Annual report pursuant to Section 13 and 15(d)

Deferred Compensation And Retirement Plans (Total Long-Term Benefit Obligations) (Detail)

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Deferred Compensation And Retirement Plans (Total Long-Term Benefit Obligations) (Detail) (USD $)
In Thousands, unless otherwise specified
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Apr. 30, 2010
Defined Benefit Plan Disclosure [Line Items]        
Total benefit obligation $ 169,657 $ 156,603    
Less: current portion of benefit obligation (9,951) (14,026)    
Non-current benefit obligation 159,706 142,577    
Deferred Compensation Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Total benefit obligation 85,562 78,479 70,319 64,890
Less: current portion of benefit obligation (5,182) (4,959) (3,682)  
Non-current benefit obligation 80,380 73,520 66,637  
Pension Plans, Defined Benefit
        
Defined Benefit Plan Disclosure [Line Items]        
Total benefit obligation 4,536 4,214 3,952 3,630
Less: current portion of benefit obligation (232) (212) (137)  
Non-current benefit obligation 4,304 4,002 3,815  
Retirement Plans
        
Defined Benefit Plan Disclosure [Line Items]        
Total benefit obligation 3,646 2,776    
Executive Capital Accumulation Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Total benefit obligation 75,913 71,134 67,214  
Less: current portion of benefit obligation (4,537) (8,855)    
Non-current benefit obligation $ 71,376 $ 62,279