Supplemental Financial Statement Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Net procurement of fixed priced propane by Ferrellgas in gallons	50,100,000
Depreciation expense	$ 58.7	$ 61.3	$ 62.3
Ferrellgas, L.P. And Subsidiaries [Member] | Maximum [Member]
Contract term duration, years	1
Supply procurement contract duration, months	24
Maximum [Member]
Contract term duration, years	1
Supply procurement contract duration, months	24
Ferrellgas, L.P. And Subsidiaries [Member]
Net procurement of fixed priced propane by Ferrellgas in gallons	50,100,000
Depreciation expense	$ 58.7	$ 61.3	$ 62.3