Fair value measurements - Assets and Liabilities (Details) - USD ($) $ in Thousands	Oct. 31, 2023	Jul. 31, 2023
Fair value measurements
Commodity derivatives propane swap assets	$ 6,513
Fair Value, Measurements, Recurring
Fair value measurements
Commodity derivatives propane swap assets	6,513	$ 12,165
Commodity derivatives propane swap liabilities	(15,718)	(11,082)
Fair Value, Measurements, Recurring \| Level 1
Fair value measurements
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	0	0
Fair Value, Measurements, Recurring \| Level 2
Fair value measurements
Commodity derivatives propane swap assets	6,513	12,165
Commodity derivatives propane swap liabilities	(15,718)	(11,082)
Fair Value, Measurements, Recurring \| Level 3
Fair value measurements
Commodity derivatives propane swap assets	0	0
Commodity derivatives propane swap liabilities	$ 0	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-3

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Fair value as of the balance sheet date of all price risk derivative assets designated as cash flow hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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