Segment and Geographic Data - Sales Information by Product (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 26, 2014	Jan. 25, 2014	Oct. 26, 2013	Jul. 27, 2013	Apr. 27, 2013	Jan. 26, 2013	Oct. 27, 2012	Jul. 28, 2012	Apr. 26, 2014	Apr. 27, 2013	Apr. 28, 2012
Segment Reporting Information [Line Items]
Net sales	$ 1,102,077	$ 1,082,679	$ 998,834	$ 880,125	$ 964,933	$ 915,861	$ 867,193	$ 889,225	$ 4,063,715	$ 3,637,212	$ 3,535,661
Consumable and printed products [Member]
Segment Reporting Information [Line Items]
Net sales									2,776,765	2,343,407	2,312,309
Equipment and software [Member]
Segment Reporting Information [Line Items]
Net sales									973,814	993,767	930,601
Other [Member]
Segment Reporting Information [Line Items]
Net sales									313,136	300,038	292,751
Dental supply [Member]
Segment Reporting Information [Line Items]
Net sales									2,382,096	2,379,970	2,287,875
Dental supply [Member] | Consumable and printed products [Member]
Segment Reporting Information [Line Items]
Net sales									1,289,652	1,273,222	1,263,515
Dental supply [Member] | Equipment and software [Member]
Segment Reporting Information [Line Items]
Net sales									828,858	843,880	768,633
Dental supply [Member] | Other [Member]
Segment Reporting Information [Line Items]
Net sales									263,586	262,868	255,727
Rehabilitation supply [Member]
Segment Reporting Information [Line Items]
Net sales									478,574	501,997	513,340
Rehabilitation supply [Member] | Consumable and printed products [Member]
Segment Reporting Information [Line Items]
Net sales									352,181	361,164	363,004
Rehabilitation supply [Member] | Equipment and software [Member]
Segment Reporting Information [Line Items]
Net sales									100,936	114,818	123,649
Rehabilitation supply [Member] | Other [Member]
Segment Reporting Information [Line Items]
Net sales									25,457	26,015	26,687
Veterinary supply [Member]
Segment Reporting Information [Line Items]
Net sales									1,203,045	755,245	734,446
Veterinary supply [Member] | Consumable and printed products [Member]
Segment Reporting Information [Line Items]
Net sales									1,134,932	709,021	685,790
Veterinary supply [Member] | Equipment and software [Member]
Segment Reporting Information [Line Items]
Net sales									44,020	35,069	38,319
Veterinary supply [Member] | Other [Member]
Segment Reporting Information [Line Items]
Net sales									$ 24,093	$ 11,155	$ 10,337