Operating Segments Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Revenue by Principal Product
Net Sales	$ 70,885	$ 64,847	$ 206,908	$ 200,387
Business to Business Products
Revenue by Principal Product
Net Sales	26,041	24,784	77,825	79,226
Business to Business Products | Cat Litter
Revenue by Principal Product
Net Sales	3,441	2,945	9,943	10,018
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	5,622	5,203	18,320	18,182
Business to Business Products | Bleaching Clay and Fluids Purification
Revenue by Principal Product
Net Sales	13,662	12,094	38,116	37,639
Business to Business Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	3,316	4,542	11,446	13,387
Retail and Wholesale Products
Revenue by Principal Product
Net Sales	44,844	40,063	129,083	121,161
Retail and Wholesale Products | Cat Litter
Revenue by Principal Product
Net Sales	34,141	29,711	101,754	93,997
Retail and Wholesale Products | Industrial and Sports
Revenue by Principal Product
Net Sales	10,080	9,850	25,509	25,536
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	623	502	1,820	1,628
Retail and Wholesale Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	$ 0	$ 0	$ 0	$ 0