Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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

Segment Information - International net sales (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 28, 2019	Jan. 27, 2019	Oct. 28, 2018	Jul. 29, 2018	Apr. 29, 2018	Jan. 28, 2018	Oct. 29, 2017	Jul. 30, 2017	Apr. 28, 2019	Apr. 29, 2018	Apr. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales	$ 70,963	$ 77,226	$ 77,006	$ 71,473	$ 78,184	$ 85,310	$ 80,698	$ 79,533	$ 296,669	$ 323,725	$ 309,544
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									22,500	21,900	22,300
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
net sales									$ 29,800	$ 32,600	$ 26,600