Intangibles (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
Jul. 31, 2021	Jul. 31, 2020	Apr. 30, 2021
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 11,400	$ 12,300
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangibles, gross	274,000		$ 274,000
Less accumulated amortization	(163,639)		(152,222)
Intangibles, net	$ 110,361		$ 121,778

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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