Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended			42 Months Ended
	Oct. 01, 2025 intallment shares	Feb. 23, 2021 shares	Sep. 30, 2025 USD ($) intallment $ / shares shares	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2025 USD ($) $ / shares shares	Mar. 30, 2022 USD ($)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based payment arrangement, expense | $			$ 10,000	$ 7,900	$ 8,200
Authorized amount | $							$ 50,000
Repurchase and retirement of shares amount | $					1,579
Stock repurchase program, remaining authorized repurchase amount | $			48,100			$ 48,100
Equity-based compensation | $			$ 10,499	$ 8,443	8,962
Quality Boats [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of economic interest retained by sellers			80.00%			80.00%
Percentage of remaining economic interest			20.00%			20.00%
OneWater LLC
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Ownership interest of parent			100.00%			100.00%
Employee stock purchase plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued as part of employee stock purchase plan (in shares)			93,477	59,089
Equity-based compensation | $			$ 500	$ 600	700
Stock to be purchased under ESPP | $			$ 200	$ 300
Class A Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Capital shares reserved for future issuance (in shares)				1,637,399
Repurchase and retirement of Class A common stock (in shares)			0			73,487
Repurchase and retirement of shares amount | $						$ 1,900
Percentage of outstanding shares, ESPP issuance		1.00%
Ratio of shares converted			1
Exchange of B shares for A shares (in shares)			1,429,940
Class A Common Stock | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued as part of employee stock purchase plan (in shares)		510,145
Class B Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Ratio of shares converted			1
Time-Based Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)			211,978
Time-Based Restricted Stock Units | Subsequent Event
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)	175,382
Vested (in shares)	36,596
Number of equal annual installments for vesting | intallment	3
Performance Shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)			152,072
Number of equal annual installments for vesting | intallment			3
Percentage of target award granted			100.00%
Number of shares of common stock consisted in each unit (in shares)			1
Performance targets achieved of installment awards, percentage			152.00%			152.00%
Share-based payment arrangement, expense | $			$ 5,100	$ 2,900	$ 3,500
Restricted stock units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)			364,050	346,481
Vested (in shares)			243,352	318,934
Nonvested award | $			$ 5,000			$ 5,000
Cost not yet recognized, period for recognition			1 year 2 months 12 days
Employee stock purchase plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued (in shares) | $ / shares			$ 12.69	$ 25.72		$ 12.69