Deferred Compensation and Retirement Plans - Components of Net Periodic Benefits Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2024	Jul. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	6.00%	6.00%
Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10,655,000	$ 9,833,000
Interest cost	4,451,000	3,357,000
Amortization of actuarial loss	32,000	184,000
Expected return on plan assets	(266,000)	(272,000)
Net periodic service credit amortization	(101,000)	(101,000)
Net periodic benefit costs	$ 14,771,000	$ 13,001,000