Document And Entity Information
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount
Statistical Measurement [Axis]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount
Note To Financial Statement Details Textual
us-gaap_IncomeTaxExpenseBenefit
Income taxes
Income taxes
Significant Accounting Policies
ecd_NonRule10b51ArrTrmntdFlag
Non-Rule 10b5-1 Arrangement Terminated [Flag]
Note 5 - Restructuring and Business Combinations
ecd_NonRule10b51ArrAdoptedFlag
Non-Rule 10b5-1 Arrangement Adopted [Flag]
Note 6 - Fair Value Measurements
Federal Funds Rate [Member]
Information pertaining to the federal funds rate.
Trading Arrangements, by Individual [Table]
Note 7 - Intangible Assets
Material Terms of Trading Arrangement [Text Block]
Note 8 - Long-term Debt
Retirement Savings Plan, First 1% of Employee Contribution [Member]
Represents the Retirement Savings Plan and the first 1% of eligible compensation contributed by employees.
Insider Trading Policies and Procedures Adopted [Flag]
Insider Trading Policies and Procedures Adopted [Flag]
Note 9 - Stock-based Compensation
Note 10 - Income Taxes
Note 11 - Employee Benefit Plans
Note 13 - Leases
Minimum [Member]
Note 14 - Earnings Per Share
Note 15 - Business Segment Information
Statistical Measurement [Domain]
Retirement Savings Plan, Next 5% of Employee Contribution [Member]
Represents the Retirement Savings Plan and the next 5% of eligible compensation contributed by employees.
Insider Trading Policies and Procedures [Line Items]
Note 16 - Other Financial Data
Maximum [Member]
Note 5 - Restructuring and Business Combinations - Restructuring Activity Related to Business Combinations (Details)
Note 5 - Restructuring and Business Combinations - Assets Acquired and Liabilities Assumed (Details)
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable, net
Retirement Plan Type [Domain]
iiin_DefinedBenefitPlanReductionForEachMonth
Defined Benefit Plan, Reduction for Each Month
The benefit will be reduced by a certain percentage for each month short of 30 years that the Participant was employed by the Company assuming the minimum continuous service and age requirements.
Note 5 - Restructuring and Business Combinations - Pro Forma Information (Details)
Accounts payable and accrued expenses
Note 6 - Fair Value Measurements - Fair Value of Financial Assets (Details)
Note 7 - Intangible Assets - Summary of Intangible Assets (Details)
Retirement Plan Type [Axis]
Note 8 - Long-term Debt - Schedule of Amortization of Financing Costs (Details)
Note 9 - Stock-based Compensation - Stock Option Valuation Assumptions (Details)
Note 9 - Stock-based Compensation - Stock Option Activity (Details)
Note 9 - Stock-based Compensation - RSU Grants and Compensation Expense (Details)
Note 9 - Stock-based Compensation - Restricted Stock Units Activity (Details)
Note 10 - Income Taxes - Components of Provision for Income Taxes (Details)
Business Description and Basis of Presentation [Text Block]
Note 10 - Income Taxes - Income Tax Reconciliation (Details)
us-gaap_InterestCostsCapitalized
Interest Costs Capitalized
iiin_LineOfCreditFacilityAdditionalBorrowingCapacity
Line Of Credit Facility, Additional Borrowing Capacity
Represents additional borrowing capacity of line of credit.
us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
Defined Benefit Plan, Accumulated Benefit Obligation
Note 10 - Income Taxes - Summary of Income Taxes Paid (Details)
Note 10 - Income Taxes - Deferred Tax Asset and Liability Components (Details)
Note 11 - Employee Benefit Plans - Projected Benefit Obligation Reconciliation for SERP (Details)
Note 11 - Employee Benefit Plans - Net Periodic Pension Costs and Related Components (Details)
Note 11 - Employee Benefit Plans - Plan Valuation Assumptions (Details)
Note 11 - Employee Benefit Plans - Projected Benefit Payments (Details)
Note 13 - Leases - Supplement Cash Flow and Non-cash Information, Weighted Average Remaining Lease Term and Discount Rate Related to Lease (Details)
Effective income tax rate
Provision for income taxes, percent
Note 13 - Leases - Supplemental Balance Sheet Information Related to Leases (Details)
Note 13 - Leases - Aggregate Future Operating Lease Payments (Details)
Forfeited (in dollars per share)
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Provision for income taxes at federal statutory rate, percent
Note 14 - Earnings Per Share - Basic and Diluted Earnings Per Share Attributable to Common Shareholders (Details)
Note 15 - Business Segment Information - Net Sales By Geographic Region (Details)
Granted, weighted average exercise price (in dollars per share)
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Note 15 - Business Segment Information - Net Sales By Product Line (Details)
Exercised, weighted average exercise price per share (in dollars per share)
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Note 16 - Other Financial Data - Balance Sheet Information (Details)
Notes To Financial Statements
us-gaap_DefinedBenefitPlanContributionsByEmployer
Actual employer contributions
Notes To Financial Statements [Abstract]
us-gaap_DividendsCommonStockCash
Cash dividends declared
Income Tax Jurisdiction [Domain]
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate
Land Improvements [Member]
Interest cost
Interest cost
Net amount recognized
us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Funded status
Other, percent
us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Plan assets at fair value at end of year
us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount
Cash dividends declared (in dollars per share)
us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
State income taxes, net of federal tax benefit, percent
us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Net periodic pension cost
us-gaap_IncreaseDecreaseInInventories
Inventories
Other adjustments, percent
us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
Unrecognized net (gain) loss
us-gaap_SharesOutstanding
Balance (in shares)
Balance (in shares)
us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits
Tax credits, percent
Service cost
Service cost
us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
Rate of increase in compensation levels
Facility Closing [Member]
Employee Severance [Member]
Segment Reporting [Text Block]
Type of Restructuring [Domain]
us-gaap_DefinedBenefitPlanBenefitObligation
Benefit obligation at beginning of year
Benefit obligation at end of year
Adjustments to reconcile net earnings to net cash provided by operating activities:
Award Type [Axis]
Preferred stock, no par value Authorized shares: 1,000 None Issued
Plan Name [Axis]
Restructuring Cost [Table]
Plan Name [Domain]
Defined Benefit Plan [Table]
Restructuring and Related Costs [Table Text Block]
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and shareholders' equity
Compensation expense
Share-Based Payment Arrangement, Expense
iiin_BusinessCombinationHoldbackAdjustment
Business Combination, Holdback Adjustment
Adjustments made to the holdback payment after the acquisition date.
