Non-controlling Interest - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018
Noncontrolling Interest [Line Items]
Tax distributions payable to non-controlling LLC Unit holders	$ 354	$ 290
Non-controlling LLC Unit holders ownership in Malibu Boats Holdings, LLC
Noncontrolling Interest [Line Items]
Tax distributions payable to non-controlling LLC Unit holders	354		$ 511
Tax distributions paid to non-controlling LLC Unit holders	$ 556	$ 312
Class A Common Stock
Noncontrolling Interest [Line Items]
Issuance LLC Units (in shares)	229,784
Treasury Stock, Common
Noncontrolling Interest [Line Items]
Treasury stock, shares, retired (in shares)	8,481,000