Restatement - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Nov. 30, 2012		Nov. 30, 2011	Nov. 30, 2012		Nov. 30, 2011
Estimated loss contingency	$ 16,926	[1]		$ 28,344	[1]
Net income (loss)	35,343	[1]	53,919	65,962	[1]	137,259
Adjustments
Estimated loss contingency	16,926			28,344
Net income (loss)	$ (10,744)			$ (17,992)

[1] Restated