flows from financing activities
Geographical [Axis]
Geographical [Domain]
us-gaap_AdvertisingExpense
Advertising Expense
Europe [Member]
us-gaap_LineOfCredit
Long-term Line of Credit
us-gaap_LongTermDebt
Long-term Debt
Pension and Other Postretirement Benefits Disclosure [Text Block]
Prepaids and other current assets
Plan Asset Categories [Domain]
Non-cash equipment impairment charge
Impairment of Long-Lived Assets to be Disposed of
2015 Increase [Member]
Increased amount of stock repurchase authorized by the Board of Directors on February 6, 2015.
Statement [Table]
Defined Benefit Plan, Asset Categories [Axis]
Foreign Exchange Forward [Member]
Products Manufactured by NAIE [Member]
Represents products manufactured by NAIE.
naii_LongTermDebtPercentageBearingFluctuatingInterestThresholdAmount
Long-term Debt, Percentage Bearing Fluctuating Interest, Threshold Amount
The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a fluctuating rate when amount is less than threshold.
Excluding Restricted Stock Purchased [Member]
Denotes the exclusion of the restricted stock purchased.
Segments [Axis]
Segments [Domain]
Income Statement [Abstract]
Revenue Recognition, Policy [Policy Text Block]
us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net
Reconciliation of Funded Status:
us-gaap_DefinedBenefitPlanActuarialGainLoss
Actuarial loss
Deferred rent
Concentration Risk, Credit Risk, Policy [Policy Text Block]
Diluted (in dollars per share)
Diluted net income per common share (in dollars per share)
Basic (in dollars per share)
Basic net income per common share (in dollars per share)
us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit
State
us-gaap_CurrentStateAndLocalTaxExpenseBenefit
State
Basic (in shares)
Basic weighted average common shares outstanding (in shares)
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
Diluted (in shares)
Diluted weighted average common shares outstanding (in shares)
Maximum [Member]
Minimum [Member]
Range [Axis]
Range [Domain]
Commodity Contract [Member]
Customer [Axis]
Customer [Domain]
Foreign Exchange Contract [Member]
us-gaap_RoyaltyExpense
Royalty Expense
Equity Securities [Member]
Corporate, Non-Segment [Member]
Property, Plant and Equipment [Table Text Block]
Property, Plant and Equipment Disclosure [Text Block]
Fair Value, Inputs, Level 3 [Member]
Fair Value, Inputs, Level 2 [Member]
Deferred tax liabilities:
us-gaap_DeferredTaxLiabilitiesPrepaidExpenses
Prepaid expenses
Consolidation Items [Domain]
Consolidation Items [Axis]
Operating Segments [Member]
Revenue from External Customers by Geographic Areas [Table Text Block]
Long-lived Assets by Geographic Areas [Table Text Block]
Fair Value, Hierarchy [Axis]
Fair Value Hierarchy [Domain]
Fair Value, Inputs, Level 1 [Member]
Non-US [Member]
Products and Services [Axis]
Products and Services [Domain]
Deferred tax assets:
Leasehold Improvements [Member]
Prepaid Expenses and Other Current Assets [Member]
Land [Member]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Property, Plant and Equipment, Type [Domain]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Property, Plant and Equipment, Type [Axis]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
Property, Plant and Equipment, Policy [Policy Text Block]
Other Noncurrent Assets [Member]
us-gaap_DeferredTaxLiabilities
Deferred tax liabilities
us-gaap_DeferredTaxLiabilitiesOther
Other
Beta Alanine Raw Material Sale Customers [Member]
Inventory, Policy [Policy Text Block]
us-gaap_DeferredTaxAssetsTaxCreditCarryforwards
Tax credit carry forward
us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
Net operating loss carry forward
Other income (expense):
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
2019
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
2018
Segment Reporting Disclosure [Text Block]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
2021
Vehicles [Member]
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
2020
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsCompensatedAbsences
Accrued vacation expense
Other noncurrent liabilities, net
us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
There-after
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
Stock-based compensation
Office Equipment [Member]
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBonuses
Accrued bonus
Derivatives, Policy [Policy Text Block]
us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions
Pension liability
us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent
2017
Balance Sheet Location [Axis]
Balance Sheet Location [Domain]
us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent
Deferred rent
Machinery and Equipment [Member]
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Income before income taxes
us-gaap_OperatingLeasesFutureMinimumPaymentsDue
Total
us-gaap_UndistributedEarningsOfForeignSubsidiaries
Undistributed Earnings of Foreign Subsidiaries
naii_MinimumPrepaymentAmountUnderLineOfCredit
Minimum Prepayment Amount Under Line of Credit
The minimum payment amount that may be prepaid on a line of credit facility with a fixed interest rate.
naii_LineOfCreditFacilityMaximumBorrowingCapacityAnnualReduction
Line of Credit Facility Maximum Borrowing Capacity Annual Reduction
Amount of annual reduction on a line of credit facility.
