v3.26.1
Revenue Recognition - Summary of Revenue Disaggregated Into Categories Depict the Nature, Amount, Timing, and Uncertainty of Revenue and Cash Flows Affected by Economic Factor (Details) - Sales [Member] - Product Concentration Risk [Member]
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 100.00% 100.00% 100.00% 100.00%
Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 100.00% 100.00% 100.00% 100.00%
Product Manufacturing [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 100.00% 100.00% 100.00% 100.00%
New Boat Sales [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 62.30% 64.30% 63.20% 62.30%
New Boat Sales [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 62.30% 63.80% 62.90% 61.60%
New Boat Sales [Member] | Product Manufacturing [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 98.10% 98.90% 98.10% 98.90%
Used Boat Sales [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 9.50% 14.00% 9.20% 12.70%
Used Boat Sales [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 9.50% 14.10% 9.40% 12.80%
Maintenance and Repair Services [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 4.50% 3.90% 5.00% 4.90%
Maintenance and Repair Services [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 4.50% 3.90% 5.10% 5.00%
Storage and Charter Rentals [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 10.90% 7.40% 10.00% 8.10%
Storage and Charter Rentals [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 10.90% 7.80% 10.00% 8.50%
Finance and Insurance Products [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 3.90% 3.40% 3.40% 3.20%
Finance and Insurance Products [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 3.90% 3.40% 3.40% 3.30%
Parts and Accessories [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 5.10% 3.90% 5.10% 4.70%
Parts and Accessories [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 5.10% 3.90% 5.10% 4.70%
Parts and Accessories [Member] | Product Manufacturing [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 1.90% 1.10% 1.90% 1.10%
Brokerage Sales [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 3.80% 3.10% 4.10% 4.10%
Brokerage Sales [Member] | Retail Operations [Member]        
Product Information [Line Items]        
Sales Revenue Goods And Services Net Percentage 3.80% 3.10% 4.10% 4.10%