Fair Value Measurements - Assets and Liabilities (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jul. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	$ 3,112	$ 1,259
Commodity derivatives propane swap liabilities	(5,425)	(16,015)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	3,112	1,259
Commodity derivatives propane swap liabilities	(5,425)	(16,015)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	0	0
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	3,112	1,259
Commodity derivatives propane swap liabilities	(5,425)	(16,015)
Ferrellgas, L.P. [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	0	0
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	3,112	1,259
Commodity derivatives propane swap liabilities	(5,425)	(16,015)
Ferrellgas, L.P. [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	$ 0	$ 0