Deferred Compensation and Retirement Plans - Schedule of Reconciliation of Deferred Compensation and Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
Change in fair value of plan assets:
Total liability	$ 526,388	$ 483,773
Deferred Compensation Plan
Change in benefit obligation:
Balance, beginning of year	280,926	246,340
Service cost	46,147	43,879	$ 40,843
Interest cost	17,772	13,447	9,511
Actuarial loss (gain)	1,482	(5,001)
Administrative expenses paid	(234)	(240)
Benefits paid from plan assets	(1,900)	(1,988)
Benefits paid from cash	(27,310)	(15,511)
Balance, end of year	316,883	280,926	246,340
Change in fair value of plan assets:
Fair value of plan assets, beginning of year	18,523	19,085
Actual return on plan assets	1,547	795
Benefits paid from plan assets	(1,900)	(1,988)
Administrative expenses paid	(234)	(240)
Employer contributions	631	871
Fair value of plan assets, end of year	18,567	18,523	$ 19,085
Funded status and balance, end of year	(298,316)	(262,403)
Current liability	36,332	26,093
Non-current liability	261,984	236,310
Total liability	$ 298,316	$ 262,403
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	$ 325,500	$ 295,900
Outstanding policy loans	$ 72,800	$ 77,000
Deferred Compensation Plan | Debt securities
Change in fair value of plan assets:
Plan assets weighted average allocation	46.00%	47.00%
Deferred Compensation Plan | Equity securities
Change in fair value of plan assets:
Plan assets weighted average allocation	50.00%	51.00%
Deferred Compensation Plan | Other
Change in fair value of plan assets:
Plan assets weighted average allocation	4.00%	2.00%