Deferred Compensation and Retirement Plans - Weighted-Average Assumptions Used In Calculating The Medical and Life Insurance Plan (Detail) - Medical and Life Insurance - Hay Group	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Discount rate, beginning of year	4.85%	4.25%	2.54%	2.45%
Discount rate, end of year	4.85%	4.25%	2.54%	2.45%
Healthcare care cost trend rate	6.50%	6.00%	6.25%

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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