Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities (Derivatives Not Designated as Hedging Effect on Earnings) (Details) - Operating Expense [Member] - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Propane and related equipment sales [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ 1,027
Propane and related equipment sales [Member] | Ferrellgas, L.P. [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		1,027
Midstream - Crude Oil Logistics [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (1,390)	(1,241)
Midstream - Crude Oil Logistics [Member] | Ferrellgas, L.P. [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (1,390)	$ (1,241)