Loss (Gain) on Extinguishment of Debt - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Aug. 31, 2011	May 31, 2011	Aug. 31, 2011	Aug. 31, 2010
Extinguishment of Debt [Line Items]
Gains (losses) on extinguishment of debt	$ (5,650,000)	$ (10,007,000)	$ (15,657,000)	$ 2,070,000
Write-off of loan fees and debt discount	1,700,000	2,900,000		1,100,000
Prepayment premiums and other costs		7,200,000
Retirement of senior unsecured notes		235,000,000
Retirement of term loan	71,800,000
Debt discount	3,900,000
Gain associated with the early retirement				3,200,000
Early retirement of convertible senior notes				$ 32,300,000