Accounts And Notes Receivable, Net And Accounts Receivable Securitization Accounts And Notes Receiable, Net And Accounts Receivable Securitization (Consolidated Interest Coverage Ratio) (Details)	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
required consolidated interest coverage ratio	250.00%	175.00%	175.00%	175.00%	175.00%	175.00%
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
required consolidated interest coverage ratio	250.00%	250.00%	250.00%	250.00%	250.00%	250.00%
Ferrellgas, L.P. [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
required consolidated interest coverage ratio	250.00%	175.00%	175.00%	175.00%	175.00%	175.00%
Ferrellgas, L.P. [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
required consolidated interest coverage ratio	250.00%	250.00%	250.00%	250.00%	250.00%	250.00%