The period of time during which amounts receivable are collected.

No definition available.

Name:	fgp_AccountsReceivableCollectionPeriod
Namespace Prefix:	fgp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The period of time over which rental income is generally recognized.

+ References

No definition available.

+ Details

Name:	fgp_RentalIncomeRecognitionPeriod
Namespace Prefix:	fgp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

For residential customers, referred to as "even-pay" customers, annual heating costs may be spread over this period of time.

+ References

No definition available.

+ Details

Name:	fgp_ResidentialCustomersPeriodOverWhichAnnualCostsMayBeSpread
Namespace Prefix:	fgp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_BilledContractReceivables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ChangeInContractWithCustomerAssetAndLiabilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130533-203044

+ Details

Name:	us-gaap_ContractWithCustomerAssetNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044

+ Details

Name:	us-gaap_ContractWithCustomerLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ Details

Name:	us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

+ Details

Name:	us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2020-05-01
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=fgp_PropaneAndRelatedEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_RetailMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=fgp_WholesaleSalesToResellersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=fgp_OtherGasSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ProductAndServiceOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis=us-gaap_CalculatedUnderRevenueGuidanceInEffectBeforeTopic606Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fgp_FerrellgasLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Revenue from contracts with customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Jul. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable collection period			30 days
Residential customer, annual cost spread period			12 months
Rental income recognition period			1 year
Revenues	$ 412,130	$ 479,625	$ 1,216,177	$ 1,405,311
Contract assets and liabilities
Accounts receivable	129,704		129,704		$ 96,450
Contract assets	15,801		15,801		13,609
Contract liabilities
Deferred revenue	$ 32,149		32,149		31,974
Deferred revenue recognized			$ 24,600
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-05-01
Contract liabilities
Remaining performance obligation recognition period	1 year		1 year
Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 412,130		$ 1,216,177
Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues	286,163		840,649
Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues	103,686		291,445
Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,896		18,283
Other Revenues
Disaggregation of Revenue [Line Items]
Revenues	20,385	20,069	$ 65,800	60,677
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues		479,625		1,405,311
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues		350,151		983,742
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues		99,311		308,646
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues		10,094		52,246
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Other Revenues
Disaggregation of Revenue [Line Items]
Revenues		20,069		60,677
Ferrellgas, L.P. [Member]
Disaggregation of Revenue [Line Items]
Accounts receivable collection period			30 days
Residential customer, annual cost spread period			12 months
Rental income recognition period			1 year
Revenues	412,130	479,625	$ 1,216,177	1,405,311
Contract assets and liabilities
Accounts receivable	129,704		129,704		96,450
Contract assets	15,801		15,801		13,609
Contract liabilities
Deferred revenue	$ 32,149		32,149		$ 31,974
Deferred revenue recognized			$ 24,600
Ferrellgas, L.P. [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-05-01
Contract liabilities
Remaining performance obligation recognition period	1 year		1 year
Ferrellgas, L.P. [Member] \| Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 412,130		$ 1,216,177
Ferrellgas, L.P. [Member] \| Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues	286,163		840,649
Ferrellgas, L.P. [Member] \| Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues	103,686		291,445
Ferrellgas, L.P. [Member] \| Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,896		18,283
Ferrellgas, L.P. [Member] \| Other Revenues
Disaggregation of Revenue [Line Items]
Revenues	$ 20,385	20,069	$ 65,800	60,677
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenues		479,625		1,405,311
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Propane And Related Equipment [Member]
Disaggregation of Revenue [Line Items]
Revenues		479,625		1,405,311
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Retail Sales To End Users [Member]
Disaggregation of Revenue [Line Items]
Revenues		350,151		983,742
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Wholesale Sales To Resellers [Member]
Disaggregation of Revenue [Line Items]
Revenues		99,311		308,646
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Other Gas Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues		10,094		52,246
Ferrellgas, L.P. [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Other Revenues
Disaggregation of Revenue [Line Items]
Revenues		$ 20,069		$ 60,677