Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income Net Income (Loss) Attributable to Parent Other comprehensive income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Foreign currency translation adjustments, before tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent Income tax expense Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Foreign currency translation adjustments, net of tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Changes in employee benefit related items: Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, Attributable to Parent [Abstract] Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Recognized actuarial gain (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Changes in employee benefit related items Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Income tax benefit (expense) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Employee benefit related items, net of tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent Other Other Comprehensive Income, Other, Net of Tax Other comprehensive income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent 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 Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Equity [Abstract] Units Outstanding Increase (Decrease) in Partners' Capital [Roll Forward] Outstanding as of December 31, 2018 (in units) Shares, Outstanding Options exercised (in units) Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Units issued (in units) Stock Issued During Period, Shares, Restricted Stock Award, Gross Units retired (in units) Stock Repurchased and Retired During Period, Shares Outstanding as of March 31, 2019 (in units) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Equity Method Investments and Joint Ventures [Abstract] Change in Equity Method Investment [Roll Forward] Change in Equity Method Investment [Roll Forward] Change in Equity Method Investment [Roll Forward] Investment in AB as of December 31, 2018 Equity Method Investments Equity in net income attributable to AB Unitholders Income (Loss) from Equity Method Investments Changes in accumulated other comprehensive income (loss) Additional investments with proceeds from exercise of compensatory options to buy AB Holding Units Payments to Acquire Interest in Subsidiaries and Affiliates Cash distributions received from AB Proceeds from Dividends Received Capital contributions from AB Proceeds from Contributions from Affiliates AB Holding Units retired Treasury Stock, Retired, Par Value Method, Amount AB Holding Units issued to fund long-term incentive compensation plans Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Change in AB Holding Units held by AB for long-term incentive compensation plans Partners' Capital Account, Treasury Units, Purchased Investment in AB as of March 31, 2019 Statement of Financial Position [Abstract] General Partner: units issued (in units) General Partners' Capital Account, Units Issued General Partner: units outstanding (in units) General Partners' Capital Account, Units Outstanding Limited partners: units issued (in units) Limited Partners' Capital Account, Units Issued Limited partners: units outstanding (in units) Limited Partners' Capital Account, Units Outstanding Income Statement [Abstract] Income taxes Income Tax Expense (Benefit) Net income Net income per unit: Earnings Per Share [Abstract] Basic (in dollars per unit) Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Diluted (in dollars per unit) Net Income (Loss), Net of Tax, Per Outstanding Limited Partnership Unit, Diluted New York City unincorporated business tax (percent) New York City unincorporated business tax rate Tax rate attributable to operating income for unincorporated business entities operating in New York City, before credits paid for unincorporated business entities by a subsidiary. Federal tax rate on partnership gross income (percent) Federal Tax on Partnership Gross Income, Percent Federal Tax on Partnership Gross Income, Percent Computation of equity in net income attributable to AllianceBernstein Unitholders [Abstract] Equity Method Investment, Financial Statement, Reported Amounts [Abstract] Net income attributable to AB Unitholders Equity Method Investment, Summarized Financial Information, Net Income (Loss) Multiplied by: weighted average equity ownership interest (percent) Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Computation of income tax [Abstract] Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] AB qualifying revenues Equity Method Investment, Summarized Financial Information, Qualifying Revenue The amount of qualifying revenue (primarily investment advisory fees and certain equity commissions) reported by an equity method investment of the entity. Multiplied by: weighted average equity ownership interest for calculating tax (percent) Equity Method Investment Weighted Average Ownership Percentage For Calculating Tax The weighted average percentage of ownership of common stock or equity participation in the investee for calculating tax, net of units held in the rabbi trust. Multiplied by: federal tax (percent) Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Federal income taxes Current Federal Tax Expense (Benefit) State income taxes Current State and Local Tax Expense (Benefit) Total income taxes Effective tax rate (percent) Effective Income Tax Rate Reconciliation, Percent Changes in components for calculation of income tax [Abstract] Income Tax Expense (Benefit), Continuing Operations [Abstract] Change in net income attributable to AllianceBernstein Unitholders (percent) Increase (decrease) in net income attributable to equity method investments The percentage change in the amount of net income (loss) reported by an equity method investments of the entity. Change in equity in net income attributable to AllianceBernstein Unitholders (percent) Increase (decrease) in equity in net income attributable to equity method investments The percentage change in the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Change in AllianceBernstein qualifying revenues (percent) Increase (decrease) in qualifying revenue of equity method investment The percentage change in the amount of qualifying revenue (primarily investment advisory fees and certain equity commissions) reported by an equity method investment of the entity. Change in income taxes (percent) Increase (decrease) in income tax The percentage change in the sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations. Organization, Consolidation and Presentation of Financial Statements [Abstract] Summary