Derivative Instruments and Hedging Activities (Changes in Derivative Value Effect on Other Comprehensive Income Loss) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Beginning balance			$ 788
Net earnings on risk management derivatives	(25,068)	22,676
Ending balance			788
Ferrellgas, L.P. [Member]
Beginning balance		5,100	788
Net earnings on risk management derivatives	(25,068)	22,676
Ending balance		5,100	788
Interest Rate Swap [Member]
Net earnings on risk management derivatives	(1,778)
Interest Rate Swap [Member] | Ferrellgas, L.P. [Member]
Net earnings on risk management derivatives	(1,778)
Commodity Derivatives Propane [Member]
Net earnings on risk management derivatives	(23,290)	22,676	12,063
Reclassification of gains (losses) from AOCI(L) to Cost of product sold - propane and other gas liquids	7,108	(17,358)	(11,231)
Commodity Derivatives Propane [Member] | Ferrellgas, L.P. [Member]
Net earnings on risk management derivatives	(23,290)	22,676	12,063
Reclassification of gains (losses) from AOCI(L) to Cost of product sold - propane and other gas liquids	7,108	(17,358)	(11,231)
Derivative [Member]
Beginning balance	(12,799)	5,161	(157)	(989)
Ending balance	(12,799)	5,161	(157)	(989)
Derivative [Member] | Ferrellgas, L.P. [Member]
Beginning balance	(12,799)	5,161	(157)	(989)
Ending balance	$ (12,799)	$ 5,161	$ (157)	$ (989)