Summary of Quarterly Data (Parenthetical) (Detail) (USD $)	3 Months Ended			6 Months Ended	12 Months Ended		3 Months Ended
	Feb. 29, 2012	Aug. 31, 2011	Feb. 28, 2010	Aug. 31, 2012	Feb. 28, 2013	Feb. 28, 2011	Aug. 31, 2012 Elk Grove Village	May 31, 2011 Elk Grove Village
Quarterly Financial Data [Line Items]
Gain on sales of assets				$ 3,200,000	$ 3,216,000	$ 6,643,000	$ 3,200,000
Employee termination benefit and related expenses	$ 300,000	$ 300,000	$ 1,600,000					$ 1,100,000