Customer Financing (Detail)	3 Months Ended
	Jul. 31, 2021 USD ($) financingAgreement	Jul. 25, 2020 USD ($)	Apr. 24, 2021 USD ($)
Customer Financing [Line Items]
Maximum credit financed for equipment purchases for any one customer	$ 1,000,000
Number of customer financing contracts | financingAgreement	2
Financing contracts sold	$ 73,043,000	$ 50,070,000
Gain on sale of financing contracts	(721,000)	(2,386,000)
Proceeds from Receivables sold	108,111,000	71,844,000
Cash and cash equivalents	136,930,000		$ 143,244,000
Current receivables of finance contracts not yet sold	19,070,000		50,638,000
Finance contracts receivable sold and outstanding	$ 618,332,000
Bad debt write-offs, percentage (less than)	1.00%
Unsettled Financing Arrangements
Customer Financing [Line Items]
Cash and cash equivalents	$ 37,858,000		$ 36,771,000
Customer Finance Contracts
Customer Financing [Line Items]
Gain on sale of financing contracts	$ 73,000	$ (342,000)
The Bank of Tokyo-Mitsubishi UFJ, Ltd.
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral (at least)	15.00%
Capacity under agreement	$ 525,000,000
Fifth Third Bank
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral (at least)	15.00%
Capacity under agreement	$ 100,000,000