Accounts And Notes Receivable, Net And Accounts Receivable Securitization (Narrative) (Details) (USD $)	6 Months Ended	12 Months Ended
	Jan. 31, 2013	Jul. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 224,428,000	$ 121,812,000
Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	224,428,000	121,812,000
Commercial Paper [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Note payable	134,000,000
Commercial Paper [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Note payable	134,000,000
Accounts Receivable Securitization [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds to Ferrellgas from securitizing receivables to a commercial paper conduit	134,000,000	74,000,000
Available proceeds from additional trade accounts receivable	0	0
Weighted average discount rate to value the retained interest in the transferred receivables	2.40%	2.60%
Accounts Receivable Securitization [Member] | Ferrellgas, L.P. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds to Ferrellgas from securitizing receivables to a commercial paper conduit	134,000,000	74,000,000
Available proceeds from additional trade accounts receivable	$ 0	$ 0
Weighted average discount rate to value the retained interest in the transferred receivables	2.40%	2.60%