Goodwill and Intangible Assets - Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
Jul. 31, 2020	Jul. 31, 2019
Intangible assets
Amortization expense	$ 14,270	$ 16,853
Depreciation and amortization expense
Intangible assets
Amortization expense	$ 14,300	$ 16,900

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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