Deferred Compensation and Retirement Plans - Schedule of Components of Net Periodic Benefits Costs (Detail) - Deferred Compensation Plan - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 46,147	$ 43,879	$ 40,843
Interest cost	17,772	13,447	9,511
Amortization of actuarial loss	248	818	945
Expected return on plan assets	(1,065)	(1,088)	(1,156)
Net prior service credit amortization	(97)	(97)	(97)
Net periodic benefit cost	$ 63,005	$ 56,959	$ 50,046