Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2009	Oct. 31, 2006
Summary Of Significant Accounting Policies [Line Items]
Foreign currency translation adjustment	$ 6,000,000	$ 1,900,000	$ 4,100,000
Allowance for doubtful accounts	3,525,000	3,913,000	3,931,000	5,612,000
Estimated useful lives	35 years
Interest in joint venture					50.00%
Research and development	2,000,000	3,000,000	2,600,000
Selling, General and Administrative Expenses
Summary Of Significant Accounting Policies [Line Items]
Restricted stock expense	8,800,000	7,100,000	5,800,000
Restricted Stock
Summary Of Significant Accounting Policies [Line Items]
Restricted stock expense	$ 400,000
Restricted Stock | Minimum
Summary Of Significant Accounting Policies [Line Items]
Vesting period	1 year
Restricted Stock | Maximum
Summary Of Significant Accounting Policies [Line Items]
Vesting period	5 years
Trade Names
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Customer Relationships | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Customer Relationships | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	20 years