Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Inventory [Line Items]
Total inventories	$ 602,364	$ 590,838
New vessels
Inventory [Line Items]
Total inventories	453,403	442,834
Pre-owned vessels
Inventory [Line Items]
Total inventories	80,294	79,234
Work in process, parts and accessories
Inventory [Line Items]
Total inventories	$ 68,667	$ 68,770

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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 852
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
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