Fair Value Measurements - Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Apr. 30, 2020	Jul. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	$ 244	$ 1,259
Commodity derivatives propane swap liabilities	(21,022)	(16,015)
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	244	1,259
Commodity derivatives propane swap liabilities	(21,022)	(16,015)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	244	1,259
Commodity derivatives propane swap liabilities	(21,022)	(16,015)
Level 2 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity derivatives propane swap assets	244	1,259
Commodity derivatives propane swap liabilities	$ (21,022)	$ (16,015)