Derivative Instruments and Hedging Activities - Effect on Earnings (Details) - Interest Rate Swap [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jan. 31, 2018	Jan. 31, 2018
Derivative [Line Items]
Amount of Gain Recognized	$ 88	$ 226
Amount of Interest Expense Recognized	(2,275)	(4,550)
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Amount of Gain Recognized	88	226
Amount of Interest Expense Recognized	$ (2,275)	$ (4,550)