Derivatives (Fair Value Of The Financial Derivative Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2012	Jul. 31, 2011
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management assets	$ 1,077	$ 7,637
Derivatives - Price risk management liabilities	2,504	2,476
Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management assets	1,077	7,637
Derivatives - Price risk management liabilities	2,504	2,476
Prepaid Expenses And Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management assets	1,077	7,637
Prepaid Expenses And Other Current Assets [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management assets	1,077	7,637
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management liabilities	2,504	2,476
Other Current Liabilities [Member] | Ferrellgas, L.P. [Member]
Derivatives, Fair Value [Line Items]
Derivatives - Price risk management liabilities	$ 2,504	$ 2,476