Stockholders’ Equity - Summary of Net (Loss) Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Numerator:
Net income attributable to OneWater Inc	$ 14,683	$ 28,570	$ 3,544	$ 60,274
Class A Common Stock
Denominator:
Weighted-average number of unrestricted outstanding common shares used to calculate basic net (loss) income per share (in shares)	14,593	14,314	14,571	14,317
Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]
Diluted weighted-average shares of Class A common stock outstanding used to calculate diluted net (loss) earnings per share (in shares)	14,891	14,675	14,835	14,639
Net (loss) earnings per share of Class A common stock – basic (in usd per share)	$ 1.01	$ 2.00	$ 0.24	$ 4.21
Net (loss) earnings per share of Class A common stock – diluted (in usd per share)	$ 0.99	$ 1.95	$ 0.24	$ 4.12
Class A Common Stock | Employee Stock
Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]
Restricted stock unit and employee stock purchase plan (in shares)	1	5	0	4
Class A Common Stock | Restricted Stock Units
Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]
Restricted stock unit and employee stock purchase plan (in shares)	297	356	264	318