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Deferred Compensation and Retirement Plans - Components of Net Periodic Benefits Costs (Parenthetical) (Detail)	9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Expected long-term rate of return on plan assets	6.25%	6.50%

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- References

No definition available.

+ Details

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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