Title and Position [Axis]
us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities
Total adjustments
Segment Reporting [Table]
Condensed Balance Sheet Statement [Table]
Selling, general and administrative expense
Stock-based compensation expense
Liabilities and shareholders' equity
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized
Share-Based Payment Arrangement [Text Block]
Non-cancelable Purchase Commitment for Raw Material [Member]
Represents the non-cancelable purchase commitment for raw material.
Purchase Commitment for Equipment [Member]
Represents the purchase commitment for equipment.
us-gaap_PreferredStockSharesIssued
Preferred Stock, Shares Issued (in shares)
Finite-lived intangible assets, Weighted-Average Useful Life (Year)
us-gaap_FiniteLivedIntangibleAssetUsefulLife
us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life (Year) (Year)
Preferred Stock, Shares Authorized (in shares)
Earliest Tax Year [Member]
us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
Net decrease in cash and cash equivalents
Software, Internally Developed and Purchased [Member]
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Table Text Block]
us-gaap_DeferredTaxLiabilitiesPrepaidExpenses
Prepaid insurance
Cash equivalents
us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1
Restructuring and Related Cost, Expected Cost Remaining
Lessor, Lease, Description [Table]
us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
SOFR Based Loans [Member]
Relating to SOFR based loans.
Concentration Risk, Credit Risk, Policy [Policy Text Block]
Statement [Table]
Credit Facility [Axis]
Cash paid for operating leases included in operating cash flows
us-gaap_PrepaidInsurance
Prepaid insurance
Credit Facility [Domain]
Revolving Credit Facility [Member]
Income Tax Authority, Name [Axis]
Income Tax Authority, Name [Domain]
us-gaap_MachineryAndEquipmentGross
Machinery and equipment
us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Debt Instrument, Basis Spread on Variable Rate
Right-of-use assets obtained in exchange for new lease obligations
us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Line of Credit Facility, Maximum Borrowing Capacity
us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent
iiin_IncreaseInCashSurrenderValueOfLifeInsurancePoliciesOverPremiumsPaid
Increase in cash surrender value of life insurance policies over premiums paid
The amount of increase in cash surrender value of life insurance policies over premiums paid during the period.
iiin_IncreaseInCashSurrenderValueOfLifeInsurancePolicies
Increase in cash surrender value of life insurance policies
The increase in the beginning and end of period in the cash surrender value of life insurance policies.
Cash surrender value of life insurance policies
Proceeds from surrender of life insurance policies
The cash inflow for proceeds from the surrender of life insurance policies.
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Restricted stock units outstanding, beginning balance (in shares)
Restricted stock units outstanding, ending balance (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Weighted average grant date fair value, beginning balance (in dollars per share)
Weighted average grant date fair value, ending balance (in dollars per share)
us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Line of Credit Facility, Remaining Borrowing Capacity
Granted, units (in shares)
Units (in shares)
srt_StockRepurchaseProgramAuthorizedAmount1
Share Repurchase Program, Authorized, Amount
Granted, units, weighed average grant date fair value (in dollars per share)
iiin_RestrictedStockUnitsAndStockOptionsSurrenderedForWithholdingTaxesPayable
Restricted stock units and stock options surrendered for withholding taxes payable
The value of restricted stock units and stock options that surrendered for withholding taxes payable.
Long-Term Debt, Type [Axis]
Product and Service [Domain]
Product and Service [Axis]
us-gaap_LineOfCredit
Long-Term Line of Credit, Total
us-gaap_PropertyPlantAndEquipmentUsefulLife
Property, Plant, and Equipment, Useful Life
Vested, units, weighted average grant date fair value (in dollars per share)
Non Financial [Member]
Assets that are non-financial in nature.
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested, units (in shares)
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue
Total future operating lease payments
Weighted average discount rate
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value
Asset Class [Axis]
iiin_PolicyTable
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Forfeited (in shares)
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
2027
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive
2031
Exercised, aggregate intrinsic value
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant
us-gaap_OperatingLeaseExpense
Operating Lease, Expense
Exercisable (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Exercisable, weighted average exercise price (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block]
Assets:
Measurement Frequency [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Outstanding, shares (in shares)
Outstanding, shares (in shares)
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree
2029
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Outstanding, weighted average exercise price (in dollars per share)
Outstanding, weighted average exercise price (in dollars per share)
Commitments and Contingencies Disclosure [Text Block]
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo
2028
Statement [Line Items]
Fair Value Hierarchy and NAV [Axis]
Outstanding, aggregate intrinsic value
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour
2030
Common Stock, Shares, Issued (in shares)
Grantee Status [Domain]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Common Stock, Shares, Outstanding (in shares)
Award Type [Domain]
Share-Based Payment Arrangement, Employee [Member]
Risk-free interest rate
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Common Stock, Shares Authorized (in shares)
Grantee Status [Axis]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
Expected volatility
us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Share Repurchase Program, Remaining Authorized, Amount
Expected dividend yield
iiin_DefinedBenefitPlanEmploymentTerm
Defined Benefit Plan, Employment Term (Year)
The number of years of continuous service required to receive the maximum benefit under the SERP.
iiin_SupplementalRetirementBenefitPeriod
Supplemental Retirement Benefit Period
The maximum period of time that a Participant will be paid supplemental retirement benefits if they are eligible for full benefits.
iiin_DefinedBenefitPlanPercentOfHighestAverageSalaryBase
Defined Benefit Plan Percent of Highest Average Salary Base
The percentage of a Participant's highest average base salary that will be paid out to the Participant as supplemental retirement benefits if they meet the continuous service requirement.
iiin_DefinedBenefitPlanNumberOfYearsInAverageAnnualBaseSalary
Defined Benefit Plan Number of Years in Average Annual Base Salary (Year)
The number of consecutive years used to determine a Participant's highest average annual base salary in a supplemental employee retirement plan.
iiin_DefinedBenefitPlanNumberOfYearsPrecedingRetirementForAverageAnnualBaseSalaryCalculation
Defined Benefit Plan Number of Years Preceding Retirement for Average Annual Base Salary Calculation (Year)
Defined benefit plan number of years preceding retirement for average annual base salary calculation
Welded Wire Reinforcement [Member]
Welded wire reinforcement.
Common stock, $1 stated value Authorized shares: 50,000 Issued and outstanding shares: 2026, 19,358; 2025, 19,420
iiin_DefinedBenefitPlanRetirementAge
Defined Benefit Plan Retirement Age
The minimum age that an employee may retire at to receive benefits.
PC Strand [Member]
Represents the product PC strand.
Reduced SERP [Member]
A supplemental employee retirement plan where the employee has not met all requirements and therefore receives reduced benefits.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
Intangible Asset, Finite-Lived, Estimated Amortization Expense, Year Two
Fair Value of Financial Instruments, Policy [Policy Text Block]
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
Intangible Asset, Finite-Lived, Estimated Amortization Expense, Year Three
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Intangible Asset, Finite-Lived, Estimated Amortization Expense, Year One
Tax Period [Domain]
Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block]
iiin_FixedChargeCoverageRatio
Fixed Charge Coverage Ratio
A ratio that indicates an entities ability to satisfy fixed expenses.
Tax Period [Axis]
Accounts payable
iiin_CreditFacilityLiquidityAmount
Credit Facility, Liquidity Amount
The minimum liquidity amount that would trigger a fixed charge coverage ratio requirement as part of a covenant under a credit facility.
us-gaap_PolicyTextBlockAbstract
Accounting Policies
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
Intangible Asset, Finite-Lived, Estimated Amortization Expense, Year Four
us-gaap_TableTextBlock
Notes Tables
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
Intangible Asset, Finite-Lived, Estimated Amortization Expense, Year Five
Other Financial Data [Text Block]
Disclosure of other financial data not otherwise disclosed.
us-gaap_OperatingLossCarryforwardsExpirationDate
Operating Loss Carryforwards, Expiration Date
us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent
Property taxes
us-gaap_ComprehensiveIncomeNetOfTax
Comprehensive income
us-gaap_AccruedSalariesCurrent
Salaries, wages and related expenses
Accrued expenses
Accrued expenses
Concentration Risk Type [Axis]
Proceeds from long-term debt
Significant Accounting Policies [Text Block]
us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount
Less: imputed interest
Outstanding, weighted average contractual term (Year)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Other liabilities
us-gaap_OperatingLeaseLiabilityNoncurrent
Operating lease liability
us-gaap_SalesAndExciseTaxPayableCurrent
State sales and use taxes
us-gaap_OperatingLeaseLiability
Total operating lease liabilities
Present value of lease liabilities
us-gaap_OtherAccruedLiabilitiesCurrent
Other
Accrued expenses
us-gaap_OperatingLeaseLiabilityCurrent
Operating lease liabilities
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
2029
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
2030
Fair Value, Assets Measured on Recurring Basis [Table Text Block]
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
2027
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
2028
Vested and anticipated to vest in the future, weighted average contractual term (Year)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1
Expected term (in years) (Year)
Exercisable, weighted average contractual term (Year)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Concentration Risk Type [Domain]
Schedule of Amortization of Financing Costs for Debt [Table Text Block]
Tabular disclosure for a fiscal year schedule of the amortization of financing costs for debt.
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
2031
us-gaap_ConstructionInProgressGross
Construction in progress
us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
2032-2036
Income Tax Jurisdiction, Domestic Federal [Member]
Proceeds from sale of property, plant and equipment
Income Tax Jurisdiction, Domestic State and Local [Member]
VEBA [Member]
Represents the voluntary employee beneficiary association also referred to as VEBA.
Statement of Stockholders' Equity [Abstract]
Intangible Asset, Finite-Lived, Class [Axis]
Loss Contingencies [Table]
Statement of Comprehensive Income [Abstract]
Intangible Asset, Finite-Lived, Class [Domain]
Statement of Cash Flows [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]
Other comprehensive income (loss)
us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
Other comprehensive income (loss)
Key Members of Management [Member]
Represents key members of managements.
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]
Shareholders’ equity:
Long-Term Debt, Type [Domain]
Equity Components [Axis]
Share-Based Payment Arrangement [Policy Text Block]
Cash received from exercise of stock options
Product Warranty Disclosure [Text Block]
Equity Component [Domain]
Other Financial Information, Balance Sheet [Table Text Block]
The tabular disclosure for other financial information related to the balance sheet that is not otherwise disclosed.
Fair Value, Inputs, Level 2 [Member]
AOCI Attributable to Parent [Member]
Fair Value, Inputs, Level 1 [Member]
Equity [Text Block]
Additional Paid-in Capital [Member]
Retained Earnings [Member]
Cost of sales
Decrease in Assumed Discount Rate [Member]
Represents the decrease in assumed discount rate.
Property, plant and equipment, net
Property, plant and equipment, net
Compensation and Employee Benefit Plans [Text Block]
us-gaap_PropertyPlantAndEquipmentGross
Property, Plant and Equipment, Gross
us-gaap_CapitalExpendituresIncurredButNotYetPaid
Purchases of property, plant and equipment in accounts payable
Property, Plant, and Equipment [Policy Text Block]
Machinery and Equipment [Member]
us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent
Deferred compensation
Defined Benefit Plan, Assumptions [Table Text Block]
Schedule of Net Benefit Costs [Table Text Block]
Compensation expense associated with stock-based plans
Schedule of Expected Benefit Payments [Table Text Block]
Market value
Share-Based Payment Arrangement, Option, Activity [Table Text Block]
Share-Based Payment Arrangement, Cost by Plan [Table Text Block]
Fair Value Disclosures [Text Block]
Share-Based Payment Arrangement, Option [Member]
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
Supplemental Disclosures of Cash Flow Information:
Liabilities, Current [Abstract]
us-gaap_CurrentIncomeTaxExpenseBenefit
Current
us-gaap_LiabilitiesCurrent
Total current liabilities
Federal, current
us-gaap_LettersOfCreditOutstandingAmount
Letters of Credit Outstanding, Amount
Secured Overnight Financing Rate (SOFR) [Member]
State, current
Accounts receivable, net
Accounts Receivable, after Allowance for Credit Loss, Current
Accounts receivable, net
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue [Table Text Block]
Florida Department of Revenue [Member]
Represents the Florida Department of Revenue.
All Other State Income Tax Authorities [Member]
Represents all other state income tax authorities.
Customer Concentration Risk [Member]
Summary of Income Tax Paid [Table Text Block]
Tabular disclosure of income taxes paid to tax authorities during the period.
Upper Sandusky Closure [Member]
Related to Upper Sandusky Closure.
Officers life insurance, percent
Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to officers life insurance.
Lease, Cost [Table Text Block]
Officers life insurance
Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to officers life insurance.
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table]
Supplemental Employee Retirement Plan [Member]
Customer Relationships [Member]
Revenue Benchmark [Member]
us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Loss on sale and disposition of property, plant and equipment
Long-Term Debt [Text Block]
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less accumulated depreciation
Accumulated other comprehensive income (loss)
us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Finite-lived intangible assets, Accumulated Amortization
Product Warranty Liability [Table]
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Earnings before income taxes
iiin_DefinedBenefitPlanIncreaseOfPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssets
Defined Benefit Plan, Increase of Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets
Amount of increase of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets.
iiin_DefinedBenefitPlanIncreaseInAccumulatedBenefitObligation
Defined Benefit Plan, Increase in Accumulated Benefit Obligation
Amount of increase in actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.
Additional paid-in capital
Use of Estimates, Policy [Policy Text Block]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)
Customer rebates
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)
us-gaap_PaymentsToAcquireProductiveAssets
Capital expenditures
Lessee, Operating Leases [Text Block]
UNITED STATES
Non-US [Member]
us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Repurchases of common stock
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]
Stock options exercised
us-gaap_AssetsCurrent
Total current assets
Fair Value, Recurring and Nonrecurring [Table]
us-gaap_GrossProfit
Gross profit
Trade Names [Member]
Restricted Stock Units (RSUs) [Member]
us-gaap_AccountsReceivableGrossCurrent
Accounts receivable
Net changes in assets and liabilities (net of assets and liabilities acquired):
Stock options exercised (in shares)
Exercised (in shares)
us-gaap_Depreciation
Depreciation
Related and Nonrelated Parties [Axis]
us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Repurchases of common stock (in shares)
Schedule of Long-Term Debt Instruments [Table]
Cash Flows From Operating Activities:
Cash Flows From Investing Activities:
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
us-gaap_InventoryRawMaterialsNetOfReserves
Raw materials
Cash Flows From Financing Activities:
Secured Overnight Financing Rate (SOFR) Credit Adjustment [Member]
Adjustment to interest rate based on U.S. Treasury repurchases between banks.
