Segment and Geographic Data - Information about Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2016	Jan. 30, 2016	Oct. 31, 2015	Aug. 01, 2015	Apr. 25, 2015	Jan. 24, 2015	Oct. 25, 2014	Jul. 26, 2014	Apr. 30, 2016	Apr. 25, 2015	Apr. 26, 2014
Segment Reporting Information [Line Items]
Net sales	$ 1,453,770	$ 1,400,853	$ 1,389,210	$ 1,142,870	$ 1,035,061	$ 958,628	$ 978,220	$ 938,956	$ 5,386,703	$ 3,910,865	$ 3,585,141
Operating income	106,344	$ 95,729	$ 83,463	$ 62,177	89,073	$ 77,377	$ 72,140	$ 65,996	347,713	304,586	293,726
Depreciation and amortization									82,383	44,523	42,446
Total assets, excluding assets held for sale	3,520,804				2,191,107				3,520,804	2,191,107
Assets held for sale	0				754,141				0	754,141
Total assets	3,520,804				2,945,248				3,520,804	2,945,248
Operating Segments [Member] | Dental [Member]
Segment Reporting Information [Line Items]
Net sales									2,476,234	2,415,003	2,348,403
Operating income									312,176	300,357	284,674
Depreciation and amortization									18,903	18,568	17,416
Total assets	994,113				1,022,257				994,113	1,022,257
Operating Segments [Member] | Animal Health [Member]
Segment Reporting Information [Line Items]
Net sales									2,862,249	1,456,570	1,203,045
Operating income									94,318	56,670	49,855
Depreciation and amortization									44,243	8,861	7,237
Total assets	2,064,302				631,445				2,064,302	631,445
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Net sales									48,220	39,292	33,693
Operating income									(58,781)	(52,441)	(40,803)
Depreciation and amortization									19,237	17,094	$ 17,793
Total assets	$ 462,389				$ 537,405				$ 462,389	$ 537,405