Segment and Geographic Data - Information about Reportable Segments (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
Operating income (loss)	41,251	$ 50,046	$ 71,759	$ 56,833	$ 96,155	$ 46,554	$ 79,803	$ 65,416	219,889	287,928	347,713
Depreciation and amortization									83,816	83,818	82,383
Total assets	3,507,913								3,471,664	3,507,913
Dental
Segment Reporting Information [Line Items]
Net sales									2,196,078	2,390,219	2,476,234
Operating income (loss)									229,201	263,671	312,176
Depreciation and amortization									7,435	11,840	18,903
Total assets	863,970								853,555	863,970
Animal Health
Segment Reporting Information [Line Items]
Net sales									3,242,564	3,159,826	2,862,249
Operating income (loss)									78,058	88,132	94,318
Depreciation and amortization									50,892	50,144	44,243
Total assets	2,119,512								2,128,800	2,119,512
Corporate
Segment Reporting Information [Line Items]
Net sales									27,041	43,082	48,220
Operating income (loss)									(87,370)	(63,875)	(58,781)
Depreciation and amortization									25,489	21,834	$ 19,237
Total assets	$ 524,431								$ 489,309	$ 524,431