Deferred Compensation And Retirement Plans - Components Of Net Periodic Benefit Costs (Detail) - Medical and Life Insurance plan - Hay Group - USD ($) $ in Thousands		12 Months Ended
		Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost		$ 140	$ 227	$ 243
Net periodic service credit amortization		(308)	(308)	(308)
Amortization of actuarial gain				(14)
Net periodic benefit cost	[1]	$ (168)	$ (81)	$ (79)

[1] The service cost, interest cost and the other components of net periodic benefit costs are included in compensation and benefits expense, interest expense, net and other income (loss), net, respectively, on the consolidated statements of income.