Guarantees [Abstract] Guarantees Guarantees [Text Block] Finite-Lived Intangible Assets, Net [Abstract] Amortization of intangible assets Amortization of Intangible Assets Retirement Benefits [Abstract] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Settlement cost Defined Benefit Plan, Settlement Cost Defined Benefit Plan, Settlement Cost Total net periodic (benefit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Statement of Comprehensive Income [Abstract] Net loss Net Income (Loss) Available to Common Stockholders, Basic Other comprehensive (loss) income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Other comprehensive (loss) income, net of taxes Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring basis Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 3 Assets Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Balance at September 30, 2017 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Acquisition of financial assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Change in fair value of financial assets Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Balance at June 30, 2018 Future expected amortization of intangible assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2018 (remaining three months) Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2022 and thereafter Finite Lived Intangible Assets Amortization Expense Year Five and Thereafter Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year and thereafter for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Total Intangible Assets, Net (Excluding Goodwill) Restructuring and Related Activities [Abstract] Restructuring and Related Costs Restructuring and Related Costs [Table Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] CAG CAG [Member] CAG [Member] GovDeals GovDeals [Member] GovDeals [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Goodwill Goodwill [Roll Forward] Balance at the beginning of the period Goodwill Translation adjustments Goodwill, Foreign Currency Translation Gain (Loss) Balance at the end of the period Stockholders' Equity Note [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Employee and director options Employee And Non Employees Stock Option [Member] An arrangement whereby an employee or non-employee is entitled to receive in the future, subject to vesting and other restrictions, a number of shares in the entity at a specified price, as defined in the agreement. Although there are variations, normally, after vesting, when an option is exercised, the holder pays the strike value in cash to the issuing employer-entity and receives equity shares. The equity shares can be sold into the market for cash at the current market price without restriction. Options may be used to attract, retain and incentivize individuals, in addition to their regular compensation and benefits. Stockholders' Equity Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stock option activity Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Options outstanding at the beginning of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Options canceled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Options outstanding at the end of the period (in shares) Options exercisable at the end of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted-Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Options outstanding at the beginning of the period (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options granted (USD per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Options exercised (USD per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Options canceled (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Options outstanding at the end of the period (USD per share) Options exercisable at the end of the period (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Commitments and Contingencies Disclosure [Abstract] Legal Proceedings Legal Matters and Contingencies [Text Block] Fair Value Measurement Fair Value Disclosures [Text Block] Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Stock compensation expense Share-based Compensation Provision for inventory allowance Inventory Write-down Provision for doubtful accounts Provision for Doubtful Accounts Deferred tax benefit Deferred Income Tax Expense (Benefit) Impairment of intangible assets Impairment of Intangible Assets, Finite-lived Change in fair value of financial instruments Gain from sale of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Inventory Increase (Decrease) in Inventories Prepaid and deferred taxes Increase (Decrease) In Prepaid Expenses And Deferred Taxes Represents the combined amount of increase (decrease) of consideration paid in advance for income and other taxes that provide economic benefits in future periods and deferred income tax expense (benefit) pertaining to income (loss) from continuing operations. Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued expenses and other current liabilities Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities Distributions payable Increase (Decrease) in Profit Sharing Distributions Payable The Net change in disbursement made as per the profit sharing arrangements after deducting the allowable operating expenses. Payables to sellers Increase (Decrease) In Payables To Sellers The net change during the reporting period in the amount of cash held on behalf of the sellers in the case of consignment sales transactions. Other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Increase in intangibles Increase (Decrease) in Intangible Assets, Current Purchases of property and equipment, including capitalized software Payments to Acquire Property, Plant, and Equipment Proceeds from sales of property and equipment Proceeds from Sale of Property, Plant, and Equipment Purchase of short-term investments Payments to Acquire Short-term Investments Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from exercise of common stock options (net of tax) Proceeds from Stock Options Exercised Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate differences on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net decrease in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid (received) for income taxes, net Income Taxes Paid, Net Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Minimum number of product categories offered (in categories) Number Of Product Categories Offered Represents the minimum number of product categories offered by the entity. Number of clients Number of Clients Represents the number of clients. Reportable segments (in segments) Number of Reportable Segments Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Cash consideration Payments to Acquire Businesses, Gross Equity consideration Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Contingent consideration, non-current Business Combination, Contingent Consideration, Liability, Noncurrent Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Corporate and Other Corporate, Non-Segment [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Employee severance and benefit costs Employee Severance [Member] Occupancy and other costs Occupancy Cost [Member] Occupancy Cost [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Beginning balance Restructuring Reserve Business Realignment Expenses Restructuring Charges Cash payments Payments for Restructuring Ending balance Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets, fair value Assets, Fair Value Disclosure Liabilities, fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Change in fair value of financial instruments Estimate of possible loss Loss Contingency, Estimate of Possible Loss Summary of stock option activity Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of restricted share activity Schedule of Nonvested Share Activity [Table Text Block] Unaudited Interim Financial Information Basis of Accounting, Policy [Policy Text Block] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Promissory Note Receivables, Policy [Policy Text Block] Risk Associated with Certain Concentrations Concentration Risk, Credit Risk, Policy [Policy Text Block] Earnings per Share Earnings Per Share, Policy [Policy Text Block] Stock-Based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Summary of goodwill activity Schedule of Goodwill [Table Text Block] Segment Reporting [Abstract] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Non-US Non-US [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Sales Revenue Sales Revenue, Net [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Geographic Concentration Risk Geographic Concentration Risk [Member] Revenue, Major Customer [Line Items] Revenue, Major Customer [Line Items] Segments percentage of revenue (as a percentage) Reportable Segments Percentage of Revenue Reportable Segments Percentage of Revenue Concentration risk (as a percentage) Concentration Risk, Percentage Schedule of intangible assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of future expected amortization of intangible assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Contractors [Abstract] Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Non-rolling stock Nonrolling Stock Surplus Contract [Member] Represents the non-rolling stock surplus contract entered into by the entity. Type of Arrangement and Non-arrangement Transactions [Axis] Type of Arrangement and Non-arrangement Transactions [Axis] Arrangements and Non-arrangement Transactions [Domain] Arrangements and Non-arrangement Transactions [Domain] Surplus Contract Surplus Contract [Member] Represents the surplus contract entered into by the entity. Scrap Contract Scrap Contract [Member] Represents the scrap contract entered into by the entity. Government Contracts Concentration Risk Government Contracts Concentration Risk [Member] Significant Contracts Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Number of contracts Number Of Contracts Number Of Contracts Term of contract Contract Term Represents the term of the contract, in PnYnMnDTnHnMnS format, for example, P1Y5M13D represents the reported fact of one year, five months, and thirteen days. Number of extensions Revenue From Contract With Customer, Number Of Contract Extensions Revenue From Contract With Customer, Number Of Contract Extensions Term of each renewal options extended Renewal Options Extended Term Represents the term of renewal options extended, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Adjusted percentage of profit sharing distribution Adjusted percentage of profit sharing distribution Represents the adjusted percentage of profits sharing distribution to the DLA Disposition Services by the entity. Concentration risk (as a percentage) Usable surplus property to be purchased as a fixed percentage of DoD's original acquisition value Usable Surplus Property to be Purchased as Percentage of Original Acquisition Value Represents the fixed percentage of DoD's original acquisition value at which the entity is required to purchase all usable surplus property offered to it by the Department of Defense. Profits from resale of the property retained (as a percent) Percentage of Profits Retained Represents the percentage of profits from resale of the property retained by the entity. Liability for inventory included in accrued expenses and other current liabilities Accrued Expenses and Other Current Liabilities Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent, utilities, PTO and accrued bonuses and commissions. It also includes aggregate carrying amount, as of the balance sheet date, of current obligations not separately disclosed in the balance sheet due to materiality considerations. Current liabilities are expected to be paid within one year (or the normal operating cycle, if longer). Schedule of Segment Reporting Information by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Reconciliation of Revenue from Segments to Consolidated Reconciliation of Revenue from Segments to Consolidated [Table Text Block] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Minimum Minimum [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Patent and trademarks Patents And Trademarks [Member] Represents rights acquired through registration of a trademark to gain or protect exclusive use of a business name, symbol or other device or style and exclusive legal right granted by the government to the owner of the patent to exploit an invention or a process for a period of time specified by law. Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Useful Life (in years) Finite-Lived Intangible Asset, Useful Life Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Schedule of net periodic benefit cost recognized Schedule of Net Benefit Costs [Table Text Block] Restricted shares Restricted Stock [Member] Restricted share activity Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested restricted shares at the beginning of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Restricted shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Restricted shares vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Restricted shares canceled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unvested restricted shares at the end of the period (in shares) Weighted-Average Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Unvested restricted shares at the beginning of the period (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Restricted shares vested (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Restricted shares cancelled (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Unvested restricted shares at the end of the period (USD per share) Stockholders' Equity Shareholders' Equity and Share-based Payments [Text Block] IronDirect IronDirect [Member] IronDirect [Member] Employee Severance Legal and Administrative Costs Legal and Administrative Costs [Member] Legal and Administrative Costs [Member] Occupancy And Contract Costs Occupancy And Contract Costs [Member] Occupancy And Contract Costs [Member] General and Administrative Expense General and Administrative Expense [Member] Selling and Marketing Expense Selling and Marketing Expense [Member] Technology and Operations Technology and Operations [Member] Technology and Operations [Member] Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] Severance Agreement Severance Agreement [Member] Severance Agreement [Member] Contract-Based Intangible Assets Contract-Based Intangible Assets [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Leasehold Improvements Leasehold Improvements [Member] Bethesda, Maryland Bethesda, Maryland [Member] Bethesda, Maryland [Member] District of Columbia DISTRICT OF COLUMBIA Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Operating Expense Other Operating Income (Expense) [Member] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Office Building Office Building [Member] Restructuring costs Restructuring Costs Asset Impairment Charges Asset Impairment Charges Impairment of long-lived assets Impairment of Long-Lived Assets Held-for-use Reversal of earn-out liability Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Area of real estate property Area of Real Estate Property Loss on contract termination Loss on Contract Termination Payment on contract loss termination Payment on Contract Loss Termination Payment on Contract Loss Termination Restructuring charges Restructuring reserve Document and Entity Information Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Segment Information Segment Reporting Disclosure [Text Block] Changes in financial assets fair value Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Options or stock appreciation rights Stock Options Or Stock Appreciation Rights [Member] Represents the stock options or stock appreciation rights. Other than options or stock appreciation rights Other Than Stock Options Or Stock Appreciation Rights [Member] Represents equity based awards other than stock options or stock appreciation rights. Cash-settled stock appreciation rights Stock Appreciation Rights (SARs) [Member] Amount yet to be expended under the program Stock Repurchase Program, Remaining Authorized Repurchase Amount Shares available for issuance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Increase in shares available for issuance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Reserve shares counted per share granted from fungible share pool (in shares) Number Of Shares Counted For Grants Of Full Value Awards From Reserve Represents information pertaining to number of shares counted for grants of full-value awards from reserve which is established as fungible share pool. Number of shares awarded per person per year (in shares) Share Based Compensation Arrangement by Share Based Payment Award Number of Shares Awarded Per Person Per Year Represents the number of shares that can be awarded to any person under the stock based compensation plan per year. Shares and options vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Forfeited (in shares) Outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Granted (in shares) Intrinsic value of outstanding shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Weighted average remaining contractual life of outstanding options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Intrinsic value of exercisable shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Weighted average remaining contractual life of exercisable options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Stock price (USD per share) Share Price Expected volatility, minimum (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Expected volatility, maximum (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Dividend yield (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Risk free interest rate, minimum (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Risk free interest rate, maximum (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Expected forfeiture rate (as a percent) Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Forfeiture Rate Represents the forfeiture rate that is used in valuing an option. Intrinsic value of unvested restricted shares Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Total Intrinsic Value Represents the aggregate intrinsic value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units, as calculated by applying the disclosed pricing methodology. Weighted average remaining contractual life of unvested restricted shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Intangible Assets Intangible Assets Disclosure [Text Block] Operating Segments Operating Segments [Member] RSCG RSCG [Member] RSCG [Member] Revenue Revenue, Net Gross profit Gross Profit Operating Expenses Operating Expenses Interest and other income, net Interest Income (Expense), Net Provision (benefit) for income taxes Income Tax Expense (Benefit) Net loss Business Realignment Expenses Restructuring and Related Activities Disclosure [Text Block] Defined Benefit Pension Plan Pension and Other Postretirement Benefits Disclosure [Text Block] Goodwill Goodwill Disclosure [Text Block] Guarantee obligation value, maximum Guarantor Obligations, Current Carrying Value Funded (unfunded) status of plan Defined Benefit Plan, Funded (Unfunded) Status of Plan Statement of Financial Position [Abstract] Accounts receivable, allowance for doubtful accounts (in dollars) Allowance for Doubtful Accounts Receivable, Current Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Income