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, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Amount of gain (loss) recognized in AOCI	$ (159)	$ (6,496)	$ 23,362	$ 13,904
Amount of gain (loss) reclassified from AOCI into income	6,568	1,933	20,260	(2,819)
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	(159)	(6,496)	23,362	13,904
Amount of gain (loss) reclassified from AOCI into income	6,568	1,933	20,260	(2,819)
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	(169)	(6,642)	23,114	12,930
Amount of gain (loss) reclassified from AOCI into income			20,646	(1,112)
Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	(169)	(6,642)	23,114	12,930
Amount of gain (loss) reclassified from AOCI into income			20,646	(1,112)
Interest Rate Swap [Member]
Amount of gain (loss) recognized in AOCI	10	146	248	974
Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	10	146	248	974
Cost of Product Sold [Member] \| Propane commodity derivatives [Member]
Amount of gain (loss) reclassified from AOCI into income	6,628	2,411	20,646	(1,112)
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	6,628	2,411	20,646	(1,112)
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
Interest Expense [Member] \| Interest Rate Swap [Member]
Amount of gain (loss) reclassified from AOCI into income	(60)	(478)	(386)	(1,707)
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	(60)	(478)	(386)	(1,707)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 0	$ 0	$ 0

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

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- 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

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- 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

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