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Derivative Instruments and Hedging Activities - Effect on Comprehensive Income and Change in FV (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	$ (11,212)		$ (24,839)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		$ (21,080)		$ (29,234)
Amount of gain (loss) reclassified from AOCI into income	(8,766)		(16,245)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		3,807		626
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,212)		(24,839)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(21,080)		(29,234)
Amount of gain (loss) reclassified from AOCI into income	(8,766)		(16,245)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		3,807		626
Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,212)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(21,080)
Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative	(11,212)		(24,839)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption		(21,080)		(29,234)
Amount of gain (loss) reclassified from AOCI into income	(8,766)		(16,245)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		3,807		626
Cost of Sales [Member] \| Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of gain (loss) recognized in AOCI on derivative			(24,839)
Amount of gain (loss) recognized in AOCI on derivative, pre-adoption				(29,234)
Amount of gain (loss) reclassified from AOCI into income			$ (16,245)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption				$ 626
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	$ (8,766)
Amount of gain (loss) reclassified from AOCI into income, pre-adoption		$ 3,807