us-gaap_InventoryWorkInProcessNetOfReserves
Work in process
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash used for investing activities
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash used for financing activities
us-gaap_InventoryFinishedGoodsNetOfReserves
Finished goods
Restructuring Type [Axis]
us-gaap_AssetsFairValueDisclosure
Total
Assets, Fair Value Disclosure
us-gaap_GoodwillImpairmentLoss
Goodwill, Impairment Loss
Accounting Policies [Abstract]
Long-Lived Asset, Excluding Intangible Asset and Goodwill, Impairment and Disposal [Policy Text Block]
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Table]
Accounting Standards Update and Change in Accounting Principle [Text Block]
us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted
Purchase Commitment, Remaining Minimum Amount Committed
us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Less allowance for credit losses
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Table]
Deferred compensation
us-gaap_DeferredCompensationLiabilityCurrent
us-gaap_StockRepurchasedDuringPeriodValue
Stock Repurchased During Period, Value
us-gaap_StockRepurchasedDuringPeriodShares
Stock Repurchased During Period, Shares
Income Statement [Abstract]
Federal, deferred
us-gaap_DeferredIncomeTaxLiabilities
Deferred tax liabilities
us-gaap_NumberOfReportableSegments
Number of Reportable Segments
us-gaap_OtherAssetsMiscellaneousNoncurrent
Other
us-gaap_LandAndLandImprovements
Land and land improvements
Deferred income taxes
Deferred
us-gaap_OtherAssetsMiscellaneousCurrent
Other
Net earnings
Net earnings
Net earnings
Amortization of capitalized financing costs
Amortization of Debt Issuance Costs
us-gaap_AmortizationOfIntangibleAssets
Intangible Asset, Finite-Lived, Amortization Expense
State, deferred
us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total
Income Tax Disclosure [Text Block]
Accounting Standards Update and Change in Accounting Principle [Table]
us-gaap_DeferredTaxAssetsNet
Deferred tax assets
The 2025 Equity Incentive Plan [Member]
Represents the 2025 Equity Incentive Plan.
Income Tax, Policy [Policy Text Block]
us-gaap_RestructuringReserveSettledWithoutCash2
Non-cash charges
Non-cash charges
2027
iiin_AmortizationOfFinancingCostsNext12Months
The amount of amortization costs in the next 12 months.
us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate
Provision for income taxes at federal statutory rate
2029
iiin_AmortizationOfFinancingCostsYear3
The amount of amortization costs in year 3.
Asset impairment charges
Asset, Impairment Loss
2028
iiin_AmortizationOfFinancingCostsYear2
The amount of amortization costs in year 2.
2031
iiin_AmortizationOfFinancingCostsYear5
The amount of amortization costs in year 5.
2030
iiin_AmortizationOfFinancingCostsYear4
State net operating loss carryforwards and tax credits
Related and Nonrelated Parties [Domain]
Net amount recognized
us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax
Net (gain) loss
Other
Defined benefit plans
Vested and anticipated to vest in the future (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
Vested and anticipated to vest in the future, aggregate intrinsic value
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes
State income taxes, net of federal tax benefit
Accrued expenses and asset reserves
us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
Stock-based compensation
Vested and anticipated to vest in the future, weighted average exercise price (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
Other adjustments
Research and Experimental Capitalization
Fair Value Hierarchy and NAV [Domain]
Operating lease liabilities
Measurement Frequency [Domain]
us-gaap_IncomeTaxReconciliationTaxCredits
Tax credits
us-gaap_RepaymentsOfLongTermDebt
Principal payments on long-term debt
us-gaap_OpenTaxYear
Open Tax Year
Statement of Financial Position [Abstract]
us-gaap_DeferredTaxAssetsValuationAllowance
Valuation allowance
Deferred Tax Assets, Valuation Allowance
Retirement Savings Plan [Member]
The amount of savings for the retirement plan.
iiin_HealthcareCoverageClaimsInExcessOf
Healthcare Coverage Claims in Excess of
Represents the amount at which stop-loss insurance covers the remainder of the claim.
iiin_BusinessCombinationHoldbackLiabilityCurrent
Business Combination, Holdback Liability, Current
Amount of holdback liability for business combination, classified as current.
us-gaap_IncomeTaxesPaidNet
Income taxes paid, net of amounts refunded
Noncompete Agreements [Member]
iiin_NonCancelablePurchaseCommitmentTerm
Non-cancelable Purchase Commitment Term (Day)
Represents the approximate length of time for which the Company's non-cancelable purchase commitments extend.
Engineered Wire Products, Inc. [Member]
Represents Engineered Wire Products, Inc.
us-gaap_DeferredTaxLiabilities
Deferred Tax Liabilities, Net
Net deferred tax liability
us-gaap_DeferredTaxLiabilitiesLeasingArrangements
Right-of-use assets
Right-of-use assets
iiin_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightofuseAssets
Amount of right-of-use assets acquired at the acquisition date.
us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill
Goodwill
O'Brien Wire Products of Texas [Member]
Represents O'Brien Wire Products of Texas.
iiin_DebtInstrumentDefaultInterestRateIncrease
Debt Instrument, Default, Interest Rate Increase
Percentage of increase in interest rate in the event of default on the debt instrument.
Liabilities, Noncurrent [Abstract]
iiin_SeveranceAgreementRenewalTerm
Severance Agreement, Renewal Term (Year)
Renewal term of severance agreement.
iiin_TerminationBenefitRatioOfAnnualBaseSalaryReceivedOnTerminationDate
Termination Benefit, Ratio of Annual Base Salary Received on Termination Date
Represents ratio of annual base salary received for termination benefit.
Fair Value, Nonrecurring [Member]
iiin_TerminationBenefitContinuationTermForHealthAndWelfareBenefit
Termination Benefit, Continuation Term for Health and Welfare Benefit (Month)
Represents continuation term for health and welfare benefits as termination benefit.
iiin_ControlAgreementInitialTerm
Control Agreement, Initial Term (Year)
Initial term of control agreement.
Current operating lease liabilities
iiin_BusinessCombinationRecognizedIdentifiableAssetAcquiredAndLiabilityAssumedCurrentLiabilitiesLeaseObligation
Amount of lease obligation assumed in business combination, classified as current.
Accrued expenses
iiin_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedLiabilities
Amount of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered, assumed at the acquisition date.
Fair Value, Recurring [Member]
No Customers [Member]
Represents no customers.
Earnings before income taxes
iiin_BusinessAcquisitionProFormaIncomeLossBeforeIncomeTaxes
The pro forma income or loss before income taxes for the period as if the business combination or combinations had been completed at the beginning of a period.
iiin_OperatingLeaseTermRequiredToBeRecordedOnTheBalanceSheetThreshold
Operating Lease, Term Required to be Recorded on the Balance Sheet, Threshold (Month)
Represents minimum lease term required for operating lease to be recorded on the balance sheet.
Non-current operating lease liabilities
iiin_BusinessCombinationRecognizedIdentifiableAssetAcquiredAndLiabilityAssumedNoncurrentLiabilitiesLeaseObligation
Amount of lease obligation assumed in business combination, classified as noncurrent.
iiin_SeveranceAgreementInitialTerm
Severance Agreement, Initial Term (Year)
Initial term of severance agreement.
Other assets
Other assets
iiin_SeveranceBenefitRatioOfBaseCompensationReceivedIfOtherKeyMembersOfManagementTerminationWithinTwoYears
Severance Benefit, Ratio of Base Compensation Received if Other Key Members of Management Termination Within Two Years
Represents ratio of base compensation received if other key members of management are terminated within two years of a change in control.
iiin_SeveranceBenefitRatioOfAverageBonusReceivedIfOtherKeyMembersOfManagementTerminationWithinTwoYears
Severance Benefit, Ratio of Average Bonus Received if Other Key Members of Management Termination Within Two Years
Represents ratio of average bonus received if other key members of management are terminated within two years of a change in control.
iiin_SeveranceBenefitsContinuationOfHealthAndWelfareBenefitsTermIfCEOTerminationWithinTwoYears
Severance Benefits Continuation of Health and Welfare Benefits Term if CEO Termination Within Two Years (Year)
Duration of health and welfare benefits received in the event CEO is terminated within two years of a change in control.
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchases of common stock
iiin_ControlAgreementAutomaticallyRenewalTerm
Control Agreement, Automatically Renewal Term (Year)
Represents automatically renewal term of control agreement.
iiin_SeveranceBenefitRatioOfAverageBonusReceivedIfCEOTerminationWithinTwoYears
Severance Benefit, Ratio of Average Bonus Received if CEO Termination Within Two Years
Represents ratio of average bonus received if CEO is terminated within two years of a change in control
dei_DocumentType
Document Type
Document Information [Line Items]
us-gaap_DefinedContributionPlanCostRecognized
Defined Contribution Plan, Cost
us-gaap_ConcentrationRiskPercentage1
Concentration Risk, Percentage
dei_DocumentAnnualReport
Document Annual Report
iiin_SeveranceBenefitsContinuationOfHealthAndWelfareBenefitsTermIfOtherMembersOfManagementTerminationWithinTwoYears
Severance Benefits Continuation of Health and Welfare Benefits Term if Other Members of Management Termination Within Two Years (Year)
Duration of health and welfare benefits received in the event other key members of management are terminated within two years of a change in control.
Weighted average lease term (Year)
Document Information [Table]
us-gaap_DefinedBenefitPlanActuarialGainLoss
Actuarial (gain) loss
iiin_SeveranceBenefitReceivedTermForThePriorYearsIfCEOTerminationWithinTwoYears
Severance Benefit Received Term for the Prior Years if CEO Termination Within Two Years (Year)
Represents the prior period used to calculate the average bonus if CEO is terminated within two years of a change in control.
iiin_SeveranceBenefitReceivedTermForThePriorYearsIfOtherMembersOfManagementTerminationWithinTwoYears
Severance Benefit Received Term for the Prior Years if Other Members of Management Termination Within Two Years (Year)
Represents the prior period used to calculate the average bonus if other key member of management is terminated within two years of a change in control.
