Employee Stock Option [Member] Document And Entity Information us-gaap_EquityMethodInvestmentSummarizedFinancialInformationGrossProfitLoss Gross profit Note To Financial Statement Details Textual statementnote3inventoriestables us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss Net income statementnote4propertyandequipmentnettables Antidilutive Securities [Axis] statementnote5patentsandtrademarksnettables statementnote6investmentsinjointventurestables statementnote9stockholdersequitytables Antidilutive Securities, Name [Domain] statementnote10netincomepercommonsharetables Amendment Flag statementnote11stockbasedcompensationtables us-gaap_AccruedBonusesCurrentAndNoncurrent Accrued Bonuses statementnote12geographicandsegmentinformationtables us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable Income tax payable Vesting [Domain] statementnote14fairvaluemeasurementstables us-gaap_ProceedsFromStockPlans Proceeds from employee stock purchase plan Vesting [Axis] Income Statement Location [Domain] statementnote3inventoriesdetails us-gaap_PaymentsForRepurchaseOfCommonStock Repurchase of common stock Plan Name [Domain] Income Statement Location [Axis] statementnote4componentsofpropertyandequipmentnetdetails Plan Name [Axis] statementnote5patentsandtrademarksnetdetails statementnote6condensedbalancesheetofexcorandallotherjointventuresdetails Minimum [Member] statementnote6condensedincomestatementofexcortianjinzerustandallotherjointventuresdetails Maximum [Member] statementnote10reconciliationoftheearningspersharecomputationsdetails Range [Axis] Range [Domain] statementnote9exercisedstockoptionsdetails statementnote12netsalesbysegmentdetails Document Fiscal Year Focus us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period statementnote11blackscholesoptionpricingmodelassumptionsdetails us-gaap_NetIncomeLoss NET (LOSS) INCOME ATTRIBUTABLE TO NTIC Net (loss) income attributable to NTIC Document Fiscal Period Focus statementnote12netsalesbygeographiclocationdetails Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] statementnote12costofgoodssoldbysegmentdetails us-gaap_ProceedsFromStockOptionsExercised Proceeds from exercise of stock options Available for sale securities statementnote12totallonglivedassetsbygeographicdistributiondetails statementnote12feesforservicesprovidedtojointventuresbygeographiclocationasapercentageoftotalfeesforservicesprovidedtojointventuresdetails Document Period End Date statementnote14assetsandliabilitiesmeasuredatfairvaluerecurringbasisdetails ntic_IncreaseDecreaseInTradeReceivablesJointVentures Trade, joint ventures The net change during the reporting period in amount due within one year (or one business cycle) from joint ventures for the credit sale of goods and services that have been delivered or sold to joint ventures in the normal course of business. statementnote12totalnetsalesbygeographicdistributiondetails us-gaap_ProfessionalFees Professional Fees Fair Value Disclosures [Text Block] Notes To Financial Statements [Abstract] ntic_IncreaseDecreaseInFeesReceivableForServicesProvidedToJointVentures Fees for services provided to joint ventures The net change during the reporting period in amount due within one year (or one business cycle) from joint ventures for royalties and service fees outside of the normal course of business. Current Fiscal Year End Date Notes To Financial Statements us-gaap_IncreaseDecreaseInAccruedLiabilities Accrued liabilities Products and Services [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized ntic_IncreaseDecreaseInTradeReceivablesExcludingJointVentures Trade, excluding joint ventures The net change during the reporting period in amount due within one year (or one business cycle) from customers or clients, but not joint ventures, for the credit sale of goods and services. Products and Services [Axis] us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Award Type [Axis] Entity Current Reporting Status Entity Voluntary Filers Entity Filer Category All Countries [Domain] Document Type Investment, Name [Axis] Statement of Comprehensive Income [Abstract] Investment, Name [Domain] Equity Award [Domain] us-gaap_AvailableForSaleSecurities Available for sale securities Cost of goods sold Cost of goods sold us-gaap_CostMethodInvestmentsAggregateCarryingAmountNotEvaluatedForImpairment Cost-method Investments, Aggregate Carrying Amount, Not Evaluated for Impairment ntic_NumberOfStockBasedCompensationPlans Number of Stock-based Compensation Plans The number of stock-based compensation plans administered