Segment Reporting - Sales Information by Product (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 25, 2014	Oct. 26, 2013	Oct. 25, 2014	Oct. 26, 2013
Segment Reporting Information [Line Items]
Consolidated	$ 1,103,325	$ 998,834	$ 2,162,854	$ 1,878,959
Consumable and printed products [Member]
Segment Reporting Information [Line Items]
Consolidated	790,840	714,643	1,587,617	1,324,592
Equipment and software [Member]
Segment Reporting Information [Line Items]
Consolidated	228,572	205,569	408,001	401,712
Other Products and Services [Member]
Segment Reporting Information [Line Items]
Consolidated	$ 83,913	$ 78,622	$ 167,236	$ 152,655