Derivative Instruments and Hedging Activities - AOCI Rollforward (Details) gal in Millions	3 Months Ended
	Oct. 31, 2020 USD ($) gal	Oct. 31, 2019 USD ($)
Derivative [Line Items]
Partners' capital balance, beginning	$ (1,208,268,000)	$ (1,138,938,000)
Change in value of derivative	5,767,000	(13,627,000)
Reclassification of losses on derivatives to earnings, net	2,150,000	7,479,000
Partners' capital balance, ending	(1,246,096,000)	(1,191,384,000)
Reclassification of net gain to earnings during next 12 months	5,200,000
Gain (loss) on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, net	$ 0	0
Number of barrels of propane covered by cash flow hedges | gal	3.6
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member]
Derivative [Line Items]
Partners' capital balance, beginning	$ (2,313,000)	(14,756,000)
Change in value of derivative	5,767,000	(13,627,000)
Reclassification of losses on derivatives to earnings, net	2,150,000	7,479,000
Partners' capital balance, ending	5,604,000	(20,904,000)
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Partners' capital balance, beginning	(831,991,000)	(780,403,000)
Change in value of derivative	5,767,000	(13,627,000)
Reclassification of losses on derivatives to earnings, net	2,150,000	7,479,000
Partners' capital balance, ending	(862,117,000)	(824,130,000)
Reclassification of net gain to earnings during next 12 months	5,200,000
Gain (loss) on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, net	$ 0	0
Number of barrels of propane covered by cash flow hedges | gal	3.6
Ferrellgas, L.P. [Member] | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member]
Derivative [Line Items]
Partners' capital balance, beginning	$ (2,313,000)	(14,756,000)
Change in value of derivative	5,767,000	(13,627,000)
Reclassification of losses on derivatives to earnings, net	2,150,000	7,479,000
Partners' capital balance, ending	$ 5,604,000	$ (20,904,000)