Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities (Schedule of Derivative Collateral) (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Jul. 31, 2017
Derivative Asset, Fair Value of Collateral	$ 4,422	$ 3,409
Derivative Liability, Fair Value of Collateral	17,417	10,802
Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	4,422	3,409
Derivative Liability, Fair Value of Collateral	17,417	10,802
Other assets, net [Member]
Derivative Asset, Fair Value of Collateral	1,404	1,631
Other assets, net [Member] | Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	1,404	1,631
Prepaid Expenses and Other Current Assets [Member]
Derivative Asset, Fair Value of Collateral	3,018	1,778
Prepaid Expenses and Other Current Assets [Member] | Ferrellgas, L.P. [Member]
Derivative Asset, Fair Value of Collateral	3,018	1,778
Other Current Liabilities [Member]
Derivative Liability, Fair Value of Collateral	12,201	7,729
Other Current Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivative Liability, Fair Value of Collateral	12,201	7,729
Other Liabilities [Member]
Derivative Liability, Fair Value of Collateral	5,216	3,073
Other Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivative Liability, Fair Value of Collateral	$ 5,216	$ 3,073