Debt (Secured Credit Facility Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jan. 31, 2018	Jul. 31, 2017
Debt Instrument [Line Items]
Debt Instrument, Covenant Description	24.9
current leverage ratio	696.00%
Debt Instrument, Covenant Compliance	193.2	67.5
Available borrowing capacity	$ 125.8	$ 190.3
Letters of credit outstanding	$ 188.0	$ 139.2
Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Description	24.9
current leverage ratio	696.00%
Debt Instrument, Covenant Compliance	193.2	67.5
Available borrowing capacity	$ 125.8	$ 190.3
Letters of credit outstanding	188.0	139.2
Secured Credit Facility [Member]
Debt Instrument [Line Items]
Total credit faciltiy borrowings outstanding	$ 261.2	245.5
Other Long-term Debt, Noncurrent		$ 185.7
Weighted average interest rate on credit facility borrowings	6.50%	6.00%
Secured Credit Facility [Member] \| Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Total credit faciltiy borrowings outstanding	$ 261.2	$ 245.5
Other Long-term Debt, Noncurrent		$ 185.7
Weighted average interest rate on credit facility borrowings	6.50%	6.00%
Letter Of Credit [Member]
Debt Instrument [Line Items]
Available borrowing capacity	$ 12.0	$ 60.8
Letter Of Credit [Member] \| Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Available borrowing capacity	$ 12.0	$ 60.8

current leverage ratio

No definition available.

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- Definition

States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure.

+ References

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Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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- Definition

Amount of long-term debt classified as other, payable after one year or the operating cycle, if longer.

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