Derivatives (Assets And Liabilities Measured At Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2012	Jul. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets	$ 1,077	$ 7,637
Price risk management liabilities	2,504	2,476
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets	1,077	7,637
Price risk management liabilities	2,504	2,476
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets
Price risk management liabilities
Level 1 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets
Price risk management liabilities
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets	1,077	7,637
Price risk management liabilities	2,504	2,476
Level 2 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets	1,077	7,637
Price risk management liabilities	2,504	2,476
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets
Price risk management liabilities
Level 3 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Price risk management assets
Price risk management liabilities