XML 16 R33.htm IDEA: XBRL DOCUMENT v2.4.0.8
Stockholders' Equity - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Jul. 31, 2014
Stock Options [Member]
Jul. 31, 2013
Stock Options [Member]
Jul. 31, 2014
Restricted Stock, Restricted Stock Units and Performance Stock Units [Member]
Jul. 31, 2013
Restricted Stock, Restricted Stock Units and Performance Stock Units [Member]
Jul. 31, 2014
Restricted Stock and Restricted Stock Unit [Member]
Jul. 31, 2014
Performance Stock Units [Member]
Jul. 31, 2014
Employee Stock Purchase Plan [Member]
Jul. 31, 2013
Employee Stock Purchase Plan [Member]
Jul. 31, 2014
Non-Employee Director [Member]
Restricted Stock Awards [Member]
Jul. 31, 2014
Employee [Member]
Restricted Stock Awards [Member]
Jul. 31, 2014
2006 Stock Incentive Plan [Member]
Minimum [Member]
Jul. 31, 2014
2006 Stock Incentive Plan [Member]
Maximum [Member]
Jul. 31, 2014
Class A Common Stock [Member]
2006 Stock Incentive Plan [Member]
Apr. 30, 2007
Class A Common Stock [Member]
2006 Stock Incentive Plan [Member]
Limited Partners' Capital Account [Line Items]                            
Common stock, issued shares                           2,475
Number of shares available for future grant                         1,169  
Options vesting period                 3 years 3 years 1 year 4 years    
Options granted period                       10 years    
Stock-based compensation expense $ 109 $ 115 $ 432 $ 492     $ 21 $ 24            
Unrecognized stock-based compensation expense $ 1,003       $ 2,714 $ 2,449                
Unrecognized stock-based compensation expense, weighted average period 1 year 9 months 18 days       2 years 9 months 18 days