Accumulated Other Comprehensive Income (loss) (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
May 31, 2014	May 31, 2013	May 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustments for gains included in net income, net of tax (benefit)	$ 586	$ 633	$ 844

Other Comprehensive Income Reclassification Adjustments And Other Tax

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration