Annual report pursuant to Section 13 and 15(d)

Deferred Compensation And Retirement Plans (Narrative) (Detail)

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Deferred Compensation And Retirement Plans (Narrative) (Detail) (USD $)
12 Months Ended 12 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2011
Apr. 30, 2013
Csv Of Coli Contracts
Apr. 30, 2012
Csv Of Coli Contracts
Apr. 30, 2013
Enhanced Wealth Accumulation Plan
Y
Apr. 30, 2012
Senior Executive Incentive Plan
Y
Apr. 30, 2013
Pension Plans, Defined Benefit
Y
Apr. 30, 2012
Pension Plans, Defined Benefit
Apr. 30, 2011
Pension Plans, Defined Benefit
Apr. 30, 2010
Pension Plans, Defined Benefit
Apr. 30, 2013
International Retirement Plans
Apr. 30, 2012
International Retirement Plans
Apr. 30, 2013
Executive Capital Accumulation Plan
Apr. 30, 2012
Executive Capital Accumulation Plan
Apr. 30, 2011
Executive Capital Accumulation Plan
Apr. 30, 2013
Defined Contribution Plan
Apr. 30, 2012
Defined Contribution Plan
Apr. 30, 2011
Defined Contribution Plan
Apr. 30, 2013
Company Owned Life Insurance Held In Trust
Csv Of Coli Contracts
Defined Benefit Plan Disclosure [Line Items]                                        
Participant contribution period towards deferred compensation plans (in years)           8 4                          
Participant after tax contribution period towards deferred compensation plans (in years)           15 15                          
Additional deferred units to acquire (in years)           5                            
Participant employment term, maximum years               20                        
Change in discount rate 3.79% to 3.12% 4.94% to 3.79%                                    
Increase in deferred compensation and pension plan liabilities $ 7,500,000 $ 8,800,000                                    
Decrease in accumulated other comprehensive income 4,578,000 5,644,000 4,048,000                                  
Net increase in deferred income tax assets 2,900,000 3,200,000                                    
Total benefit obligation 169,657,000 156,603,000           4,536,000 4,214,000 3,952,000 3,630,000 3,600,000 2,800,000 75,913,000 71,134,000 67,214,000        
Long-term benefit obligation accrued, number of participants                       221 188              
Company's contributions                       1,100,000 1,100,000 20,000,000 15,800,000 400,000        
Deferred compensation arrangement vesting terms                           The Company amortizes these contributions on a straight-line basis as they vest, generally over a four year period.            
Gain on investment                           6,281,000 884,000 6,700,000        
Company's contributions, unamortized portion                           23,300,000 11,500,000          
Company's matching contributions                                     1,200,000  
Percentage contribution by the participants to defined contribution plan                                 50.00% 50.00%    
Gross CSV       159,200,000 151,100,000                              
Outstanding policy loans       73,300,000 73,300,000                              
Total death benefits payable, net of loans       212,700,000 202,900,000                              
Increase in market value of the underlying COLI investments 6,502,000 6,268,000 7,218,000 6,502,000 6,268,000                              
Net CSV 85,873,000 77,848,000                                   64,400,000
Total death benefits payable, net of loans held in trust       $ 123,900,000