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Deferred Compensation And Retirement Plans (Components Of Net Periodic Benefit Costs) (Detail) (Pension Plans, Defined Benefit, USD $)
In Thousands, unless otherwise specified
12 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Pension Plans, Defined Benefit
     
Defined Benefit Plan Disclosure [Line Items]      
Interest cost $ 154 $ 189 $ 197
Amortization of actuarial (gain) loss 18 47 (2)
Net periodic benefit cost $ 172 $ 236 $ 195