v3.26.1

Document And Entity Information - shares	9 Months Ended
Document And Entity Information - shares	May 31, 2026	Jul. 09, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	May 31, 2026
Document Transition Report	false
Entity File Number	001-11038
Entity Registrant Name	NORTHERN TECHNOLOGIES INTERNATIONAL CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-0857886
Entity Address, Address Line One	4201 Woodland Road
Entity Address, City or Town	Circle Pines
Entity Address, State or Province	MN
Entity Address, Postal Zip Code	55014
City Area Code	763
Local Phone Number	225-6600
Title of 12(b) Security	Common stock, par value $0.02 per share
Trading Symbol	NTIC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		9,496,439
Entity Central Index Key	0000875582
Current Fiscal Year End Date	--08-31
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q3
Amendment Flag	false

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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No definition available.

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- Definition

Area code of city

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- Definition

End date of current fiscal year in the format --MM-DD.

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No definition available.

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- Definition

Fiscal period values are FY, Q1, Q2, and Q3. 1st, 2nd and 3rd quarter 10-Q or 10-QT statements have value Q1, Q2, and Q3 respectively, with 10-K, 10-KT or other fiscal year statements having FY.

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No definition available.

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- Definition

This is focus fiscal year of the document report in YYYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.

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No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true only for a form used as an quarterly report.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 10-Q
-Number 240
-Section 308
-Subsection a

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Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true only for a form used as a transition report.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Forms 10-K, 10-Q, 20-F
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-Subsection a-1

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Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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No definition available.

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- Definition

Address Line 1 such as Attn, Building Name, Street Name

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No definition available.

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Name of the City or Town

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No definition available.

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Code for the postal or zip code

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- Definition

Name of the state or province.

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No definition available.

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- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

+ References

No definition available.

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- Definition

Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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No definition available.

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- Definition

Indicate if registrant meets the emerging growth company criteria.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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No definition available.

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- Definition

Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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- Definition

Two-character EDGAR code representing the state or country of incorporation.

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No definition available.

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- Definition

Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 405

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- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Section 12
-Subsection b-2

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- Definition

Boolean flag that is true when the registrant is a shell company as defined in Rule 12b-2 of the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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-Section 12
-Subsection b-2

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Period Type:	duration

- Definition

Indicates that the company is a Smaller Reporting Company (SRC).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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Data Type:	xbrli:booleanItemType
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Period Type:	duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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Period Type:	duration

- Definition

Local phone number for entity.

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No definition available.

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Balance Type:	na
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- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b

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- Definition

Name of the Exchange on which a security is registered.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection d1-1

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- Definition

Trading symbol of an instrument as listed on an exchange.

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No definition available.

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Namespace Prefix:	dei_
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NORTHERN TECHNOLOGIES INTERNATIONAL CORP 10-Q