Customer Financing (Detail)	3 Months Ended
	Jul. 29, 2017 USD ($) finance_agreement	Jul. 30, 2016 USD ($)	Apr. 29, 2017 USD ($)	Apr. 30, 2016 USD ($)
Customer Financing [Line Items]
Maximum credit financed for equipment purchases for any one customer	$ 1,000,000
Number of customer financing contracts | finance_agreement	2
Financing contracts sold under ASC 860	$ 56,123,000	$ 109,594,000
Revenues from Sale of Financing Contracts	4,260,000	10,185,000
Cash and cash equivalents	99,779,000	$ 89,978,000	$ 94,959,000	$ 137,453,000
Current receivables of finance contracts not yet sold	114,532,000		124,098,000
Unearned income	0		940,000
Finance contracts receivable sold and outstanding	592,681,000
Deferred purchase price	$ 105,618,000		119,798,000
Bad debt write-offs, percentage (less than)	1.00%
Unsettled Financing Arrangements
Customer Financing [Line Items]
Cash and cash equivalents	$ 23,525,000		$ 17,902,000
The Bank of Tokyo-Mitsubishi UFJ, Ltd.
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral (at least)	9.00%
Capacity under agreement	$ 575,000,000
Fifth Third Bank
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral (at least)	10.00%
Capacity under agreement	$ 100,000,000