Derivative Instruments and Hedging Activities (Fair Value Hedge Derivative Effect on Earnings) (Details) - Interest Rate Swap [Member] - USD ($) $ in Thousands	3 Months Ended
Oct. 31, 2017	Oct. 31, 2016
Derivative, Gain (Loss) on Derivative, Net	$ 138	$ 420
Interest expense recognized on fixed-rate debt	(2,275)	(2,275)
Ferrellgas, L.P. [Member]
Derivative, Gain (Loss) on Derivative, Net	138	420
Interest expense recognized on fixed-rate debt	$ (2,275)	$ (2,275)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration