Other Non-Operating Income (Expense) - Additional Information (Detail) (Series A Preferred Stock [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2012
Series A Preferred Stock [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Redeemed shares		100,000
Original issue price of redeemed shares	$ 23.5	$ 40.0
Accrued dividend of redeemed shares	5.4	8.9
Accelerated discount accretion	3.2	5.5
Amortization of issuance cost		$ 1.1