Document And Entity Information	9 Months Ended
Document And Entity Information	May 31, 2015	Jul. 06, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	Northern Technologies International Corporation
Trading Symbol	ntic
Document Type	10-Q
Current Fiscal Year End Date	--08-31
Entity Common Stock, Shares Outstanding		4,525,109
Amendment Flag	false
Entity Central Index Key	0000875582
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	May 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3

Consolidated Balance Sheets (Current Period Unaudited) (USD $)	May 31, 2015	Aug. 31, 2014
CURRENT ASSETS:
Cash and cash equivalents	$ 3,793,571	$ 2,477,017
Available for sale securities	2,527,847	5,519,766
Trade excluding joint ventures, less allowance for doubtful accounts of $40,000 at May 31, 2015 and August 31, 2014	4,293,038	3,596,247
Trade joint ventures	626,948	951,286
Fees for services provided to joint ventures	1,354,901	2,612,899
Income taxes	178,110	762
Inventories	6,732,441	5,961,399
Prepaid expenses	527,597	411,226
Deferred income taxes	789,364	789,364
Total current assets	20,823,817	22,319,966
PROPERTY AND EQUIPMENT, NET	7,136,334	6,477,987
OTHER ASSETS:
Investments in joint ventures	19,644,767	22,961,989
Investments at carrying value (Note 6)	1,883,668
Deferred income taxes	970,783	943,279
Patents and trademarks, net	1,270,739	1,197,700
Other	141,303	156,854
Total other assets	23,911,260	25,259,822
Total assets	51,871,411	54,057,775
CURRENT LIABILITIES:
Accounts payable	2,117,239	2,225,029
Accrued liabilities:
Payroll and related benefits	1,038,931	1,847,246
Deferred joint venture royalties	288,000	288,000
Other	81,523	106,380
Total current liabilities	3,525,693	4,466,655
COMMITMENTS AND CONTINGENCIES (Note 14)
EQUITY:
Preferred stock, no par value; authorized 10,000 shares; none issued and outstanding	0	0
Common stock, $0.02 par value per share; authorized 10,000,000 shares; issued and outstanding 4,525,109 and 4,504,552, respectively	90,502	90,092
Additional paid-in capital	13,211,987	12,676,546
Retained earnings	34,518,356	32,733,300
Accumulated other comprehensive income	(3,125,074)	253,925
Stockholders’ equity	44,695,771	45,753,863
Non-controlling interest	3,649,947	3,837,257
Total equity	48,345,718	49,591,120
Total liabilities and equity	$ 51,871,411	$ 54,057,775

Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) (USD $)	May 31, 2015	Aug. 31, 2014
Trade allowance (in Dollars)	$ 40,000	$ 40,000
Preferred stock, par value (in Dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock par value (in Dollars per share)	$ 0.02	$ 0.02
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	4,525,109	4,504,552
Common stock, shares outstanding	4,525,109	4,504,552

Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
NET SALES:
Net sales, excluding joint ventures	$ 7,553,957	$ 6,056,078	$ 20,030,491	$ 17,188,462
Net sales, to joint ventures	723,618	864,742	2,189,888	2,260,466
Total net sales	8,277,575	6,920,820	22,220,379	19,448,928
Cost of goods sold	5,595,207	4,669,322	15,059,558	12,879,186
Gross profit	2,682,368	2,251,498	7,160,821	6,569,742
JOINT VENTURE OPERATIONS:
Equity in income of joint ventures	1,724,915	1,593,465	4,806,247	4,416,664
Fees for services provided to joint ventures	1,303,964	2,001,775	4,432,494	6,169,094
Total joint venture operations	3,028,879	3,595,240	9,238,741	10,585,758
OPERATING EXPENSES:
Selling expenses	1,434,627	1,315,264	4,168,955	3,925,466
General and administrative expenses	1,703,083	1,307,653	4,794,206	3,905,082
Expenses incurred in support of joint ventures	327,586	353,958	1,510,830	1,049,691
Research and development expenses	1,064,710	1,104,632	2,968,879	3,342,497
Total operating expenses	4,530,006	4,081,507	13,442,870	12,222,736
OPERATING INCOME	1,181,241	1,765,231	2,956,692	4,932,764
INTEREST INCOME	7,943	1,369	25,504	5,728
INTEREST EXPENSE	(6,004)	(7,063)	(14,232)	(32,709)
OTHER INCOME			2,145
INCOME BEFORE INCOME TAX EXPENSE	1,183,180	1,759,537	2,970,109	4,905,783
INCOME TAX EXPENSE	114,180	361,280	495,478	819,039
NET INCOME	1,069,000	1,398,257	2,474,631	4,086,744
NET INCOME ATTRIBUTABLE TO NON- CONTROLLING INTEREST	163,565	418,040	689,575	1,222,897
NET INCOME ATTRIBUTABLE TO NTIC	$ 905,435	$ 980,217	$ 1,785,056	$ 2,863,847
NET INCOME ATTRIBUTABLE TO NTIC PER COMMON SHARE:
Basic (in Dollars per share)	$ 0.20	$ 0.22	$ 0.40	$ 0.64
Diluted (in Dollars per share)	$ 0.20	$ 0.21	$ 0.39	$ 0.63
WEIGHTED AVERAGE COMMON SHARES ASSUMED OUTSTANDING:
Basic (in Shares)	4,525,109	4,461,880	4,519,279	4,452,798
Diluted (in Shares)	4,594,992	4,590,344	4,635,561	4,583,174

Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $)	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
NET INCOME	$ 1,069,000	$ 1,398,257	$ 2,474,631	$ 4,086,744
OTHER COMPREHENSIVE (LOSS) INCOME – FOREIGN CURRENCY TRANSLATION ADJUSTMENT	(439,459)	(133,296)	(3,695,884)	472,315
COMPREHENSIVE INCOME (LOSS)	629,541	1,264,961	(1,221,253)	4,559,059
COMPREHENSIVE INCOME ATTRIBUTABLE TO NON- CONTROLLING INTERESTS	130,133	405,333	372,690	1,198,539
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO NTIC	$ 499,408	$ 859,628	$ (1,593,943)	$ 3,360,520

Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
	May 31, 2015	May 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 2,474,631	$ 4,086,744
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	378,421	345,319
Depreciation expense	385,126	335,350
Amortization expense	65,747	64,736
Loss on disposal of assets	20,689	2,176
Equity in income from joint ventures	(4,806,247)	(4,416,664)
Dividends received from joint ventures	2,767,771	7,307,895
Increase in allowance on doubtful accounts		20,000
Deferred income taxes	(27,558)
Receivables:
Trade, excluding joint ventures	(896,173)	80,459
Trade, joint ventures	324,338	90,860
Fees for services provided to joint ventures	1,257,998	(387,356)
Income taxes	(217,055)	(155,319)
Inventories	(887,748)	(397,090)
Prepaid expenses and other	(95,316)	(455,900)
Accounts payable	82,550	(227,486)
Income tax payable	22,943	(4,081)
Accrued liabilities	(813,896)	411,211
Net cash provided by operating activities	36,221	6,700,854
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the sale of investment in joint venture		134,606
Proceeds from the sale of available for sale securities	2,991,919
Additions to property and equipment	(1,098,035)	(428,536)
Additions to patents	(138,786)	(189,393)
Net cash provided by (used in) investing activities	1,755,098	(483,323)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of note payable		(933,414)
Dividend received by non-controlling interest	(560,000)	(1,440,000)
Investment by non-controlling interest		34,770
Proceeds from employee stock purchase plan	57,980	42,514
Proceeds from exercise of stock options	99,450	305,996
Net cash used in financing activities	(402,570)	(1,990,134)
EFFECT OF EXCHANGE RATE CHANGES ON CASH:	(72,195)	8,134
NET INCREASE IN CASH AND CASH EQUIVALENTS	1,316,554	4,235,531
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	2,477,017	4,314,258
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 3,793,571	$ 8,549,789

