Segment Reporting - Sales Information by Product (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 30, 2016	Aug. 01, 2015
Segment Reporting Information [Line Items]
Net sales	$ 1,332,436	$ 1,142,870
Consumable [Member]
Segment Reporting Information [Line Items]
Net sales	1,076,221	895,307
Equipment and Software [Member]
Segment Reporting Information [Line Items]
Net sales	160,946	153,483
Other [Member]
Segment Reporting Information [Line Items]
Net sales	$ 95,269	$ 94,080