by the Compensation Committee of the Board of Directors and the Board of Directors, during the period. Disclosure of Compensation Related Costs, Share-based Payments [Text Block] CASH FLOWS FROM INVESTING ACTIVITIES: Entity Well-known Seasoned Issuer BRAZIL us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice Exercise Price (in dollars per share) us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements Weighted shares assumed upon exercise of stock options (in shares) OTHER ASSETS: Segments [Domain] Segments [Axis] Trade allowance ntic_FeesReceivableForServicesProvidedToJointVenturesCurrent Fees for services provided to joint ventures Amounts due for royalties and service fees outside of the normal course of business from entities in which the reporting entity shares joint control with another party or group, due within 1 year (or 1 business cycle). Net sales, excluding joint ventures Net sales either directly to end users or to distributors worldwide, but not sales to the reporting entity's joint ventures and not sales by the reporting entity's joint ventures. Statement [Table] us-gaap_LineOfCredit Long-term Line of Credit us-gaap_CashAndCashEquivalentsAtCarryingValue CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD CASH AND CASH EQUIVALENTS AT END OF PERIOD Net sales, to joint ventures Net sales by the reporting entity to the reporting entity's joint ventures, but not sales by the reporting entity either directly to end users or to distributors or sales by the reporting entity’s joint ventures. Tianjin Zerust [Member] Represents the Tianjin Zerust. ntic_FeesForServicesProvidedToJointVentures Fees for services provided to joint ventures Royalties and service fees from transactions directly with the reporting entity's joint ventures outside the normal course of business. us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Research and development expenses us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term CURRENT ASSETS: us-gaap_ImpairmentOfInvestments Other than Temporary Impairment Losses, Investments us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents EFFECT OF EXCHANGE RATE CHANGES ON CASH: us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease NET INCREASE IN CASH AND CASH EQUIVALENTS JOINT VENTURE OPERATIONS: Joint venture operations WEIGHTED AVERAGE COMMON SHARES ASSUMED OUTSTANDING: Weighted average number of shares outstanding, basic and diluted[abstract] us-gaap_InterestExpense INTEREST EXPENSE Income Statement [Abstract] us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations Net cash used in financing activities us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations Net cash provided by investing activities Selling expenses us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations Net cash used in operating activities Geographical [Axis] Credit Facility [Domain] Credit Facility [Axis] Investments at carrying value (Note 6) Cost Method Investments us-gaap_EquityMethodInvestments Investments in joint ventures Revolving Credit Facility [Member] Deferred income taxes us-gaap_GainLossOnDispositionOfAssets1 Loss on disposal of assets us-gaap_DeferredTaxAssetsNetNoncurrent Deferred income taxes us-gaap_PaymentsOfDividendsMinorityInterest Dividend received by non-controlling interest us-gaap_StockholdersEquity Stockholders’ equity us-gaap_TableTextBlock Notes Tables Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate Average risk-free interest rate Preferred stock, shares issued (in shares) Preferred stock, shares authorized (in shares) Preferred stock, par value (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate Expected volatility us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings Term Loan and Line of Credit, Agreements, Loan Agreements [Member] Term loan and line of credit, agreements, loan agreements [member] us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1 Expected life of option (years) Other comprehensive (LOSS) income – foreign currency translation adjustment us-gaap_TreasuryStockAcquiredAverageCostPerShare Treasury Stock Acquired, Average Cost Per Share us-gaap_InventoryNet Inventories Preferred stock, shares outstanding (in shares) Common stock, shares outstanding (in shares) Prepaid expenses OPERATING EXPENSES: Executive Officer [Member] Stockholders' Equity Note Disclosure [Text Block] Relationship to Entity [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate Dividend yield Title of Individual [Axis] Description of New Accounting Pronouncements Not yet Adopted [Text