XML 94 R44.htm IDEA: XBRL DOCUMENT v2.4.0.8
Stock Options and Share-Based Compensations - Additional Information (Detail) (USD $)
12 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Stock based compensation expense $ 239,000 $ 261,000 $ 225,000
Deferred income tax benefit 93,000 100,000 86,000
Compensation expense not yet recorded 373,000    
Deferred income tax on remaining compensation expense $ 145,000    
Maximum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Terms of award 10 years    
2010 Plan [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized under stock option plan 100,000    
Number of shares each director can purchase 10,000    
Terms of award 5 years    
Stock options plan, description Options will be exercisable in four equal installments, one-fourth becoming exercisable on the next August 1 following the date of grant, and one-fourth becoming exercisable on August 1 of each of the next three years    
Shares available for future grants 45,000    
2008 Plan [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized under stock option plan 300,000    
Shares available for future grants 80,300