Document And Entity Information Note To Financial Statement Details Textual statementsignificantaccountingpoliciespolicies statementnoteabasisofpresentationandsummaryofsignificantaccountingpoliciestables London Interbank Offered Rate (LIBOR) [Member] statementnotebinventoriesnettables statementnotecpropertyandequipmentnettables statementnotedaccumulatedothercomprehensivelossincometables statementnotefeconomicdependencytables Variable Rate [Domain] statementnotegsegmentinformationtables Variable Rate [Axis] statementnoteabasisofpresentationandsummaryofsignificantaccountingpoliciescalculationofbasicanddilutednetincomepercommonsharedetails statementnotebinventoriesnetsummaryofinventoriesdetails statementnotecpropertyandequipmentnetsummaryofpropertyandequipmentdetails us-gaap_LongTermDebt Long-term Debt statementnotedaccumulatedothercomprehensivelossincomeothercomprehensivelossincomedetails statementnotefeconomicdependencysubstantialnetsalestocertaincustomersdetails Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] statementnotefeconomicdependencysubstantialnetpurchasefromcertainsupplierdetails statementnotegsegmentinformationoperatingresultsbybusinesssegmentdetails statementnotegsegmentinformationassetsbybusinesssegmentdetails statementnotegsegmentinformationnetsalesbygeographicregiondetails statementnotegsegmentinformationassetsandcapitalexpendituresbygeographicalregiondetails Notes To Financial Statements Notes To Financial Statements [Abstract] 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. 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. us-gaap_PaymentsForRepurchaseOfCommonStock Repurchase of common stock Fair Value, Inputs, Level 2 [Member] Credit Agreement [Member] Name of the debt instrument. Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 3 [Member] naii_RatioOfTotalCurrentAssetsToTotalCurrentLiabilities Ratio of Total Current Assets to Total Current Liabilities Total current assets divided by total current liabilities. us-gaap_LineOfCredit Long-term Line of Credit Fair Value Hierarchy [Domain] Cash flows from investing activities Fair Value, Hierarchy [Axis] Equity Component [Domain] Equity Components [Axis] Customer 1 [Member] Customer 1 in a set of customers. Prepaid Expenses and Other Current Assets [Member] Customer 2 [Member] Customer 2 in a set of customers. Customer 3 [Member] Customer 3 in a set of customers. Raw Material Purchases [Member] Aggregate raw material purchases during the period from major suppliers. us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months us-gaap_ComprehensiveIncomeNetOfTax Comprehensive income us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities Accounts payable and accrued liabilities us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities Accrued compensation and employee benefits us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity Line of Credit Facility, Remaining Borrowing Capacity us-gaap_TreasuryStockSharesAcquired Treasury Stock, Shares, Acquired Preferred stock, shares outstanding (in shares) Cash Flow Hedging Foreign Exchange Contract [Member] A foreign currency derivative designated as cash flow hedging instruments. Common stock, outstanding (in shares) us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Treasury Stock [Text Block] Diluted (in shares) Diluted weighted average common shares outstanding (in shares) us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Private Label Contract Manufacturing [Member] Business segment related to private label contract manufacturing. Patent and Trademark Licensing [Member] Business segment related to patentand trademark licensing. Legal Matters and Contingencies [Text Block] us-gaap_CashFlowHedgeDerivativeInstrumentAssetsAtFairValue Cash Flow Hedge Derivative Instrument Assets at Fair Value Vehicles [Member] Line of Credit Facility, Lender [Domain] Diluted (in dollars per share) Diluted net income per common share (in dollars per share) Lender Name [Axis] Net Sales by Customer Net sales Revenue, Net Supplier 1 [Member] Supplier 1 in a set of suppliers. Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Raw Material Purchases by Supplier Raw material purchases by supplier % of Total Raw Material Purchases Percentage of raw materials purchased from supplier 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. Office Equipment [Member] Machinery and Equipment [Member] Basic (in shares) Basic weighted average common shares outstanding (in shares) Balance Sheet Location [Domain] Basic (in dollars per share) Basic net income per common share (in dollars per share) Balance Sheet Location [Axis] Scenario, Unspecified [Domain] Long-lived Assets by Geographic Areas [Table Text Block] Wells Fargo Bank, N.A. [Member] Represents Wells Fargo Bank, N.A, the lender. Revenue from External Customers by Geographic Areas [Table Text Block] Scenario [Axis] Internal Revenue Service (IRS) [Member] Income Tax Authority, Name [Domain] Debt Disclosure [Text Block] naii_StockRepurchaseProgramIncreaseInAuthorizedAmount Stock Repurchase Program, Increase in Authorized Amount Amount of increase in the stock repurchase plan authorized. Domestic