Property, Plant and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 336,700,000	$ 297,100,000	$ 257,400,000
Capitalized interest related to constructed facilities	154,000	14,400
Maintenance and repair expense	$ 123,100,000	$ 113,900,000	$ 81,800,000