Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Jun. 30, 2018
Accounting Policies [Abstract]
Fair Value of Financial Instruments	The carrying amounts of our financial instruments reported on the balance sheet as of June 30, 2018, approximated fair value due either to length to maturity or existence of variable interest rates, which approximate prevailing market rates.
Use of Estimates	The preparation of unaudited condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the unaudited condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates made by us in the accompanying unaudited condensed consolidated financial statements include valuation allowances, valuation of goodwill and intangible assets, valuation of long-lived assets, and valuation of accruals. Actual results could differ from those estimates.
Consolidation	In order to provide comparability between periods presented, certain amounts have been reclassified from the previously reported unaudited condensed consolidated financial statements to conform to the unaudited condensed consolidated financial statement presentation for the current period. The unaudited condensed consolidated financial statements include our accounts and the accounts of our subsidiaries, all of which are wholly owned. All significant intercompany transactions and accounts have been eliminated.
New Accounting Pronouncements	In May 2014, the FASB issued Accounting Standards Update No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”), a converged standard on revenue recognition. The new pronouncement requires revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance also specifies the accounting for some costs to obtain or fulfill a contract with a customer, as well as enhanced disclosure requirements. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Early adoption is permitted for annual reporting periods beginning after December 15, 2016. While we have not completed the implementation process, we currently do not believe the adoption of this standard will have a material impact on our unaudited condensed consolidated financial statements, or will cause a significant change to our current accounting policies or internal control over financial reporting for revenue recognition on boat, motor, and trailer sales, brokerage commissions, slip and storage services, charter rentals, and fee income generated from finance and insurance products. However, the timing of revenue recognition for certain parts and service operations will be accelerated, as we have determined these performance obligations are satisfied over time under the new standard. We currently anticipate adopting the standard using the modified retrospective approach applied only to contracts not completed as of the date of adoption, with no restatement of comparative periods and if material a cumulative effect adjustment recognized as of the date of adoption. We plan to adopt ASU 2014-09 in fiscal 2019. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)” (“ASU 2016-02”). This update requires organizations to recognize lease assets and lease liabilities on the balance sheet and also disclose key information about leasing arrangements. ASU 2016-02 is effective for annual reporting periods beginning on or after December 15, 2018, and interim periods within those annual periods. Earlier application is permitted for all entities as of the beginning of an interim or annual period. While we are continuing to evaluate the impact of the adoption of ASU 2016-02 on our unaudited condensed consolidated financial statements, we believe the adoption of ASU 2016-02 may have a significant and material impact to our unaudited condensed consolidated balance sheet given our current lease agreements for our leased retail locations. We are currently evaluating the impact the adoption of ASU 2016-02 will have on our other unaudited condensed consolidated financial statements. Based on a preliminary assessment, we expect that most of our operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a material increase in the assets and liabilities recorded on our unaudited condensed consolidated balance sheet. We are continuing our assessment, which may identify additional impacts this standard will have on our consolidated financial statements and related disclosures and internal control over financial reporting. We plan to adopt ASU 2016-02 in fiscal 2020. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment (Topic 350)” (“ASU 2017-04”). This update removes the requirement to compare the implied fair value of goodwill with its carrying amount as part of step 2 of the goodwill impairment test. As a result, under ASU 2017-04, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the impairment loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. This guidance is effective prospectively for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed after January 1, 2017. The adoption of ASU 2017-04 is not expected to have a significant impact on the Company’s unaudited condensed consolidated financial statements or internal control over financial reporting.
Revenue Recognition	We recognize revenue from boat, motor, and trailer sales, and parts and service operations at the time the boat, motor, trailer, or part is delivered to or accepted by the customer or the service is completed. We recognize deferred revenue from service operations and slip and storage services on a straight-line basis over the term of the contract as services are completed. We recognize commissions earned from a brokerage sale at the time the related brokerage transaction closes. We recognize income from the rentals of chartering power and sailing yachts on a straight-line basis over the term of the contract as services are completed. We recognize commissions earned by us for placing notes with financial institutions in connection with customer boat financing when we recognize the related boat sales. We recognize marketing fees earned on credit, life, accident, disability, gap, and hull insurance products sold by third-party insurance companies at the later of customer acceptance of the insurance product as evidenced by contract execution or when the related boat sale is recognized. Pursuant to negotiated agreements with financial and insurance institutions, we are charged back for a portion of these fees should the customer terminate or default on the related finance or insurance contract before it is outstanding for a stipulated minimum period of time. We base the chargeback allowance, which was not material to the unaudited condensed consolidated financial statements taken as a whole as of June 30, 2018, on our experience with repayments or defaults on the related finance or insurance contracts. We also recognize commissions earned on extended warranty service contracts sold on behalf of third-party insurance companies at the later of customer acceptance of the service contract terms as evidenced by contract execution or recognition of the related boat sale. We are charged back for a portion of these commissions should the customer terminate or default on the service contract prior to its scheduled maturity. We determined the chargeback allowance, which was not material to the unaudited condensed consolidated financial statements taken as a whole as of June 30, 2018, based upon our experience with terminations or defaults on the service contracts.
Inventories	Inventory costs consist of the amount paid to acquire inventory, net of vendor consideration and purchase discounts, the cost of equipment added, reconditioning costs, and transportation costs relating to acquiring inventory for sale. We state new and used boat, motor, and trailer inventories at the lower of cost, determined on a specific-identification basis, or net realizable value. We state parts and accessories at the lower of cost, determined on an average cost basis, or net realizable value. We utilize our historical experience, the aging of the inventories, and our consideration of current market trends as the basis for determining a lower of cost or net realizable value valuation allowance. As of September 30, 2017 and June 30, 2018, our lower of cost or net realizable value valuation allowance for new and used boat, motor, and trailer inventories was $1.8 million and $2.5 million, respectively. If events occur and market conditions change, causing the fair value to fall below carrying value, the lower of cost or net realizable value valuation allowance could increase.
Impairment of Long-Lived Assets	FASB Accounting Standards Codification 360-10-40, “Property, Plant, and Equipment - Impairment or Disposal of Long-Lived Assets” (“ASC 360-10-40”), requires that long-lived assets, such as property and equipment and purchased intangibles subject to amortization, be reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of the asset is measured by comparison of its carrying amount to undiscounted future net cash flows the asset is expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the asset exceeds its fair market value. Estimates of expected future cash flows represent our best estimate based on currently available information and reasonable and supportable assumptions. Any impairment recognized in accordance with ASC 360-10-40 is permanent and may not be restored. The analysis is performed at a regional level for indicators of permanent impairment given the geographical interdependencies among our locations. Based upon our most recent analysis, which excludes fixed assets classified as held for sale which are recorded at fair value, we believe no impairment of long-lived assets existed as of June 30, 2018.