Deferred Compensation and Retirement Plans - Reconciliation of Deferred Compensation and Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Change in fair value of plan assets:
Total liability	$ 483,773	$ 423,753
Deferred Compensation Plan
Change in benefit obligation:
Balance, beginning of year	246,340	211,598
Service cost	43,879	40,843	$ 37,952
Interest cost	13,447	9,511	4,028
Actuarial gain	(5,001)	(6,083)
Administrative expenses paid	(240)	(168)
Benefits paid from plan assets	(1,988)	(1,901)
Benefits paid from cash	(15,511)	(7,460)
Balance, end of year	280,926	246,340	211,598
Change in fair value of plan assets:
Fair value of plan assets, beginning of year	19,085	21,990
Actual return on plan assets	795	(836)
Benefits paid from plan assets	(1,988)	(1,901)
Administrative expenses paid	(240)	(168)
Employer contributions	871	0
Fair value of plan assets, end of year	18,523	19,085	$ 21,990
Funded status and balance, end of year	(262,403)	(227,255)
Current liability	26,093	15,447
Non-current liability	236,310	211,808
Total liability	$ 262,403	$ 227,255
Plan assets weighted average allocation	100.00%	100.00%
Deferred Compensation Plan | CSV of COLI Contracts
Change in fair value of plan assets:
Gross CSV	$ 295,900	$ 275,100
Outstanding policy loans	$ 77,000	$ 77,100
Deferred Compensation Plan | Debt securities
Change in fair value of plan assets:
Plan assets weighted average allocation	47.00%	44.00%
Deferred Compensation Plan | Equity securities
Change in fair value of plan assets:
Plan assets weighted average allocation	51.00%	52.00%
Deferred Compensation Plan | Other
Change in fair value of plan assets:
Plan assets weighted average allocation	2.00%	4.00%