Property, Plant, and Equipment - Summary of Depreciation and Amortization Expense (Detail) - USD ($) $ in Thousands		12 Months Ended
		Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Depreciation And Other Amortization Expenses [Line Items]
Depreciation and amortization		$ 19,826	$ 23,909	$ 24,990
Cost of Sales
Depreciation And Other Amortization Expenses [Line Items]
Depreciation and amortization		1,016	1,837	1,969
Research and Development
Depreciation And Other Amortization Expenses [Line Items]
Depreciation and amortization		43	83	81
Selling, Marketing, and Distribution Expenses
Depreciation And Other Amortization Expenses [Line Items]
Depreciation and amortization		114	175	39
General and Administrative
Depreciation And Other Amortization Expenses [Line Items]
Depreciation and amortization	[1]	$ 18,653	$ 21,814	$ 22,901

[1] General and administrative expenses included $16.3 million, $18.6 million, and $21.5 million of amortization for the fiscal years ended April 30, 2021, 2020, and 2019, respectively, which were recorded as a result of our acquisitions.