Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Inventory [Line Items]
Inventory, net	$ 593,347	$ 372,959
New vessels
Inventory [Line Items]
Inventory, net	443,885	243,090
Pre-owned vessels
Inventory [Line Items]
Inventory, net	66,522	51,607
Work in process, parts and accessories
Inventory [Line Items]
Inventory, net	$ 82,940	$ 78,262