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Partners' Deficit - Contributions and AOCI (Details) $ in Thousands, gal in Millions	3 Months Ended
	Oct. 31, 2019 USD ($) shares gal	Oct. 31, 2018 USD ($)	Jul. 31, 2019 shares
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	97,152,665		97,152,665
Net procurement of fixed priced propane by Ferrellgas in gallons \| gal	1.3
Contributions in connection with non-cash ESOP compensation charges	$ 795	$ 2,748
Ferrellgas, L.P. [Member]
Capital Unit [Line Items]
Net procurement of fixed priced propane by Ferrellgas in gallons \| gal	1.3
Contributions in connection with non-cash ESOP compensation charges	$ 795	$ 2,748
Ferrellgas Inc., General Partner [Member] \| Ferrellgas, L.P. [Member]
Capital Unit [Line Items]
General partner ownership interest	1.0101%	1.0101%
Ferrellgas Inc., General Partner [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
General partner ownership interest	1.00%
Ferrell Companies [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Limited partner ownership interest	23.20%
Ferrell Companies [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	22,529,361		22,529,361
Ferrell Companies [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Limited partner ownership interest	23.40%
Ferrell Companies [Member] \| FCI Trading Corp. [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	195,686
Ferrell Companies [Member] \| Ferrell Propane, Inc. [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	51,204
James E. Ferrell [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	4,763,475		4,763,475
James E. Ferrell [Member] \| JEF Capital Management [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	4,758,859
James E. Ferrell [Member] \| Ferrell Resources Holdings, Inc. [Member] \| Ferrellgas Partners LP [Member]
Capital Unit [Line Items]
Common unitholders, units outstanding \| shares	4,616
Common Unitholders [Member]
Capital Unit [Line Items]
Contributions in connection with non-cash ESOP compensation charges	$ 779	$ 2,693
Common Unitholders [Member] \| Ferrellgas, L.P. [Member]
Capital Unit [Line Items]
Contributions in connection with non-cash ESOP compensation charges	787	2,720
General Partner [Member]
Capital Unit [Line Items]
Non-cash contribution	16	100
Contributions in connection with non-cash ESOP compensation charges	8	27
General Partner [Member] \| Ferrellgas, L.P. [Member]
Capital Unit [Line Items]
Non-cash contribution	8	100
Contributions in connection with non-cash ESOP compensation charges	$ 8	$ 28