Note 1 - Interim Financial Information

9 Months Ended

May 31, 2015

Disclosure Text Block [Abstract]

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

1.	INTERIM FINANCIAL INFORMATION

In the opinion of management, the accompanying unaudited consolidated financial statements contain all necessary adjustments, which are of a normal recurring nature, and present fairly the consolidated financial position of Northern Technologies International Corporation and its subsidiaries (the Company) as of May 31, 2015 and August 31, 2014 and the results of their operations for the three and nine months ended May 31, 2015 and 2014 and their cash flows for the nine months ended May 31, 2015 and 2014, in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP).

These consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Company’s annual report on Form 10-K for the fiscal year ended August 31, 2014. These consolidated financial statements also should be read in conjunction with the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” section appearing in this report.

Operating results for the three and nine months ended May 31, 2015 are not necessarily indicative of the results that may be expected for the full fiscal year ending August 31, 2015.

Certain amounts reported in the consolidated financial statements for the previous reporting periods have been reclassified to conform to the current period presentation. Beginning in the second quarter of fiscal 2015, the Company reclassified dividends received from equity method from investing cash flows to operating cash flows on the consolidated statements of cash flows for all periods presented. The classification reflects the continued profitability and returns of those profits to its owners, including the Company. The reclassification did not impact net income or equity.

The Company evaluates events occurring after the date of the consolidated financial statements requiring recording or disclosure in the consolidated financial statements.

Note 6 - Investments in Joint Ventures

9 Months Ended

May 31, 2015

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments and Joint Ventures Disclosure [Text Block]

6.	INVESTMENTS IN JOINT VENTURES

Financial information from the financial statements of the Company’s joint venture in Germany, Excor Korrosionsschutz – Technologien und Produkte GmbH (EXCOR), joint venture in China, Tianjin-Zerust Anticorrosion Co., Ltd. (Tianjin Zerust), for the periods for which it was accounted for under the equity method (See Note 7) and all of the Company’s other joint ventures, are summarized as follows:

	At May 31, 2015
	Total		EXCOR		All Other
Current assets	$	49,454,666	$	22,205,218	$	27,249,448
Total assets		52,993,622		24,155,320		28,838,303
Current liabilities		12,368,822		3,298,480		9,070,342
Noncurrent liabilities		1,231,277		—		1,231,277
Joint ventures’ equity		39,393,523		20,856,840		18,536,683
Northern Technologies International Corporation’s share of joint ventures’ equity		19,644,767		10,428,422		9,216,345
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	17,583,956	$	10,397,517	$	7,186,439

	At August 31, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Current assets	$	61,491,957	$	24,361,157	$	9,774,680	$	27,356,120
Total assets		65,466,964		26,652,165		9,793,803		29,020,996
Current liabilities		17,542,634		3,512,143		4,438,380		9,592,111
Noncurrent liabilities		1,929,488		—		868,377		1,061,111
Joint ventures’ equity		45,994,842		23,140,022		4,487,046		18,367,775
Northern Technologies International Corporation’s share of joint ventures’ equity		22,961,989		11,570,013		2,243,524		9,148,452
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	20,540,523	$	11,539,108	$	2,193,524	$	6,807,891

	Nine Months Ended May 31, 2015
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	75,974,770	$	27,580,051	$	3,735,457	$	44,659,262
Gross profit		37,469,186		15,113,100		1,783,673		20,572,413
Net income		9,634,318		6,334,009		265,648		3,034,661
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	4,806,247	$	3,152,489	$	132,824	$	1,520,934

	Nine Months Ended May 31, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	88,213,101	$	29,020,416	$	11,952,115	$	47,240,570
Gross profit		41,609,619		15,000,023		5,550,166		21,059,430
Net income		9,960,639		5,574,387		1,543,155		1,913,097
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	4,416,664	$	2,787,048	$	659,684	$	969,932

All material profits recorded on sales from the Company to its joint ventures have been eliminated for financial reporting purposes.

On January 2, 2015, the Company announced that, effective as of December 31, 2014, the Company terminated its joint venture agreements with its previous joint venture in China, Tianjin Zerust, and began the process of liquidating the joint venture entity. The Company intends to conduct future business in China through a newly formed wholly owned subsidiary, NTIC (Shanghai) Co. Ltd. (NTIC China). As of December 31, 2014, the Company started recognizing Tianjin Zerust based on its carrying value instead of the equity method since the Company no longer expects to significantly affect the joint venture’s operations or decision making during its anticipated liquidation.

The Company records expenses that are directly attributable to the joint ventures on its consolidated statements of operations in the line item “Expenses incurred in support of joint ventures.” The expenses include items such as employee compensation and benefit expenses, travel expense and consulting expense.

The Company did not make any joint venture investments during the nine months ended May 31, 2015. On May 31, 2014, NTI Asean bought out the other 50% owner in its joint venture in Singapore for $110,988, thereby increasing NTI Asean’s ownership in the joint venture from 50% to 100%. The Company did not make any other joint venture investments during the nine months ended May 31, 2014.

On November 30, 2013, the Company agreed to sell its indirect ownership interest in Mütec GmbH (Mütec), the Company’s former joint venture in Germany which manufactures proprietary electronic sensing instruments. Since the purchase price paid to the Company was less than the book value of the Company’s investment in Mütec, the Company recognized a $50,000 impairment charge during the three months ended November 30, 2013, which is included in the consolidated statements of operations in the line item “Equity income of joint ventures.” In connection with the transaction, the owner of Mütec borrowed $168,000 from the Company to be repaid over four years with no interest. As of May 31, 2015 and August 31, 2014, $134,097 and $156,854 was due to the Company related to this transaction.

Note 7 - China Operations

9 Months Ended

May 31, 2015

Fair Value Disclosures [Abstract]

Fair Value Disclosures [Text Block]

7.	CHINA OPERATIONS

On January 2, 2015, the Company announced that, effective as of December 31, 2014, the Company terminated its joint venture agreements with its previous joint venture in China, Tianjin Zerust, began the process of liquidating the joint venture entity, and has commenced conducting business in China through a newly formed wholly owned subsidiary, NTIC (Shanghai) Co. Ltd. on January 1, 2015. Effective December 31, 2014, the Company’s investment in Tianjin Zerust is reported at carrying value based on the Company’s decreased level of influence over the entity, and the Company has reclassified previously unrecognized gains on foreign currency translation from other comprehensive income. Any declines in the fair value are reflected as adjustments to the carrying value. No such adjustments were recorded during the nine months ended May 31, 2015.

