Acquisitions and Dispositions - Summary of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	May 01, 2024	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Business Combination [Line Items]
Goodwill		$ 258,954	$ 336,602	$ 336,602
Consideration transferred				42,000
Total Acquisitions [Member]
Business Combination [Line Items]
Accounts receivable				286
Inventories				6,424
Prepaid expenses				72
Property and equipment				11,588
Operating lease right-of-use assets				3,820
Identifiable intangible assets				8,800
Goodwill				18,481
Accounts payable				(17)
Accrued expenses				(361)
Customer deposits				(1,013)
Notes payable - floor plan				(2,228)
Operating lease liabilities				(3,820)
Aggregate acquisition date fair value				42,032
Consideration transferred				$ 42,032
Garden State Yacht Sales
Business Combination [Line Items]
Accounts receivable	$ 113
Inventories	6,676
Prepaid expenses	11
Property and equipment	478
Operating lease right-of-use assets	4,360
Accounts payable	(1,263)
Accrued expenses	(36)
Customer deposits	(267)
Operating lease liabilities	(4,360)
Aggregate acquisition date fair value	5,712
Consideration transferred	$ 5,712