Fair Value Measurements - Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jan. 31, 2021	Jul. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	$ 34,433	$ 3,112
Commodity derivatives propane swap liabilities	(313)	(5,425)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	34,433	3,112
Commodity derivatives propane swap liabilities	(313)	(5,425)
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	34,433	3,112
Commodity derivatives propane swap liabilities	(313)	(5,425)
Ferrellgas, L.P. [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	34,433	3,112
Commodity derivatives propane swap liabilities	$ (313)	$ (5,425)