Deferred Compensation and Retirement Plans - Components of Net Periodic Benefits Costs (Detail) - Deferred Compensation Plan - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 40,843	$ 37,952	$ 31,947
Interest cost	9,511	4,028	4,035
Amortization of actuarial loss	945	2,170	4,117
Net prior service credit amortization	(97)	(97)	(97)
Expected return on plan assets	(1,156)	(1,554)	(1,404)
Net periodic benefit cost	$ 50,046	$ 42,499	$ 38,598