Fair Value Measurements (Assets And Liabilities Fair Value Hierarchy) (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Jul. 31, 2017
Interest rate swap assets		$ 583
Propane commodity derivative assets	$ 25,725	16,212
Interest rate swap liabilities	(2,423)	(707)
Propane commodity derivative liabilities	(1,417)	(1,258)
Ferrellgas, L.P. [Member]
Interest rate swap assets		583
Propane commodity derivative assets	25,725	16,212
Interest rate swap liabilities	(2,423)	(707)
Propane commodity derivative liabilities	(1,417)	(1,258)
Fair Value, Inputs, Level 1 [Member]
Interest rate swap assets		0
Propane commodity derivative assets	0	0
Interest rate swap liabilities	0	0
Propane commodity derivative liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Ferrellgas, L.P. [Member]
Interest rate swap assets		0
Propane commodity derivative assets	0	0
Interest rate swap liabilities	0	0
Propane commodity derivative liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Interest rate swap assets		583
Propane commodity derivative assets	25,725	16,212
Interest rate swap liabilities	(2,423)	(707)
Propane commodity derivative liabilities	(1,417)	(1,258)
Fair Value, Inputs, Level 2 [Member] | Ferrellgas, L.P. [Member]
Interest rate swap assets		583
Propane commodity derivative assets	25,725	16,212
Interest rate swap liabilities	(2,423)	(707)
Propane commodity derivative liabilities	(1,417)	(1,258)
Fair Value, Inputs, Level 3 [Member]
Interest rate swap assets		0
Propane commodity derivative assets	0	0
Interest rate swap liabilities	0	0
Propane commodity derivative liabilities	0	0
Fair Value, Inputs, Level 3 [Member] | Ferrellgas, L.P. [Member]
Interest rate swap assets		0
Propane commodity derivative assets	0	0
Interest rate swap liabilities	0	0
Propane commodity derivative liabilities	$ 0	$ 0