Statement [Abstract] Revenue Sales Revenue, Goods, Net Fee revenue Sales Revenue, Services, Net Total revenue Costs and expenses from operations: Costs and Expenses [Abstract] Cost of goods sold Cost of Goods Sold Seller distributions Profit Sharing Distributions This element represents the disbursement made as per the profit sharing arrangements after deducting the allowable operating expenses. Technology and operations Technology And Operations Expense Includes technology expenses which consist primarily of personnel costs related to programming staff who develop and deploy new marketplaces and continuously enhance existing marketplaces. These personnel also develop and upgrade the software systems that support operations, such as sales processing. It also includes operations expenses which consist primarily of operating costs, including buyer relations, shipping logistics and distribution center operating costs. Sales and marketing Sales and Marketing Sales and marketing expenses include the cost of sales and marketing personnel as well as the cost of marketing and promotional activities. These activities include online marketing campaigns such as paid search advertising. General and administrative General and Administrative Expense Other operating expenses Other Operating Income (Expense), Net Total costs and expenses Costs and Expenses Loss from operations Operating Income (Loss) Loss before provision (benefit) for income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Basic and diluted loss per common share (in dollars per share) Earnings Per Share, Basic and Diluted Basic and diluted weighted average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Summary of the basic and diluted income per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Significant Contracts Long-term Contracts or Programs Disclosure [Text Block] Organization Nature of Operations [Text Block] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Short-term investments Short-term Investments Accounts receivable, net of allowance for doubtful accounts of $531 and $668 at June 30, 2018 and September 30, 2017, respectively Accounts Receivable, Net, Current Inventory Inventory, Net Prepaid taxes Prepaid Taxes Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property and equipment, net Property, Plant and Equipment, Net Intangible assets, net Goodwill Net deferred long-term tax assets Deferred Tax Assets, Gross, Noncurrent Other assets Other Assets, Noncurrent Total assets Assets Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued expenses and other current liabilities Distributions payable Profit Sharing Distributions Payable This element represents the current portion of the profit sharing distributions payable. Payables to sellers Payables To Sellers, Current Payables to Sellers, Current Total current liabilities Liabilities, Current Deferred taxes and other long-term liabilities Deferred Tax and Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 12) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $0.001 par value; 120,000,000 shares authorized; 32,109,731 shares issued and outstanding at June 30, 2018; 31,503,349 shares issued and outstanding at September 30, 2017 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings (accumulated deficit) Retained Earnings (Accumulated Deficit) Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-09 Accounting Standards Update 2016-09 [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Retained Earnings Retained Earnings [Member] Schedule of Receivables with Imputed Interest, Name of Receivable with Imputed Interest [Axis] Schedule of Receivables with Imputed Interest, Name of Receivable with Imputed Interest [Axis] Name of Receivable with Imputed Interest [Domain] Name of Receivable with Imputed Interest [Domain] Tanager Acquisitions Promissory Note Tanager Acquisitions Promissory Note [Member] Tanager Acquisitions Promissory Note [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Assets Other Assets [Member] Prepaid Expenses and Other Current Assets Prepaid Expenses and Other Current Assets [Member] Supplier Concentration Risk Supplier Concentration Risk [Member] Cost of Goods Cost of Goods, Total [Member] Contract With Commercial Client Contract With Commercial Client [Member] Represents the information pertaining to the contract with commercial client. Business Combination [Line Items] Business Acquisition [Line Items] Decrease to retained earnings Cumulative Effect of New Accounting Principle in Period of Adoption Receivable with imputed interest, face amount Receivable with Imputed Interest, Face Amount Receivable with imputed interest, term Receivable With Imputed Interest, Term Receivable with Imputed Interest, Term Proceeds from collection of notes receivable Proceeds from Collection of Notes Receivable Receivable with imputed interest, net amount Receivable with Imputed Interest, Net Amount Income Tax Examination [Table] Income Tax Examination [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Federal Tax Authority Domestic Tax Authority [Member] Income Tax Examination [Line Items] Income Tax Examination [Line Items] Blended effective tax rate (as a percentage) Tax Cuts and Jobs Act of 2017, Blended Tax Rate, Percent Tax Cuts and Jobs Act of 2017, Blended Tax Rate, Percent Tax benefit relating to adjustment in corporate tax rate Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense (Benefit) Tax benefit relating to adjustment to ATM credits Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Alternative Minimum Income Tax Credit, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Alternative Minimum Income Tax Credit, Income Tax Expense (Benefit) Expected effective tax rate (as a percent) Estimated Effective Income Tax Rate Continuing Operations Represents the estimated effective tax rate for the current fiscal year. Change in tax rate, income tax benefit Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit) Income Tax Examination, Penalties Expense Income Tax Examination, Penalties Expense Subsequent Event Subsequent Events [Text Block] Earnings per Share Earnings Per Share [Abstract] Weighted average shares calculation: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic weighted average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Treasury stock effect of options and restricted stock (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Diluted weighted average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted