XML 33 R47.htm IDEA: XBRL DOCUMENT v3.2.0.727
Stock Options and Share-Based Compensations - Summary of Stock Option Activity and Weighted Average Exercise Price (Detail) - $ / shares
 12 Months Ended
Apr. 30, 2015
Apr. 30, 2014
Apr. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Number of Shares, Outstanding at beginning of year 228,250 295,550 298,050
Number of Shares, Granted 45,800 46,600 40,000
Number of Shares, Canceled (5,400) (16,650) (15,750)
Number of Shares, Exercised (29,075) (97,250) (26,750)
Number of Shares, Outstanding at end of year 239,575 228,250 295,550
Number of Shares, Exercisable at end of year 136,700 113,175 157,250
Weighted Average Exercise Price, Outstanding at beginning of year $ 12.17 $ 11.84 $ 11.60
Weighted Average Exercise Price, Granted 17.78 15.26 11.78
Weighted Average Exercise Price, Canceled 11.74 10.10 10.57
Weighted Average Exercise Price, Exercised 12.28 13.00 9.86
Weighted Average Exercise Price, Outstanding at end of year 13.24 12.17 11.84
Weighted Average Exercise Price, Exercisable at end of year $ 11.66 $ 11.90 $ 12.91