Name:	iiin_DefinedBenefitPlanEmploymentTerm
Namespace Prefix:	iiin_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of consecutive years used to determine a Participant's highest average annual base salary in a supplemental employee retirement plan.

No definition available.

Name:	iiin_DefinedBenefitPlanNumberOfYearsInAverageAnnualBaseSalary
Namespace Prefix:	iiin_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Defined benefit plan number of years preceding retirement for average annual base salary calculation

No definition available.

Name:	iiin_DefinedBenefitPlanNumberOfYearsPrecedingRetirementForAverageAnnualBaseSalaryCalculation
Namespace Prefix:	iiin_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	iiin_DefinedBenefitPlanPercentOfHighestAverageSalaryBase
Namespace Prefix:	iiin_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	iiin_DefinedBenefitPlanReductionForEachMonth
Namespace Prefix:	iiin_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The minimum age that an employee may retire at to receive benefits.

No definition available.

Name:	iiin_DefinedBenefitPlanRetirementAge
Namespace Prefix:	iiin_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The maximum period of time that a Participant will be paid supplemental retirement benefits if they are eligible for full benefits.

No definition available.

Name:	iiin_SupplementalRetirementBenefitPeriod
Namespace Prefix:	iiin_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The increase in the fair value of plan assets from contributions made by the employer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

No definition available.

Name:	us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: