Retirement Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2019 USD ($)	Aug. 31, 2018 USD ($) item	Aug. 31, 2017 USD ($)	Aug. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 1,700	$ 1,700	$ 1,500
Number of former executives | item		5
Number of highest compensation years | item		3
Discount rate, liability		4.00%	3.70%
Discount Rate, net periodic benefit cost		3.70%	3.30%	4.10%
Actuarial loss		$ 134	$ 287
Scenario, Forecast [Member] | Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss	$ 200