Derivative Instruments and Hedging Activities (Changes in Derivative Value Effect on Other Comprehensive Income Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Beginning balance	$ 32,915		$ 14,601
Change in value of risk management derivatives	22,449	$ 5,138
Reclassification of gains and losses on commodity hedges to cost of product sold - propane and other gas liquids sales	(3,949)	4,238
Ending balance	32,915
Ferrellgas, L.P. [Member]
Beginning balance	33,264		14,764
Change in value of risk management derivatives	22,449	5,138
Reclassification of gains and losses on commodity hedges to cost of product sold - propane and other gas liquids sales	(3,949)	4,238
Ending balance	33,264
Propane commodity derivatives [Member]
Change in value of risk management derivatives	22,323	4,873
Reclassification of gains and losses on commodity hedges to cost of product sold - propane and other gas liquids sales	(4,132)	3,596
Propane commodity derivatives [Member] | Ferrellgas, L.P. [Member]
Change in value of risk management derivatives	22,323	4,873
Reclassification of gains and losses on commodity hedges to cost of product sold - propane and other gas liquids sales	(4,132)	3,596
Interest Rate Swap [Member]
Change in value of risk management derivatives	126	265
Derivative, Net Hedge Ineffectiveness Gain (Loss)	183	642
Interest Rate Swap [Member] | Ferrellgas, L.P. [Member]
Change in value of risk management derivatives	126	265
Derivative, Net Hedge Ineffectiveness Gain (Loss)	183	642
Derivative [Member]
Beginning balance	33,148	(439)	14,648	$ (9,815)
Ending balance	33,148	(439)
Derivative [Member] | Ferrellgas, L.P. [Member]
Beginning balance	33,148	(439)	$ 14,648	$ (9,815)
Ending balance	$ 33,148	$ (439)