Stock-Based Compensation Plans (Total Cost Of Share-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 2,846	$ 3,658	$ 3,121
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	2,034	2,902	2,492
Unvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	642	500	450
Fully Vested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	15	135	60
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 155	$ 121	$ 119