Employee Stock Option And Retirement Plans (401(k) Plan) (Narrative) (Details) (401 (k) Plan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2009
401 (k) Plan [Member]
Employee Stock Option And Retirement Plans [Line Items]
Percentage of annual compensation	60.00%
Percentage of increase to employee earnings	4.00%
Contribution to defined contribution plan	$ 5.9	$ 5.5	$ 5.0