Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Fair Value of Financial Instruments	The carrying amounts of our financial instruments reported on the balance sheet as of March 31, 2017, 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 2014-9”), 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 2014-9 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 are continuing to evaluate the impact the adoption of ASU 2014-09 will have on our unaudited condensed consolidated financial statements, 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 controls over financial reporting for revenue recognition on boat, motor, and trailer sales, parts and service operations, brokerage commissions, slip and storage services, charter rentals, and fee income generated from finance and insurance products. In July 2015, the FASB issued ASU No. 2015-11, “Inventory (Topic 330)” (“ASU 2015-11”). The pronouncement was issued to simplify the measurement of inventory and change the measurement from lower of cost or market to lower of cost and net realizable value. This pronouncement is effective for reporting periods beginning after December 15, 2016. We elected to early adopt the new guidance in the first quarter of fiscal 2017. The adoption of ASU 2015-11 did not have an impact on the Company’s unaudited condensed consolidated financial position, results of operations, or internal controls. 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 unaudited condensed consolidated financial statements and related disclosures and internal controls over financial reporting. In March 2016, the FASB issued ASU 2016-09, “Compensation – Stock Compensation (Topic 718)” (“ASU 2016-09”). This update was issued as part of the FASB’s simplification initiative and affects all entities that issue share-based payment awards to their employees. The amendments in this update cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess tax benefits on the statement of cash flows, an accounting policy election for forfeitures, the amount an employer can withhold to cover income taxes and still qualify for equity classification and the classification of those taxes paid on the statement of cash flows. This update is effective for annual and interim periods beginning after December 15, 2016. We elected to early adopt the new guidance in the fourth quarter of fiscal 2016 which requires us to reflect any adjustments as of October 1, 2015, the beginning of the annual period that includes the interim period of adoption. The primary effect of adoption was the recognition of excess tax benefits in our provision for income taxes rather than paid-in capital for all periods in fiscal 2016. This early adoption resulted in an approximately $5.2 million increase in deferred tax assets and retained earnings as of October 1, 2015, the beginning of fiscal 2016. The adoption in the fourth quarter of fiscal 2016 of ASU 2016-09 resulted in additional income tax benefit of $67,000 for the three months ended March 31, 2016 and an additional income tax expense of $134,000 for the six months ended March 31, 2016 from the previously reported income tax provisions in the unaudited condensed consolidated statements of operations for the second quarter and six months ended March 31, 2016 during fiscal 2016. 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 position, results of operations, or internal controls.
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 or when service is 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 or when service is 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 March 31, 2017, 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 March 31, 2017, 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, 2016 and March 31, 2017, our lower of cost or net realizable value valuation allowance for new and used boat, motor, and trailer inventories was $1.0 million and $1.5 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.
Property Plant and Equipment Impairment or Disposal 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 March 31, 2017.
Income Taxes	INCOME TAXES: We account for income taxes in accordance with FASB Accounting Standards Codification 740, “Income Taxes” (“ASC 740”). Under ASC 740, we recognize deferred tax assets and liabilities for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. We measure deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which we expect those temporary differences to be recovered or settled. We record valuation allowances to reduce our deferred tax assets to the amount expected to be realized by considering all available positive and negative evidence. As of September 30, 2016 and March 31, 2017, we had a valuation allowance on our deferred tax assets of $454,000. During the three months ended March 31, 2016 and March 31, 2017 we recognized an income tax provision of $1.5 million. During the six months ended March 31, 2016 and March 31, 2017 we recognized an income tax provision of $2.2 million and $3.3 million, respectively. The effective income tax rate for the three months ended March 31, 2016 and March 31, 2017 was 37.6% and 35.1%, respectively. The effective income tax rate for the six months ended March 31, 2016 and March 31, 2017 was 41.4% and 38.1%, respectively. The adoption in the fourth quarter of fiscal 2016 of ASU 2016-09 resulted in a decrease in income tax expense of $67,000 for the three months ended March 31, 2016, and an increase in income tax expense of $134,000 for the six months ended March 31, 2016.

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.