Operating Segments Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Revenue by Principal Product
Net Sales	$ 76,097	$ 71,122
Business to Business Products
Revenue by Principal Product
Net Sales	27,522	26,478
Business to Business Products | Cat Litter
Revenue by Principal Product
Net Sales	3,876	3,697
Business to Business Products | Industrial and Sports
Revenue by Principal Product
Net Sales	0	0
Business to Business Products | Agricultural and Horticultural
Revenue by Principal Product
Net Sales	6,987	5,719
Business to Business Products | Bleaching Clay and Fluids Purification
Revenue by Principal Product
Net Sales	12,641	12,223
Business to Business Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	4,018	4,839
Retail and Wholesale Products
Revenue by Principal Product
Net Sales	48,575	44,644
Retail and Wholesale Products | Cat Litter
Revenue by Principal Product
Net Sales	40,794	36,379
Retail and Wholesale Products | Industrial and Sports
Revenue by Principal Product
Net Sales	7,262	7,600
Retail and Wholesale Products | Agricultural and Horticultural
Revenue by Principal Product
Net Sales	0	0
Retail and Wholesale Products | Bleaching Clay and Fluids Purification
Revenue by Principal Product
Net Sales	519	665
Retail and Wholesale Products | Animal Health and Nutrition
Revenue by Principal Product
Net Sales	$ 0	$ 0