Deferred Compensation and Retirement Plans - Fair Value Measurements of Defined Benefit Plan Assets (Detail) - Deferred compensation and pension plans - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	$ 19,085	$ 21,990
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	18,350	21,353
Money market funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	735	637
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	735	637
Level 1 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	0	0
Level 1 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	735	637
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	18,350	21,353
Level 2 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	18,350	21,353
Level 2 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	0	0
Level 3 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	0	0
Level 3 | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit plan assets	$ 0	$ 0