Accounts And Notes Receivable, Net And Accounts Receivable Securitization - Additional information (Details)	6 Months Ended	12 Months Ended
	Jan. 31, 2021 USD ($)	Jul. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 200,443,000	$ 103,703,000
Required fixed charge coverage ratio	175.00%
Accounts Receivable Securitization Facility [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateralized notes payable	$ 0	0
Receipts from accounts receivable securitization	0	0
Capacity to receive additional proceeds	$ 87,000,000	11,000,000
Agreement extension period	3 years
Accounts Receivable Securitization Facility [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured leverage ratio	3.00
Accounts Receivable Securitization Facility [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Required fixed charge coverage ratio	100.00%
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 200,443,000	103,703,000
Note receivable, original principal amount	$ 19,900,000
Required fixed charge coverage ratio	175.00%
Ferrellgas, L.P. [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured leverage ratio	5.5
Ferrellgas, L.P. [Member] | Accounts Receivable Securitization Facility [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateralized notes payable	$ 0	0
Receipts from accounts receivable securitization	0	0
Capacity to receive additional proceeds	$ 87,000,000	$ 11,000,000
Agreement extension period	3 years
Ferrellgas, L.P. [Member] | Accounts Receivable Securitization Facility [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured leverage ratio	3.00
Ferrellgas, L.P. [Member] | Accounts Receivable Securitization Facility [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Required fixed charge coverage ratio	100.00%