Accounts And Notes Receivable, Net And Accounts Receivable Securitization (Narrative) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Apr. 30, 2018	Jul. 31, 2017	May 14, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 182,486,000	$ 109,407,000
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	182,486,000	109,407,000
Accounts Receivable Securitization [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	182,500,000	109,400,000
Collateralized notes payable	104,000,000	69,000,000
Proceeds from accounts receivable securitization	104,000,000	69,000,000
Available proceeds from additional trade accounts receivable	$ 19,000,000.0	$ 0
Weighted average interest rate on borrowings under accounts receivable securitization	4.20%	4.00%
Accounts Receivable Securitization [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 182,500,000	$ 109,400,000
Collateralized notes payable	104,000,000	69,000,000
Proceeds from accounts receivable securitization	104,000,000	69,000,000
Available proceeds from additional trade accounts receivable	$ 19,000,000.0	$ 0
Weighted average interest rate on borrowings under accounts receivable securitization	4.20%	4.00%
Asset-backed Securities, Securitized Loans and Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable Securitization Program, Maximum Capacity	$ 225,000,000
Asset-backed Securities, Securitized Loans and Receivables [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable Securitization Program, Maximum Capacity	$ 225,000,000
Asset-backed Securities, Securitized Loans and Receivables [Member] | Subsequent Event [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable Securitization Program, Maximum Capacity			$ 250,000,000
Asset-backed Securities, Securitized Loans and Receivables [Member] | Subsequent Event [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable Securitization Program, Maximum Capacity			$ 250,000,000