Preferred units - Distributions (Details) - USD ($) $ in Thousands			12 Months Ended
	Aug. 15, 2022	Aug. 16, 2021	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2020	Apr. 30, 2021
Temporary Equity [Line Items]
Quarterly distribution accrued			$ 17,500	$ 16,000		$ 8,000
Cash distribution		$ 15,700	63,356	8,011	$ 0
Preferred units additional quarterly distribution			900
Preferred units additional quarterly distribution accrued			$ 2,100
Cash tax distribution rate			25.00%
Tax rate multiplied by estimated taxable income percentage			0.25%
Additional distribution, percentage of taxable income			20.00%
Additional distribution, divisor			0.8
Subsequent Event [Member]
Temporary Equity [Line Items]
Cash distribution	$ 15,400
Minimum [Member]
Temporary Equity [Line Items]
Applicable premium distribution rate			0.75
Maximum [Member]
Temporary Equity [Line Items]
Applicable premium distribution rate			3
First Five Years After March 30, 2021 [Member] | Minimum [Member]
Temporary Equity [Line Items]
Preferred units distribution rate			8.956%
First Five Years After March 30, 2021 [Member] | Maximum [Member]
Temporary Equity [Line Items]
Preferred units distribution rate			11.125%
Ferrellgas, L.P. [Member]
Temporary Equity [Line Items]
Cash distribution			$ 63,356	$ 8,011