Gain on Sale of Product Line (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	May 31, 2011	May 31, 2011
Gain on Sale of Product Line
Proceeds from sale of product line	$ 10,000	$ 10,000
Net carrying value of the assets sold	4,078	4,078
Pre-tax gain on sale of product line	$ 5,922	$ 5,922