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Other Assets - Additional Information (Detail) (USD $)
Feb. 28, 2015
May 31, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]    
Cash surrender value of life insurance $ 6,511,000us-gaap_CashSurrenderValueOfLifeInsurance $ 6,452,000us-gaap_CashSurrenderValueOfLifeInsurance