15. Product Warranties (Details)	12 Months Ended
Apr. 30, 2019
Product Warranties Disclosures [Abstract]
Standard Product Warranty Description	The Company generally provides its customers with a one-year warranty regarding the manufactured quality and functionality of its products. For some limited products, the warranty period has been extended.

Describes the nature of the product warranty, including the approximate term of the product warranty, how the product warranty arose, and the events or circumstances that would require the warrantor to perform under the product warranty.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration