Accounting Policies [Abstract] Management Fees Revenue [Abstract] Management Fees Revenue [Abstract] Performance Fees Performance Fees Mutual fund administration gross and net revenue Mutual Fund Administration Gross and Net Revenue [Abstract] Mutual fund administration gross and net revenue. Mutual fund administration: Mutual Fund Administration [Abstract] Mutual fund administration. Administration revenue, gross Administrative Services Revenue 12b-1/service fees and commission revenue received from fund clients Fees and Commissions 12b-1/service fees and commission expense payments to third parties Service Fees and Commission Expense Payments to Third Parties Service fees and commission expense payments to third parties. Fund related expense Fund Related Expense Fund related expense. Revenue, net of fund related expenses Revenue from Administrative Services Excluding Financial Activity Net Revenue from administrative services excluding financial activity net. DHCM C-Share financing: Share Financing [Abstract] DHCM C-Share financing. Broker commission advance repayments Broker Commission Advance Repayments Broker commission advance repayments. Broker commission amortization Broker Commission Amortization Broker commission amortization. Financing activity, net Financing Activity Net Financing activity, net. Mutual fund administration revenue, net Revenue from Administrative Services Net Revenue from administrative services net. Investments, Debt and Equity Securities [Abstract] Investment Holdings [Table] Investment Holdings [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Securities held in Consolidated Funds Securities held in Consolidated Funds [Member] Securities held in Consolidated Funds [Member] Company Sponsored Investments Seed Capital Investments [Member] Seed Capital Investments [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Total Parent [Member] Redeemable Noncontrolling Interest Noncontrolling Interest [Member] Investment Holdings [Line Items] Investment Holdings [Line Items] Trading Investments Trading Securities Seed capital equity method investments Equity Method Investments Deferred compensation plan assets Deferred Compensation Plan Assets Total Investment Portfolio Investments Equity Method Investments [Abstract] Equity Method Investments [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Mid Cap Fund Mid Cap Fund [Member] Mid Cap Fund [Member] Research Opportunities Fund Research Opportunities Fund [Member] Research opportunities fund. High Yield Fund High Yield Fund [Member] High Yield Fund Global Fund LP Global Fund LP [Member] Global Fund LP Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Income Tax Disclosure [Abstract] Summary of Deferred tax assets and liabilities Components of Deferred Tax Assets and Liabilities [Abstract] Stock-based compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Accrued incentive compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Deferred Tax Liabilities, Unrealized Gains on Trading Securities Deferred Tax Liabilities, Unrealized Gains on Trading Securities Deferred Tax Liabilities, Property and Equipment Deferred Tax Liabilities, Property, Plant and Equipment Other assets and liabilities Deferred Tax Assets (Liabilities) Other Deferred tax assets (liabilities) other. Net deferred tax assets Deferred Tax Assets, Net Income Taxes Income Tax Disclosure [Text Block] Leases [Abstract] Operating Leases Leases of Lessee Disclosure [Text Block] Summary of consolidated Federal income tax return Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Summary of reconciliation of income tax expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Summary of Deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] 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] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Equity Award [Domain] Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Expense recognition of deferred compensation Deferred Compensation Arrangements [Abstract] 2017 Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized in Year One Employee service share based compensation nonvested awards compensation cost not yet recognized in year one. 2018 Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized in Year Two Employee service share based compensation nonvested awards compensation cost not yet recognized in year two. 2019 Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized in Year Three Employee service share based compensation nonvested awards compensation cost not yet recognized in year three. 2020 Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized in Year Four Employee service share based compensation nonvested awards compensation cost not yet recognized in year four 2021 Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized in Year Five Employee service share based compensation nonvested awards compensation cost not yet recognized in year five. Thereafter Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Thereafter Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Thereafter Total Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Debt Disclosure [Abstract] Line of Credit Debt Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Reclassification Reclassification, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Redeemable Noncontrolling Interest Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Segment Information Segment Reporting, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Accounts Receivable Receivables, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Revenue Recognition - General Revenue Recognition, Policy [Policy Text Block] Revenue Recognition - Variable Fee Revenue Revenue Recognition, Services, Management