Annual report pursuant to Section 13 and 15(d)

Additional Information Pertaining to Stock Options and SARs (Detail)

v2.4.0.6
Additional Information Pertaining to Stock Options and SARs (Detail) (USD $)
In Thousands, except Per Share data, unless otherwise specified
12 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Weighted-average fair value of stock options granted   $ 9.61 $ 6.07
Total fair value of stock options vested $ 1,001 $ 1,065 $ 747
Total intrinsic value of stock options exercised $ 1,547 $ 1,485 $ 5,164