Income Taxes (Provision For Income Taxes Computed By Applying The Statutory Federal Income Tax Rate) (Details)	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Income Tax Disclosure [Abstract]
Amount computed by applying the statutory federal tax rate	25.70%	35.00%	35.00%
State income taxes (net of federal income tax benefit)	3.80%	2.60%	2.80%
Employment related and other tax credits, net	(1.80%)	(1.90%)	(2.50%)
Change in uncertain tax positions	0.20%	0.00%	(3.30%)
Federal tax benefit of statutory tax deduction	(1.30%)	(1.60%)	(1.40%)
Stock option excess tax benefit	(2.90%)	(1.00%)	0.00%
Deferred tax revaluation	(19.10%)	0.00%	0.00%
Other	(0.90%)	0.20%	0.10%
Provision for income taxes	3.70%	33.30%	30.70%