Derivative Instruments and Hedging Activities - Effect on Comprehensive Income and Change in FV (Details) - USD ($) $ in Thousands	3 Months Ended
Oct. 31, 2019	Oct. 31, 2018
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	$ (13,627)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		$ (8,154)
Amount of gain (loss) reclassified from AOCI into income	(7,479)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		4,433
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(13,627)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(8,154)
Amount of gain (loss) reclassified from AOCI into income	(7,479)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		4,433
Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(13,627)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(8,154)
Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(13,627)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(8,154)
Propane [Member] \| Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	(7,479)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		4,433
Propane [Member] \| Cost of Sales [Member] \| Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	$ (7,479)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		$ 4,433

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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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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