Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Inventory [Line Items]
Inventories	$ 788,642	$ 867,328
Work-in-process	19,478	13,394
Raw materials	18,350	16,613
New and Used Boats, Motors, and Trailers [Member]
Inventory [Line Items]
Inventories	678,683	786,920
In Transit Inventory and Deposits [Member]
Inventory [Line Items]
Inventories	56,767	36,847
Parts, Accessories, and Other [Member]
Inventory [Line Items]
Inventories	$ 15,364	$ 13,554

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No definition available.

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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