Note 9 - Net Income Per Common Share - Reconciliation of the Earnings Per Share Computations (Details) - USD ($)	3 Months Ended		9 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017
Net income attributable to NTIC	$ 2,142,752	$ 1,352,416	$ 4,559,225	$ 2,037,021
Basic – weighted shares outstanding (in shares)	4,539,353	4,526,771	4,538,838	4,528,523
Weighted shares assumed upon exercise of stock options (in shares)	167,679	64,756	125,009	42,872
Diluted – weighted shares outstanding (in shares)	4,707,032	4,591,527	4,663,847	4,571,395
Basic income per share: (in dollars per share)	$ 0.47	$ 0.30	$ 1	$ 0.45
Diluted income per share: (in dollars per share)	$ 0.46	$ 0.30	$ 0.98	$ 0.45