Supplemental Financial Statement Information (Narrative) (Details)	3 Months Ended
	Oct. 31, 2012 gal
Supplemental Financial Statement Information [Line Items]
Net procurement of fixed priced propane by Ferrellgas in gallons	128,400,000
Ferrellgas, L.P. [Member]
Supplemental Financial Statement Information [Line Items]
Net procurement of fixed priced propane by Ferrellgas in gallons	128,400,000
Maximum [Member]
Supplemental Financial Statement Information [Line Items]
Supply procurement contract duration	36 months
Maximum [Member] | Ferrellgas, L.P. [Member]
Supplemental Financial Statement Information [Line Items]
Supply procurement contract duration	36 months