The investment in Tianjin Zerust is as follows:

	Investment
Equity method investment – August 31, 2014	$	2,243,524
Equity in earnings – nine months ended May 31, 2015		132,824
Reclassification of translation gains on foreign currency translation		(492,680	)
Investment at carrying value – May 31, 2015	$	1,883,668

The Company incurred expenses of $1,138,000 during the nine months ended May 31, 2015 related to the termination of the joint venture agreement with Tianjin Zerust, the initiation of the liquidation of Tianjin Zerust and the formation and initial operation of NTIC China. Such expenses consisted primarily of legal expenses and personnel expenses associated with the establishment of the subsidiary and the hiring of new personnel. These expenses are recorded as operating expenses on the consolidated statements of operations and are partially off-set by the gross margin contribution from sales of NTIC China .

Note 8 - Corporate Debt

9 Months Ended

May 31, 2015

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

8.	CORPORATE DEBT

The Company has a revolving line of credit with PNC Bank of $3,000,000. No amounts were outstanding under the line of credit as of both May 31, 2015 and August 31, 2014. At the option of the Company, outstanding advances under the line of credit bear interest at either (a) an annual rate based on LIBOR plus 2.15% for the applicable LIBOR interest period selected by the Company or (b) at the rate publicly announced by PNC Bank from time to time as its prime rate.

The line of credit is subject to standard covenants, including affirmative financial covenants, such as the maintenance of a minimum fixed charge coverage ratio, and negative covenants, which, among other things, limit the incurrence of additional indebtedness, loans and equity investments, disposition of assets, mergers and consolidations and other matters customarily restricted in such agreements. Under the loan agreement, the Company is subject to a minimum fixed charge coverage ratio of 1.10:1.00. As of May 31, 2015, the Company was in compliance with all debt covenants.

On January 5, 2015, PNC Bank extended the maturity date of the line of credit from January 7, 2015 to January 7, 2016 under substantially similar terms, and waived a technical covenant default by the Company to deliver quarterly compliance certificates.

Note 9 - Stockholders' Equity

9 Months Ended

May 31, 2015

Stockholders' Equity Note [Abstract]

Stockholders' Equity Note Disclosure [Text Block]

9.	STOCKHOLDERS’ EQUITY

During the nine months ended May 31, 2015, the Company did not purchase or retire any shares of its common stock. The following stock options to purchase shares of common stock were exercised during the nine months ended May 31, 2015:

Options Exercised	Exercise Price
18,000	$ 7.65
2,333	10.20

The Company granted stock options under the Northern Technologies International Corporation Amended and Restated 2007 Stock Incentive Plan (the 2007 Plan) to purchase an aggregate of 45,067 shares of its common stock to various employees and directors during the nine months ended May 31, 2015. The weighted average per share exercise price of the stock options is $20.10, which was equal to the fair market value of the Company’s common stock on the date of grant.

During the nine months ended May 31, 2014, the Company did not purchase or retire any shares of its common stock. The following stock options to purchase shares of common stock were exercised during the nine months ended May 31, 2014:

Options Exercised	Exercise Price
44,000	$ 7.65

The Company granted stock options under the 2007 Plan to purchase an aggregate of 56,373 shares of its common stock to various employees and directors during the nine months ended May 31, 2014. The weighted average per share exercise price of the stock options is $14.83, which was equal to the fair market value of the Company’s common stock on the date of grant.

Note 10 - Net Income Per Common Share

9 Months Ended

May 31, 2015

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

10.	NET INCOME PER COMMON SHARE

Basic net income per common share is computed by dividing net income by the weighted average number of common shares outstanding. Diluted net income per share assumes the exercise of stock options using the treasury stock method, if dilutive.

The following is a reconciliation of the net income per share computation for the three and nine months ended May 31, 2015 and 2014:

	Three Months Ended				Nine Months Ended
Numerators:	May 31, 2015		May 31, 2014		May 31, 2015		May 31, 2014
Net income attributable to NTIC	$	905,435	$	980,217	$	1,785,056	$	2,863,847

Denominator:
Basic – weighted shares outstanding		4,525,109		4,461,880		4,519,279		4,452,798
Weighted shares assumed upon exercise of stock options		69,883		128,464		116,282		130,376
Diluted – weighted shares outstanding		4,594,992		4,590,344		4,635,561		4,583,174
Basic earnings per share:	$	0.20	$	0.22	$	0.40	$	0.64
Diluted earnings per share:	$	0.20	$	0.21	$	0.39	$	0.63

The dilutive impact summarized above relates to the periods when the average market price of the Company’s common stock exceeded the exercise price of the potentially dilutive option securities granted. Earnings (loss) per common share were based on the weighted average number of common shares outstanding during the periods when computing the basic earnings (loss) per share. When dilutive, stock options are included as equivalents using the treasury stock market method when computing the diluted earnings (loss) per share.

Note 11 - Stock-based Compensation

9 Months Ended

May 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

11.	STOCK-BASED COMPENSATION

The Company has two stock-based compensation plans under which stock options and other stock-based awards have been granted, the Northern Technologies International Corporation Amended and Restated 2007 Stock Incentive Plan and the Northern Technologies International Corporation Employee Stock Purchase Plan (the ESPP). The Compensation Committee of the Board of Directors and the Board of Directors administer these plans.

The 2007 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, stock unit awards, performance awards and stock bonuses to eligible recipients to enable the Company and its subsidiaries to attract and retain qualified individuals through opportunities for equity participation in the Company, and to reward those individuals who contribute to the achievement of the Company’s economic objectives. Subject to adjustment as provided in the 2007 Plan, up to a maximum of 800,000 shares of the Company’s common stock are issuable under the 2007 Plan. Options granted under the 2007 Plan generally have a term of ten years and become exercisable over a three- or four-year period beginning on the one-year anniversary of the date of grant. Options are granted at per share exercise prices equal to the market value of the Company’s common stock on the date of grant. The Company issues new shares upon the exercise of options. As of May 31, 2015, only stock options and stock bonuses had been granted under the 2007 Plan.

The maximum number of shares of common stock of the Company available for issuance under the ESPP is 100,000 shares, subject to adjustment as provided in the ESPP. The ESPP provides for six-month offering periods beginning on September 1 and March 1 of each year. The purchase price of the shares is 90% of the lower of the fair market value of common stock at the beginning or end of the offering period. This discount may not exceed the maximum discount rate permitted for plans of this type under Section 423 of the Internal Revenue Code of 1986, as amended. The ESPP is compensatory for financial reporting purposes.

