Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Basic Earnings per Share
Net income	$ 9,008	$ 9,908	$ 7,879	$ 7,362	$ 10,074	$ 8,541	$ 5,273	$ 8,823	$ 34,157	$ 32,711	$ 43,143
Less: Allocated to participating securities									273	257	410
Available to common shareholders									$ 33,884	$ 32,454	$ 42,733
Basic weighted average shares outstanding									9,359,940	9,334,232	9,296,648
Net income per share - Basic (in dollars per share)	$ 0.95	$ 1.05	$ 0.83	$ 0.78	$ 1.07	$ 0.91	$ 0.56	$ 0.94	$ 3.62	$ 3.48	$ 4.60
Diluted Earnings per Share
Net income	$ 9,008	$ 9,908	$ 7,879	$ 7,362	$ 10,074	$ 8,541	$ 5,273	$ 8,823	$ 34,157	$ 32,711	$ 43,143
Basic weighted average shares outstanding									9,359,940	9,334,232	9,296,648
Additional dilutive common stock equivalents (in shares)									79,810	44,975	69,423
Diluted weighted average shares outstanding									9,439,750	9,379,207	9,366,071
Net income per share - Diluted (in dollars per share)	$ 0.95	$ 1.04	$ 0.83	$ 0.77	$ 1.07	$ 0.90	$ 0.56	$ 0.93	$ 3.59	$ 3.46	$ 4.56
Antidilutive securities
Antidilutive stock options excluded from computation of earnings per share amount (in shares)									11,183	12,901	404