UNITED STATES
naii_DebtPrePaymentPenalty
Debt Pre Payment Penalty
Amount of penalties associated with the prepayment of debt.
naii_LineOfCreditFacilityMaximumAmountOutstandingAfterReduction
Line of Credit Facility Maximum Amount Outstanding after Reduction
Maximum amount outstanding after an annual reduction on a line of credit facility.
naii_DebtPrepaymentPenaltyRate
Debt Prepayment Penalty Rate
Percentage of penalties associated with the prepayment of debt.
us-gaap_DerivativeAverageForwardExchangeRate1
Derivative, Average Forward Exchange Rate
naii_DebtInstrumentBasisSpreadOnElectedFixedRateBorrowing
Debt Instrument Basis Spread on Elected Fixed Rate Borrowing
The percentage points added to the reference rate to compute fixed rate elections on the debt instrument.
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]
Provision for income taxes
Provision for income taxes
Class of Stock [Axis]
Accrued compensation and employee benefits
Concentration Risk Benchmark [Axis]
Income taxes payable
Concentration Risk Benchmark [Domain]
Accounts payable
Accounts Receivable [Member]
Accrued liabilities
Customer 1 [Member]
Customer 1 in a set of customers.
Customer 2 [Member]
Customer 2 in a set of customers.
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]
Customer 3 [Member]
Customer 3 in a set of customers.
New Accounting Pronouncements, Policy [Policy Text Block]
Concentration Risk Disclosure [Text Block]
Use of Estimates, Policy [Policy Text Block]
Natural Alternatives International Europe SA [Member]
The entity Natural alternatives international Europe SA.
Fixed Loans [Member]
Fixed loans [member]
naii_NumberOfYearsCompensationUsedForBenefitObligationAssumptions
Number of Years Compensation Used for Benefit Obligation Assumptions
The period of employment before retirement that is used to determine what amount of compensation to use as a a baseline for the companies defined benefit plan.
Designated as Hedging Instrument [Member]
Hedging Designation [Axis]
Hedging Designation [Domain]
Cash Flow Hedging [Member]
Hedging Relationship [Axis]
Hedging Relationship [Domain]
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]
us-gaap_OperatingLeasesRentExpenseNet
Operating Leases, Rent Expense, Net
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Comprehensive Income (Loss) Note [Text Block]
Patent and Trademark Licensing [Member]
Business segment related to patentand trademark licensing.
Branded Products [Member]
Business segment related to branded products.
us-gaap_LiabilitiesCurrent
Total current liabilities
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]
Private Label Contract Manufacturing [Member]
Business segment related to private label contract manufacturing.
Consolidation, Policy [Policy Text Block]
Schedule of Net Benefit Costs [Table Text Block]
Cash Flow Hedging Foreign Exchange Contract [Member]
A foreign currency derivative designated as cash flow hedging instruments.
Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block]
us-gaap_LiabilityForUncertainTaxPositionsCurrent
Liability for Uncertainty in Income Taxes, Current
us-gaap_StockRepurchaseProgramAuthorizedAmount1
Stock Repurchase Program, Authorized Amount
Share Repurchase Program [Domain]
Deferred:
Share Repurchase Program [Axis]
Sales Revenue, Net [Member]
Schedule of Assumptions Used [Table Text Block]
us-gaap_CurrentIncomeTaxExpenseBenefit
Sales Revenue, Goods, Net [Member]
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]
Current:
Schedule of Allocation of Plan Assets [Table Text Block]
Cash flows from investing activities
Schedule of Expected Benefit Payments [Table Text Block]
us-gaap_CurrentForeignTaxExpenseBenefit
Foreign
us-gaap_TreasuryStockAcquiredAverageCostPerShare
Treasury Stock Acquired, Average Cost Per Share
Legal Matters and Contingencies [Text Block]
us-gaap_DeferredFederalIncomeTaxExpenseBenefit
Federal
us-gaap_CurrentFederalTaxExpenseBenefit
Federal
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options
Reclassification out of Accumulated Other Comprehensive Income [Member]
Scenario, Unspecified [Domain]
Reclassification out of Accumulated Other Comprehensive Income [Axis]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
us-gaap_ConcentrationRiskPercentage1
Concentration Risk, Percentage
Scenario [Axis]
Plan Name [Domain]
Plan Name [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less: accumulated depreciation and amortization
Property and equipment, net
Property and equipment, net
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]
us-gaap_DerivativeNumberOfInstrumentsHeld
Derivative, Number of Instruments Held
Pension and Other Postretirement Plans, Policy [Policy Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements
Dilutive effect of stock options and restricted stock shares (in shares)
Research and Development Expense, Policy [Policy Text Block]
Denominator
Income Tax Disclosure [Text Block]
us-gaap_PropertyPlantAndEquipmentGross
Property and equipment
Weighted average common shares outstanding:
Commitments Disclosure [Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential
Foreign tax rate differential
us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes
State income taxes, net of federal income tax expense
us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate
Income taxes computed at statutory federal income tax rate
us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax
Total recognized in net periodic benefit cost and other comprehensive income
us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Net periodic benefit expense
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Outstanding, beginning balance (in shares)
Outstanding, ending balance (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Weighted-average exercise price, outstanding (in dollars per share)
Weighted-average exercise price, outstanding (in dollars per share)
Advertising Costs, Policy [Policy Text Block]
Shipping and Handling Cost, Policy [Policy Text Block]
us-gaap_DerivativeRemainingMaturity1
Derivative, Remaining Maturity
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Weighted-average exercise price, granted (in dollars per share)
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Weighted-average exercise price, exercised (in dollars per share)
us-gaap_IncomeTaxReconciliationNondeductibleExpense
Expenses not deductible for tax purposes
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number
Net income
Net income
Net Income (Loss) Attributable to Parent
Cost of Sales, Policy [Policy Text Block]
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Weighted-average exercise price. forfeited (in dollars per share)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Weighted-average contractual term, vested and exercisable
Numerator
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
Weighted-average exercise price, vested and exercisable (in dollars per share)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Aggregate intrinsic value, vested and exercisable
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Vested and exercisable (in shares)
us-gaap_Assets
Total assets
Assets
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Weighted-average contractual term, outstanding
Current liabilities:
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Aggregate intrinsic value, outstanding
Restricted Stock [Member]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Nonvested, beginning balance (in shares)
Nonvested, ending balance (in shares)
Employee Stock Option [Member]
SWITZERLAND
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Granted (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested (in shares)
us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Purchases of property and equipment
Capital Expenditures
Earnings Per Share, Policy [Policy Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Weighted-average grant date fair value, nonvested (in dollars per share)
Weighted-average grant date fair value, nonvested (in dollars per share)
Income Tax, Policy [Policy Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
Weighted-average grant date fair value, forfeited (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Weighted-average grant date fair value, vested (in dollars per share)
Product Concentration Risk [Member]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value
Concentration Risk Type [Domain]
Concentration Risk Type [Axis]
Customer Concentration Risk [Member]
Fair Value Measurement, Policy [Policy Text Block]
us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax
Amounts Reclassified from OCI
us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax
Other comprehensive loss before reclassifications
Net income per common share:
us-gaap_OtherComprehensiveIncomeLossNetOfTax
Other comprehensive loss
Proceeds from sale of property and equipment
us-gaap_OtherComprehensiveIncomeLossTax
Tax Effect of OCI Activity
us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1
Settlement loss
Tax Period [Domain]
us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses
Amortization of net loss
Recognized actuarial loss
Tax Period [Axis]
