Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Sep. 30, 2024
Inventory [Line Items]
Total inventories	$ 636,676	$ 590,838
New vessels
Inventory [Line Items]
Total inventories	481,060	442,834
Pre-owned vessels
Inventory [Line Items]
Total inventories	86,142	79,234
Work in process, parts and accessories
Inventory [Line Items]
Total inventories	$ 69,474	$ 68,770