Note 16 - Rights Agreement (Details Textual)			12 Months Ended
May 17, 1999	Apr. 26, 1999 shares	Sep. 29, 2018 $ / shares
Dividend Distribution of Rights \| shares		1
Rights Assigned to Common Stock Issued	1
Ownership Percentage to Trigger Rights Exercisable			20.00%
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.005
Portion of Company Sold Triggers Exercisability of Rights			50.00%
Series A Junior Participating Preferred Stock [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 46

Represents dividend distribution of rights.

No definition available.

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Namespace Prefix:	iiin_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the beneficial ownership percentage that must be obtained by either a person or a group of affiliated or associates persons that will cause the rights distributed to be exercisable.

+ References

No definition available.

+ Details

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

- Definition

This item represents the portion of the Company that, if sold will trigger the exercisability of the rights.

+ References

No definition available.

+ Details

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

- Definition

This item represents the number of rights that attach to each share of the Company's common stock that is issued after May 17, 1999.

+ References

No definition available.

+ Details

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

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_StatementClassOfStockAxis=iiin_SeriesAJuniorParticipatingPreferredStockMember
Namespace Prefix:
Data Type:	na
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Period Type: