Inventories - Schedule of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2014	May 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 7,553	$ 6,797
Work in process	3,247	3,922
Finished goods	2,152	611
Total inventories	$ 12,952	$ 11,330

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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