Condensed parent only debtor in possession financial information - Balance Sheet (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Jul. 31, 2020	Jan. 31, 2020	Jul. 31, 2019
ASSETS
Cash and cash equivalents	$ 326,483	$ 333,761	$ 13,706	$ 11,054
Prepaid expenses and other current assets	72,914	35,944
Total assets	1,819,018	1,668,190
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Other current liabilities	191,908	167,466
Total liabilities not subject to compromise	2,581,744	2,876,458
Liabilities subject to compromise	390,101
Liabilities, Total	2,971,845	2,876,458
Partners' capital (deficit)
Partners' capital (deficit)	(1,145,317)	(1,200,042)
Total liabilities and partners' capital (deficit)	1,819,018	1,668,190
Debtor In Possession [Member]
ASSETS
Cash and cash equivalents	19,906	$ 6
Prepaid expenses and other current assets	269
Total assets	20,175
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Other current liabilities	1,661
Loan payable to Ferrellgas, L.P.	19,900
Accrued interest payable	251
Total liabilities not subject to compromise	21,812
Liabilities subject to compromise	390,101
Liabilities, Total	411,913
Investment in Ferrellgas, L.P.	753,579
Partners' capital (deficit)
Partners' capital (deficit)	(1,145,317)
Total liabilities and partners' capital (deficit)	$ 20,175