Operating Segments Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Revenue by Principal Product
Net Sales	$ 76,256	$ 70,885	$ 218,383	$ 206,908
Business to Business Products
Revenue by Principal Product
Net Sales	26,683	26,041	77,632	77,825
Business to Business Products | Cat Litter
Revenue by Principal Product
Net Sales	3,779	3,441	11,026	9,943
Business to Business Products | Industrial and Sports
Revenue by Principal Product
Net Sales	0	0	0	0
Business to Business Products | Agricultural and Horticultural
Revenue by Principal Product
Net Sales	6,222	5,622	16,518	18,320
Business to Business Products | Bleaching Clay and Fluids Purification
Revenue by Principal Product
Net Sales	12,537	13,662	37,142	38,116
Business to Business Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	4,145	3,316	12,946	11,446
Retail and Wholesale Products
Revenue by Principal Product
Net Sales	49,573	44,844	140,751	129,083
Retail and Wholesale Products | Cat Litter
Revenue by Principal Product
Net Sales	41,040	34,141	116,010	101,754
Retail and Wholesale Products | Industrial and Sports
Revenue by Principal Product
Net Sales	7,894	10,080	22,906	25,509
Retail and Wholesale Products | Agricultural and Horticultural
Revenue by Principal Product
Net Sales	0	0	0	0
Retail and Wholesale Products | Bleaching Clay and Fluids Purification
Revenue by Principal Product
Net Sales	639	623	1,835	1,820
Retail and Wholesale Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	$ 0	$ 0	$ 0	$ 0