Tax Effects of Temporary Differences that Give Rise to Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2013	May 31, 2012
Deferred tax assets:
Accrued compensation and benefits	$ 3,819	$ 4,386
Receivables	1,686	1,330
Inventory	598	598
Stock options	3,671	4,755
Net operating loss carry forwards	175	242
Other	1,158	818
Deferred tax assets	11,107	12,129
Less: Valuation allowance	(65)
Deferred tax assets, net	11,042	12,129
Deferred tax liabilities:
Property, plant and equipment	(12,548)	(9,798)
Goodwill and intangible costs	(5,308)	(4,406)
Foreign currency translation and other equity adjustments	(261)	(672)
Unremitted earnings of foreign subsidiaries	(1,973)	(420)
Prepaids	(1,263)	(1,518)
Other	(718)	(766)
Deferred tax liabilities	(22,071)	(17,580)
Net deferred tax liability	$ (11,029)	$ (5,451)