Compensation expense related to stock compensation plans
us-gaap_DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeLossNetGainLossBeforeTax
Net loss
Amendment Flag
us-gaap_TreasuryStockValue
Treasury stock, at cost, 958,049 shares at June 30, 2016 and 875,584 at June 30, 2015
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate
us-gaap_TreasuryStockValueAcquiredCostMethod
Repurchase of common stock
Treasury Stock, Value, Acquired, Cost Method
Disclosure of non-cash activities:
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Discount rate
Tax effect of stock compensation
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Compensation increase rate
Document Fiscal Year Focus
Changes in operating assets and liabilities:
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Expected long-term rate of return
Document Fiscal Period Focus
us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax
Total recognized in other comprehensive income (loss)
Document Period End Date
Current Fiscal Year End Date
us-gaap_EffectiveIncomeTaxRateContinuingOperations
Effective Income Tax Rate Reconciliation, Percent
us-gaap_CashFlowHedgeDerivativeInstrumentAssetsAtFairValue
Cash Flow Hedge Derivative Instrument Assets at Fair Value
Document Information [Line Items]
us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax
Change in minimum pension liability, net of tax
Document Information [Table]
us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Weighted-average asset allocation
us-gaap_OperatingLossCarryforwards
Operating Loss Carryforwards
Entity Current Reporting Status
Entity Voluntary Filers
Entity Public Float
Entity Filer Category
Document Type
us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
Weighted-average target allocation
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
2018
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
2017
Common stock, outstanding (in shares)
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
2022-2026
us-gaap_SharesOutstanding
Balance (in shares)
Balance (in shares)
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
2021
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate
us-gaap_AccountsReceivableNet
Accounts Receivable, Net
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
2020
Cash and Cash Equivalents [Member]
Unrealized loss resulting from change in fair value of derivative instruments, net of tax
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
2019
us-gaap_StockholdersEquity
Balance
Balance
Total stockholders’ equity
Entity Well-known Seasoned Issuer
us-gaap_ComprehensiveIncomeNetOfTax
Comprehensive income
Statement of Financial Position [Abstract]
us-gaap_DefinedBenefitPlanBenefitObligation
Benefit obligation at beginning of year
Benefit obligation at end of year
us-gaap_DefinedBenefitPlanSettlementsBenefitObligation
Settlement loss
Repurchase of common stock (in shares)
Treasury Stock, Shares, Acquired
us-gaap_DefinedBenefitPlanAdministrationExpenses
Plan expenses
Plan expenses
Preferred stock, shares outstanding (in shares)
us-gaap_DefinedBenefitPlanBenefitsPaid
Benefits paid
us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Actual return on plan assets
us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Difference between benefit obligation and fair value of plan assets
us-gaap_IncreaseDecreaseInInventories
Inventories
us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
Net amount recognized
us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
us-gaap_TableTextBlock
Notes Tables
us-gaap_IncomeTaxReconciliationOtherAdjustments
Other, net
us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
Unrecognized net actuarial loss in accumulated other comprehensive income
us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Valuation allowance
Statement of Stockholders' Equity [Abstract]
us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year
us-gaap_IncomeTaxReconciliationTaxContingenciesStateAndLocal
Adjust state deferred due to change in apportionment
Supplemental disclosures of cash flow information
us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
Expected return on plan assets
us-gaap_DefinedBenefitPlanInterestCost
Interest cost
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable
Statement of Cash Flows [Abstract]
us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets
Fair value of plan assets at end of year
us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation
Accumulated benefit obligation
us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation
Projected benefit obligation
Long-term Debt, Type [Domain]
Long-term Debt, Type [Axis]
us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
Prepaids and other assets
invest_DerivativeNotionalAmount
Derivative, Notional Amount
Debt Instrument [Axis]
Debt Instrument, Name [Domain]
Retained earnings
Accumulated other comprehensive loss
Accumulated Other Comprehensive Loss, Beginning Balance
Accumulated Other Comprehensive Loss, Ending Balance
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and stockholders’ equity
Net sales
Revenue, Net
us-gaap_IncreaseDecreaseInIncomeTaxes
Income taxes
Legal Entity [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
Swiss Federal Tax Administration (FTA) [Member]
Income Tax Authority, Name [Axis]
Entity Registrant Name
Income Tax Authority, Name [Domain]
Entity Central Index Key
Entity [Domain]
naii_RoyaltyAndLicensingRevenue
Royalty and Licensing Revenue
Royalty and licensing revenue
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Forfeited (in shares)
2009 Omnibus Stock Incentive Plan [Member]
Omnibus stock incentive plan adopted in 2009.
Entity Common Stock, Shares Outstanding (in shares)
Issuance of common stock for restricted stock grants (in shares)
Stock Issued During Period, Shares, Restricted Stock Award, Gross
Issuance of common stock for restricted stock grants
Income Tax Authority [Domain]
State and Local Jurisdiction [Member]
Foreign Tax Authority [Member]
Income Tax Authority [Axis]
us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Change in unrealized (loss) gain resulting from change in fair value of derivative instruments, net of tax
The change during the period in an unrealized gain (loss) on derivatives.
