Fair Value Measurements - Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Oct. 31, 2020	Jul. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	$ 7,161	$ 3,112
Commodity derivatives propane swap liabilities	(1,557)	(5,425)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	7,161	3,112
Commodity derivatives propane swap liabilities	(1,557)	(5,425)
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	7,161	3,112
Commodity derivatives propane swap liabilities	(1,557)	(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	7,161	3,112
Commodity derivatives propane swap liabilities	$ (1,557)	$ (5,425)