Revenue from contracts with customers (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Disaggregation of Revenue [Line Items]
Accounts receivable collection period													30 days
Residential customer, annual cost spread period													12 months
Rental income recognition period													1 year
Revenues	$ 281,649	$ 412,130	$ 510,833	$ 293,214	$ 279,081	$ 479,625	$ 573,377	$ 352,309	$ 347,521	$ 515,810	$ 755,156	$ 454,655	$ 1,497,826	$ 1,684,392	$ 2,073,142
Contract assets and liabilities
Accounts receivable	108,483				96,450								108,483	96,450
Contract assets	7,079				13,609								7,079	13,609
Contract liabilities
Deferred revenue	$ 42,911				31,974								42,911	31,974
Deferred revenue recognized													$ 29,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01
Contract liabilities
Remaining performance obligation recognition period	1 year												1 year
Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues													$ 1,497,826
Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues													964,087
Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues													430,435
Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues													21,269
Other Revenues
Disaggregation of Revenue [Line Items]
Revenues													$ 82,035	75,534	147,847
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,684,392	1,790,823
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,128,991	1,082,046
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues														419,349	448,943
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues														60,518	111,987
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues														75,534	147,847
Ferrellgas, L.P. [Member]
Disaggregation of Revenue [Line Items]
Accounts receivable collection period													30 days
Residential customer, annual cost spread period													12 months
Rental income recognition period													1 year
Revenues	$ 281,649	$ 412,130	$ 510,833	$ 293,214	279,081	$ 479,625	$ 573,377	$ 352,309	$ 347,521	$ 515,810	$ 755,156	$ 454,655	$ 1,497,826	1,684,392	2,073,142
Contract assets and liabilities
Accounts receivable	108,483				96,450								108,483	96,450
Contract assets	7,079				13,609								7,079	13,609
Contract liabilities
Deferred revenue	$ 42,911				$ 31,974								42,911	31,974
Deferred revenue recognized													$ 29,800
Ferrellgas, L.P. [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01
Contract liabilities
Remaining performance obligation recognition period	1 year												1 year
Ferrellgas, L.P. [Member] | Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues													$ 1,497,826
Ferrellgas, L.P. [Member] | Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues													964,087
Ferrellgas, L.P. [Member] | Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues													430,435
Ferrellgas, L.P. [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues													21,269
Ferrellgas, L.P. [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues													$ 82,035	75,534	147,847
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenues															2,073,142
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,684,392	1,790,823
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,128,991	1,082,046
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues														419,349	448,943
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues														60,518	111,987
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues														$ 75,534	$ 147,847