of Ownership Structure of AllianceBernstein Schedule of Other Ownership Interests [Table Text Block] ASSETS Assets [Abstract] Investment in AB Other Assets Other Assets Total assets Assets LIABILITIES AND PARTNERS’ CAPITAL Liabilities and Equity [Abstract] Liabilities: Liabilities [Abstract] Other liabilities Other Liabilities Total liabilities Liabilities Commitments and contingencies (See Note 8) Commitments and Contingencies Partners’ capital: Partners' Capital [Abstract] General Partner: 100,000 general partnership units issued and outstanding General Partners' Capital Account Limited partners: 94,894,404 and 96,558,278 limited partnership units issued and outstanding Limited Partners' Capital Account AB Holding Units held by AB to fund long-term incentive compensation plans Deferred Compensation Equity Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total partners’ capital Partners' Capital Total liabilities and partners’ capital Liabilities and Equity Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Long-term Incentive Compensation Plans Compensation Related Costs, General [Text Block] Units Outstanding Capital Units [Text Block] Entire disclosure of an entity's capital units or capital shares. Earnings Per Unit [Abstract] Net Income per Unit Earnings Per Share [Text Block] Net income – basic Additional allocation of equity in net income attributable to AB resulting from assumed dilutive effect of compensatory options Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Net income – diluted Net Income (Loss) Attributable to Parent, Diluted Weighted average units outstanding – basic (in units) Weighted Average Limited Partnership Units Outstanding, Basic Dilutive effect of compensatory options (in units) Weighted Average Number Diluted Limited Partnership Units Outstanding Adjustment Weighted average units outstanding – diluted (in units) Weighted Average Limited Partnership Units Outstanding, Diluted Basic net income per unit (in dollars per unit) Diluted net income per unit (in dollars per unit) Anti-dilutive units excluded from diluted net income computation (in units) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Cash Distributions Cash Distributions Disclosure [Text Block] The entire disclosure for cash distributions. Investment in AB Investments in and Advances to Affiliates, Schedule of Investments [Text Block] Holding units purchased in period (in units) Stock Repurchased During Period, Shares Dollar amount paid for holding units acquired Stock Repurchased During Period, Value Open-market purchases of holding units (in units) Share-based Compensation Arrangement by Share-based Payment Award, Shares Purchased for Award Dollar amount paid for open-market purchases of holding units Payments for Repurchase of Equity Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Title of Individual [Axis] Title of Individual [Axis] Title of Individual with Relationship to Entity [Domain] Relationship to Entity [Domain] Employees and Eligible Directors Employees and Eligible Directors [Member] Individuals employed for wages or salary. Also includes individuals serving on the board of directors (who collectively have responsibility for governing the entity). Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Restricted AB Holding Unit awards granted to employees and Eligible Directors Stock Issued During Period, Shares, Share-based Compensation, Gross Units issued upon options exercised (in units) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Proceeds from stock options exercised Proceeds from Stock Options Exercised Changes in Holding Units Outstanding Schedule of Capital Units [Table Text Block] Summary of Changes in Investment in AB Schedule of Investments in and Advances to Affiliates, Schedule of Investments [Table Text Block] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Distributions Made to Member or Limited Partner by Distribution Type [Axis] Distribution Type [Axis] Distribution Type [Domain] Distribution Type [Domain] Cash Distribution Cash Distribution [Member] Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Declaration date Distribution Made to Limited Partner, Declaration Date Cash distribution declared (in dollars per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Distribution date Distribution Made to Limited Partner, Distribution Date Record date Distribution Made to Limited Partner, Date of Record Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] EQH EQH [Member] EQH [Member] AB Holding AB Holding [Member] AB Holding [Member] EQH and its subsidiaries EQH And Its Subsidiaries [Member] EQH And Its Subsidiaries [Member] Unaffiliated holders Unaffiliated Holders [Member] Represents holders of ownership interest in Company that are otherwise unaffiliated with Company. AB AllianceBernstein L.P. [Member] AllianceBernstein L.P. [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] AXA AXA [Member] AXA [Member] AllianceBernstein Corporation AllianceBernstein Corporation [Member] AllianceBernstein Corporation [Member] Ownership structure of AB Holding General partnership interest (percent) Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Units outstanding (in units) Limited partners or members ownership interest in Company (percent) Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Computation of Effective Income Tax Rate and Changes in Components of Income Tax Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [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] Equity in net income attributable to AB Unitholders Cash distributions received from AB Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Increase in other assets Increase (Decrease) in Other Operating Assets Decrease in other liabilities Increase (Decrease) in Other Operating Liabilities 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, Continuing Operations [Abstract] Investments in AB with proceeds from exercise of compensatory options to buy AB Holding Units 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, Continuing Operations [Abstract] Cash distributions to Unitholders Payments of Ordinary Dividends Capital contributions from AB Proceeds from exercise of compensatory options to buy AB Holding Units Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Change in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents as of beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents as of end of period Schedule of Earnings Per Unit, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Business Description, Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]