Deferred Compensation and Retirement Plans - Total Long-Term Benefit Obligations (Detail) - USD ($) $ in Thousands		Apr. 30, 2021	Apr. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation		$ 364,793	$ 308,279
Less: current portion of benefit obligation	[1]	(18,338)	(19,143)
Deferred compensation and other retirement plans		346,455	289,136
Deferred Compensation and Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation		178,994	156,586
Medical and Life Insurance Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation		6,584	7,527
International Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation		15,633	14,851
Executive Capital Accumulation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation		$ 163,582	$ 129,315

[1] Current portion of benefit obligation is included in Compensation and benefits payable in the consolidated balance sheet