Accounts And Notes Receivable, Net And Accounts Receivable Securitization (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Oct. 31, 2017	Jul. 31, 2017	Jul. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
current leverage ratio	757.00%
current consolidated interest coverage ratio	193.00%
Debt Instrument, Covenant Compliance	40.6	67.5
Debt Instrument, Covenant Description	5.2
Accounts receivable pledged as collateral	$ 137,244,000	$ 109,407,000
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
current leverage ratio	757.00%
current consolidated interest coverage ratio	193.00%
Debt Instrument, Covenant Compliance	40.6	67.5
Debt Instrument, Covenant Description	5.2
Accounts receivable pledged as collateral	$ 137,244,000	$ 109,407,000
Accounts Receivable Securitization [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	137,200,000	109,400,000
Collateralized notes payable	88,000,000	$ 69,000,000
Proceeds from accounts receivable securitization	88,000,000		$ 69,000,000
Available proceeds from additional trade accounts receivable	$ 0		0
Weighted average interest rate on borrowings under accounts receivable securitization	3.70%	4.00%
Accounts Receivable Securitization [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 137,200,000	$ 109,400,000
Collateralized notes payable	88,000,000	$ 69,000,000
Proceeds from accounts receivable securitization	88,000,000		69,000,000
Available proceeds from additional trade accounts receivable	$ 0		$ 0
Weighted average interest rate on borrowings under accounts receivable securitization	3.70%	4.00%
Interest Coverage Covenant [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Instrument, Covenant Compliance	12.1
Debt Instrument, Covenant Description	21.1
Interest Coverage Covenant [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Instrument, Covenant Compliance	12.1
Debt Instrument, Covenant Description	21.1