XML 19 R37.htm IDEA: XBRL DOCUMENT v3.3.0.814
Borrowings - Additional Information (Detail) - USD ($)
Nov. 19, 2013
Aug. 31, 2015
May. 31, 2015
Line of Credit Facility [Line Items]      
Additional borrowing capacity under Credit Agreement $ 25,000,000    
Credit Agreement      
Line of Credit Facility [Line Items]      
Borrowing outstanding   $ 0 $ 2,387,000
Weighted average interest rate     1.25%
JP Morgan Chase Bank | Credit Agreement      
Line of Credit Facility [Line Items]      
Current borrowing capacity under Credit Agreement $ 25,000,000    
Expiration period of Credit Agreement 3 years    
JP Morgan Chase Bank | Credit Agreement | Eurodollar      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 0.75%    
Commitment fee percentage on unused capacity 0.10%    
JP Morgan Chase Bank | Credit Agreement | CB Floating Rate      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 2.50%    
JP Morgan Chase Bank | Credit Agreement | Adjusted LIBO Rate      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 2.00%    
JP Morgan Chase Bank | Credit Agreement | Maximum | Eurodollar      
Line of Credit Facility [Line Items]      
Commitment fee threshold on unused capacity $ 8,000,000