Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Inventory [Line Items]
Inventory, net	$ 572,932	$ 372,959
New vessels
Inventory [Line Items]
Inventory, net	426,932	243,090
Pre-owned vessels
Inventory [Line Items]
Inventory, net	68,508	51,607
Work in process, parts and accessories
Inventory [Line Items]
Inventory, net	$ 77,492	$ 78,262