Goodwill and Other Identifiable Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Indefinite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 3,300	$ 2,600	$ 6,586	$ 2,600
Goodwill	397,469		397,469		$ 378,588
Internally Developed Software
Indefinite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			$ 231
Weighted average useful life			5 years
Dealerships
Indefinite-Lived Intangible Assets [Line Items]
Goodwill	298,500		$ 298,500		280,000
Distribution
Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 99,000		$ 99,000		$ 98,600