Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024
Indefinite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 2,100	$ 2,100	$ 6,438	$ 5,700
Weighted average useful life			3 years 8 months 12 days
Goodwill	336,602		$ 336,602		$ 336,602
Internally Developed Software
Indefinite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	400	$ 300	989	$ 800
Dealerships
Indefinite-Lived Intangible Assets [Line Items]
Goodwill	295,300		295,300		295,300
Distribution
Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 41,300		$ 41,300		$ 41,300