Supplemental financial statement information - Property, Plant And Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,317,436	$ 1,268,256
Less: accumulated depreciation	714,288	686,138
Property, plant and equipment, net	603,148	582,118
Depreciation	71,000	64,100	$ 64,500
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	41,814	40,346
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 15,560	15,128
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Property, plant and equipment, gross	$ 88,970	88,620
Vehicles, Including Transport Trailers [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	117,746	110,517
Bulk Equipment And District Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	115,927	110,983
Tanks, Cylinders And Customer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	825,361	786,912
Computer And Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	104,364	107,272
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 7,694	8,478
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minimum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minimum [Member] | Vehicles, Including Transport Trailers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	8 years
Minimum [Member] | Bulk Equipment And District Facilities [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Minimum [Member] | Tanks, Cylinders And Customer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minimum [Member] | Computer And Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years
Maximum [Member] | Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Maximum [Member] | Vehicles, Including Transport Trailers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Maximum [Member] | Bulk Equipment And District Facilities [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years
Maximum [Member] | Tanks, Cylinders And Customer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years
Maximum [Member] | Computer And Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Ferrellgas, L.P. [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 603,148	$ 582,118