Income Taxes - Schedule of Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Deferred tax assets:
Federal and state net operating loss and tax credit carryforwards	$ 140,962	$ 126,547
Inventory adjustments	21,286	7,914
Property, equipment and other assets	7,900	6,199
Warranty and other reserves	7,789	6,613
Incentive compensation	7,565	8,621
Uncertain tax positions	705	705
Other	1,953	4,816
Total deferred tax assets	188,160	161,415
Valuation allowance	(35,758)	(27,578)
Total deferred tax assets, net of valuation allowance	152,402	133,837
Operating lease right-of-use assets	(8,449)	(4,286)
Intangible assets	(1,306)	(1,026)
Total deferred tax liabilities	(9,755)	(5,312)
Net deferred tax assets	$ 142,647	$ 128,525