Supplemental Information - Inventories (Details) $ in Thousands, gal in Millions	3 Months Ended
	Oct. 31, 2020 USD ($) gal	Jul. 31, 2020 USD ($)
Supplemental Financial Statement Information [Line Items]
Propane gas and related products	$ 65,513	$ 58,733
Appliances, parts and supplies	13,467	13,931
Inventories	$ 78,980	72,664
Supply procurement contract duration	36 months
Net procurement of fixed priced propane by Ferrellgas in gallons | gal	1.7
Ferrellgas, L.P. [Member]
Supplemental Financial Statement Information [Line Items]
Propane gas and related products	$ 65,513	58,733
Appliances, parts and supplies	13,467	13,931
Inventories	$ 78,980	$ 72,664
Supply procurement contract duration	36 months
Net procurement of fixed priced propane by Ferrellgas in gallons | gal	1.7