Accounts Receivable (Detail) - USD ($) $ in Thousands	Jul. 30, 2017	Apr. 30, 2017		Jul. 31, 2016	May 01, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customers	$ 23,548	$ 26,211		$ 24,669
Accounts receivable, net	22,140	24,577	[1]	22,690
Allowance for doubtful accounts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Valuation allowance, balance	(325)	(414)		(850)	$ (1,088)
Reserve for returns and allowances and discounts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Valuation allowance, balance	$ (1,083)	$ (1,220)		$ (1,129)	$ (962)

[1] Derived from audited financial statements.