Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 31, 2017	Apr. 30, 2017	Jul. 31, 2016
Notes Receivable, Fair Value Disclosure	$ 38.4
Increase (Decrease) in Notes Receivables	4.3
Estimated fair value of long-term debt	$ 1,966.6		$ 1,920.1
Common unitholders, units outstanding	97,152,665		98,002,665
Ferrellgas, L.P. [Member]
Notes Receivable, Fair Value Disclosure	$ 38.4
Increase (Decrease) in Notes Receivables	4.3
Estimated fair value of long-term debt	1,645.3		$ 1,736.2
Jamex Marketing, LLC [Member]
Accounts Receivable, Related Parties			44.8
Notes Receivable, Related Parties	20.0
Notes Receivable, Related Parties	42.5
Jamex Marketing, LLC [Member] \| Ferrellgas, L.P. [Member]
Accounts Receivable, Related Parties			$ 44.8
Notes Receivable, Related Parties	$ 20.0	$ 42.5

For an unclassified balance sheet, amount of receivables arising from transactions with related parties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SX 210.7-03(a)(3))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

The increase (decrease) during the reporting period of the amounts due from borrowers for outstanding secured or unsecured loans evidenced by a note.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The number of limited partner units outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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- Definition

Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

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Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due after 1 year (or 1 business cycle).

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