Tax Authority [Member] Supplier 3 [Member] Represents third supplier. Income Tax Authority, Name [Axis] State and Local Jurisdiction [Member] Income Tax Authority [Domain] Income Tax Authority [Axis] Corporate, Non-Segment [Member] us-gaap_ConcentrationRiskPercentage1 Concentration Risk, Percentage us-gaap_IncreaseDecreaseInIncomeTaxes Income taxes Consolidation Items [Domain] us-gaap_TreasuryStockValueAcquiredCostMethod Treasury Stock, Value, Acquired, Cost Method Supplier Concentration Risk [Member] Consolidation Items [Axis] Product Concentration Risk [Member] us-gaap_ProceedsFromLongTermLinesOfCredit Proceeds from Long-term Lines of Credit Operating Segments [Member] Maximum [Member] Customer Concentration Risk [Member] Range [Domain] us-gaap_OpenTaxYear Open Tax Year Other income (expense): Minimum [Member] us-gaap_TreasuryStockValue Treasury stock, at cost, 1,043,325 shares at March 31, 2017 and 958,049 at June 30, 2016 us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease Unrecognized Tax Benefits, Period Increase (Decrease) Customer [Axis] Concentration Risk Type [Domain] Range [Axis] Accounting Policies [Abstract] Customer [Domain] Statement of Financial Position [Abstract] Relationship to Entity [Domain] Concentration Risk Type [Axis] Title of Individual [Axis] us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaids and other assets us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation Shares Paid for Tax Withholding for Share Based Compensation Sales Revenue, Net [Member] Statement of Cash Flows [Abstract] Sales Revenue, Goods, Net [Member] Earliest Tax Year [Member] us-gaap_AllocatedShareBasedCompensationExpense Allocated Share-based Compensation Expense Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Products and Services [Domain] Products and Services [Axis] Tax Period [Domain] Tax Period [Axis] Non-US [Member] us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net us-gaap_IncreaseDecreaseInAccountsReceivable Accounts receivable invest_DerivativeNotionalAmount Derivative, Notional Amount Europe [Member] Geographical [Domain] Geographical [Axis] Other noncurrent liabilities, net us-gaap_NoncurrentAssets Long-Lived Assets us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments Income before income taxes us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders’ equity us-gaap_EffectiveIncomeTaxRateContinuingOperations Effective Income Tax Rate Reconciliation, Percent Provision for income taxes Retained earnings Accumulated other comprehensive loss Segments [Axis] Segments [Domain] us-gaap_PolicyTextBlockAbstract Accounting Policies Reconciliation of Assets from Segment to Consolidated [Table Text Block] us-gaap_IncreaseDecreaseInInventories Inventories, net us-gaap_DeferredTaxAssetsNetNoncurrent Deferred income taxes Deferred rent Statement [Table] Foreign exchange (loss) gain Income Statement [Abstract] Schedule of Segment Reporting Information, by Segment [Table Text Block] Cash flows from financing activities us-gaap_NumberOfReportableSegments Number of Reportable Segments Class of Stock [Axis] Award Type [Axis] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Equity Award [Domain] us-gaap_InterestIncomeExpenseNet Interest expense Supplier 2 [Member] Supplier 2 in a set of suppliers. us-gaap_DerivativeInstrumentsGainReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion Segment Reporting Disclosure [Text Block] us-gaap_DerivativeInstrumentsGainRecognizedInOtherComprehensiveIncomeEffectivePortion Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion Fair Value Measurement, Policy [Policy Text Block] Hedging Relationship [Domain] Derivative Instruments and Hedging Activities Disclosure [Text Block] Hedging Relationship [Axis] us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Cash Flow Hedging [Member] Prepaids and other current assets us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Share-based Goods and Nonemployee Services Transaction, Supplier [Domain] us-gaap_LiabilitiesCurrent Total current liabilities Supplier [Axis] Earnings Per Share, Policy [Policy Text Block] Other, net Other Nonoperating Income (Expense) Changes in operating assets and liabilities: Property, Plant and Equipment [Table Text Block] Interest income Property, Plant and Equipment Disclosure [Text Block] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Income from Operations Income from operations Schedule of Inventory, Current [Table Text Block] Inventory Disclosure [Text Block] us-gaap_FairValueNetAssetLiability Fair Value, Net Asset (Liability) Deferred taxes us-gaap_GrossProfit Gross profit Treasury stock, shares (in shares) Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Derivative Contract [Domain] Derivative Instrument [Axis] Amendment Flag us-gaap_RoyaltyExpense Royalty Expense Common stock; $.01 par value; 20,000,000 shares authorized; issued and outstanding (net of treasury shares) 6,933,352 at March 31, 2017 and 6,868,628 at June 30, 2016 Common stock, shares authorized (in shares) Common stock, issued (in shares) Other noncurrent assets, net Common stock, par value (in dollars per share) Income Tax