Business Description Organization and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The interim condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). In the opinion of management, all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the interim results, have been made. The preparation of the condensed consolidated financial statements requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the interim reporting periods. Actual results could differ from those estimates. The condensed consolidated statement of financial condition as of December 31, 2016 was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”).
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include AB and its majority-owned and/or controlled subsidiaries, and the consolidated entities that are considered to be variable interest entities ("VIEs") and voting interest entities ("VOEs") and for which AB has a controlling financial interest. Non-controlling interests on the condensed consolidated statements of financial condition includes the portion of consolidated company-sponsored investment funds in which we do not have direct equity ownership. All significant inter-company transactions and balances among the consolidated entities have been eliminated.
Reclassifications	Reclassifications During 2017, prior period amounts for our VOEs' investments previously presented as other investments are now presented as investments of consolidated company-sponsored investment funds in the condensed consolidated statements of financial condition to conform to the current period's presentation. Additionally, prior period amounts for dividend and interest related to our consolidated company-sponsored investment funds previously presented as other revenues are now presented as dividend and interest income in the condensed consolidated statements of income to conform to the current period's presentation.
Recently Adopted Accounting Pronouncements/Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU') 2016-07, Investments - Equity Method and Joint Ventures: Simplifying the Transition to the Equity Method of Accounting. The amendment eliminates the current requirement for a retroactive adjustment and instead requires that the investor add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Additionally, the amendment requires that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. We adopted this standard on January 1, 2017. The adoption of this standard did not have a material impact on our financial condition or results of operations. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. The amendment includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements, including income tax effects of share-based payments, minimum statutory tax withholding requirements and forfeitures. We adopted this standard on January 1, 2017 on a prospective basis. The adoption of this standard did not have a material impact on our financial condition or results of operations. Accounting Pronouncements Not Yet Adopted In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The amendment is effective retrospectively for fiscal years (and interim reporting periods within those years) beginning after December 15, 2017. Management currently is evaluating the impact that the adoption of this standard will have on our consolidated financial statements. We have not yet completed this analysis, but based on the analysis completed to date management does not expect the standard to have a material impact on our financial condition or results of operations. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. The amendment addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments and is effective for fiscal years (and interim periods within those years) beginning after December 15, 2017. The amendment will result in a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption, except for one provision relating to equity securities without readily determinable fair values, which provision will be applied prospectively. The amendment is not expected to have a material impact on our financial condition or results of operations. In February 2016, the FASB issued ASU 2016-02, Leases. The amendment requires recognition of lease assets and lease liabilities on the statement of financial condition and disclosure of key information about leasing arrangements. Specifically, this guidance requires an operating lease lessee to recognize on the statement of financial condition a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. However, for leases with a term of twelve months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. The amendment is effective for fiscal years (and interim periods within those years) beginning after December 15, 2018 and requires lessees to recognize and measure leases at the beginning of the earliest period presented in the financial statements using a modified retrospective approach. Management currently is evaluating the impact that the adoption of this standard will have on our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230). The amendment is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The amendment is effective for fiscal years (and interim periods within those years) beginning after December 15, 2017 and should be applied using a retrospective transition method. The amendment is not expected to have a material impact on our financial condition or results of operations. In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The revised guidance will be applied prospectively, and is effective in 2020. The revised guidance is not expected to have a material impact on our financial condition or results of operations. In March 2017, the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires that an employer disaggregate the service cost component from the other components of net benefit costs on the income statement. The amendment is effective for fiscal years (and interim periods within those years) beginning after December 15, 2017 and should be applied retrospectively. The amendment is not expected to have a material impact on our results of operations. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation, Scope of Modification Accounting. The amendment provides clarity and reduces both diversity in practice and cost and complexity when applying the guidance in Topic 718, Compensation - Stock Compensation, to a change to the terms or conditions of a share-based payment award. This amendment is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017 and will be applied prospectively to an award modified on or after the adoption date. This amendment is not expected to have a material impact on our results of operations.
Consolidation of company-sponsored investment funds	Consolidation of company-sponsored investment funds We adopted ASU 2015-02, Consolidation - Amendments to the Consolidation Analysis ("ASU 2015-02") effective January 1, 2016. For legal entities (company-sponsored investment funds) evaluated for consolidation, we first determine whether the fees we receive and the interests we hold qualify as a variable interest in the entity, including an evaluation of fees paid to us as a decision maker or service provider to the entity being evaluated. Fees received by us are not variable interests if (i) the fees are compensation for services provided and are commensurate with the level of effort required to provide those services, (ii) the service arrangement includes only terms, conditions or amounts that are customarily present in arrangements for similar services negotiated at arm’s length, and (iii) our other economic interests in the entity held directly and indirectly through our related parties, as well as economic interests held by related parties under common control, would not absorb more than an insignificant amount of the entity’s losses or receive more than an insignificant amount of the entity’s benefits. For those entities in which we have a variable interest, we perform an analysis to determine whether the entity is a VIE by considering whether the entity’s equity investment at risk is insufficient, whether the investors lack decision making rights proportional to their ownership percentage of the entity, and whether the investors lack the obligation to absorb an entity’s expected losses or the right to receive an entity’s expected income. A VIE must be consolidated by its primary beneficiary, which generally is defined as the party that has a controlling financial interest in the VIE. We are deemed to have a controlling financial interest in a VIE if we have (i) the power to direct the activities of the VIE that most significantly affect the VIE's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive income from the VIE that could potentially be significant to the VIE. For purposes of evaluating (ii) above, fees paid to us as a decision maker or service provider are excluded if the fees are compensation for services provided commensurate with the level of effort required to be performed and the arrangement includes only customary terms, conditions or amounts present in arrangements for similar services negotiated at arm’s length. The primary beneficiary evaluation generally is performed qualitatively based on all facts and circumstances, as well as quantitatively, as appropriate. If we have a variable interest in an entity that is determined not to be a VIE, the entity is then evaluated for consolidation under the VOE model. For limited partnerships and similar entities, we are deemed to have a controlling financial interest in a VOE, and would be required to consolidate the entity, if we own a majority of the entity’s kick-out rights through voting limited partnership interests and limited partners do not hold substantive participating rights (or other rights that would indicate that we do not control the entity). For entities other than limited partnerships, we are deemed to have a controlling financial interest in a VOE if we own a majority voting interest in the entity. The analysis performed regarding the determination of variable interests held, whether entities are VIEs or VOEs, and whether we have a controlling financial interest in such entities requires the exercise of judgment. The analysis is updated continuously as circumstances change or new entities are formed.