Segment and Geographic Data - Sales Information by Product (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 29, 2017	Jan. 28, 2017	Oct. 29, 2016	Jul. 30, 2016	Apr. 30, 2016	Jan. 30, 2016	Oct. 31, 2015	Aug. 01, 2015	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Segment Reporting Information [Line Items]
Net sales	$ 1,400,609	$ 1,375,222	$ 1,385,737	$ 1,304,115	$ 1,445,032	$ 1,397,418	$ 1,418,241	$ 1,332,436	$ 5,465,683	$ 5,593,127	$ 5,386,703
Consumable
Segment Reporting Information [Line Items]
Net sales									4,415,643	4,400,888	4,153,921
Equipment and software
Segment Reporting Information [Line Items]
Net sales									709,253	834,526	857,001
Other
Segment Reporting Information [Line Items]
Net sales									340,787	357,713	375,781
Dental
Segment Reporting Information [Line Items]
Net sales									2,196,078	2,390,219	2,476,234
Dental | Consumable
Segment Reporting Information [Line Items]
Net sales									1,251,642	1,321,764	1,378,886
Dental | Equipment and software
Segment Reporting Information [Line Items]
Net sales									660,355	780,868	806,993
Dental | Other
Segment Reporting Information [Line Items]
Net sales									284,081	287,587	290,355
Animal Health
Segment Reporting Information [Line Items]
Net sales									3,242,564	3,159,826	2,862,249
Animal Health | Consumable
Segment Reporting Information [Line Items]
Net sales									3,164,001	3,079,124	2,775,035
Animal Health | Equipment and software
Segment Reporting Information [Line Items]
Net sales									48,898	53,658	50,008
Animal Health | Other
Segment Reporting Information [Line Items]
Net sales									29,665	27,044	37,206
Corporate
Segment Reporting Information [Line Items]
Net sales									27,041	43,082	48,220
Corporate | Other
Segment Reporting Information [Line Items]
Net sales									$ 27,041	$ 43,082	$ 48,220