Disclosure [Text Block] Non-cash compensation us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Current Fiscal Year End Date Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date Pension expense Preferred stock; $.01 par value; 500,000 shares authorized; none issued or outstanding Preferred stock, shares issued (in shares) Document Type Income taxes payable us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent Net current period OCI/OCL Depreciation and amortization us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1 Tax effect of OCI activity Preferred stock, shares authorized (in shares) Accounts payable Document Information [Line Items] Document Information [Table] Preferred stock par value (in dollars per share) Accrued compensation and employee benefits us-gaap_AssetsCurrent Total current assets Accrued liabilities Entity Filer Category Entity Current Reporting Status Entity Voluntary Filers Entity Well-known Seasoned Issuer us-gaap_TreasuryStockAcquiredAverageCostPerShare Treasury Stock Acquired, Average Cost Per Share Income tax receivable us-gaap_StockRepurchaseProgramAuthorizedAmount1 Stock Repurchase Program, Authorized Amount Adjustments to reconcile net income to net cash provided by operating activities: Dilutive effect of stock options (in shares) Entity Central Index Key us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures Entity Registrant Name Entity [Domain] Weighted average common shares outstanding: Legal Entity [Axis] Denominator Current liabilities: Entity Common Stock, Shares Outstanding (in shares) us-gaap_ForeignCurrencyContractAssetFairValueDisclosure Foreign Currency Contract, Asset, Fair Value Disclosure Proceeds from sale of property and equipment Taxes Interest Additional paid-in capital Assets Total assets Reclassification out of Accumulated Other Comprehensive Income [Axis] Inventories, net Inventories, net Stockholders’ equity: Revenue Recognition, Policy [Policy Text Block] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Domain] Work in progress Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Trading Symbol us-gaap_InventoryValuationReserves Reserves Comprehensive Income (Loss) Note [Text Block] Finished goods OCI/OCL before reclassifications us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchases of property and equipment Capital Expenditures us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period us-gaap_GainLossOnDispositionOfAssets Gain on disposal of assets us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent Amounts reclassified from OCI Net income Net income us-gaap_StockholdersEquity Total stockholders’ equity Beginning balance Ending balance Plan Name [Axis] Numerator Selling, general and administrative expenses Plan Name [Domain] Raw materials Commitments and contingencies us-gaap_Liabilities Total liabilities Cost of goods sold Unrealized (loss) gain resulting from change in fair value of derivative instruments, net of tax Restricted Stock [Member] Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Concentration Risk Disclosure [Text Block] Board of Directors and Management Members [Member] Represents the board of directors and certain key management members. Employee Stock Option [Member] Cash flows from operating activities Change in unrealized gain (loss) resulting from change in fair value of derivative instruments, net of tax The change during the period in an unrealized gain (loss) on derivatives. Accounts receivable, allowance for doubtful accounts Accounts receivable - less allowance for doubtful accounts of $21 at March 31, 2017 and $45 at June 30, 2016 Statement [Line Items] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Disclosure of non-cash activities: Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] AOCI Attributable to Parent [Member] UNITED STATES Depreciable Life In Years (Year) Property and equipment, net Property and equipment, net Current assets: Supplemental disclosures of cash flow information us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Less: accumulated depreciation and amortization Property and equipment, gross Foreign Exchange Forward [Member] Debt Instrument [Axis] Debt Instrument, Name [Domain] naii_RoyaltyAndLicensingRevenue Royalty and Licensing Revenue Royalty and licensing revenue us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Building and Building Improvements [Member] 2009 Omnibus Stock Incentive Plan [Member] Omnibus stock incentive plan adopted in 2009. Leasehold Improvements [Member] us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease Net increase (decrease) in cash and cash equivalents us-gaap_TableTextBlock Notes Tables Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Axis] Land [Member] us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations Net cash used in financing activities us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations Net cash used in investing activities us-gaap_RatioOfIndebtednessToNetCapital1 Ratio of Indebtedness to Net Capital us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations Net cash provided by operating activities Net income per common share: