Derivative Instruments and Hedging Activities - Effect on Comprehensive Income and Change in FV (Details) - USD ($)	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	$ (48,184,000)	$ 30,231,000	$ 22,525,000
Amount of gain (loss) reclassified from AOCI into income	(12,868,000)	24,319,000	(1,938,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	(1,293,000)	3,457,000
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(48,184,000)	30,231,000	22,525,000
Amount of gain (loss) reclassified from AOCI into income	(12,868,000)	24,319,000	(1,938,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	(1,293,000)	3,457,000
Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(48,184,000)	30,231,000	21,659,000
Commodity Derivatives Propane [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(48,184,000)	30,231,000	21,659,000
Interest Rate Swap [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative		0	866,000
Cost of Sales [Member] | Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	(12,868,000)	24,714,000	154,000
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0
Cost of Sales [Member] | Commodity Derivatives Propane [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	(12,868,000)	24,714,000	154,000
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	0	0
Operating Expense [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			1,090,000
Operating Expense [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			1,090,000
Interest Expense [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income		(395,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net		0
Interest Expense [Member] | Interest Rate Swap [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income		(395,000)	(2,092,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net		0
Midstream Operations [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		(3,470,000)	(425,000)
Midstream Operations [Member] | Cost of Sales [Member] | Ferrellgas, L.P. [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ (3,470,000)	$ (425,000)