Quarterly Results (unaudited) - Summary of Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 25, 2020	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 28, 2018	Apr. 25, 2020	Apr. 27, 2019	Apr. 28, 2018
Quarterly Financial Information [Line Items]
Net sales	$ 1,286,461	$ 1,456,155	$ 1,418,744	$ 1,328,651	$ 1,436,706	$ 1,396,745	$ 1,404,752	$ 1,336,320	$ 5,490,011	$ 5,574,523	$ 5,465,683
Gross profit	294,032	311,830	301,494	290,054	312,527	299,509	295,076	283,663	1,197,410	1,190,775	1,199,366
Operating (loss) income	(614,463)	43,816	(18,146)	16,674	46,623	45,363	41,216	4,514	(572,119)	137,716	219,889
Net (loss) income	(608,797)	22,972	(33,349)	29,807	27,685	31,054	28,646	(4,509)	(589,367)	82,876	200,974
Net loss attributable to noncontrolling interests	(211)	(255)	(220)	(235)	(305)	(171)	(223)	(53)	(921)	(752)	0
Net (loss) income attributable to Patterson Companies, Inc.	$ (608,586)	$ 23,227	$ (33,129)	$ 30,042	$ 27,990	$ 31,225	$ 28,869	$ (4,456)	$ (588,446)	$ 83,628	$ 200,974
(Loss) earnings per share attributable to Patterson Companies, Inc.:
Basic (in usd per share)	$ (6.44)	$ 0.25	$ (0.35)	$ 0.32	$ 0.30	$ 0.34	$ 0.31	$ (0.05)	$ (6.25)	$ 0.90	$ 2.17
Diluted (in usd per share)	$ (6.44)	$ 0.24	$ (0.35)	$ 0.32	$ 0.30	$ 0.33	$ 0.31	$ (0.05)	$ (6.25)	$ 0.89	$ 2.16
Goodwill impairment									$ 675,055	$ 0	$ 0
Investment gain				$ (34,334)					34,334	0	0
Litigation settlement				17,666				$ 28,263
Dental net sales
Quarterly Financial Information [Line Items]
Net sales									2,101,922	2,191,790	2,196,078
Operating (loss) income									$ 168,304	179,236	229,201
(Loss) earnings per share attributable to Patterson Companies, Inc.:
Revenue decrease, percentage									71.00%
Animal Health net sales
Quarterly Financial Information [Line Items]
Net sales									$ 3,336,253	3,354,528	3,242,564
Operating (loss) income									$ (594,743)	$ 81,472	$ 78,058
(Loss) earnings per share attributable to Patterson Companies, Inc.:
Goodwill impairment	$ 269,000			$ 406,055
Revenue decrease, percentage									9.00%