Note 3 - Business Combination - Pro Forma Information (Details) - Engineered Wire Products, Inc. [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 29, 2025	Mar. 30, 2024	Mar. 29, 2025	Mar. 30, 2024
Net sales	$ 160,656	$ 149,493	$ 295,582	$ 291,245
Earnings before income taxes	13,325	8,810	14,867	7,593
Net earnings	$ 10,230	$ 6,831	$ 11,370	$ 5,945

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.

No definition available.

+ Details

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Namespace Prefix:	iiin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

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- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

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- Details

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