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Derivative Instruments and Hedging Activities - Effect on Comprehensive Income and Change in FV (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	$ (11,501)		$ (36,340)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		$ 1,870		$ (27,364)
Amount of gain (loss) reclassified from AOCI into income	(14,073)		(30,318)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(6,416)		(5,790)
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,501)		(36,340)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		1,870		(27,364)
Amount of gain (loss) reclassified from AOCI into income	(14,073)		(30,318)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(6,416)		(5,790)
Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,501)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		1,870
Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,501)		(36,340)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		1,870		(27,364)
Amount of gain (loss) reclassified from AOCI into income	(14,073)		(30,318)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		(6,416)		(5,790)
Cost of Sales [Member] \| Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative			(36,340)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption				(27,364)
Amount of gain (loss) reclassified from AOCI into income			$ (30,318)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption				$ (5,790)
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	$ (14,073)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		$ (6,416)