Block] us-gaap_OtherAccruedLiabilitiesCurrent Other Inventories Non-controlling interest The 2007 Plan [Member] Represents Northern Technologies International Corporation Amended and Restated 2007 Stock Incentive Plan. Accrued liabilities: Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] us-gaap_ComprehensiveIncomeNetOfTax COMPREHENSIVE (LOSS) INCOME ATTRIBUTABLE TO NTIC One Year after Date of Grant [Member] The vesting term that options become exercisable. us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest Total equity us-gaap_PaymentsToAcquireIntangibleAssets Additions to patents us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Additions to property and equipment PNC Bank [Member] Represents PNC bank. us-gaap_Assets Total assets Additional paid-in capital Termination of Joint Venture and Formation of NTIC China [Member] The direct expenses associated with the termination of the joint venture in China and the formation of the wholly owned subsidiary NTIC China. Such expenses include, but not limited to: legal expenses, formation expenses, and hiring expenses. ESPP [Member] Represents Northern Technologies International Corporation Employee Stock Purchase Plan (the ESPP). Reconciliation of Revenue from Segments to Consolidated [Table Text Block] CURRENT LIABILITIES: Fair Value, Measurement Inputs, Disclosure [Text Block] Patents and Trademarks [Member] Represents patents and trademarks. Entity Registrant Name PROPERTY AND EQUIPMENT, NET Net Total long-lived assets Entity Central Index Key us-gaap_NumberOfReportableSegments Number of Reportable Segments Commitments and Contingencies Disclosure [Text Block] us-gaap_PropertyPlantAndEquipmentGross Gross us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Less accumulated depreciation us-gaap_SalesRevenueNet Total net sales Net sales by segment Other Entity Common Stock, Shares Outstanding (in shares) All Other [Member] Represents all other joint ventures. COMMITMENTS AND CONTINGENCIES (Note 18) us-gaap_Land Land us-gaap_MachineryAndEquipmentGross Machinery and equipment us-gaap_BuildingsAndImprovementsGross Buildings and improvements Earnings Per Share [Text Block] NET (LOSS) INCOME ATTRIBUTABLE TO NTIC PER COMMON SHARE: Segment Reporting Disclosure [Text Block] EXCOR [Member] Represents EXCOR. us-gaap_IncomeLossIncludingPortionAttributableToNoncontrollingInterest (LOSS) INCOME BEFORE INCOME TAX EXPENSE Trading Symbol Scenario [Axis] Scenario, Unspecified [Domain] Cash and cash equivalents Scenario, Forecast [Member] Patents and trademarks, net Patents and trademarkes, net us-gaap_FiniteLivedIntangibleAssetsGross Patents and trademarks us-gaap_AssetsCurrent Total current assets us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization Less accumulated amortization us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities Proceeds from the sale of available for sale securities ntic_DebtInstrumentCovenantsFixedChargeCoverageRatio Debt Instrument, Covenants, Fixed Charge Coverage Ratio Represents the fixed charge coverage ratio for the debt instrument under the covenant terms. Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block] us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Debt Instrument, Name [Domain] Debt Instrument [Axis] Income taxes Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block] UNITED STATES us-gaap_LiabilitiesCurrent Total current liabilities us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Property, Plant and Equipment [Table Text Block] Adjustments to reconcile net (loss) income to net cash used in operating activities: ntic_EntityWideFeesForServicesProvidedToJointVenturesGeographicPercentage Percentage of total fees Percentage of entity wide fees for services provided to joint ventures generated from geographic location. THAILAND us-gaap_PaymentsToAcquireInterestInJointVenture Payments to Acquire Interest in Joint Venture NET INCOME ATTRIBUTABLE TO NON-CONTROLLING INTERESTS Fair Value, Inputs, Level 1 [Member] us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and equity Fair Value Hierarchy [Domain] us-gaap_Depreciation Depreciation expense ntic_TotalFeesForServicesProvidedToJointVenturesGeographicLocation Fees Total fees for services provided to joint ventures by geographic locations. Accumulated other comprehensive loss Fair Value, Hierarchy [Axis] Retained earnings Revenue from External Customers by Geographic Areas [Table Text Block] Fees for Services Provided to Joint Ventures [Member] Represents fees for services provided to joint ventures. COMPREHENSIVE INCOME ATTRIBUTABLE TO NON-CONTROLLING INTERESTS Joint Ventures in Which the Company is a Shareholder Directly and Indirectly Outside the USA [Member] Joint ventures in which the company is a shareholder directly and indirectly outside the USA [member] Other Countries [Member] Other countries [member] Unaffiliated Customers Outside the USA [Member] Unaffiliated customers outside the USA [member] Inside the USA to Unaffiliated Customers [Member] Inside the USA to Unaffiliated Customers. us-gaap_AdjustmentForAmortization Amortization expense ntic_EstimatedForfeitureRateForStockOptions Estimated Forfeiture Rate for Stock Options Estimated forfeiture rate used for stock options. Statement of Financial Position [Abstract] ntic_AllocatedShareBasedCompensationExpenseEstimateFiscalYearTwo Allocated Share-based Compensation Expense, Estimate, Fiscal Year Two Estimated expense to be recognized for the second fiscal year following the most recent fiscal year arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. ntic_AllocatedShareBasedCompensationExpenseEstimateNextFiscalYear Allocated Share-based Compensation Expense, Estimate, Next Fiscal Year Estimated expense to be recognized for the next fiscal year following the most recent fiscal year arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. us-gaap_ShareBasedCompensation Stock-based compensation ntic_AllocatedShareBasedCompensationExpenseEstimateRemainderOfFiscalYear Allocated Share-based Compensation Expense, Estimate Remainder of Fiscal Year Estimated expense to be recognized for the remainder of the fiscal year arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. us-gaap_StockOptionPlanExpense Stock or Unit Option Plan Expense Net of Estimated Forfeitures [Member] Represents amount net of estimated forfeitures. us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Condensed Income Statement [Table Text Block] Condensed Balance Sheet [Table Text Block] Statement of Cash Flows [Abstract] NET (LOSS) INCOME NET (LOSS) INCOME Net (loss) income us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest COMPREHENSIVE (LOSS) INCOME us-gaap_ProceedsFromDividendsReceived Dividends received from joint ventures CASH FLOWS FROM OPERATING ACTIVITIES: CASH FLOWS FROM FINANCING ACTIVITIES: POLAND ntic_PercentageOfIndividualBonusPayoutDeterminedByActualVersusTargetedEBITOIResults Percentage of Individual Bonus Payout Determined by Actual Versus Targeted EBITOI Results Percentage of individual's bonus payout determined based upon the Company's actual EBITOI for the fiscal year compared to pre-established target EBITOI for the fiscal year. ntic_PercentageOfIndividualsPayoutDeterminedUponAchievementOfCertainPreEstablishedIndividualPerformanceObjectives Percentage of Individuals Payout Determined Upon Achievement of Certain Pre-Established Individual Performance Objectives Percentage of individual's payout determined based upon achievement of certain pre-established individual performance objectives. Reconciliation of Cost of Goods Sold from Segments to Consolidated [Table Text Block] Tabular disclosure of all significant reconciling items in the reconciliation of total cost of goods sold from reportable segments to the entity's consolidated revenues. Cost of Goods Sold Type [Axis] Cost of goods sold type [axis] Direct Cost of Goods Sold [Member] Direct cost of goods sold [member] Cost of Goods Sold Type [Domain] ntic_CostOfGoodsSoldAsPercentageOfProductSales Percentage of product sales Represents cost of goods sold as percentage of product sales. us-gaap_StockRepurchasedAndRetiredDuringPeriodShares Stock Repurchased and Retired During Period, Shares Indirect Cost of Goods Sold [Member] Indirect cost of goods sold [member] NaturTec [Member] Represents NaturTec segment. Diluted (in dollars per share) Diluted (loss) earnings per share: (in dollars per share) ZERUST [Member] Represents ZERUST. us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Diluted (in shares) Diluted – weighted shares outstanding (in shares) us-gaap_AssetsNoncurrent Total other assets us-gaap_IncreaseDecreaseInInventories Inventories Equity in income of joint ventures Northern Technologies International Corporation’s share of equity in income of joint ventures Equity in income from joint ventures Payroll and related benefits INCOME TAX (BENEFIT) EXPENSE Accounts payable Basic (in shares) Basic – weighted shares outstanding (in shares) us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Basic (in dollars per share) Basic (loss) earnings per share: (in dollars per share) SWEDEN Receivables: Common stock, $0.02 par value per share; authorized 10,000,000 shares; issued and outstanding 4,538,317 and 4,539,045, respectively Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Class of Stock [Axis] us-gaap_IncreaseDecreaseInIncomeTaxesReceivable Income taxes Common stock, shares issued (in shares) Accounting Policies [Abstract] Common stock, shares authorized (in shares) JAPAN us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Common stock par value (in dollars per share) us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive Finite-Lived Intangible Assets, Amortization Expense, Year Five NET SALES: INDIA Schedule of Inventory, Current [Table Text Block] Preferred stock, no par value; authorized 10,000 shares; none issued and outstanding Inventory Disclosure [Text Block] London Interbank Offered Rate (LIBOR) [Member] us-gaap_InventoryFinishedGoodsNetOfReserves Finished goods Trade joint ventures Amounts due from joint ventures, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold to joint ventures in the normal course of business. Trade excluding joint ventures, less allowance for doubtful accounts of $40,000 at November 30, 2015 and August 31, 2015 Amount due from customers or clients, but not joint ventures, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection. Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Variable Rate [Domain] Variable Rate [Axis] ntic_OtherThanTemporaryImpairmentLossesPercentageOfInvestment Other than Temporary Impairment Losses, Percentage of Investment Percentage of investment amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date. us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaid expenses and other us-gaap_OperatingExpenses Total operating expenses General and administrative expenses Statement [Line Items] KOREA, REPUBLIC OF us-gaap_InventoryRawMaterialsNetOfReserves Production materials us-gaap_EquityMethodInvestmentSummarizedFinancialInformationEquity Joint ventures’ equity GERMANY us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue Net sales us-gaap_GrossProfit Gross profit us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAssets Total assets us-gaap_EquityMethodInvestmentSummarizedFinancialInformationCurrentLiabilities Current liabilities Expenses incurred in support of joint ventures us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNoncurrentLiabilities Noncurrent liabilities EQUITY: Debt Disclosure [Text Block] Interim Period, Costs Not Allocable [Domain] CHINA us-gaap_EquityMethodInvestmentSummarizedFinancialInformationCurrentAssets Current assets Nature of Expense [Axis] Intangible Assets Disclosure [Text Block] us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets Northern Technologies International Corporation’s share of joint ventures’ equity us-gaap_FiniteLivedIntangibleAssetUsefulLife Finite-Lived Intangible Asset, Useful Life us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Equity Component [Domain] Equity Components [Axis] Schedule of Finite-Lived Intangible Assets [Table Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] UNITED KINGDOM us-gaap_PolicyTextBlockAbstract Accounting Policies us-gaap_OtherOperatingIncome Total joint venture operations OPERATING (LOSS) INCOME us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo Finite-Lived Intangible Assets, Amortization Expense, Year Two us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree Finite-Lived Intangible Assets, Amortization Expense, Year Three FRANCE us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour Finite-Lived Intangible Assets, Amortization Expense, Year Four us-gaap_IncreaseDecreaseInAccountsPayable Accounts payable INTEREST INCOME Finite-Lived Intangible Assets by Major Class [Axis] FINLAND Finite-Lived Intangible Assets, Major Class Name [Domain] Property, Plant and Equipment Disclosure [Text Block] Fiscal 2016 Bonus Plan [Member] The Fiscal 2016 Bonus Plan. Line of Credit Facility, Lender [Domain] ntic_NumberOfJointVenturesAccountedForCertainPercentageOfCompanysTradeJointVentureReceivables Number of Joint Ventures Accounted For Certain Percentage of Company's Trade Joint Venture Receivables Number of Joint Ventures Accounted for a Certain Percentage of Company’s Trade Joint Venture Receivables. ntic_EntityWideTradeJointVentureReceivablesFourJointVenturespercentage Entity Wide Trade Joint Venture Receivables, Four Joint Ventures,Percentage Percentage of total trade joint venture receivables accounted for by four joint ventures. Lender Name [Axis]