Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended			18 Months Ended
	Oct. 01, 2024 intallment shares	Feb. 23, 2021 shares	Sep. 30, 2024 USD ($) intallment $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) $ / shares shares	Mar. 30, 2022 USD ($)	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based payment arrangement, expense | $			$ 7,900	$ 8,200	$ 9,800
Authorized amount | $							$ 50,000
Repurchase and retirement of shares amount | $				1,579	354
Stock repurchase program, remaining authorized repurchase amount | $			48,100
Equity-based compensation | $			$ 8,443	$ 8,962	10,013
Quality Boats
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of economic interest retained by sellers			80.00%					20.00%
Percentage of remaining economic interest			20.00%
OneWater LLC
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Ownership interest of parent			91.10%
Noncontrolling interest, ownership percentage by noncontrolling owners			8.90%
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)			59,089	86,050
Equity-based compensation | $			$ 600	$ 700	200
Stock to be purchased under ESPP | $			$ 300	$ 400
Class A Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Capital shares reserved for future issuance (in shares)				1,611,664		1,611,664
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
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)		453,870
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)			204,557
Time-Based Restricted Stock Units | Subsequent Event
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)	170,397
Vested (in shares)	34,160
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)			141,924
Percentage of target award granted			100.00%
Number of shares of common stock consisted in each unit (in shares)			1
Share-based payment arrangement, expense | $			$ 2,900	$ 3,500	$ 5,400
Performance Shares | Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of equal annual installments for vesting | intallment			3
Performance targets achieved of installment awards, percentage			74.00%
Restricted stock units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awarded (in shares)			346,481	225,075
Vested (in shares)			318,934	257,082
Nonvested award | $			$ 3,100
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			$ 25.72	$ 24.31		$ 24.31