Derivative and Hedging Instruments - Effect of the Interest Rate Swap Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Recognized in Accumulated Other Comprehensive Income (Loss) (effective Portion)	$ 1,440	$ (1,188)	$ 3,865	$ 4,463
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) to Earnings	156	814	937	2,952
Location, Statement of Income, Balance [Axis]: us-gaap:InterestExpenseDebt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) to Earnings	105	408	456	1,395
Location, Statement of Income, Balance [Axis]: onew:FloorplanInterestExpense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) to Earnings	$ 51	$ 406	$ 481	$ 1,557

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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