Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities (Schedule of Derivative Collateral) (Details) - USD ($) $ in Thousands	Oct. 31, 2017	Jul. 31, 2017
Derivative Asset, Fair Value of Collateral	$ 5,184	$ 3,409
Derivative Liability, Fair Value of Collateral	25,641	10,802
Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	5,184	3,409
Derivative Liability, Fair Value of Collateral	25,641	10,802
Other assets, net [Member]
Derivative Asset, Fair Value of Collateral	1,461	1,631
Other assets, net [Member] | Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	1,461	1,631
Prepaid Expenses and Other Current Assets [Member]
Derivative Asset, Fair Value of Collateral	3,723	1,778
Prepaid Expenses and Other Current Assets [Member] | Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	3,723	1,778
Other Current Liabilities [Member]
Derivative Liability, Fair Value of Collateral	19,696	7,729
Other Current Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivative Liability, Fair Value of Collateral	19,696	7,729
Other Liabilities [Member]
Derivative Liability, Fair Value of Collateral	5,945	3,073
Other Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivative Liability, Fair Value of Collateral	$ 5,945	$ 3,073