Fees [Policy Text Block] Revenue Recognition - Mutual Fund Administration Revenue Recognition Accounting Policy, Gross and Net Revenue Disclosure [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Investment Portfolio Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Summary of total lease and operating expense Operating Leases of Lessee Disclosure [Table Text Block] Future minimum lease payments under the operating leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Business and Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Future minimum lease payments under the operating leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2017 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2018 Operating Leases, Future Minimum Payments, Due in Two Years 2019 Operating Leases, Future Minimum Payments, Due in Three Years 2020 Operating Leases, Future Minimum Payments, Due in Four Years 2021 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Operating Leases, Future Minimum Payments Due Operating Leases, Future Minimum Payments Due Significant Accounting Policies Significant Accounting Policies [Text Block] Statement of Financial Position [Abstract] Common Stock, No Par Value Common Stock, No Par Value Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Common stock, unvested shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Summary of consolidated Federal income tax return Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current city income tax provision Current Local Tax Expense (Benefit) Current local tax expense (benefit). Current state income tax provision Current State Tax Expense (Benefit) Current state tax expense (benefit). Current federal income tax provision Current Federal Tax Expense (Benefit) Deferred federal income tax benefit Deferred Federal Income Tax Expense (Benefit) Provision for income taxes Income Tax Expense (Benefit) Computation for earnings per share Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Less: Net income attributable to redeemable noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to common shareholders Net Income (Loss) Attributable to Parent Weighted average number of outstanding shares Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per share Earnings Per Share, Basic and Diluted [Abstract] Basic (per share) Earnings Per Share, Basic Diluted (per share) Earnings Per Share, Diluted Income Statement [Abstract] REVENUES: Revenues [Abstract] Investment advisory Investment Advisory Fees Mutual fund administration, net Total revenue Revenues OPERATING EXPENSES: Operating Expenses [Abstract] Compensation and related costs Labor and Related Expense General and administrative General and Administrative Expense Sales and marketing Selling and Marketing Expense Mutual fund administration Asset Management Costs Total operating expenses Operating Expenses NET OPERATING INCOME Operating Income (Loss) Investment income (loss) Investment Income, Net Gain on sale of subsidiary Gain (Loss) on Disposition of Business INCOME BEFORE TAXES Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense NET INCOME Less: Net income attributable to redeemable noncontrolling interest NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS Earnings per share attributable to common shareholders Weighted average shares outstanding Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation Depreciation Share-based compensation Share-based Compensation Decrease (increase) in accounts receivable Increase (Decrease) in Accounts Receivable Change in current income taxes Increase (Decrease) in Income Taxes Payable Change in deferred income taxes Increase (Decrease) in Deferred Income Taxes Gain on sale of subsidiary Net (gains)/losses on investments Gain (Loss) on Investments Net change in trading securities held by Consolidated Funds Increase (Decrease) in Trading Securities Increase in accrued incentive compensation Increase (Decrease) in Employee Related Liabilities Increase in deferred compensation Increase (Decrease) in Deferred Compensation Excess income tax benefit from share-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Income tax benefit from dividends paid on restricted stock Income Tax Benefit From Dividends Paid On Restricted Stock Operating Activities Income tax benefit from dividends paid on restricted stock. Other changes in assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Purchase of Company sponsored investments Payments to Acquire Investments Proceeds from sale of Company sponsored investments Proceeds from Sale, Maturity and Collection of Investments Proceeds from sale of subsidiary, net of cash disposed Proceeds from Divestiture of Businesses, Net of Cash Divested Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Value of shares withheld related to employee tax withholding Payments Related to Tax Withholding for Share-based Compensation Excess income tax benefit from share-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Income tax benefit from dividends paid on restricted stock Income Tax Benefit From Dividends Paid On Restricted Stock Financing Activities Income tax benefit from dividends paid on restricted stock. Payment of dividends Payments of Ordinary Dividends, Common Stock Net subscriptions received from (redemptions and distributions paid to) redeemable noncontrolling interest holders Proceeds from (Payments to) Noncontrolling Interests Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, at Carrying Value [Abstract] Net change during the year Cash and Cash Equivalents, Period Increase (Decrease) At beginning of year Cash and Cash Equivalents, at Carrying Value At end of year Supplemental cash flow information: Supplemental Cash Flow Information [Abstract] Income taxes paid Income Taxes Paid Supplemental disclosure of non-cash transactions: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Charitable donation of corporate investments Contribution of Investments Value of investments contributed in noncash investing and financing activities. Common stock issued as incentive compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Cumulative-effect adjustment from the adoption of ASU 2015-02 (Note 2) New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification Net redemption of ETF Shares for marketable securities Net issuance of ETF shares for marketable securities Value of ETF shares issued in exchange for marketable securities. 