Cash and cash equivalents
Cash and cash equivalents at beginning of year
Cash and cash equivalents at end of year
Trading Symbol
us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Fair value of plan assets at beginning of year
Cash and money market funds
us-gaap_OpenTaxYear
Open Tax Year
us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Defined Contribution Plan, Employer Discretionary Contribution Amount
Earliest Tax Year [Member]
us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
Accounts payable and accrued liabilities
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_IncreaseDecreaseInEmployeeRelatedLiabilities
Accrued compensation and employee benefits
Investment Type [Axis]
Investments [Domain]
us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Debt Instrument, Basis Spread on Variable Rate
us-gaap_InterestIncomeExpenseNet
Interest expense
Common Stock [Member]
Current assets:
Equity Component [Domain]
Equity Components [Axis]
us-gaap_DebtInstrumentInterestRateStatedPercentage
Debt Instrument, Interest Rate, Stated Percentage
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Net increase (decrease) in cash and cash equivalents
Additional Paid-in Capital [Member]
naii_FederalStateAndLocalIncomeTaxExpenseBenefitGrossContinuingOperations
Federal, State and Local Income Tax Expense (Benefit), Gross, Continuing Operations
Amount before valuation allowance of current and deferred federal, state and local income tax expense (benefit) attributable to income (loss) from continuing operations.
Retained Earnings [Member]
Mid-cap and Small-cap Funds [Member]
Represents the mid-cap and small-cap funds.
Treasury Stock [Member]
Long-term Fixed Income Funds [Member]
Represents the long-term fixed income funds.
us-gaap_LesseeLeasingArrangementsOperatingLeasesRenewalTerm
Lessee Leasing Arrangements, Operating Leases, Renewal Term
us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract
Lessee Leasing Arrangements, Operating Leases, Term of Contract
Accounts receivable – less allowance for doubtful accounts of $45 at June 30, 2016 and $20 at June 30, 2015
us-gaap_RatioOfIndebtednessToNetCapital1
Ratio of Indebtedness to Net Capital
Accounts receivable, allowance for doubtful accounts
naii_FederalStateAndLocalIncomeTaxExpenseBenefitContinuingOperations
Federal, State and Local Income Tax Expense Benefit, Continuing Operations
Amount of current and deferred federal, state and local income tax expense (benefit) attributable to income (loss) from continuing operations.
London Interbank Offered Rate (LIBOR) [Member]
naii_HealthInsurancePlanPremiumExpense
Health Insurance Plan Premium Expense
The expense in the period incurred with respect to providing health care benefits to employees.
us-gaap_InventoryRawMaterials
Raw materials
naii_DefinedBenefitPlanEquitySecuritiesByTypePercentage
Defined Benefit Plan Equity Securities by Type, Percentage
Percentage of equity securities by type of publicly traded funds.
Variable Rate [Domain]
Variable Rate [Axis]
Common stock, par value (in dollars per share)
naii_DefinedBenefitPlanDebtSecuritiesByTypePercentage
Defined Benefit Plan Debt Securities by Type, Percentage
Percentage of debt securities by type of publicly traded funds.
Defined Contribution Plans Disclosure [Axis]
naii_ConcentrationOfRiskNumberOfMajorCustomers
Concentration of Risk Number of Major Customers
Concentration Of Risk Number Of Major Customers
naii_NetDeferredIncomeTaxExpenseBenefit
Represents the net amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.
us-gaap_InventoryWorkInProcess
Work in progress
Preferred stock, shares issued (in shares)
us-gaap_InventoryValuationReserves
Reserve
Preferred stock; $.01 par value; 500,000 shares authorized; none issued or outstanding
us-gaap_InventoryFinishedGoods
Finished goods
Preferred stock par value (in dollars per share)
Change in minimum pension liability, net of tax
Disclosure of change in pension plan obligations.
Foreign exchange gain (loss)
Preferred stock, shares authorized (in shares)
Debt Securities [Member]
us-gaap_OperatingIncomeLoss
Income from operations
Income from Operations
us-gaap_GrossProfit
Gross profit
Treasury stock, shares (in shares)
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchase of common stock
Wells Fargo Bank, N.A. [Member]
Represents Wells Fargo Bank, N.A, the lender.
Common stock; $.01 par value; 20,000,000 shares authorized at June 30, 2016 and June 30, 2015, issued and outstanding (net of treasury shares) 6,868,628 at June 30, 2016 and 6,743,093 at June 30, 2015
us-gaap_DebtInstrumentTerm
Debt Instrument, Term
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent [Member]
Common stock, issued (in shares)
Common stock, shares authorized (in shares)
Customer 1, 2 and 3 [Member]
Represents information pertaining to major customer 1, 2, and 3.
