Revenue from contracts with customers (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	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, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
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	$ 279,081	$ 479,625	$ 573,377	$ 352,309	$ 347,521	$ 515,810	$ 755,156	$ 454,655	$ 433,376	$ 538,109	$ 579,250	$ 379,542	$ 1,684,392	$ 2,073,142	$ 1,930,277
Contract assets and liabilities
Accounts receivable	96,450				119,818								96,450	119,818
Contract assets	13,609				8,691								13,609	8,691
Contract liabilities
Deferred revenue	$ 31,974				29,933								31,974	29,933
Deferred revenue recognized													$ 27,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-02-01
Contract liabilities
Remaining performance obligation recognition period	1 year												1 year
Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues													$ 1,684,392
Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues													1,128,991
Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues													419,349
Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues													60,518
Other Revenues
Disaggregation of Revenue [Line Items]
Revenues													$ 75,534	147,847	145,162
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,790,823	1,463,574
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues														1,082,046	852,130
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues														448,943	396,100
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues														111,987	70,182
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues														147,847	145,162
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	$ 279,081	$ 479,625	$ 573,377	$ 352,309	347,521	$ 515,810	$ 755,156	$ 454,655	$ 433,376	$ 538,109	$ 579,250	$ 379,542	$ 1,684,392	2,073,142	1,930,277
Contract assets and liabilities
Accounts receivable	96,450				119,818								96,450	119,818
Contract assets	13,609				8,691								13,609	8,691
Contract liabilities
Deferred revenue	$ 31,974				$ 29,933								31,974	29,933
Deferred revenue recognized													$ 27,000
Ferrellgas, L.P. [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-02-01
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													$ 1,684,392
Ferrellgas, L.P. [Member] | Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues													1,128,991
Ferrellgas, L.P. [Member] | Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues													419,349
Ferrellgas, L.P. [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues													60,518
Ferrellgas, L.P. [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues													$ 75,534	147,847	145,162
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenues														2,073,142	1,930,277
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														1,790,823	1,463,574
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														1,082,046	852,130
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														448,943	396,100
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues														111,987	70,182
Ferrellgas, L.P. [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues														$ 147,847	$ 145,162