Supplemental Financial Statement Information (Narrative) (Details)	3 Months Ended
	Oct. 31, 2011
Supplemental Financial Statement Information [Line Items]
Net procurement of fixed priced propane by Ferrellgas in gallons	104,600,000
Ferrellgas, L.P. And Subsidiaries [Member]
Supplemental Financial Statement Information [Line Items]
Net procurement of fixed priced propane by Ferrellgas in gallons	104,600,000
Maximum [Member]
Supplemental Financial Statement Information [Line Items]
Contract term duration, years	1
Supply procurement contract duration, months	24
Maximum [Member] | Ferrellgas, L.P. And Subsidiaries [Member]
Supplemental Financial Statement Information [Line Items]
Contract term duration, years	1
Supply procurement contract duration, months	24