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