Derivative Instruments and Hedging Activities - Balance Sheet (Details) - USD ($)	6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jul. 31, 2020
Derivatives, Fair Value [Line Items]
Gain (loss) recognized due to ineffectiveness	$ 0	$ 0
Derivative Asset, Fair Value, Gross Asset	34,433,000		$ 3,112,000
Derivative Liability, Fair Value, Gross Liability	313,000		5,425,000
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	32,270,000		2,846,000
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	209,000		5,029,000
Other Assets, Net [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	2,163,000		266,000
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	104,000		396,000
Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) recognized due to ineffectiveness	0	$ 0
Derivative Asset, Fair Value, Gross Asset	34,433,000		3,112,000
Derivative Liability, Fair Value, Gross Liability	313,000		5,425,000
Ferrellgas, L.P. [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	32,270,000		2,846,000
Ferrellgas, L.P. [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	209,000		5,029,000
Ferrellgas, L.P. [Member] | Other Assets, Net [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	2,163,000		266,000
Ferrellgas, L.P. [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	$ 104,000		$ 396,000