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Employee Stock Plans (Additional Information Stock Options And SARs) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended 6 Months Ended
Oct. 31, 2011
Oct. 31, 2010
Oct. 31, 2011
Oct. 31, 2010
Employee Stock Plans [Abstract]        
Weighted-average fair value of stock options granted   $ 6.86 $ 9.61 $ 6.05
Total fair value of stock options and SARs vested $ 78 $ 71 $ 894 $ 615
Total intrinsic value of stock options exercised 11 509 859 685
Total intrinsic value of SARs paid   $ 67 $ 11 $ 67