Consolidated Statements Of Partners' Deficit - USD ($)	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	$ (1,208,268,000)	$ (1,138,938,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	708,000	795,000
Distributions		(1,000)
Net loss	(46,453,000)	(45,717,000)
Other comprehensive income (loss)	7,917,000	(6,148,000)
Partners' capital balance, ending	(1,246,096,000)	(1,191,384,000)
Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		(1,375,000)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(2,303,000)	(14,512,000)
Other comprehensive income (loss)	7,837,000	(6,086,000)
Partners' capital balance, ending	5,534,000	(20,598,000)
Parent [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(1,200,042,000)	(1,131,233,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	701,000	787,000
Net loss	(46,062,000)	(45,344,000)
Other comprehensive income (loss)	7,837,000	(6,086,000)
Partners' capital balance, ending	(1,237,566,000)	(1,183,237,000)
Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		(1,361,000)
Non-Controlling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(8,226,000)	(7,705,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	7,000	8,000
Distributions		(1,000)
Net loss	(391,000)	(373,000)
Other comprehensive income (loss)	80,000	(62,000)
Partners' capital balance, ending	$ (8,530,000)	(8,147,000)
Non-Controlling Interest [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		$ (14,000)
Common Unitholders [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance (in shares)	97,152,700	97,152,700
Partners' capital balance, beginning	$ (1,126,452,000)	$ (1,046,245,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	694,000	779,000
Distributions	0
Net loss	$ (45,601,000)	$ (44,891,000)
Partners' capital balance (in shares)	97,152,700	97,152,700
Partners' capital balance, ending	$ (1,171,359,000)	$ (1,091,704,000)
Common Unitholders [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		$ (1,347,000)
General Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance (in shares)	989,900	989,900
Partners' capital balance, beginning	$ (71,287,000)	$ (70,476,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	7,000	8,000
Net loss	$ (461,000)	$ (453,000)
Partners' capital balance (in shares)	989,900	989,900
Partners' capital balance, ending	$ (71,741,000)	$ (70,935,000)
General Partner [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		(14,000)
Ferrellgas, L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(831,991,000)	(780,403,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	708,000	795,000
Distributions		(101,000)
Net loss	(38,751,000)	(36,898,000)
Other comprehensive income (loss)	7,917,000	(6,148,000)
Partners' capital balance, ending	(862,117,000)	(824,130,000)
Ferrellgas, L.P. [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		(1,375,000)
Ferrellgas, L.P. [Member] | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(2,313,000)	(14,647,000)
Other comprehensive income (loss)	7,917,000	(6,148,000)
Partners' capital balance, ending	5,604,000	(20,795,000)
Ferrellgas, L.P. [Member] | Common Unitholders [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(821,462,000)	(758,186,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	701,000	787,000
Distributions		(100,000)
Net loss	(38,360,000)	(36,525,000)
Partners' capital balance, ending	(859,121,000)	(795,385,000)
Ferrellgas, L.P. [Member] | Common Unitholders [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		(1,361,000)
Ferrellgas, L.P. [Member] | General Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning	(8,216,000)	(7,570,000)
Contributions in connection with non-cash ESOP and stock and unit-based compensation charges	7,000	8,000
Distributions		(1,000)
Net loss	(391,000)	(373,000)
Partners' capital balance, ending	$ (8,600,000)	(7,950,000)
Ferrellgas, L.P. [Member] | General Partner [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' capital balance, beginning		$ (14,000)