Accounts And Notes Receivable, Net And Accounts Receivable Securitization - Additional information (Details)			9 Months Ended	12 Months Ended
	Apr. 10, 2020	Apr. 09, 2020	Apr. 30, 2020 USD ($)	Jul. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral			$ 134,443,000	$ 106,145,000
Required fixed charge coverage ratio			175.00%
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral			$ 134,443,000	106,145,000
Required fixed charge coverage ratio			175.00%
Minimum [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured leverage ratio			5.5
Increase in interest rate (as a percent)	0.50%
Accounts Receivable Securitization Facility [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateralized notes payable			$ 0	62,000,000
Receipts from accounts receivable securitization			0	62,000,000
Capacity to receive additional proceeds			91,000,000	$ 0
Weighted average interest rate of debt				5.50%
Margin added to variable rate (as a percent)	2.50%
Increase in interest rate (as a percent)	0.50%
Accounts Receivable Securitization Facility [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateralized notes payable			0	$ 62,000,000
Receipts from accounts receivable securitization			0	62,000,000
Capacity to receive additional proceeds			$ 91,000,000	$ 0
Weighted average interest rate of debt				5.50%
Required fixed charge coverage ratio			100.00%
Senior secured leverage ratio			3.00
Margin added to variable rate (as a percent)	2.50%
Accounts Receivable Securitization Facility [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured leverage ratio			3.00
Margin added to variable rate (as a percent)	4.50%
Agreement extension period			3 years
Accounts Receivable Securitization Facility [Member] | Maximum [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Margin added to variable rate (as a percent)	4.50%
Accounts Receivable Securitization Facility [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Required fixed charge coverage ratio			100.00%
Margin added to variable rate (as a percent)	1.00%	0.00%
Accounts Receivable Securitization Facility [Member] | Minimum [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Margin added to variable rate (as a percent)	1.00%	0.00%