Derivative Instruments and Hedging Activities - Effect on Comprehensive Income and Change in FV (Details) - USD ($)	12 Months Ended
Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	$ (22,872,000)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		$ (48,184,000)	$ 30,231,000
Amount of gain (loss) reclassified from AOCI into income	(35,315,000)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(12,868,000)	24,319,000
Amount of gain (loss) reclassified, ineffective portion	0	0	0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0
Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(22,872,000)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(48,184,000)	30,231,000
Interest Rate Swap [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income, pre-adoption			(395,000)
Amount of gain (loss) reclassified, ineffective portion			0
Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	(35,315,000)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(12,868,000)	24,714,000
Amount of gain (loss) reclassified, ineffective portion	0	0	0
Midstream Operations [Member] \| Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			(3,470,000)
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(22,872,000)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(48,184,000)	30,231,000
Amount of gain (loss) reclassified from AOCI into income	(35,315,000)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(12,868,000)	24,319,000
Amount of gain (loss) reclassified, ineffective portion	0	0	0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0
Ferrellgas, L.P. [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(22,872,000)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(48,184,000)	30,231,000
Ferrellgas, L.P. [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income, pre-adoption			(395,000)
Ferrellgas, L.P. [Member] \| Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	(35,315,000)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(12,868,000)	24,714,000
Amount of gain (loss) reclassified, ineffective portion	$ 0	$ 0	0
Ferrellgas, L.P. [Member] \| Midstream Operations [Member] \| Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			$ (3,470,000)

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount before tax of reclassification adjustments of other comprehensive income (loss).

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