Derivative Instruments and Hedging Activities (Cash Flow Hedge Derivative Effect on Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Amount of gain (loss) recognized in AOCI	$ (6,496)	$ 14,681	$ 13,904	$ 3,561
Amount of gain (loss) reclassified from AOCI into income	1,933	(6,138)	(2,819)	(22,931)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	(6,496)	14,681	13,904	3,561
Amount of gain (loss) reclassified from AOCI into income	1,933	(6,138)	(2,819)	(22,931)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Propane commodity derivatives [Member]
Amount of gain (loss) recognized in AOCI	(6,642)	14,998	12,930	5,823
Amount of gain (loss) reclassified from AOCI into income			(1,112)	(20,729)
Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	(6,642)	14,998	12,930	5,823
Amount of gain (loss) reclassified from AOCI into income			(1,112)	(20,729)
Interest Rate Swap [Member]
Amount of gain (loss) recognized in AOCI	146	(317)	974	(2,262)
Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	146	(317)	974	(2,262)
Cost of Product Sold [Member] \| Propane commodity derivatives [Member]
Amount of gain (loss) reclassified from AOCI into income	2,411	(5,467)	(1,112)	(20,729)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Cost of Product Sold [Member] \| Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	2,411	(5,467)	(1,112)	(20,729)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Interest Expense [Member] \| Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Interest Expense [Member] \| Interest Rate Swap [Member]
Amount of gain (loss) reclassified from AOCI into income	(478)	(671)	(1,707)	(2,202)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0	0	0
Interest Expense [Member] \| Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	$ (478)	$ (671)	$ (1,707)	$ (2,202)

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=64837297&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=64837297&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=64837297&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

- Details

Name:	dei_LegalEntityAxis=fgp_FerrellgasLPMember
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: