Goodwill and Other Intangible Assets - Goodwill Balances and Related Activity by Business Segment (Detail) $ in Thousands	9 Months Ended
	Jan. 30, 2016 USD ($)
Goodwill [Roll Forward]
Balance at April 25, 2015	$ 299,924
Acquisition Activity and Divestitures	518,370
Other Activity	(2,978)
Balance at January 30, 2016	815,316
Operating Segments [Member] | Corporate [Member]
Goodwill [Roll Forward]
Balance at April 25, 2015	0
Acquisition Activity and Divestitures	0
Other Activity	0
Balance at January 30, 2016	0
Operating Segments [Member] | Dental [Member]
Goodwill [Roll Forward]
Balance at April 25, 2015	139,449
Acquisition Activity and Divestitures	0
Other Activity	(1,381)
Balance at January 30, 2016	138,068
Operating Segments [Member] | Animal Health [Member]
Goodwill [Roll Forward]
Balance at April 25, 2015	160,475
Acquisition Activity and Divestitures	518,370
Other Activity	(1,597)
Balance at January 30, 2016	$ 677,248