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Repurchase of Common Stock - Additional Information (Detail) - USD ($)
3 Months Ended
Aug. 31, 2015
Jun. 23, 2014
Equity, Class of Treasury Stock [Line Items]    
Stock repurchased and retired during period, shares 0  
Remaining stock available to repurchase $ 15,500,000  
Maximum [Member]    
Equity, Class of Treasury Stock [Line Items]    
Stock repurchase program, authorized amount   $ 50,000,000
Stock repurchases leverage ratio 250.00%