Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Inventory [Line Items]
Total inventories	$ 590,838	$ 609,616
New vessels
Inventory [Line Items]
Total inventories	442,834	471,147
Pre-owned vessels
Inventory [Line Items]
Total inventories	79,234	61,627
Parts and accessories, work in process
Inventory [Line Items]
Total inventories	$ 68,770	$ 76,842