Net loss per unitholders' interest (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Oct. 31, 2022	Oct. 31, 2021
Earnings Distribution Allocation [Line Items]
Net loss attributable to Ferrellgas Partners, L.P.	$ (4,545)	$ (8,606)
Less: General partner's interest in net loss	(45)	(86)
Undistributed net loss attributable to Class A unitholders	$ (20,751)	(25,525)
Allocation of earnings to Class B units relative to allocation to Class A units	6
Preferred Units
Earnings Distribution Allocation [Line Items]
Less: Distributions to preferred unitholders	$ 16,251	$ 17,005
Class A Limited Partner Units
Earnings Distribution Allocation [Line Items]
Weighted average Class A Units outstanding	4,857,600	4,857,600
Basic and diluted net loss per Class A unit	$ (4.27)	$ (5.25)
Class B Limited Partner Units
Earnings Distribution Allocation [Line Items]
Percentage of allocated earnings	100.00%