Warranty Reserves Estimated Cost (Details)	3 Months Ended
Jul. 28, 2018 USD ($)
Warranty Reserves
Standard Product Warranty Accrual, Preexisting, Increase (Decrease)	$ 712,000
UAS \| Warranty reserve.
Warranty Reserves
Standard Product Warranty Accrual, Preexisting, Increase (Decrease)	$ 712,000

Amount of increase (decrease) in the standard product warranty accrual from changes in estimates attributable to preexisting product warranties. Excludes extended product warranties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph ((c)(4))
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

Name:	us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration