Accounts And Notes Receivable, Net And Accounts Receivable Securitization (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2018	Jul. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
current leverage ratio	696.00%
current consolidated interest coverage ratio	214.00%	214.00%
Debt Instrument, Covenant Compliance	193.2		67.5
Debt Instrument, Covenant Description	24.9
Accounts receivable pledged as collateral	$ 235,150,000	$ 235,150,000	$ 109,407,000
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
current leverage ratio	696.00%
current consolidated interest coverage ratio	214.00%	214.00%
Debt Instrument, Covenant Compliance	193.2		67.5
Debt Instrument, Covenant Description	24.9
Accounts receivable pledged as collateral	$ 235,150,000	$ 235,150,000	$ 109,407,000
Accounts Receivable Securitization [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	235,200,000	235,200,000	109,400,000
Collateralized notes payable	$ 166,000,000	166,000,000	69,000,000
Proceeds from accounts receivable securitization		166,000,000	69,000,000
Available proceeds from additional trade accounts receivable		$ 0	$ 0
Weighted average interest rate on borrowings under accounts receivable securitization	4.00%	4.00%	4.00%
Accounts Receivable Securitization [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 235,200,000	$ 235,200,000	$ 109,400,000
Collateralized notes payable	$ 166,000,000	166,000,000	69,000,000
Proceeds from accounts receivable securitization		166,000,000	69,000,000
Available proceeds from additional trade accounts receivable		$ 0	$ 0
Weighted average interest rate on borrowings under accounts receivable securitization	4.00%	4.00%	4.00%
Interest Coverage Covenant [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Instrument, Covenant Compliance	25.3
Debt Instrument, Covenant Description	44.3
Interest Coverage Covenant [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Instrument, Covenant Compliance	25.3
Debt Instrument, Covenant Description	44.3