Deferred Compensation and Retirement Plans - Additional Information (Detail)	12 Months Ended
	Apr. 30, 2023 USD ($) jurisdiction participant	Apr. 30, 2022 USD ($) participant	Apr. 30, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Fair value of marketable securities increase (decrease)	$ 2,900,000	$ (12,000,000)	$ 38,500,000
Increase in market value of the underlying COLI investments	10,576,000	5,819,000	13,017,000
Net CSV	197,998,000	183,308,000
CSV of COLI Contracts
Defined Benefit Plan Disclosure [Line Items]
Total death benefits payable, net of loans	444,100,000	449,300,000
Increase in market value of the underlying COLI investments	10,600,000	5,800,000	13,000,000
Net CSV	$ 198,000,000	183,300,000
Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation range	40.00%
Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation range	40.00%
Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation range	60.00%
Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation range	60.00%
Long Term Performance Unit Plan
Defined Benefit Plan Disclosure [Line Items]
Vesting percentage on each anniversary date	25.00%
Number of payments after the seventh anniversary of the grant date	5 years
Long Term Performance Unit Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Value per unit award	$ 25,000
Annual benefit payments per vested unit after anniversary period	12,500
Long Term Performance Unit Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Value per unit award	50,000
Annual benefit payments per vested unit after anniversary period	$ 25,000
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
Medical and Life Insurance | Hay Group
Defined Benefit Plan Disclosure [Line Items]
Benefit plan, number of participants | participant	107
Total benefit obligation	$ 4,838,000	5,365,000	6,584,000
International retirement plans
Defined Benefit Plan Disclosure [Line Items]
Number of foreign jurisdictions | jurisdiction	25
Total benefit obligation	$ 13,600,000	$ 14,400,000
Long-term benefit obligation accrued, number of participants | participant	4,058	3,568
Company's contributions	$ 16,400,000	$ 14,800,000
Executive Capital Accumulation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	178,043,000	166,723,000	163,582,000
Company's contributions	$ 6,500,000	$ 7,500,000	8,200,000
Deferred compensation arrangement vesting period	5 years	5 years
Deferred compensation plan expense (income)	$ 3,464,000	$ (10,602,000)	37,300,000
Company's contributions, unamortized portion	$ 16,100,000	18,200,000
Executive Capital Accumulation Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Option to receive employee benefits by quarterly installments periods	1 year
Executive Capital Accumulation Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Option to receive employee benefits by quarterly installments periods	15 years
Defined Contribution Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage contribution by the participants to defined contribution plan	50.00%
Employer matching contribution percentage	10.00%
Company's matching contributions	$ 3,500,000	2,100,000
Company's matching contributions next fiscal year	3,100,000
Company's additional matching contribution	2,700,000	3,000,000
Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	246,340,000	211,598,000	$ 205,740,000
Deferred Compensation Plan | CSV of COLI Contracts
Defined Benefit Plan Disclosure [Line Items]
Gross CSV	275,100,000	263,200,000
Outstanding policy loans	77,100,000	$ 79,800,000
Company Owned Life Insurance Held In Trust | CSV of COLI Contracts
Defined Benefit Plan Disclosure [Line Items]
Net CSV	173,900,000
Total death benefits, net of loans held in trust	$ 393,300,000