Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

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Amount of expense charged against earnings to allocate the cost of tangible and intangible assets over their remaining economic lives, classified as other.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Apr. 30, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 477,792		$ 477,792		$ 462,943
Less accumulated amortization and depreciation	(270,893)		(270,893)		(254,680)
Property, Plant and Equipment, Net, Total	206,899		206,899		208,263
Amortization and depreciation expense on property, plant and equipment	9,200	$ 9,000	18,300	$ 17,800
Accumulated amortization on capital leases	31,400		31,400		30,800
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,431		4,431		4,751
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	114,794		114,794		114,421
Buildings and improvements - finance leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,202		11,202		11,202
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	304,075		304,075		294,993
Machinery and equipment - finance leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	30,649		30,649		30,574
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12,641		$ 12,641		$ 7,002