Quarterly report pursuant to Section 13 or 15(d)

Basic and Diluted Earnings per Common Share Attributable to Common Stockholders (Detail)

v3.3.1.900
Basic and Diluted Earnings per Common Share Attributable to Common Stockholders (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended
Oct. 31, 2015
Oct. 31, 2014
Oct. 31, 2015
Oct. 31, 2014
Earnings Per Share Disclosure [Line Items]        
Net income $ 17,971 $ 25,403 $ 41,053 $ 39,936
Less: distributed and undistributed earnings to nonvested restricted stockholders 167   390  
Basic net earnings attributable to common stockholders 17,804 25,403 40,663 39,936
Add: undistributed earnings to nonvested restricted stockholders 118   292  
Less: reallocation of undistributed earnings to nonvested restricted stockholders 117   289  
Diluted net earnings attributable to common stockholders $ 17,805 $ 25,403 $ 40,666 $ 39,936
Basic weighted-average number of common shares outstanding 49,981 49,082 49,737 48,893
Diluted weighted-average number of common shares outstanding 50,362 49,740 50,233 49,720
Basic earnings per share $ 0.36 $ 0.52 $ 0.82 $ 0.82
Diluted earnings per share $ 0.35 $ 0.51 $ 0.81 $ 0.80
ESPP        
Earnings Per Share Disclosure [Line Items]        
Stock 2   5  
Restricted Stock        
Earnings Per Share Disclosure [Line Items]        
Stock 330 554 433 710
Stock Options        
Earnings Per Share Disclosure [Line Items]        
Stock 49 104 58 117