401(k) Plan Four Zero One k Plan [Member] 401(k) Plan. Summary of Company expenses attributable to the 401(k) Plan Company Expenses Attributable to Plan [Abstract] Company's expenses attributable to the 401 (k) plan. Expenses attributable to the 401(k) Plan Allocated Share-based Compensation Expense Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Valuation Allowance Income Taxes (Textual) [Abstract] Income Taxes (Textual) [Abstract] Income Taxes (Textual) [Abstract] Income tax benefit to shareholders equity Income Tax Effects Allocated Directly to Equity Statement [Table] Statement [Table] Common Stock Common Stock [Member] Statement [Line Items] Statement [Line Items] Shares Issued Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Issuance of stock grants Fair Value Measurements, Recurring and Nonrecurring Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Variable Performance Fees Earned [Table Text Block] Variable Performance Fees Earned [Table Text Block] Schedule of Variable Performance Fees Earned Assets under management (AUM) subject to variable fees and the variable fees Assets Under Management Variable Performance Fees [Table Text Block] Assets under management (AUM) subject to variable performance fees and variance performance fees. Mutual fund administration gross and net revenue Mutual Fund Administration Gross and Net Revenue [Table Text Block] Mutual fund administration gross and net revenue. Lessee Leasing Agreements, Operating Leases, Area under Lease Lessee Leasing Agreements, Operating Leases, Area under Lease Lessee Leasing Agreements, Operating Leases, Area under Lease Operating Lease Expense Excluding Rent Operating Lease Expense Excluding Rent Operating Lease Expense Excluding Rent Number of office space locations Property Subject to or Available for Operating Lease, Number of Units Operating Leases, Future Minimum Payments Due Line of Credit Facility [Table] Line of Credit Facility [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] The Credit Agreement The Credit Agreement [Member] The Credit Agreement [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Line of Credit Line of Credit [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Interest Rate Description Debt Instrument, Basis Spread on Variable Rate Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Summary of reconciliation of income tax expense Effective Income Tax Rate Reconciliation, Amount [Abstract] Income tax computed at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount City and state income taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Sale of Beacon Hill [Abstract] Sale of Beacon Hill [Abstract] Sale of Beacon Hill Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Common Stock Deferred Equity Compensation Deferred Compensation, Share-based Payments [Member] Retained Earnings/(Deficit) Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance, shares Beginning Balance Stockholders' Equity Attributable to Parent Issuance of restricted stock grants Stock Issued During Period, Value, Restricted Stock Award, Gross Issuance of restricted stock grants, shares Stock Issued During Period, Shares, Restricted Stock Award, Gross Amortization of restricted stock grants Amortization Of Restricted Stock Grants Amortization of restricted stock grants. Issuance of stock grants, shares Issuance of common stock related to 401k plan match Stock Issued During Period, Value, New Issues Issuance of common stock related to 401k plan match, shares Stock Issued During Period, Shares, New Issues Tax benefit from dividend payments related to restricted stock grants Tax Benefit From Dividend Payments Related To Restricted Stock Grants Tax benefit from dividend payments related to restricted stock grants. Net excess tax benefit from vested restricted stock grants Income Tax Effects Allocated Directly to Equity, Equity Transactions Shares withheld related to employee tax withholding Adjustments Related to Tax Withholding for Share-based Compensation Shares withheld related to employee tax withholding (shares) Shares Paid for Tax Withholding for Share Based Compensation Forfeiture of restricted stock grants Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Forfeiture of restricted stock grants, shares Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Cash dividend paid of $4.00 in 2014, $5.00 in 2015, and $6.00 in 2016 per share respectively Dividends, Common Stock, Cash Net income Ending Balance, shares Ending Balance Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balances attributable to redeemable noncontrolling interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Net Income Attributable to Redeemable Noncontrolling Interest Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Net subscriptions of consolidated funds Subscription From Redemption Distribution To Noncontrolling Interest A positive value represents subscriptions net of redemptions and distributions to redeemable non-controlling interest holders. A negative value represents redemptions