Retirement Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2020 USD ($)	Aug. 31, 2019 USD ($) item	Aug. 31, 2018 USD ($)	Aug. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 1,200	$ 1,700	$ 1,700
Number of former executives | item		5
Number of highest compensation years | item		3
Discount rate, liability		3.30%	4.00%
Discount Rate, net periodic benefit cost		4.00%	3.70%	3.30%
Actuarial loss		$ (439)	$ 134
Scenario, Forecast [Member] | Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss	$ 200