The Company granted options to purchase an aggregate of 45,067 and 56,373 shares of its common stock during the nine months ended May 31, 2015 and 2014, respectively. The fair value of option grants is determined at date of grant, using the Black-Scholes option pricing model with the assumptions listed below. The Company recognized compensation expense of $378,421 and $345,319 during the nine months ended May 31, 2015 and 2014, respectively, related to the options that vested during such time period. As of May 31, 2015, the total compensation cost for non-vested options not yet recognized in the Company’s consolidated statements of operations was $376,847 net of estimated forfeitures. Stock-based compensation expense of $117,262 is expected through the remainder of fiscal year 2015, and $179,785 and $79,800 is expected to be recognized during fiscal 2016 and fiscal 2017, respectively, based on outstanding options as of May 31, 2015. Future option grants will impact the compensation expense recognized. Stock-based compensation expense is included in general and administrative expense on the consolidated statements of operations.

The Company currently estimates a ten percent forfeiture rate for stock options and continually reviews this estimate for future periods.

The fair value of each option grant is estimated on the grant date using the Black-Scholes option-pricing model with the following assumptions and results for the grants:

	Nine Months Ended
	May 31, 2015			May 31, 2014
Dividend yield		0.00	%		0.00	%
Expected volatility		46.6	%		47.3	%
Expected life of option (years)		10			10
Average risk-free interest rate		1.63	%		1.36	%

The weighted average per share fair value of options granted during nine months ended May 31, 2015 and 2014 was $11.58 and $8.57, respectively. The weighted average remaining contractual life of the options outstanding as of May 31, 2015 and 2014 was 6.56 years and 5.44 years, respectively.

Note 12 - Geographic and Segment Information

9 Months Ended

May 31, 2015

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

12.	GEOGRAPHIC AND SEGMENT INFORMATION

Net sales by geographic location as a percentage of total consolidated net sales for the three and nine months ended May 31, 2015 and 2014 were as follows:

	Three Months Ended						Nine Months Ended
	May 31, 2015			May 31, 2014			May 31, 2015			May 31, 2014
Inside the U.S.A. to unaffiliated customers		63.0	%		69.0	%		63.8	%		67.4	%
Outside the U.S.A to:
Joint ventures in which the Company is a shareholder directly and indirectly		7.3	%		13.6	%		11.7	%		12.4	%
Unaffiliated customers		29.7	%		17.4	%		24.5	%		20.2	%
		100.0	%		100.0	%		100.0	%		100.0	%

Net sales by geographic location are based on the location of the customer.

Fees for services provided to joint ventures accounted for under the equity method by geographic location as a percentage of total fees for services provided to joint ventures during the three and nine months ended May 31, 2015 and 2014 were as follows:

	Three Months Ended
	May 31, 2015		% of Total Fees for Services Provided to Joint Ventures			May 31, 2014		% of Total Fees for Services Provided to Joint Ventures
Germany	$	219,182		16.8	%	$	257,215		12.8	%
Poland		149,771		11.5	%		152,157		7.6	%
Thailand		128,164		9.8	%		148,113		7.4	%
Japan		124,772		9.6	%		170,079		8.5	%
France		108,788		8.4	%		139,719		7.0	%
Sweden		103,234		7.9	%		130,613		6.5	%
United Kingdom		93,229		7.2	%		127,697		6.4	%
Finland		74,711		5.7	%		87,416		4.4	%
India		72,285		5.5	%		204,777		10.2	%
China		—		0.0	%		478,979		23.9	%
Other		229,828		17.6	%		104,840		5.3	%
	$	1,303,964		100.0	%	$	2,001,775		100.0	%

	Nine Months Ended
	May 31, 2015		% of Total Fees for Services Provided to Joint Ventures			May 31, 2014		% of Total Fees for Services Provided to Joint Ventures
Germany	$	660,135		14.9	%	$	784,326		12.7	%
China		516,139		11.6	%		1,590,612		25.8	%
Poland		437,607		9.9	%		469,242		7.6	%
Thailand		425,316		9.6	%		431,112		7.0	%
Japan		409,316		9.2	%		510,769		8.3	%
France		318,686		7.2	%		390,794		6.3	%
United Kingdom		304,600		6.9	%		282,329		4.6	%
Sweden		262,451		5.9	%		332,806		5.4	%
Finland		220,926		5.0	%		269,155		4.4	%
India		215,548		4.9	%		371,635		6.0	%
Other		661,770		14.9	%		736,314		11.9	%
	$	4,432,494		100.0	%	$	6,169,094		100.0	%

The following table sets forth the Company’s net sales for the three and nine months ended May 31, 2015 and 2014 by segment:

	Three Months Ended				Nine Months Ended
	May 31, 2015		May 31, 2014		May 31, 2015		May 31, 2014
ZERUST® sales	$	7,076,760	$	5,992,095	$	19,098,816	$	17,296,159
Natur-Tec™ sales		1,200,815		928,725		3,121,563		2,152,769
Total net sales	$	8,277,575	$	6,920,820	$	22,220,379	$	19,448,928

The following table sets forth the Company’s cost of goods sold for the three and nine months ended May 31, 2015 and 2014 by segment:

	Three Months Ended										Nine Months Ended
	May 31, 2015		% of Product Sales*			May 31, 2014		% of Product Sales*			May 31, 2015		% of Product Sales*			May 31, 2014		% of Product Sales*
Direct cost of goods sold
ZERUST®	$	3,942,776		55.7	%	$	3,288,809		54.9	%	$	10,452,467		54.7	%	$	9,336,363		54.0	%
Natur-Tec®		889,976		74.1	%		695,778		74.9	%		2,391,599		76.6	%		1,635,815		76.0	%
Indirect cost of goods sold		762,455		—			684,735		—			2,215,492		—			1,907,008		—
Total net cost of goods sold	$	5,595,207				$	4,669,322				$	15,059,558				$	12,879,186

*	The percent of segment sales is calculated by dividing the direct cost of goods sold for each individual segment category by the net sales for each segment category.

The Company utilizes product net sales and direct and indirect cost of goods sold for each product in reviewing the financial performance of a product type. Further allocation of Company expenses or assets, aside from amounts presented in the tables above, is not utilized in evaluating product performance, nor does such allocation occur for internal financial reporting.

Sales to the Company’s joint ventures are included in the foregoing geographic and segment information, however, sales by the Company’s joint ventures to other parties are not included. The foregoing geographic and segment information represents only sales and cost of goods sold recognized directly by the Company.

The geographical distribution of key financial statement data is as follows:

	As of May 31, 2015		As of August 31, 2014
Brazil	$	1,046,801	$	1,429,054
China		1,395,952		—
India		389,659		363,894
United States		49,038,999		52,264,827
Total assets	$	51,871,411	$	54,057,775

	Nine Months Ended
	May 31, 2015		May 31, 2014
Brazil	$	2,103,589	$	1,865,137
China		442,262		—
India		708,635		361,700
United States		18,965,893		17,222,091
Total net sales	$	22,220,379	$	19,448,928

	Nine Months Ended
	May 31, 2015			May 31, 2014
Brazil	$	(72,785	)	$	(75,491	)
China		(585,790	)		—
India		20,440			5,872
United States		3,594,827			5,002,383
Total operating income	$	2,956,692		$	4,932,764

Total assets located in Brazil, China and India primarily consist of cash and cash equivalents, customer receivables and inventory. These assets are periodically reviewed to assure the net realizable value from the estimated future production based on forecasted sales exceeds the carrying value of the assets. Total assets located in the United States include the Company’s investments in joint ventures.