and distributions paid to redeemable non-controlling interest holders net of subscriptions received. Ending balances attributable to redeemable noncontrolling interests Summary of total lease and operating expense Operating Leases, Rent Expense, Net [Abstract] Lease and operating expenses Operating Leases, Rent Expense, Net Computation for earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] 2011 Equity and Cash Incentive Plan Equity and Cash Incentive Plan [Member] 2011 equity and cash incentive plan. Deferred Compensation Arrangement, Fully Vested Employee Elected Deferral Period Deferred Compensation Arrangement, Fully Vested Employee Elected Deferral Period Deferred Compensation Arrangement, Fully Vested Employee Elected Deferral Period Deferred Compensation Equity Deferred Compensation Equity Stock Based Compensation (Textual) [Abstract] Stock Based Compensation (Textual) [Abstract] Stock-based compensation. Authorizes the issuance of Common Shares in various forms of equity awards Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Common Shares available for awards Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Deferred compensation related to unvested restricted stock grants Employee's compensation contributed to the plan Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Number of years of employment required to vest in contribution Defined Contribution Plan Number Years of Service of Employees Required Number years of service required of employees to vest in contribution. Defined Contribution Plan, Employer Matching Contribution, Percent of Match Defined Contribution Plan, Employer Matching Contribution, Percent of Match Deferred Compensation Liability, Current and Noncurrent Deferred Compensation Liability, Current and Noncurrent Summary of market value of investments Summary Investment Holdings [Table Text Block] Equity Method Investments Equity Method Investments [Table Text Block] Schedule of Investments [Table] Schedule of Investments [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Investment Advisory Services Investment Advisory Services [Member] Investment Advisory Services [Member] Mutual fund administrative services Mutual fund administrative services [Member] Mutual fund administrative services [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Inputs Fair Value, Inputs, Level 1 [Member] Money Market Funds Money Market Funds [Member] Parent Schedule of Investments [Line Items] Schedule of Investments [Line Items] Cumulative-effect adjustment from the adoption of ASU 2015-02 Number of business segment Number of Operating Segments Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Accounts Receivable, Related Parties Accounts Receivable, Related Parties Cash Equivalents Cash and Cash Equivalents, Fair Value Disclosure Transfers between fair value levels Fair Value, Transfers Between Level 1, Level 2, or Level 3, Amount Fair Value, Transfers Between Level 1, Level 2, or Level 3, Amount Revenue from Related Parties Revenue from Related Parties Rolling Client Investment Performance Period Rolling Client Investment Performance Period Rolling Client Investment Performance Period Advance Commissions Amortization Period Advance Commissions Amortization Period Advance commissions amortization period. Liability for Uncertain Tax Positions, Current Liability for Uncertainty in Income Taxes, Current Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Estimated Future Excess Tax Benefit Estimated Future Excess Tax Benefit Estimated Future Excess Tax Benefit To Be Recognized in Tax Provision Equity [Abstract] Capital Stock (Textual) [Abstract] Capital Stock (Textual) [Abstract] Capital stock. Preferred Stock, Shares Issued Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Equity Method Investments Equity Method Investments [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Level 2 Inputs Fair Value, Inputs, Level 2 [Member] Level 3 inputs 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] Company sponsored equity method investments Equity Method Investments, Fair Value Disclosure Investments measured at NAV Alternative Investments, Fair Value Disclosure Deferred Compensation Investments Deferred Compensation Investments, Fair Value Disclosure Deferred Compensation Investments, Fair Value Disclosure Capital Stock Stockholders' Equity Note Disclosure [Text Block] ASSETS Assets [Abstract] Cash and cash equivalents Investment portfolio Accounts receivable Accounts Receivable, Net Prepaid expenses Prepaid Expense Income taxes receivable Income Taxes Receivable, Current Property and equipment, net of depreciation Property, Plant and Equipment, Net Deferred taxes Deferred Tax Assets, Net of Valuation Allowance Total assets Assets LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Liabilities Liabilities [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Accrued incentive compensation Accrued Bonuses, Current Deferred compensation Total liabilities Liabilities Redeemable Noncontrolling Interest, Equity, Common, Fair Value Redeemable Noncontrolling Interest, Equity, Common, Fair Value Shareholders’ Equity Stockholders' Equity Attributable to Parent [Abstract] Common stock, no par value 7,000,000 shares authorized; 3,411,556 issued and outstanding at December 31, 2016 (inclusive of 201,800 unvested shares); 3,414,338 issued and outstanding at December 31, 2015 (inclusive of 310,356 unvested shares) Common Stock, Value, Issued Preferred stock, undesignated, 1,000,000 shares authorized and unissued Preferred Stock, Value, Issued Deferred equity compensation Retained Earnings Retained Earnings (Accumulated Deficit) Total shareholders’ equity Total liabilities and shareholders’ equity Liabilities and Equity Book value per share Book Value Per Share Book value per share is computed by dividing total shareholders' equity by the number of shares issued and outstanding at the end of the measurement period. Fair value of investments Investments, Fair Value Disclosure Trading Securities [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2015-02 [Member] Accounting Standards Update 2015-02 [Member] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] New Accounting Pronouncement, Early Adoption, Effect [Member] New Accounting Pronouncement, Early Adoption, Effect [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Trading Securities Trading Securities [Member] Schedule of Trading Securities and Other Trading Assets [Line Items] Schedule of Trading Securities and Other Trading Assets [Line Items] Cumulative Effect of New Accounting Principle in Period of Adoption Cumulative Effect of New Accounting Principle in Period of Adoption Trading Securities Roll-forward of outstanding restricted stock grants issued Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Outstanding shares, Beginning Balance Weighted-Average Grant Date Price per Share, Beginning of Period Grants issued Weighted-Average Grant Date Price Per Share, Grants issued Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Grants vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Weighted-Average Grant Date Price Per Share, Grants vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Grants forfeited Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Weighted-Average Grant Date Price per Share, Grants forfeited Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Outstanding shares, Ending Balance Weighted-Average Grant Date Price per Share, End of Period Principal Transaction Revenue [Table] Principal Transaction Revenue [Table] Principal Transaction Revenue, Description of Reporting Category [Axis] Principal Transaction Revenue, Description of Reporting Category [Axis] Name of Reporting Category [Domain] Name of Reporting Category [Domain] Quarter Ended December 31, 2018 Asset Under Management Contractual Period End Date [Member] Asset under management contractual period end date. Quarter Ended September 30, 2019 Asset Under Management Contractual Period End Date 2 [Member] Asset Under Management Contractual Period End Date 2 [Member] Quarter Ended March 31, 2020 Asset Under Management Contractual Period End Date 3 [Member] Asset Under Management Contractual Period End Date 3 [Member] Quarter Ended September 30, 2021 Asset Under Management Contractual Period End Date 4 [Member] Asset Under Management Contractual Period End Date 4 [Member] Total Asset Under Management Contractual Period End Total [Member] Asset Under Management Contractual Period End Total Principal Transaction Revenue [Line Items] Principal Transaction Revenue [Line Items] Assets under management (AUM) subject to variable fees and the variable fees Investment Advisory, Management and Administrative Fees [Abstract] Total AUM Subject to Variable Fees Assets Under Management Variable Performance Fees Assets under management (AUM) subject to variable performance fees and variable performance fees. Potential Variable Fees Based Upon Current Investment Results Potential Variable Fees Based Upon Current Investment Results Potential Variable Fees Based Upon Current Investment Results Dividend paid per share Common Stock, Dividends, Per Share, Cash Paid Total assets Equity Method Investment, Summarized Financial Information, Assets Total liabilities Equity Method Investment, Summarized Financial Information, Liabilities Net assets Equity Method Investment Summarized Financial Information, Equity DHCM's portion of net assets Equity Method Investment, Underlying Equity in Net Assets Investment income Equity Method Investment, Summarized Financial Information, Revenue Expenses Equity Method Investment, Summarized Financial Information, Expenses The amount of expenses reported by an equity method investment of the entity. Net realized gains (losses) Equity Method Investment, Summarized Financial Information, Net realized gains (losses) The amount of net realized gains (losses) reported by an equity method investment of the entity. Net change in unrealized appreciation/depreciation Equity Method Investment, Summarized Financial Information, Net change in unrealized appreciation/depreciation The amount of net change in unrealized appreciation/depreciation reported by an equity method investment of the entity. Net income Equity Method Investment, Summarized Financial Information, Net Income (Loss) DHCM's portion of net income Income (Loss) from Equity Method Investments Roll-forward of outstanding restricted stock grants issued Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Expense recognition of deferred compensation Schedule of Expense Recognition of Deferred Compensation Arrangement [Table Text Block] Schedule of expense recognition of deferred compensation arrangement. Schedule of Grants Issued and Grant Date Fair Value Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block] Summary of company expenses attributable to the 401(k) Plan Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Beacon Hill Beacon Hill [Member] Beacon Hill [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Discontinued Operations, Disposed of by Sale Discontinued Operations, Disposed of by Sale [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Foreside Foreside [Member] Foreside [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Proceeds from sale of subsidiary, net of cash disposed Promissory Note Receivable Other Assets, Current Gain (Loss) on sale of subsidiary, net of tax Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax