Disclosure of Compensation Related Costs, Share-based Payments [Abstract] 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 Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block] Leases [Abstract] Lease and operating expenses Operating Leases, Rent Expense, Net Debt Disclosure [Abstract] Line of Credit Debt Disclosure [Text Block] Accounting Policies [Abstract] Mutual fund administration: Mutual Fund Administration [Abstract] Mutual Fund Administration [Abstract] Administration revenue, gross Administrative Services Revenue Fund related expense Fund Related Expense Fund related expense. Revenue, net of related expenses Revenue from Administrative Services Excluding Financial Activity Net Revenue from administrative services excluding financial activity net. Share Financing [Abstract] Share Financing [Abstract] 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. Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Investment portfolio Investments 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 Deferred Compensation Liability, Current and Noncurrent Income taxes payable Taxes Payable, Current Total liabilities Liabilities Redeemable noncontrolling interest Redeemable Noncontrolling Interest, Equity, Common, Fair Value Permanent Shareholders’ equity Stockholders' Equity Attributable to Parent [Abstract] Common stock, no par value 7,000,000 shares authorized; 3,534,148 issued and outstanding at September 30, 2018 (inclusive of 207,500 unvested shares); 3,470,428 issued and outstanding at December 31, 2017 (inclusive of 191,900 unvested shares) Common Stock, Value, Issued Preferred stock, undesignated, 1,000,000 shares authorized and unissued Preferred Stock, Value, Issued Deferred equity compensation Deferred Compensation Equity Retained earnings Retained Earnings (Accumulated Deficit) Total permanent shareholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and shareholders’ equity Liabilities and Equity Book value per share (usd 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. Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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 (Increase) decrease 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 Net gains on investments Gain (Loss) on Investments Net change in 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 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 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 Net subscriptions received from redeemable noncontrolling interest holders Proceeds from (Payments to) Noncontrolling Interests Net cash provided by 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 period Cash and Cash Equivalents, Period Increase (Decrease) At beginning of period At end of period 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] Common stock issued as incentive compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Charitable donation of corporate investments and property and equipment Contribution of Investments and Property and Equipment Value of investments and property and equipment contributed in noncash investing and financing activities. Net subscriptions (redemptions) of ETF shares for marketable securities Net issuance of ETF shares for marketable securities Value of ETF shares issued in exchange for marketable securities. Investments, Debt and Equity Securities [Abstract] Summary of Market Value of Investments Summary Investment Holdings [Table Text Block] Equity Method Investments Equity Method Investments [Table 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] Equity Award [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] 2018 (Remaining Period) Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Current Employee service share based compensation nonvested awards compensation cost not yet recognized current. 2019 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. 2020 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. 2021 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. 2022 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 Thereafter 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. Total Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Fair Value Measurements, Recurring and Nonrecurring Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Assets under Management (AUM) Subject to Incentive Fees and Incentive 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. 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 Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [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 Company Sponsored Investments [Member] Company Sponsored 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] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 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] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Fair value investments Investment Owned, at Fair Value Compensation Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Earnings Per Share [Abstract] Computation for Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Area of operating lease Lessee Leasing Agreements, Operating Leases, Area under Lease Lessee Leasing Agreements, Operating Leases, Area under Lease Number of office space locations Lessee Leasing Agreements, Operating Leases, locations Lessee Leasing Agreements, Operating Leases, locations Operating lease expense excluding rent Operating Lease Expense Excluding Rent Operating Lease Expense Excluding Rent 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 [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Dividends declared (in usd per share) Common Stock, Dividends, Per Share, Declared Dividends to be paid in cash Dividends, Common Stock, Cash Investment Portfolio Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Common stock, par value (usd per share) 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 Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred Stock, shares Outstanding Preferred Stock, Shares Outstanding Unvested shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Investment Holdings [Table] Investment Holdings [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Parent Parent [Member] Redeemable Noncontrolling Interest Noncontrolling Interest [Member] Investment Holdings [Line Items] Investment Holdings [Line Items] Company sponsored equity method investments Equity Method Investments Total Investment portfolio Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Proprietary funds Proprietary Funds [Member] Proprietary Funds [Member] Sub-advised funds and institutional accounts Sub-advised Funds And Institutional Accounts [Member] Sub-advised Funds And Institutional Accounts [Member] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Investment advisory Investment Advisory Services [Member] Investment Advisory Services [Member] Mutual fund administration, net Mutual Fund Administrative Services [Member] Mutual fund administrative services [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenue earned Revenue from Contract with Customer, Excluding Assessed Tax Organization, Consolidation and Presentation of Financial Statements [Abstract] Business and Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Summary of Total Lease and Operating Expenses Lessee, Operating Lease, Disclosure [Table Text Block] Future Minimum Lease Payments under Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Subsequent Events Subsequent Events [Text Block] Statement [Table] Statement [Table] Redeemable Noncontrolling Interest Statement [Line Items] Statement [Line Items] New consolidations of Company sponsored investments Noncontrolling Interest, Increase from Consolidation The amount of the increase during the period of a noncontrolling interest resulting from the parent's increase in control and consolidation of the entity in which one or more outside parties had a noncontrolling interest. Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus 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 Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Outstanding shares, Beginning Balance (shares) Shares issued (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Grants vested (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Grants forfeited (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Outstanding shares, Ending Balance (shares) Weighted-Average Grant Date Price per Share Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted-Average Grant Date Price per Share, Beginning of 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 Weighted-Average Grant Date Price per Share, Grants issued (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 Weighted-Average Grant Date Price per Share, Grants 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 Weighted-Average Grant Date Price per Share, Grants forfeited (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted-Average Grant Date Price per Share, End of Period (usd per share) 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] Maximum borrowing amount Line of Credit Facility, Maximum Borrowing Capacity Line of credit facility, interest rate description Debt Instrument, Basis Spread on Variable Rate Borrowing under line of credit facility Long-term Line of Credit, Noncurrent Line of credit, unused capacity, commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Business Organization And Significant Accounting Policies [Table] Business Organization And Significant Accounting Policies [Table] Business Organization And Significant Accounting Policies [Table] Money Market Funds Money Market Funds [Member] Business Organization And Significant Accounting Policies [Line Items] Business Organization And Significant Accounting Policies [Line Items] [Line Items] for Business Organization And Significant Accounting Policies [Table] 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 Transfers between Level 1, Level 2, or Level 3, amount Fair Value, Transfers Between Level 1, Level 2, or Level 3, Amount Fair Value, Transfers Between Level 1, Level 2, or Level 3, Amount Client performance period Rolling Client Investment Performance Period Rolling Client Investment Performance Period Variable fees Performance Fees Advance commissions amortization period Advance Commissions Amortization Period Advance commissions amortization period. Liability for uncertain tax positions Liability for Uncertainty in Income Taxes, Current 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 Ending December 31, 2018 Asset Under Management Contractual Period End Date [Member] Asset under management contractual period end date. Quarter Ending September 30, 2019 Asset Under Management Contractual Period End Date 2 [Member] Asset Under Management Contractual Period End Date 2 [Member] Quarter Ending March 31, 2020 Asset Under Management Contractual Period End Date 3 [Member] Asset Under Management Contractual Period End Date 3 [Member] Quarter Ending 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] AUM subject to variable rate fees Assets Under Management Variable Performance Fees Assets under management (AUM) subject to variable performance fees and variable performance fees. Unearned variable rate fees Potential Variable Fees Based Upon Current Investment Results Potential Variable Fees Based Upon Current Investment Results Earnings Per Share Earnings Per Share [Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Research Opportunities Fund Research Opportunities Fund [Member] Research opportunities fund. International Equity Fund LP International Equity Fund LP [Member] International Equity 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 Net Income 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 shares outstanding Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted average number of outstanding shares - Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive impact of restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted average number of outstanding shares - Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per share Earnings Per Share, Basic and Diluted [Abstract] Basic (USD per share) Earnings Per Share, Basic Diluted (USD per share) Earnings Per Share, Diluted Statement of Stockholders' Equity [Abstract] Total Common Stock Common Stock [Member] Deferred Equity Compensation Deferred Compensation, Share-based Payments [Member] Retained Earnings Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (shares) Beginning Balance Issuance of restricted stock grants (shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Issuance of restricted stock grants Stock Issued During Period, Value, 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 stock grants Issuance of common stock related to 401k plan match (shares) Stock Issued During Period, Shares, New Issues Issuance of common stock related to 401k plan match Stock Issued During Period, Value, New Issues Shares withheld related to employee tax withholding (shares) Shares Paid for Tax Withholding for Share Based Compensation Shares withheld related to employee tax withholding Adjustments Related to Tax Withholding for Share-based Compensation Forfeiture of restricted stock grants (shares) Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Forfeiture of restricted stock grants Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Net income Ending balance (shares) Ending Balance Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balance 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 balance attributable to redeemable noncontrolling Interests Operating Leases Leases of Lessee Disclosure [Text Block] Shares Issued Shares Outstanding [Member] Shares outstanding. Grant Date Value Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] 2014 Equity and Cash Incentive Plan Equity and Cash Incentive Plan [Member] 2011 equity and cash incentive plan. Common shares available for issuance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Deferred compensation equity 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 liability Significant Accounting Policies Significant Accounting Policies [Text Block] 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, net Investment Income, Net INCOME BEFORE TAXES Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) NET INCOME Earnings per share attributable to common shareholders Basic (in shares) Diluted (in shares) Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, 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] Fair Value Measurements Fair Value Measurement, 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 - Investment Advisory and Variable Incentive 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] Newly Issued But Not Yet Adopted Accounting Guidance New Accounting Pronouncements, Policy [Policy Text Block] Remainder of 2018 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total future lease payments due Operating Leases, Future Minimum Payments Due Income tax expense (benefit) Effective tax rate Effective Income Tax Rate Reconciliation, Percent Federal statutory income tax rate, percent Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective income tax rate reconciliation, share-based compensation, excess tax benefit (tax shortfall), Amount Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit (Tax Shortfall), Amount Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit (Tax Shortfall), Amount Valuation allowance Deferred Tax Assets, Valuation Allowance