Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill (Details) $ in Thousands	12 Months Ended
	Apr. 30, 2016 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 299,924
Acquisition Activity and Divestitures	517,965
Other Activity	(1,297)
Ending Balance	816,592
Operating Segments [Member] | Dental [Member]
Goodwill [Roll Forward]
Beginning Balance	139,449
Acquisition Activity and Divestitures	0
Other Activity	(320)
Ending Balance	139,129
Operating Segments [Member] | Animal Health [Member]
Goodwill [Roll Forward]
Beginning Balance	160,475
Acquisition Activity and Divestitures	517,965
Other Activity	(977)
Ending Balance	677,463
Operating Segments [Member] | Corporate [Member]
Goodwill [Roll Forward]
Beginning Balance	0
Acquisition Activity and Divestitures	0
Other Activity	0
Ending Balance	$ 0