Annual report pursuant to Section 13 and 15(d)

Deferred Compensation and Retirement Plans - Additional Information (Detail)

v3.7.0.1
Deferred Compensation and Retirement Plans - Additional Information (Detail)
 12 Months Ended
Apr. 30, 2017
USD ($)
Person
Apr. 30, 2016
USD ($)
Person
Apr. 30, 2015
USD ($)
Dec. 01, 2015
Person
Apr. 30, 2014
USD ($)
Defined Benefit Plan Disclosure [Line Items]          
Recognized investment income(expense) $ 10,842,000 $ (3,333,000) $ 8,829,000    
Increase in market value of the underlying COLI investments 4,918,000 3,984,000 10,509,000    
Net CSV 113,067,000 107,296,000      
Long Term Performance Unit Plan          
Defined Benefit Plan Disclosure [Line Items]          
Value per unit award 50,000        
Annual Benefit Payments per vested unit after anniversary period $ 25,000        
Number of payments after the seventh anniversary of the grant date 5 years        
Vesting percentage on each anniversary date 25.00%        
CSV of COLI Contracts          
Defined Benefit Plan Disclosure [Line Items]          
Gross CSV $ 180,300,000 175,700,000      
Outstanding policy loans 67,200,000 68,400,000      
Total death benefits payable, net of loans 220,600,000 216,700,000      
Increase in market value of the underlying COLI investments $ 4,900,000 4,000,000 10,500,000    
Equity Securities          
Defined Benefit Plan Disclosure [Line Items]          
Target allocation range, minimum 50.00%        
Target allocation range, maximum 70.00%        
Debt Securities          
Defined Benefit Plan Disclosure [Line Items]          
Target allocation range, minimum 30.00%        
Target allocation range, maximum 50.00%        
Other Assets          
Defined Benefit Plan Disclosure [Line Items]          
Target allocation range, minimum 0.00%        
Target allocation range, maximum 10.00%        
Enhanced Wealth Accumulation Plan          
Defined Benefit Plan Disclosure [Line Items]          
Participant contribution period towards deferred compensation plans (in years) 8 years        
Participant after tax contribution period towards deferred compensation plans (in years) 15 years        
Additional deferred units to acquire (in years) 5 years        
Senior Executive Incentive Plan          
Defined Benefit Plan Disclosure [Line Items]          
Participant contribution period towards deferred compensation plans (in years) 4 years        
Participant after tax contribution period towards deferred compensation plans (in years) 15 years        
Pension Plans, Defined Benefit          
Defined Benefit Plan Disclosure [Line Items]          
Participant employment term, maximum years 20 years        
Deferred Compensation Plan          
Defined Benefit Plan Disclosure [Line Items]          
Deferred compensation and pension plans in periodic benefit expense cost expected to be recognized $ 2,300,000        
Total benefit obligation 121,042,000 124,566,000 89,138,000   $ 86,577,000
Deferred Compensation Plan | CSV of COLI Contracts          
Defined Benefit Plan Disclosure [Line Items]          
Gross CSV 180,300,000 175,700,000 172,300,000    
Outstanding policy loans $ 67,200,000 68,400,000 69,600,000    
Medical and Life Insurance | Legacy Hay          
Defined Benefit Plan Disclosure [Line Items]          
Benefit plan, number of participants | Person       190  
Defined benefit plan health care cost trend rate assumed 7.00%        
Defined benefit plan ultimate health care cost trend rate 5.00%        
Defined benefit plan year that rate reaches ultimate trend rate 2022        
Defined benefit plan effect of one percentage point increase on accumulated postretirement benefit obligation $ 100,000        
Defined benefit plan effect of one percentage point decrease on accumulated postretirement benefit obligation 100,000        
Total benefit obligation 12,147,000 13,006,000      
International Retirement Plans          
Defined Benefit Plan Disclosure [Line Items]          
Total benefit obligation $ 12,000,000 $ 15,400,000      
Long-term benefit obligation accrued, number of participants | Person 1,710 1,450      
Company's contributions $ 9,300,000 $ 5,100,000      
Executive Capital Accumulation Plan          
Defined Benefit Plan Disclosure [Line Items]          
Total benefit obligation 111,584,000 105,676,000 99,461,000    
Company's contributions 6,200,000 23,200,000 19,100,000    
Gain (loss) on deferred compensation plan 10,565,000 (1,654,000) $ 5,900,000    
Company's contributions, unamortized portion $ 25,500,000 33,200,000      
Executive Capital Accumulation Plan | Minimum          
Defined Benefit Plan Disclosure [Line Items]          
Deferred compensation arrangement vesting period 4 years        
Executive Capital Accumulation Plan | Maximum          
Defined Benefit Plan Disclosure [Line Items]          
Deferred compensation arrangement vesting period 5 years        
Defined Contribution Plan          
Defined Benefit Plan Disclosure [Line Items]          
Company's matching contributions $ 1,800,000 $ 1,700,000      
Percentage contribution by the participants to defined contribution plan 50.00%        
Company Owned Life Insurance Held In Trust | CSV of COLI Contracts          
Defined Benefit Plan Disclosure [Line Items]          
Net CSV $ 59,500,000        
Total death benefits, net of loans held in trust $ 99,900,000