Customer Financing - Additional Information (Detail)	3 Months Ended
	Aug. 01, 2015 USD ($) Customer	Jul. 26, 2014 USD ($)	Apr. 25, 2015 USD ($)	Apr. 26, 2014 USD ($)
Customer Financing [Line Items]
Maximum credit financed for equipment purchases for any one customer	$ 500,000
Number of customer financing contracts | Customer	2
Financing contracts sold under ASC 860	$ 94,767,000	$ 85,100,000
Cash and cash equivalents	186,440,000	$ 260,740,000	$ 347,260,000	$ 264,908,000
Current receivables of finance contracts not yet sold	66,886,000		88,470,000
Unearned income	4,506,000		4,197,000
Finance contracts receivable sold and outstanding	554,072,000
Deferred purchase price	$ 79,392,000		66,715,000
Bad debt write-offs, percentage, maximum	1.00%
Unsettled Financing Arrangements [Member]
Customer Financing [Line Items]
Cash and cash equivalents	$ 26,202,000		$ 29,863,000
The Bank of Tokyo-Mitsubishi UFJ, Ltd. [Member]
Customer Financing [Line Items]
Capacity under agreement	500,000,000
Fifth Third Bank [Member]
Customer Financing [Line Items]
Capacity under agreement	$ 100,000,000
Minimum [Member] | The Bank of Tokyo-Mitsubishi UFJ, Ltd. [Member]
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral	13.00%
Minimum [Member] | Fifth Third Bank [Member]
Customer Financing [Line Items]
Percentage of principal amount of financing contracts held as collateral	23.00%