Note 9 - Net Income Per Common Share - Reconciliation of the Earnings Per Share Computations (Details) - USD ($)	3 Months Ended		9 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Net income attributable to NTIC	$ 1,482,149	$ 2,142,752	$ 4,380,776	$ 4,559,225
Basic – weighted shares outstanding (in shares)	9,084,354	9,078,706	9,085,584	9,077,676
Weighted shares assumed upon exercise of stock options (in shares)	308,090	335,358	355,274	250,018
Diluted – weighted shares outstanding (in shares)	9,392,444	9,414,064	9,440,858	9,327,694
Basic net income per share: (in dollars per share)	$ 0.16	$ 0.24	$ 0.48	$ 0.50
Diluted net income per share: (in dollars per share)	$ 0.16	$ 0.23	$ 0.46	$ 0.49