Derivative Instruments and Hedging Activities (Cash Flow Hedge Derivative Effect on Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 0	$ (199)
Ferrellgas, L.P. [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	(199)
Derivative [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	22,525	1,789	(73,647)
Amount of gain (loss) reclassified from AOCI into income	(1,938)	(27,302)	(28,059)
Derivative [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	22,525	1,789	(73,647)
Amount of gain (loss) reclassified from AOCI into income	(1,938)	(27,302)	(28,059)
Commodity Derivatives Propane [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	21,659	4,409	(70,291)
Amount of gain (loss) reclassified from AOCI into income	154	(24,438)	(28,059)
Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	21,659	4,409	(70,291)
Amount of gain (loss) reclassified from AOCI into income	154	(24,438)	(28,059)
Interest Rate Swap [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	866	(2,620)	(3,356)
Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI(L) on derivative	866	(2,620)	(3,356)
Cost of Sales [Member] \| Commodity Derivatives Propane [Member]
Amount of gain (loss) reclassified from AOCI into income	154	(24,438)	(28,059)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0
Cost of Sales [Member] \| Commodity Derivatives Propane [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	154	(24,438)	(28,059)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0
Interest Expense [Member] \| Interest Rate Swap [Member]
Amount of gain (loss) reclassified from AOCI into income	(2,092)	(2,864)	0
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	(199)
Interest Expense [Member] \| Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	(2,092)	(2,864)	0
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	(199)
Midstream - Crude Oil Logistics [Member] \| Cost of Sales [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(425)	1,084
Midstream - Crude Oil Logistics [Member] \| Cost of Sales [Member] \| Ferrellgas, L.P. [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(425)	1,084
Propane and related equipment sales [Member] \| Operating Expense [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1,090	(4,351)	(2,412)
Propane and related equipment sales [Member] \| Operating Expense [Member] \| Ferrellgas, L.P. [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 1,090	$ (4,351)	$ (2,412)

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959

+ Details

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

- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1),(2)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

+ Details

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

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

+ Details

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

- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

+ Details

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

- Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_DerivativeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_EnergyRelatedDerivativeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=fgp_MidstreamCrudeOilLogisticsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=fgp_PropaneandrelatedequipmentsalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OperatingExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: