Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2021		Apr. 30, 2020		Apr. 30, 2019
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 932,203	$ 751,191	$ 812,856	$ 802,573	$ 770,850	$ 761,352	$ 861,929	$ 847,176	$ 3,298,823		$ 3,241,307		$ 3,116,032
Gross Profit	293,850	243,324	265,071	260,458	251,594	253,473	284,493	273,654	1,062,703		1,063,214		1,004,119
Net income	$ 33,746	$ 16,126	$ 28,469	$ 27,219	$ (41,456)	$ 10,879	$ 29,138	$ 24,820	$ 105,560		$ 23,381		$ 56,002
Weighted average shares outstanding:
Basic (in shares)	42,994	42,726	42,723	42,624	42,435	42,223	41,761	41,001	42,765		41,853		40,914
Diluted (in shares)	43,828	43,361	43,174	43,017	42,435	42,949	42,635	41,615	43,343		42,504		41,589
Net income per share:
Basic (in dollars per share)	$ 0.78	$ 0.38	$ 0.67	$ 0.64	$ (0.98)	$ 0.26	$ 0.70	$ 0.60	$ 2.47	[1]	$ 0.56	[1]	$ 1.33	[1]
Diluted (in dollars per share)	$ 0.77	$ 0.37	$ 0.66	$ 0.63	$ (0.98)	$ 0.25	$ 0.68	$ 0.59	$ 2.44	[1]	$ 0.55	[1]	$ 1.31	[1]
Impairment of goodwill					$ 63,100				$ 0		$ 63,074		$ 0
Gain on legal settlement					$ 14,000				$ 1,382		$ 14,029		$ 0

[1] See Note 18 for detailed calculations.