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Derivative instruments and hedging activities - Balance Sheet (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Jul. 31, 2023
Derivative instruments and hedging activities
Gain (loss) recognized due to ineffectiveness	$ 0	$ 0
Commodity derivatives propane swap assets	6,513
Derivative Asset, Fair Value, Gross Asset			$ 12,165
Derivative Liability, Fair Value, Gross Liability	15,718		11,082
Price risk management asset
Derivative instruments and hedging activities
Commodity derivatives propane swap assets	6,465		11,966
Other Current Liabilities
Derivative instruments and hedging activities
Commodity derivatives propane swap liabilities	15,257		9,554
Other Assets, Net
Derivative instruments and hedging activities
Commodity derivatives propane swap assets	48		199
Other Liabilities
Derivative instruments and hedging activities
Commodity derivatives propane swap liabilities	$ 461		$ 1,528