Income Taxes Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details)	3 Months Ended		6 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate			25.70%	35.00%
State income taxes, net of federal tax benefit			3.90%	2.90%
Federal tax benefit of statutory tax deduction			(1.50%)	(1.40%)
Employment related and other tax credits, net			(1.60%)	(1.70%)
Stock option excess tax benefit			(6.60%)	(2.10%)
Deferred tax revaluation			(67.00%)	0.00%
Other			(0.20%)	0.40%
Effective tax rate	(231.10%)	30.00%	(47.30%)	33.10%