Derivative and Hedging Instruments - Effect of the Interest Rate Swap Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain or (Loss) Recognized in Accumulated Other Comprehensive Loss (effective Portion)	$ 4,926	$ (2,066)
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	3,776	0
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	3,776	0
Floorplan Interest Expense
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	1,970	0
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	1,970	0
Interest Expense, Debt
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	1,806	0
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Loss to Earnings	$ 1,806	$ 0