Note 14 - Commitments and Contingencies

9 Months Ended

May 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

14.	COMMITMENTS AND CONTINGENCIES

On August 19, 2014, the Compensation Committee of the Board of Directors of the Company approved the material terms of an annual bonus plan for the Company’s executive officers as well as certain officers and employees for the fiscal year ending August 31, 2015. For fiscal 2015 as in past years, the total amount available under the bonus plan for all plan participants, including executive officers, is dependent upon the Company’s earnings before interest, taxes and other income, as adjusted to take into account amounts to be paid under the bonus plan and certain other adjustments (Adjusted EBITOI). Each plan participant’s percentage of the overall bonus pool is based upon the number of plan participants, the individual’s annual base salary and the individual’s position and level of responsibility within the company. In the case of each of the Company’s executive officer participants, 75% of the amount of their individual bonus payout will be determined based upon the Company’s actual Adjusted EBITOI for fiscal 2015 compared to a pre-established target Adjusted EBITOI for fiscal 2015 and 25% of the payout will be determined based upon such executive officer’s achievement of certain pre-established individual performance objectives. The payment of bonuses under the plan are discretionary and may be paid to executive officer participants in both cash and shares of the Company’s common stock, the exact amount and percentages will be determined by the Company’s Board of Directors, upon recommendation of the Compensation Committee, after the completion of the Company’s consolidated financial statements for fiscal 2015. There was an accrual of $466,000 for management bonuses for the nine months ended May 31, 2015 compared to an accrual of $1,063,000 for management bonuses for the nine months ended May 31, 2014.

Three joint ventures (consisting of the Company’s joint venture in Korea, Thailand and remaining payables balance to the Company at Tianjin Zerust) accounted for 54.1% of the Company’s trade joint venture receivables at May 31, 2015. Three joint ventures (consisting of the Company’s joint ventures in Korea, Thailand and Tianjin Zerust) accounted for 62.9% of the Company’s trade joint venture receivables at August 31, 2014.

On March 23, 2015, the Company and NTI Asean LLC (NTI Asean), a majority owned subsidiary of the Company, filed a lawsuit in Tianjin No 1 Intermediate People’s Court against two individuals, Meng Tao and Xu Hui, related to breaches of duties and contractual commitments owed to NTI Asean under certain agreements related to the Company’s former joint venture in China, Tianjin Zerust Anti-Corrosion Technologies Ltd (Tianjin Zerust). The lawsuit alleges, among other things, that Mr. Meng Tao and Xu Hui have engaged in self-dealing, usurped business opportunities, and received economic benefits that were required to go to Tianjin Zerust. At this point it is too early in the lawsuit to reasonably estimate the amount of any recovery to NTI Asean, if any. On April 21, 2015, the Company and NTI Asean initiated a lawsuit in the District Court for the Second Judicial District, County of Ramsey, State of Minnesota against Cortec Corporation alleging, among other things, that Cortec Corporation aided and abetted breaches of duties and contractual commitments owed to the Company and NTI Asean related to the Company’s joint venture in China, Tianjin Zerust.

From time to time, the Company is subject to other various claims and legal actions in the ordinary course of its business. The Company records a liability in its consolidated financial statements for costs related to claims, including future legal costs, settlements and judgments, where the Company has assessed that a loss is probable and an amount can be reasonably estimated. If the reasonable estimate of a probable loss is a range, the Company records the most probable estimate of the loss or the minimum amount when no amount within the range is a better estimate than any other amount. The Company discloses a contingent liability even if the liability is not probable or the amount is not estimable, or both, if there is a reasonable possibility that material loss may be have been incurred. In the opinion of management, as of May 31, 2015, the amount of liability, if any, with respect to these matters, individually or in the aggregate, will not materially affect the Company’s consolidated results of operations, financial position or cash flows.

Note 6 - Investments in Joint Ventures (Tables)

9 Months Ended

May 31, 2015

Equity Method Investments and Joint Ventures [Abstract]

Condensed Balance Sheet [Table Text Block]

	At May 31, 2015
	Total		EXCOR		All Other
Current assets	$	49,454,666	$	22,205,218	$	27,249,448
Total assets		52,993,622		24,155,320		28,838,303
Current liabilities		12,368,822		3,298,480		9,070,342
Noncurrent liabilities		1,231,277		—		1,231,277
Joint ventures’ equity		39,393,523		20,856,840		18,536,683
Northern Technologies International Corporation’s share of joint ventures’ equity		19,644,767		10,428,422		9,216,345
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	17,583,956	$	10,397,517	$	7,186,439

	At August 31, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Current assets	$	61,491,957	$	24,361,157	$	9,774,680	$	27,356,120
Total assets		65,466,964		26,652,165		9,793,803		29,020,996
Current liabilities		17,542,634		3,512,143		4,438,380		9,592,111
Noncurrent liabilities		1,929,488		—		868,377		1,061,111
Joint ventures’ equity		45,994,842		23,140,022		4,487,046		18,367,775
Northern Technologies International Corporation’s share of joint ventures’ equity		22,961,989		11,570,013		2,243,524		9,148,452
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	20,540,523	$	11,539,108	$	2,193,524	$	6,807,891

Condensed Income Statement [Table Text Block]

	Nine Months Ended May 31, 2015
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	75,974,770	$	27,580,051	$	3,735,457	$	44,659,262
Gross profit		37,469,186		15,113,100		1,783,673		20,572,413
Net income		9,634,318		6,334,009		265,648		3,034,661
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	4,806,247	$	3,152,489	$	132,824	$	1,520,934

	Nine Months Ended May 31, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	88,213,101	$	29,020,416	$	11,952,115	$	47,240,570
Gross profit		41,609,619		15,000,023		5,550,166		21,059,430
Net income		9,960,639		5,574,387		1,543,155		1,913,097
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	4,416,664	$	2,787,048	$	659,684	$	969,932

Note 12 - Geographic and Segment Information (Tables)

9 Months Ended

May 31, 2015

Note 12 - Geographic and Segment Information (Tables) [Line Items]

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	Three Months Ended						Nine Months Ended
	May 31, 2015			May 31, 2014			May 31, 2015			May 31, 2014
Inside the U.S.A. to unaffiliated customers		63.0	%		69.0	%		63.8	%		67.4	%
Outside the U.S.A to:
Joint ventures in which the Company is a shareholder directly and indirectly		7.3	%		13.6	%		11.7	%		12.4	%
Unaffiliated customers		29.7	%		17.4	%		24.5	%		20.2	%
		100.0	%		100.0	%		100.0	%		100.0	%

Reconciliation of Revenue from Segments to Consolidated [Table Text Block]

	Three Months Ended				Nine Months Ended
	May 31, 2015		May 31, 2014		May 31, 2015		May 31, 2014
ZERUST® sales	$	7,076,760	$	5,992,095	$	19,098,816	$	17,296,159
Natur-Tec™ sales		1,200,815		928,725		3,121,563		2,152,769
Total net sales	$	8,277,575	$	6,920,820	$	22,220,379	$	19,448,928

Reconciliation of Cost of Good Sold from Segments to Consolidated [Table Text Block]

	Three Months Ended										Nine Months Ended
	May 31, 2015		% of Product Sales*			May 31, 2014		% of Product Sales*			May 31, 2015		% of Product Sales*			May 31, 2014		% of Product Sales*
Direct cost of goods sold
ZERUST®	$	3,942,776		55.7	%	$	3,288,809		54.9	%	$	10,452,467		54.7	%	$	9,336,363		54.0	%
Natur-Tec®		889,976		74.1	%		695,778		74.9	%		2,391,599		76.6	%		1,635,815		76.0	%
Indirect cost of goods sold		762,455		—			684,735		—			2,215,492		—			1,907,008		—
Total net cost of goods sold	$	5,595,207				$	4,669,322				$	15,059,558				$	12,879,186

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

	As of May 31, 2015		As of August 31, 2014
Brazil	$	1,046,801	$	1,429,054
China		1,395,952		—
India		389,659		363,894
United States		49,038,999		52,264,827
Total assets	$	51,871,411	$	54,057,775

Revenue from External Customers by Geographic Areas [Table Text Block]

	Nine Months Ended
	May 31, 2015		May 31, 2014
Brazil	$	2,103,589	$	1,865,137
China		442,262		—
India		708,635		361,700
United States		18,965,893		17,222,091
Total net sales	$	22,220,379	$	19,448,928

Schedule of Segment Reporting Information, by Segment [Table Text Block]

	Nine Months Ended
	May 31, 2015			May 31, 2014
Brazil	$	(72,785	)	$	(75,491	)
China		(585,790	)		—
India		20,440			5,872
United States		3,594,827			5,002,383
Total operating income	$	2,956,692		$	4,932,764

Fees For Services Provided to Joint Ventures [Member]

Note 12 - Geographic and Segment Information (Tables) [Line Items]

Reconciliation of Revenue from Segments to Consolidated [Table Text Block]

	Three Months Ended
	May 31, 2015		% of Total Fees for Services Provided to Joint Ventures			May 31, 2014		% of Total Fees for Services Provided to Joint Ventures
Germany	$	219,182		16.8	%	$	257,215		12.8	%
Poland		149,771		11.5	%		152,157		7.6	%
Thailand		128,164		9.8	%		148,113		7.4	%
Japan		124,772		9.6	%		170,079		8.5	%
France		108,788		8.4	%		139,719		7.0	%
Sweden		103,234		7.9	%		130,613		6.5	%
United Kingdom		93,229		7.2	%		127,697		6.4	%
Finland		74,711		5.7	%		87,416		4.4	%
India		72,285		5.5	%		204,777		10.2	%
China		—		0.0	%		478,979		23.9	%
Other		229,828		17.6	%		104,840		5.3	%
	$	1,303,964		100.0	%	$	2,001,775		100.0	%

	Nine Months Ended
	May 31, 2015		% of Total Fees for Services Provided to Joint Ventures			May 31, 2014		% of Total Fees for Services Provided to Joint Ventures
Germany	$	660,135		14.9	%	$	784,326		12.7	%
China		516,139		11.6	%		1,590,612		25.8	%
Poland		437,607		9.9	%		469,242		7.6	%
Thailand		425,316		9.6	%		431,112		7.0	%
Japan		409,316		9.2	%		510,769		8.3	%
France		318,686		7.2	%		390,794		6.3	%
United Kingdom		304,600		6.9	%		282,329		4.6	%
Sweden		262,451		5.9	%		332,806		5.4	%
Finland		220,926		5.0	%		269,155		4.4	%
India		215,548		4.9	%		371,635		6.0	%
Other		661,770		14.9	%		736,314		11.9	%
	$	4,432,494		100.0	%	$	6,169,094		100.0	%

Note 4 - Property and Equipment, Net (Details) - Components of Property and Equipment, Net (USD $)	May 31, 2015	Aug. 31, 2014
Components of Property and Equipment, Net [Abstract]
Land	$ 310,365	$ 310,365
Buildings and improvements	6,317,360	5,695,268
Machinery and equipment	3,662,754	3,713,145
	10,290,479	9,718,778
Less accumulated depreciation	(3,154,144)	(3,240,791)
	$ 7,136,334	$ 6,477,987

Note 5 - Patents and Trademarks, Net (Details) (Patents and Trademarks [Member], USD $)	9 Months Ended
	May 31, 2015
Patents and Trademarks [Member]
Note 5 - Patents and Trademarks, Net (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 90,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	90,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	90,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	90,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 90,000

Note 5 - Patents and Trademarks, Net (Details) - Patents and Trademarks, Net (USD $)	May 31, 2015	Aug. 31, 2014
Finite-Lived Intangible Assets [Line Items]
	$ 1,270,739	$ 1,197,700
Patents and Trademarks Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Patents and trademarks	2,426,627	2,287,840
Less accumulated amortization	(1,155,888)	(1,090,140)
	$ 1,270,739	$ 1,197,700

Note 6 - Investments in Joint Ventures (Details) (USD $)	9 Months Ended		3 Months Ended	0 Months Ended	3 Months Ended
	May 31, 2015	May 31, 2014	Nov. 30, 2013 Mutec [Member]	May 31, 2014 NTI Asean LLC [Member] SINGAPORE	Nov. 30, 2013 Mutec [Member]	May 31, 2015 Mutec [Member]	Aug. 31, 2014 Mutec [Member]
Note 6 - Investments in Joint Ventures (Details) [Line Items]
Payments to Acquire Interest in Joint Venture	$ 0	$ 0		$ 110,988
Joint Venture, Ownership Acquired				50.00%
Joint Venture, Ownership Percentage				100.00%
Other than Temporary Impairment Losses, Investments					50,000
Financing Receivable, Net			168,000
Notes Receivable, Term			4 years
Due from Joint Ventures						$ 134,097	$ 156,854

