Segment Reporting - Information about Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 27, 2019	Jul. 28, 2018	Apr. 27, 2019
Segment Reporting Information [Line Items]
Net sales	$ 1,328,651	$ 1,336,320
Operating income (loss)	16,674	4,514
Total assets	3,349,622		$ 3,269,269
Consumable
Segment Reporting Information [Line Items]
Net sales	1,096,017	1,109,397
Equipment and software
Segment Reporting Information [Line Items]
Net sales	139,237	146,898
Other
Segment Reporting Information [Line Items]
Net sales	93,397	80,025
Dental
Segment Reporting Information [Line Items]
Net sales	501,136	506,064
Dental | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	34,004	35,873
Total assets	702,292		641,721
Dental | Consumable
Segment Reporting Information [Line Items]
Net sales	302,011	304,239
Dental | Equipment and software
Segment Reporting Information [Line Items]
Net sales	125,684	134,957
Dental | Other
Segment Reporting Information [Line Items]
Net sales	73,441	66,868
Animal Health
Segment Reporting Information [Line Items]
Net sales	817,539	825,214
Animal Health | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	19,624	19,032
Total assets	2,214,787		2,156,723
Animal Health | Consumable
Segment Reporting Information [Line Items]
Net sales	794,006	805,158
Animal Health | Equipment and software
Segment Reporting Information [Line Items]
Net sales	13,553	11,941
Animal Health | Other
Segment Reporting Information [Line Items]
Net sales	9,980	8,115
Corporate
Segment Reporting Information [Line Items]
Net sales	9,976	5,042
Corporate | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	(36,954)	(50,391)
Total assets	432,543		$ 470,825
Corporate | Other
Segment Reporting Information [Line Items]
Net sales	9,976	5,042
United States
Segment Reporting Information [Line Items]
Net sales	1,090,715	1,096,464
United States | Dental
Segment Reporting Information [Line Items]
Net sales	444,642	453,573
United States | Animal Health
Segment Reporting Information [Line Items]
Net sales	636,097	637,849
United States | Corporate
Segment Reporting Information [Line Items]
Net sales	9,976	5,042
United Kingdom
Segment Reporting Information [Line Items]
Net sales	149,414	153,905
United Kingdom | Animal Health
Segment Reporting Information [Line Items]
Net sales	149,414	153,905
Canada
Segment Reporting Information [Line Items]
Net sales	88,522	85,951
Canada | Dental
Segment Reporting Information [Line Items]
Net sales	56,494	52,491
Canada | Animal Health
Segment Reporting Information [Line Items]
Net sales	$ 32,028	$ 33,460