Accounting Policies [Abstract]
Subsequent Event Type [Domain]
Cash and Cash Equivalents, Policy [Policy Text Block]
Subsequent Event Type [Axis]
us-gaap_NonoperatingIncomeExpense
Statement [Line Items]
Other, net
Board of Directors and Management Members [Member]
Represents the board of directors and certain key management members.
Subsequent Event [Member]
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Subsequent Events [Text Block]
Trade and Other Accounts Receivable, Policy [Policy Text Block]
Cash flows from operating activities
us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations
Net cash provided by operating activities
us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations
Net cash used in investing activities
Interest income
us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations
Net cash used in financing activities
Title of Individual [Axis]
Relationship to Entity [Domain]
Lender Name [Axis]
Line of Credit Facility, Lender [Domain]
Other noncurrent assets, net
Inventory Disclosure [Text Block]
Schedule of Inventory, Current [Table Text Block]
Schedule of Weighted Average Allocation of Assets Related to Defined Benefit Plans Disclosure [Table Text Block]
Tabular disclosure of the weighted-average asset allocation related to defined benefit plans.
naii_DefinedBenefitPlanExpectedFutureBenefitPayment
Total amount of benefits expected to be paid through the tenth fiscal year following the latest fiscal year from a defined benefit plan.
us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Shares Paid for Tax Withholding for Share Based Compensation
Debt Disclosure [Text Block]
California [Member]
Geographic location.
naii_AccumulatedOtherComprehensiveIncomeLossCumulativeCashFlowHedgesGainLoss
Accumulated Other Comprehensive Income (Loss) Cumulative Cash Flow Hedges, Gain (Loss)
Accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges recorded to Accumulated Other Comprehensive Income Loss.
naii_OperatingLeaseFacilityArea
Operating Lease Facility Area
Area of leased facility in square feet.
naii_AccumulatedOtherComprehensiveIncomeLossCumulativeCashFlowHedgesGainLossTaxEffect
Accumulated Other Comprehensive Income (Loss) Cumulative Cash Flow Hedges Gain (Loss), Tax Effect
The amount of deferred taxes which offsets the net gain related to derivative instruments designated as cash flow hedges.
Taxes
Interest
Adjustments to reconcile net income to net cash provided by operating activities:
Stockholders' Equity Note Disclosure [Text Block]
Equity Award [Domain]
Award Type [Axis]
Depreciation and amortization
us-gaap_Liabilities
Total liabilities
Inventories, net
Cost of goods sold
Change in Plan Assets:
Emerging Market Equity Funds [Member]
Information by emerging market equity funds.
Non-cash compensation
Large-cap Funds [Member]
Information by large-cap funds.
First Contributions [Member]
Contributions on first 3% of participant's compensation that the Company must match.
Next Contributions [Member]
Contributions on next 2% of participant's compensation that the Company must match.
Defined Contribution Plans Disclosure [Domain]
us-gaap_FairValueNetAssetLiability
Fair Value, Net Asset (Liability)
Change in Benefit Obligation:
us-gaap_NoncurrentAssets
Long-lived Assets
International Emerging Markets Funds [Member]
Information by international/emerging markets funds.
Line of Credit [Member]
Long-term pension liability
Intermediate Fixed Income Funds [Member]
Information by intermediate fixed income funds.
Pension expense
REIT and MPL Funds [Member]
Information by REITs and MPLs funds.
International Equity Funds [Member]
Information by international equity funds.
High-yield Fixed Income Funds [Member]
Information by high-yield fixed income funds.
Additional paid-in capital
Total Assets
Income tax receivable
us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Line of Credit Facility, Maximum Borrowing Capacity
Derivative Instrument [Axis]
us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Line of Credit Facility, Remaining Borrowing Capacity
Reconciliation of Assets from Segment to Consolidated [Table Text Block]
Schedule of Segment Reporting Information, by Segment [Table Text Block]
us-gaap_NumberOfReportableSegments
Number of Reportable Segments
Derivative Contract [Domain]
us-gaap_LineOfCreditFacilityCommitmentFeeAmount
Line of Credit Facility, Commitment Fee Amount
us-gaap_AssetsCurrent
Total current assets
Net Sales
Stockholders’ equity:
Deferred income taxes