Debt (Details) (USD $)	6 Months Ended	12 Months Ended
	Jan. 31, 2012 years	Jul. 31, 2011
Debt Instrument [Line Items]
Short-term borrowings	$ 56,037,000	$ 64,927,000
Estimated fair value of long-term debt	1,007,200,000	1,134,200,000
Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Short-term borrowings	56,037,000	64,927,000
Estimated fair value of long-term debt	845,300,000	941,300,000
Letter Of Credit [Member]
Debt Instrument [Line Items]
Letters of credit outstanding	64,400,000	47,500,000
Letter of credit facility, remaining capacity	135,600,000	152,500,000
Letter Of Credit [Member] | Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Letters of credit outstanding	64,400,000	47,500,000
Letter of credit facility, remaining capacity	135,600,000	152,500,000
Secured Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maturity period	5
Secured line of credit facility	400,000,000
Debt instrument, maturity date	September 2016
Line of credit facility	102,100,000	129,500,000
Amount classified as long-term debt	46,100,000	64,600,000
Weighted average interest rate of secured credit facility	4.20%	6.50%
Secured Credit Facility [Member] | Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Line of credit facility, maturity period	5
Secured line of credit facility	400,000,000
Debt instrument, maturity date	September 2016
Line of credit facility	102,100,000	129,500,000
Amount classified as long-term debt	46,100,000	64,600,000
Weighted average interest rate of secured credit facility	4.20%	6.50%
Secured Credit Facility [Member] | Letter Of Credit [Member]
Debt Instrument [Line Items]
Secured line of credit facility	200,000,000
Secured Credit Facility [Member] | Letter Of Credit [Member] | Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Secured line of credit facility	$ 200,000,000
Reductions From Previous Facility Rate [Member] | Secured Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate, minimum	1.25%
Interest rate, maximum	1.50%
Reductions From Previous Facility Rate [Member] | Secured Credit Facility [Member] | Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Interest rate, minimum	1.25%
Interest rate, maximum	1.50%