Derivative Instruments and Hedging Activities - Balance Sheet (Details) - USD ($)	6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jul. 31, 2018
Derivatives, Fair Value [Line Items]
Gain (loss) recognized due to ineffectiveness	$ 0	$ 0
Derivative Asset, Fair Value, Gross Asset	5,848,000		$ 22,470,000
Derivative Liability, Fair Value, Gross Liability	15,148,000		1,910,000
Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) recognized due to ineffectiveness	0	$ 0
Derivative Asset, Fair Value, Gross Asset	5,848,000		22,470,000
Derivative Liability, Fair Value, Gross Liability	15,148,000		1,910,000
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	5,408,000		17,123,000
Prepaid Expenses and Other Current Assets [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	5,408,000		17,123,000
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	13,859,000		1,832,000
Other Current Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	13,859,000		1,832,000
Other Assets, Net [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	440,000		5,347,000
Other Assets, Net [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap assets	440,000		5,347,000
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	1,289,000		78,000
Other Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Commodity derivatives propane swap liabilities	$ 1,289,000		$ 78,000