Quarterly Results (unaudited) - Summary of Quarterly Results (Details) - USD ($)	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. 29, 2017	Apr. 30, 2016	Apr. 25, 2015
Condensed Income Statements, Captions [Line Items]
Asset impairment charges									$ 36,312,000	$ 0	$ 0
Repatriation of foreign earnings								$ 200,000,000	200,000,000
Tax impact of repatriation of foreign earnings								$ 11,800,000	(2,406,000)	12,300,000
Tax impact of repatriation of foreign earnings per diluted share (in usd per share)								$ 0.12
Net sales	$ 1,445,032,000	$ 1,397,418,000	$ 1,418,241,000	$ 1,332,436,000	$ 1,453,770,000	$ 1,400,853,000	$ 1,389,210,000	$ 1,142,870,000	5,593,127,000	5,386,703,000	3,910,865,000
Gross profit	335,498,000	329,761,000	318,960,000	317,178,000	363,741,000	339,864,000	330,899,000	288,244,000	1,301,397,000	1,322,748,000	1,060,549,000
Operating income from continuing operations	96,155,000	46,554,000	79,803,000	65,416,000	106,344,000	95,729,000	83,463,000	62,177,000	287,928,000	347,713,000	304,586,000
Net income from continuing operations	61,357,000	27,769,000	45,756,000	38,906,000	65,620,000	57,190,000	42,563,000	20,311,000	173,788,000	185,684,000	180,083,000
Net income from discontinued operations	334,000	(3,229,000)	0	0	0	(750,000)	(7,142,000)	9,392,000
Net income	$ 61,691,000	$ 24,540,000	$ 45,756,000	$ 38,906,000	$ 65,620,000	$ 56,440,000	$ 35,421,000	$ 29,703,000	$ 170,893,000	$ 187,184,000	$ 223,261,000
Basic earnings (loss) per share:
Continuing operations (in usd per share)	$ 0.65	$ 0.29	$ 0.48	$ 0.41	$ 0.69	$ 0.60	$ 0.43	$ 0.20	$ 1.83	$ 1.91	$ 1.82
Discontinued operations (in usd per share)	0.01	(0.03)	0.00	0.00	0.00	(0.01)	(0.07)	0.10	(0.03)	0.02	0.44
Basic (in usd per share)	0.66	0.26	0.48	0.41	0.69	0.59	0.36	0.30	1.80	1.93	2.26
Diluted earnings (loss) per share:
Continuing operations (in usd per share)	0.65	0.29	0.48	0.40	0.68	0.60	0.43	0.20	1.82	1.90	1.81
Discontinued operations (in usd per share)	0.00	(0.03)	0.00	0.00	0.00	(0.01)	(0.07)	0.10	(0.03)	0.01	0.43
Diluted (in usd per share)	$ 0.65	$ 0.26	$ 0.48	$ 0.40	$ 0.68	$ 0.59	$ 0.36	$ 0.30	$ 1.79	$ 1.91	$ 2.24
Animal Health International [Member]
Condensed Income Statements, Captions [Line Items]
Pre-tax transaction costs								$ 9,302,000
Diluted earnings (loss) per share:
Diluted (in usd per share)								$ 0.09
Dental [Member]
Condensed Income Statements, Captions [Line Items]
Asset impairment charges		$ 36,312,000
Net sales									$ 2,390,219,000	$ 2,476,234,000	$ 2,415,003,000
Operating income from continuing operations									$ 263,671,000	$ 312,176,000	$ 300,357,000