Supplemental Information - Inventories (Details) $ in Thousands, gal in Millions	6 Months Ended
	Jan. 31, 2021 USD ($) gal	Jul. 31, 2020 USD ($)
Supplemental Financial Statement Information [Line Items]
Propane gas and related products	$ 76,843	$ 58,733
Appliances, parts and supplies	13,630	13,931
Inventories	$ 90,473	72,664
Supply procurement contract duration	36 months
Net procurement of fixed priced propane by Ferrellgas in gallons | gal	2.7
Ferrellgas, L.P. [Member]
Supplemental Financial Statement Information [Line Items]
Propane gas and related products	$ 76,843	58,733
Appliances, parts and supplies	13,630	13,931
Inventories	$ 90,473	$ 72,664
Supply procurement contract duration	36 months
Net procurement of fixed priced propane by Ferrellgas in gallons | gal	2.7