Note 6 - Investments in Joint Ventures (Details) - Condensed Balance Sheet of EXCOR and Tianjin Zerust, and All Other Joint Ventures (USD $)	May 31, 2015	Aug. 31, 2014
Condensed Balance Sheet Statements, Captions [Line Items]
Current assets	$ 49,454,666	$ 61,491,957
Total assets	52,993,622	65,466,964
Current liabilities	12,368,822	17,542,634
Noncurrent liabilities	1,231,277	1,929,488
Joint ventures’ equity	39,393,523	45,994,842
Northern Technologies International Corporation’s share of joint ventures’ equity	19,644,767	22,961,989
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	17,583,956	20,540,523
EXCOR [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Current assets	22,205,218	24,361,157
Total assets	24,155,320	26,652,165
Current liabilities	3,298,480	3,512,143
Joint ventures’ equity	20,856,840	23,140,022
Northern Technologies International Corporation’s share of joint ventures’ equity	10,428,422	11,570,013
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	10,397,517	11,539,108
All Other [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Current assets	27,249,448	27,356,120
Total assets	28,838,303	29,020,996
Current liabilities	9,070,342	9,592,111
Noncurrent liabilities	1,231,277	1,061,111
Joint ventures’ equity	18,536,683	18,367,775
Northern Technologies International Corporation’s share of joint ventures’ equity	9,216,345	9,148,452
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	7,186,439	6,807,891
Tianjin Zerust [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Current assets		9,774,680
Total assets		9,793,803
Current liabilities		4,438,380
Noncurrent liabilities		868,377
Joint ventures’ equity		4,487,046
Northern Technologies International Corporation’s share of joint ventures’ equity		2,243,524
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings		$ 2,193,524

Note 6 - Investments in Joint Ventures (Details) - Condensed Income Statement of EXCOR and Tianjin Zerust, and All Other Joint Ventures (USD $)	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
Condensed Income Statements, Captions [Line Items]
Net sales			$ 75,974,770	$ 88,213,101
Gross profit			37,469,186	41,609,619
Net income			9,634,318	9,960,639
Company’s share of equity in income of joint ventures	1,724,915	1,593,465	4,806,247	4,416,664
EXCOR [Member]
Condensed Income Statements, Captions [Line Items]
Net sales			27,580,051	29,020,416
Gross profit			15,113,100	15,000,023
Net income			6,334,009	5,574,387
Company’s share of equity in income of joint ventures			3,152,489	2,787,048
Tianjin Zerust [Member]
Condensed Income Statements, Captions [Line Items]
Net sales			3,735,457	11,952,115
Gross profit			1,783,673	5,550,166
Net income			265,648	1,543,155
Company’s share of equity in income of joint ventures			132,824	659,684
All Other [Member]
Condensed Income Statements, Captions [Line Items]
Net sales			44,659,262	47,240,570
Gross profit			20,572,413	21,059,430
Net income			3,034,661	1,913,097
Company’s share of equity in income of joint ventures			$ 1,520,934	$ 969,932

Note 7 - China Operations (Details) - Investment in Tianjin Zerust (Tianjin Zerust [Member], USD $)	9 Months Ended
	May 31, 2015	Aug. 31, 2014
Tianjin Zerust [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment – August 31, 2014		$ 2,243,524
Equity in earnings – nine months ended May 31, 2015	132,824
Reclassification of translation gains on foreign currency translation	(492,680)
Investment at carrying value – May 31, 2015	$ 1,883,668

Note 8 - Corporate Debt (Details) (PNC Bank [Member], USD $)			9 Months Ended
	May 31, 2015 Revolving Credit Facility [Member]	Aug. 31, 2014 Revolving Credit Facility [Member]	May 31, 2015 Revolving Credit Facility [Member] London Interbank Offered Rate (LIBOR) [Member]	May 31, 2015 Term Loan and Line of Credit Agreements "Loan Agreements" [Member]
Note 8 - Corporate Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 3,000,000
Long-term Line of Credit	$ 0	$ 0
Debt Instrument, Basis Spread on Variable Rate			2.15%
Debt Instrument, Covenants, Fixed Charge Coverage Ratio				1.10

Note 9 - Stockholders' Equity (Details) (USD $)	9 Months Ended
Note 9 - Stockholders' Equity (Details) (USD $)	May 31, 2015	May 31, 2014
Note 9 - Stockholders' Equity (Details) [Line Items]
Stock Repurchased and Retired During Period, Shares	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	45,067	56,373
2007 Plan [Member]
Note 9 - Stockholders' Equity (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	45,067	56,373
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in Dollars per share)	$ 20.10	$ 14.83

Note 10 - Net Income Per Common Share (Details) - Reconciliation of the Earnings Per Share Computations (USD $)	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
Reconciliation of the Earnings Per Share Computations [Abstract]
Net income attributable to NTIC (in Dollars)	$ 905,435	$ 980,217	$ 1,785,056	$ 2,863,847
Basic – weighted shares outstanding	4,525,109	4,461,880	4,519,279	4,452,798
Weighted shares assumed upon exercise of stock options	69,883	128,464	116,282	130,376
Diluted – weighted shares outstanding	4,594,992	4,590,344	4,635,561	4,583,174
Basic earnings per share: (in Dollars per share)	$ 0.20	$ 0.22	$ 0.40	$ 0.64
Diluted earnings per share: (in Dollars per share)	$ 0.20	$ 0.21	$ 0.39	$ 0.63

Note 11 - Stock-based Compensation (Details) (USD $)	9 Months Ended
Note 11 - Stock-based Compensation (Details) (USD $)	May 31, 2015	May 31, 2014
Note 11 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	10 years	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)	45,067	56,373
Allocated Share-based Compensation Expense, Estimate, Remainder of Fiscal Year	$ 117,262
Allocated Share-based Compensation Expense, Estimate, Next Fiscal Year	179,785
Allocated Share-based Compensation Expense, Estimate, Fiscal Year Two	79,800
Estimated Forfeiture Rate For Stock Options	10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)	$ 11.58	$ 8.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 204 days	5 years 160 days
2007 Plan [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	800,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)	45,067	56,373
ESPP [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	100,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	90.00%
Net of Estimated Forfeitures [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Allocated Share-based Compensation Expense, Estimate, Remainder of Fiscal Year	376,847
Employee Stock Option [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Stock or Unit Option Plan Expense	$ 378,421	$ 345,319
Minimum [Member] \| One Year after Date of Grant [Member] \| 2007 Plan [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Maximum [Member] \| One Year after Date of Grant [Member] \| 2007 Plan [Member]
Note 11 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years

Note 11 - Stock-based Compensation (Details) - Black-Scholes Option-pricing Model Assumptions	9 Months Ended
	May 31, 2015	May 31, 2014
Black-Scholes Option-pricing Model Assumptions [Abstract]
Dividend yield	0.00%	0.00%
Expected volatility	46.60%	47.30%
Expected life of option (years)	10 years	10 years
Average risk-free interest rate	1.63%	1.36%

Note 12 - Geographic and Segment Information (Details) - Net Sales by Geographic Location as Percentage of Total Consolidated Net Sales (Sales Revenue, Net [Member], Geographic Concentration Risk [Member])	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
Note 12 - Geographic and Segment Information (Details) - Net Sales by Geographic Location as Percentage of Total Consolidated Net Sales [Line Items]
Net Sales, Percentage	100.00%	100.00%	100.00%	100.00%
Inside the U.S.A to Unaffiliated Customers [Member]
Note 12 - Geographic and Segment Information (Details) - Net Sales by Geographic Location as Percentage of Total Consolidated Net Sales [Line Items]
Net Sales, Percentage	63.00%	69.00%	63.80%	67.40%
Joint Ventures in which the Company is a Shareholder Directly and Indirectly - Outside the U.S.A [Member]
Note 12 - Geographic and Segment Information (Details) - Net Sales by Geographic Location as Percentage of Total Consolidated Net Sales [Line Items]
Net Sales, Percentage	7.30%	13.60%	11.70%	12.40%
Unaffiliated Customers - Outside the U.S.A [Member]
Note 12 - Geographic and Segment Information (Details) - Net Sales by Geographic Location as Percentage of Total Consolidated Net Sales [Line Items]
Net Sales, Percentage	29.70%	17.40%	24.50%	20.20%

