Retirement Plans (Schedules of Net Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 146	$ 208	$ 246
Net amortization and deferral	269	226	199
Total	$ 415	$ 434	$ 445