Acquisitions, dispositions and other significant transactions - Aggregate Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	$ 247,195	$ 246,098
Ferrellgas, L.P. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	247,195	246,098
Propane and related equipment sales
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Working capital	31	758	$ 139
Customer tanks, buildings, land, salt water disposal wells, and other	11,560	10,022	1,220
Goodwill	247,195	246,098	256,103
Aggregate fair value of transactions	15,201	20,567	4,395
Propane and related equipment sales \| Ferrellgas, L.P. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Working capital	31	758	139
Customer tanks, buildings, land, salt water disposal wells, and other	11,560	10,022	1,220
Goodwill	247,195	246,098	256,103
Aggregate fair value of transactions	15,201	20,567	4,395
Propane and related equipment sales \| Customer Lists [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Finite-lived Intangible Assets Acquired	1,272	7,758	2,648
Propane and related equipment sales \| Customer Lists [Member] \| Ferrellgas, L.P. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Finite-lived Intangible Assets Acquired	1,272	7,758	2,648
Propane and related equipment sales \| Non-Compete Agreements [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Finite-lived Intangible Assets Acquired	928	2,029	388
Propane and related equipment sales \| Non-Compete Agreements [Member] \| Ferrellgas, L.P. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Finite-lived Intangible Assets Acquired	928	$ 2,029	$ 388
Series of Individually Immaterial Business Acquisitions [Member] \| Propane and related equipment sales
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	1,410
Series of Individually Immaterial Business Acquisitions [Member] \| Propane and related equipment sales \| Ferrellgas, L.P. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	$ 1,410

Amount of assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Amount recognized as of the acquisition date for the assets, including goodwill, in excess of (less than) the aggregate liabilities assumed, less the noncontrolling interest in the acquiree.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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