Note 12 - Geographic and Segment Information (Details) - Fees for Services Provided to Joint Ventures by Geographic Location as a Percentage of Total Fees for Services Provided to Joint Ventures (USD $)	3 Months Ended		9 Months Ended
	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	$ 1,303,964	$ 2,001,775	$ 4,432,494	$ 6,169,094
Fees for services provided, percentage	100.00%	100.00%	100.00%	100.00%
GERMANY
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	219,182	257,215	660,135	784,326
Fees for services provided, percentage	16.80%	12.80%	14.90%	12.70%
POLAND
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	149,771	152,157	437,607	469,242
Fees for services provided, percentage	11.50%	7.60%	9.90%	7.60%
THAILAND
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	128,164	148,113	425,316	431,112
Fees for services provided, percentage	9.80%	7.40%	9.60%	7.00%
JAPAN
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	124,772	170,079	409,316	510,769
Fees for services provided, percentage	9.60%	8.50%	9.20%	8.30%
FRANCE
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	108,788	139,719	318,686	390,794
Fees for services provided, percentage	8.40%	7.00%	7.20%	6.30%
SWEDEN
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	103,234	130,613	262,451	332,806
Fees for services provided, percentage	7.90%	6.50%	5.90%	5.40%
UNITED KINGDOM
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	93,229	127,697	304,600	282,329
Fees for services provided, percentage	7.20%	6.40%	6.90%	4.60%
FINLAND
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	74,711	87,416	220,926	269,155
Fees for services provided, percentage	5.70%	4.40%	5.00%	4.40%
INDIA
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	72,285	204,777	215,548	371,635
Fees for services provided, percentage	5.50%	10.20%	4.90%	6.00%
CHINA
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)		478,979	516,139	1,590,612
Fees for services provided, percentage	0.00%	23.90%	11.60%	25.80%
Other Countries [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Fees for services provided (in Dollars)	$ 229,828	$ 104,840	$ 661,770	$ 736,314
Fees for services provided, percentage	17.60%	5.30%	14.90%	11.90%

Note 12 - Geographic and Segment Information (Details) - Cost of Goods Sold by Segment (USD $)

3 Months Ended

9 Months Ended

May 31, 2015

May 31, 2014

May 31, 2015

May 31, 2014

Note 12 - Geographic and Segment Information (Details) - Cost of Goods Sold by Segment [Line Items]

Cost of Goods Sold

$ 5,595,207

$ 4,669,322

$ 15,059,558

$ 12,879,186

Direct Cost of Goods Sold [Member] | ZERUST [Member]

Note 12 - Geographic and Segment Information (Details) - Cost of Goods Sold by Segment [Line Items]

Cost of Goods Sold

3,942,776

3,288,809

10,452,467

9,336,363

% of Product Sales

55.70%

^[1]

54.90%

^[1]

54.70%

54.00%

Direct Cost of Goods Sold [Member] | Natur-Tec [Member]

Note 12 - Geographic and Segment Information (Details) - Cost of Goods Sold by Segment [Line Items]

Cost of Goods Sold

889,976

695,778

2,391,599

1,635,815

% of Product Sales

74.10%

^[1]

74.90%

^[1]

76.60%

76.00%

Indirect Cost of Goods Sold [Member]

Note 12 - Geographic and Segment Information (Details) - Cost of Goods Sold by Segment [Line Items]

Cost of Goods Sold

$ 762,455

$ 684,735

$ 2,215,492

$ 1,907,008

% of Product Sales

^[1]

[1]	The percent of segment sales is calculated by dividing the direct cost of goods sold for each individual segment category by the net sales for each segment category.

Note 14 - Commitments and Contingencies (Details) (USD $)				9 Months Ended
	May 31, 2015	Aug. 31, 2014	May 31, 2014	May 31, 2015 Fiscal 2015 Bonus Plan [Member] Executive Officer [Member]
Note 14 - Commitments and Contingencies (Details) [Line Items]
Percentage of Individual Bonus Payout Determined By Actual Versus Targeted EBITOI Results				75.00%
Percentage of Individual's Payout Determined Upon Achievement of Certain Pre-Established Individual Performance Objectives				25.00%
Accrued Bonuses (in Dollars)	$ 466,000		$ 1,063,000
Entity-Wide Trade Joint Venture Receivables, Three Joint Ventures, Percentage	54.10%	62.90%

Note 3 - Inventories (Details) - Inventories (USD $)	May 31, 2015	Aug. 31, 2014
Inventories [Abstract]
Production materials	$ 1,509,359	$ 1,242,649
Finished goods	5,223,082	4,718,750
	$ 6,732,441	$ 5,961,399

Note 7 - China Operations (Details) (Termination of Joint Venture and Formation of NTIC China [Member], USD $)	9 Months Ended
	May 31, 2015
Termination of Joint Venture and Formation of NTIC China [Member]
Note 7 - China Operations (Details) [Line Items]
Professional Fees	$ 1,138,000

Note 13 - Research and Development (Details) (USD $)	3 Months Ended		9 Months Ended
Note 13 - Research and Development (Details) (USD $)	May 31, 2015	May 31, 2014	May 31, 2015	May 31, 2014
Research and Development [Abstract]
Research and Development Expense	$ 1,064,710	$ 1,104,632	$ 2,968,879	$ 3,342,497
Research and Development Arrangement, Contract to Perform for Others, Costs Incurred, Gross			$ 0	$ 45,788

Note 15 - Fair Value Measurements (Details) - Assets and Liabilities Measured at Fair Value Recurring Basis (USD $)	May 31, 2015	Aug. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available for sale securities	$ 2,527,847	$ 5,519,766
Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available for sale securities	$ 2,527,847	$ 5,519,766

Note 9 - Stockholders' Equity (Details) - Exercised Stock Options (USD $)	9 Months Ended
	May 31, 2015	May 31, 2014
Exercise 1 [Member]
Note 9 - Stockholders' Equity (Details) - Exercised Stock Options [Line Items]
Options Exercised	18,000	44,000
Exercise Price	$ 7.65	$ 7.65
Exercise 2 [Member]
Note 9 - Stockholders' Equity (Details) - Exercised Stock Options [Line Items]
Options Exercised	2,333
Exercise Price	$ 10.20

Note 12 - Geographic and Segment Information (Details) - Total Assets by Geographic Distribution (USD $)	May 31, 2015	Aug. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 51,871,411	$ 54,057,775
BRAZIL
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	1,046,801	1,429,054
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	1,395,952
INDIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	389,659	363,894
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 49,038,999	$ 52,264,827