Net sales
us-gaap_BusinessAcquisitionsProFormaRevenue
iiin_SeveranceBenefitRatioOfBaseCompensationReceivedIfTerminationWithinTwoYears
Severance Benefit, Ratio of Base Compensation Received if Termination Within Two Years
Represents ratio of base compensation received if CEO is terminated within two years of a change in control.
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)
dei_EntityInteractiveDataCurrent
Entity Interactive Data Current
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)
dei_DocumentTransitionReport
Document Transition Report
Diluted (in shares)
us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding
Diluted weighted average shares outstanding (in shares)
dei_DocumentFinStmtErrorCorrectionFlag
Document Financial Statement Error Correction [Flag]
Net earnings per share:
Purchase Commitment, Excluding Long-Term Commitment [Domain]
iiin_DefinedBenefitPlanExpectedFutureBenefitPayment
Defined Benefit Plan, Expected Future Benefit Payment
Amount of benefit for defined benefit plan expected to be paid.
Purchase Commitment, Excluding Long-Term Commitment [Axis]
Dilutive effect of stock-based compensation (in shares)
Basic (in shares)
us-gaap_WeightedAverageNumberOfSharesOutstandingBasic
Basic weighted average shares outstanding (in shares)
Net earnings
us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Basic (in dollars per share)
Basic (in dollars per share)
Effect of cross-border tax laws
Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table]
Effect of cross-border tax laws, percent
Effective Income Tax Rate Reconciliation [Table]
State
us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived
Title and Position [Domain]
Pension and Other Postretirement Plans, Policy [Policy Text Block]
us-gaap_TaxJurisdictionOfDomicileExtensibleEnumeration
Tax Jurisdiction of Domicile [Extensible Enumeration]
Earnings Per Share, Policy [Policy Text Block]
Federal
us-gaap_IncomeTaxPaidFederalAfterRefundReceived
Intangibles, net
Income Tax Jurisdiction [Axis]
dei_IcfrAuditorAttestationFlag
ICFR Auditor Attestation Flag
Vested and released restricted stock units (in shares)
Finite-lived intangible assets, Net Book Value
us-gaap_FiniteLivedIntangibleAssetsNet
us-gaap_BuildingsAndImprovementsGross
Buildings
Lessee, Operating Lease, Assets and Liabilities [Table Text Block]
Tabular disclosure of balance sheet location for operating lease right-of-use asset and operating lease liabilities for lessee.
Document Fiscal Period Focus
Vested and released restricted stock units
Equipment Relocation [Member]
Represents the equipment relocation.
Finite-lived intangible assets, gross
us-gaap_FiniteLivedIntangibleAssetsGross
Customer [Domain]
Document Fiscal Year Focus
Amendment Flag
Technology-Based Intangible Assets [Member]
Common Stock [Member]
Goodwill
Goodwill
Restructuring charges, net
Restructuring charges, net
dei_DocumentPeriodEndDate
Document Period End Date
Building [Member]
Long-Lived Asset, Class [Domain]
Vested, units, aggregate intrinsic value
Granted (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Legal Entity [Axis]
iiin_DefinedBenefitPlanDecreaseInNetPeriodicPensionCost
Defined Benefit Plan, Decrease in Net Periodic Pension Cost
Represents the decrease in net periodic pension cost.
Business Combination [Domain]
dei_EntityFileNumber
Entity File Number
dei_EntityTaxIdentificationNumber
Entity Tax Identification Number
us-gaap_NoncashInvestingAndFinancingItemsAbstract
Non-cash investing and financing activities:
us-gaap_RestructuringReserveCurrent
Restructuring Reserve, Current
Liability, ending balance
Beginning balance, liability
Business Combination [Axis]
Disaggregation of Revenue [Table]
Entity [Domain]
Entity Central Index Key
us-gaap_RestructuringAndRelatedCostIncurredCost
Restructuring and Related Cost, Incurred Cost
dei_EntityRegistrantName
Entity Registrant Name
dei_EntityWellKnownSeasonedIssuer
Entity Well-known Seasoned Issuer
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Defined Contribution Plan, Employer Matching Contribution, Percent of Match
dei_EntityCurrentReportingStatus
Entity Current Reporting Status
Business Combination [Table]
dei_EntityVoluntaryFilers
Entity Voluntary Filers
dei_EntityIncorporationStateCountryCode
Entity Incorporation, State or Country Code
us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax
Total recognized in other comprehensive income
Business Combination, Pro Forma Information [Table Text Block]
Current Fiscal Year End Date
dei_EntityPublicFloat
Entity Public Float
us-gaap_SegmentReportingExpenseInformationUsedByCodmTypeExtensibleEnumeration
Segment Reporting, Expense Information Used by CODM, Type [Extensible Enumeration]
Inventories
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory
Proceeds from sale of assets held for sale
The cash inflow from the sale of assets held for sale.
