Stockholders' and Members' Equity, OneWater LLC Preferred Distribution (Q3) (Details) - Preferred Distribution [Member] - USD ($) $ in Millions		12 Months Ended
Feb. 11, 2020	Sep. 30, 2019
Preferred Distribution [Abstract]
Unpaid balance		$ 3.2
Preferred distribution cumulative interest accrual rate		5.00%
Unpaid amount of cumulative interest		$ 0.0
Payment in exchange for surrender of preferred distribution right	$ 3.2

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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