Unaudited Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Net sales	$ 306,130	$ 295,503	$ 265,838	$ 277,227	$ 251,744	$ 265,943	$ 276,665	$ 286,947	$ 1,144,698	$ 1,081,299
Gross margin	147,649	148,847	129,522	135,428	118,506	129,527	139,127	141,405	561,446	528,565	$ 578,678
Operating income (1)	40,802	46,725	37,412	42,188	33,219	22,669	41,244	40,891	167,127	138,023	$ 162,428
Net income	$ 28,027	$ 37,291	$ 30,860	$ 33,481	$ 27,685	$ 13,633	$ 33,553	$ 37,498	$ 129,659	$ 112,369
Class A Nonvoting Common Stock
Earnings (loss) from discontinued operations per Class A Common Share:
Basic	$ 0.54	$ 0.72	$ 0.59	$ 0.64	$ 0.53	$ 0.26	$ 0.63	$ 0.71	$ 2.49	$ 2.13	$ 2.50
Diluted	$ 0.53	$ 0.71	$ 0.59	$ 0.64	$ 0.53	$ 0.26	$ 0.62	$ 0.70	$ 2.47	$ 2.11	$ 2.46