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