dei_EntityFilerCategory
Entity Filer Category
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Total assets acquired
dei_EntityShellCompany
Entity Shell Company
Total liabilities assumed
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
Total liabilities assumed
dei_EntityEmergingGrowthCompany
Entity Emerging Growth Company
dei_EntitySmallBusiness
Entity Small Business
Intangible assets
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet
Net assets acquired
us-gaap_OperatingLossCarryforwards
Operating Loss Carryforwards
Segment Reporting, Expense Information Used by CODM, Type [Domain]
Property, plant and equipment
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
Segment Reporting, Expense Information Used by CODM, Consolidated [Member]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
us-gaap_ContractWithCustomerAssetNet
Contract with Customer, Asset, after Allowance for Credit Loss
us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description
Interest expense
us-gaap_Revenues
Revenue
Adjusted purchase price
us-gaap_BusinessCombinationConsiderationTransferred1
Business Combination, Consideration Transferred
dei_EntityAddressStateOrProvince
Entity Address, State or Province
dei_EntityAddressCityOrTown
Entity Address, City or Town
Retained earnings
dei_EntityAddressAddressLine1
Entity Address, Address Line One
dei_CityAreaCode
City Area Code
us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet
Other changes
us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual
us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
Payment of employee tax withholdings related to net share transactions
dei_LocalPhoneNumber
Local Phone Number
dei_EntityAddressPostalZipCode
Entity Address, Postal Zip Code
Revenue from Contract with Customer [Text Block]
us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]
dei_Security12bTitle
Title of 12(b) Security
dei_SecurityExchangeName
Security Exchange Name
dei_TradingSymbol
Trading Symbol
Class of Stock [Axis]
Base Rate [Member]
Variable Rate [Axis]
Variable Rate [Domain]
Revenue [Policy Text Block]
dei_EntityCommonStockSharesOutstanding
Entity Common Stock, Shares Outstanding (in shares)
Earnings Per Share [Text Block]
us-gaap_PreferredStockNoParValue
Preferred Stock, No Par Value (in dollars per share)
Other current assets
Other current assets
Chief Executive Officer [Member]
Director [Member]
Acquisition costs
Business Combination, Acquisition-Related Cost, Expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table]
us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid
Actual distributions
Scenario [Axis]
us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid
Distributions
Scenario [Domain]
Forecast [Member]
Weighted average shares outstanding:
us-gaap_AccruedIncomeTaxesCurrent
Income taxes
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]
Exercisable, aggregate intrinsic value
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Common Stock, Par or Stated Value Per Share (in dollars per share)
us-gaap_OtherNonoperatingIncomeExpense
Other expense, net
iiin_SelfinsuredHealthInsurancePlanContributionCost
Self-insured Health Insurance Plan, Contribution Cost
Represents contribution cost for self-insured health plan.
Long-Lived Asset, Class [Axis]
us-gaap_Assets
Total assets
Cash and Cash Equivalents, Policy [Policy Text Block]
Cash and cash equivalents
dei_AuditorFirmId
Auditor Firm ID
dei_AuditorName
Auditor Name
Geographical [Domain]
dei_AuditorLocation
Auditor Location
Geographical [Axis]
Adjustment to defined benefit plan liability, net of income taxes of ($127), ($182) and $103, respectively
Diluted (in dollars per share)
Diluted (in dollars per share)
us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay
us-gaap_PaymentsForRestructuring
Cash payments
Customer [Axis]
us-gaap_PaymentsToAcquireBusinessesGross
Acquisition of businesses
Other comprehensive income (loss)
Other comprehensive (loss) income, related income taxes [1]
Depreciation and amortization
Other current assets
us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther
Schedule of Defined Benefit Plans Disclosures [Table Text Block]
Asset Class [Domain]
us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation
Restricted stock units and stock options surrendered for withholding taxes payable
Intangible Asset [Text Block]
Consolidation, Policy [Policy Text Block]
Restructuring Plan [Domain]
us-gaap_InvestmentIncomeInterest
Interest income
Interest
Restructuring Plan [Axis]
us-gaap_CashSurrenderValueOfLifeInsurance
Cash surrender value of life insurance policies
Intangible Asset, Finite-Lived [Table Text Block]
Intangible Asset, Finite-Lived [Table]
Intangible Asset, Indefinite-Lived [Table]
Inventories
Inventories
us-gaap_DeferredFinanceCostsNoncurrentNet
Capitalized financing costs, net
Business Combination [Text Block]
us-gaap_StockholdersEquity
Total shareholders' equity
Balance
Balance
us-gaap_PaymentsOfDividendsCommonStock
Cash dividends paid
Stock, Class of Stock [Table]
Patents [Member]
Award Timing Disclosures [Line Items]
Concentration Risk Benchmark [Axis]
Nature of Operation, Product Information, Concentration of Risk [Table]
Concentration Risk Benchmark [Domain]
Right-of-use assets
us-gaap_OperatingLeaseRightOfUseAsset
Other assets
Award Timing, How MNPI Considered [Text Block]
Other liabilities
Other liabilities
Asset Impairments [Member]
Information pertaining to the asset impairments.
ecd_MnpiDiscTimedForCompValFlag
MNPI Disclosure Timed for Compensation Value [Flag]
Net sales
us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment
Plant and equipment
ecd_Rule10b51ArrTrmntdFlag
Rule 10b5-1 Arrangement Terminated [Flag]
ecd_Rule10b51ArrAdoptedFlag
Rule 10b5-1 Arrangement Adopted [Flag]
Commitments and Contingencies
Inventory, Policy [Policy Text Block]
us-gaap_SegmentReportingNoAssetInformation
Segment Reporting, No Asset Information [true false]