Physical Commodities Inventory (Details) - USD ($) $ in Millions	Jun. 30, 2025	Sep. 30, 2024
Inventory [Line Items]
Physical agriculture and energy	$ 181.0	$ 169.0
Precious metals - held by broker-dealer subsidiary	397.0	376.6
Physical commodities inventory, net	705.4	681.1
Physical Commodities Inventory - Precious Metals
Inventory [Line Items]
Precious metals - held by broker-dealer subsidiary	216.0	207.6
Precious metals - held by non-broker-dealer subsidiaries	308.4	$ 304.5
Raw materials	5.5
Work in process	$ 24.2

Physical commodities inventory at fair value - precious metals

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Carrying amount as of the balance sheet date of merchandise or supplies held which are related to plants and animals.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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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.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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