Fair Value of Financial Instruments - Summary of Fair Value Hierarchy for Financial Assets and Liabilities Measured Recurring Basis (Detail) $ in Thousands	Jan. 31, 2022 USD ($) CompensationPlan	Apr. 30, 2021 USD ($) CompensationPlan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	$ 2,715	$ 2,757
Financial Liabilities	$ 3,164	$ 3,169
Number of non-qualified compensation plans maintained | CompensationPlan	2	2
Non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities	$ 3,164	$ 3,169
Trading securities held in non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	1,274	1,299
Cash surrender value of life insurance policies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	1,441	1,458
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	1,274	1,299
Financial Liabilities	0	0
Level 1 | Non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities	0	0
Level 1 | Trading securities held in non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	1,274	1,299
Level 1 | Cash surrender value of life insurance policies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	1,441	1,458
Financial Liabilities	3,164	3,169
Level 2 | Non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities	3,164	3,169
Level 2 | Trading securities held in non-qualified compensation plans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	0	0
Level 2 | Cash surrender value of life insurance policies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets	$ 1,441	$ 1,458