Segment Reporting - Information about Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 25, 2020	Jul. 27, 2019	Apr. 25, 2020
Segment Reporting Information [Line Items]
Net sales	$ 1,245,837	$ 1,328,651
Operating income (loss)	37,872	16,674
Total assets	2,646,196		$ 2,715,350
Consumable
Segment Reporting Information [Line Items]
Net sales	1,044,981	1,095,184
Equipment and software
Segment Reporting Information [Line Items]
Net sales	129,377	142,533
Value-added services and other
Segment Reporting Information [Line Items]
Net sales	71,479	90,934
Dental
Segment Reporting Information [Line Items]
Net sales	430,295	501,136
Dental | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	37,769	34,004
Total assets	748,001		704,216
Dental | Consumable
Segment Reporting Information [Line Items]
Net sales	256,603	303,474
Dental | Equipment and software
Segment Reporting Information [Line Items]
Net sales	112,963	125,684
Dental | Value-added services and other
Segment Reporting Information [Line Items]
Net sales	60,729	71,978
Animal Health
Segment Reporting Information [Line Items]
Net sales	812,153	817,539
Animal Health | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	17,399	19,624
Total assets	1,345,259		1,485,284
Animal Health | Consumable
Segment Reporting Information [Line Items]
Net sales	788,378	791,710
Animal Health | Equipment and software
Segment Reporting Information [Line Items]
Net sales	16,414	16,849
Animal Health | Value-added services and other
Segment Reporting Information [Line Items]
Net sales	7,361	8,980
Corporate
Segment Reporting Information [Line Items]
Net sales	3,389	9,976
Corporate | Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	(17,296)	(36,954)
Total assets	552,936		$ 525,850
Corporate | Value-added services and other
Segment Reporting Information [Line Items]
Net sales	3,389	9,976
United States
Segment Reporting Information [Line Items]
Net sales	1,034,872	1,090,715
United States | Dental
Segment Reporting Information [Line Items]
Net sales	397,460	444,642
United States | Animal Health
Segment Reporting Information [Line Items]
Net sales	634,023	636,097
United States | Corporate
Segment Reporting Information [Line Items]
Net sales	3,389	9,976
United Kingdom
Segment Reporting Information [Line Items]
Net sales	149,392	149,414
United Kingdom | Animal Health
Segment Reporting Information [Line Items]
Net sales	149,392	149,414
Canada
Segment Reporting Information [Line Items]
Net sales	61,573	88,522
Canada | Dental
Segment Reporting Information [Line Items]
Net sales	32,835	56,494
Canada | Animal Health
Segment Reporting Information [Line Items]
Net sales	$ 28,738	$ 32,028