Derivative Instruments and Hedging Activities (Cash Flow Hedge Derivative Effect on Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
Oct. 31, 2017	Oct. 31, 2016
Amount of gain (loss) recognized in AOCI	$ 22,449	$ 5,138
Amount of gain (loss) reclassified from AOCI into income	3,949	(4,238)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0
Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	22,449	5,138
Amount of gain (loss) reclassified from AOCI into income	3,949	(4,238)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0
Propane commodity derivatives [Member]
Amount of gain (loss) recognized in AOCI	22,323	4,873
Amount of gain (loss) reclassified from AOCI into income	4,132	(3,596)
Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	22,323	4,873
Amount of gain (loss) reclassified from AOCI into income	4,132	(3,596)
Interest Rate Swap [Member]
Amount of gain (loss) recognized in AOCI	126	265
Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) recognized in AOCI	126	265
Cost of Product Sold [Member] \| Propane commodity derivatives [Member]
Amount of gain (loss) reclassified from AOCI into income	4,132	(3,596)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0
Cost of Product Sold [Member] \| Propane commodity derivatives [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	4,132	(3,596)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	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
Interest Expense [Member] \| Interest Rate Swap [Member]
Amount of gain (loss) reclassified from AOCI into income	(183)	(642)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	0
Interest Expense [Member] \| Interest Rate Swap [Member] \| Ferrellgas, L.P. [Member]
Amount of gain (loss) reclassified from AOCI into income	$ (183)	$ (642)

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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