Investment in AB (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018
Change in Equity Method Investment [Roll Forward]
Investment in AB as of December 31, 2017	$ 1,544,704
Equity in net income attributable to AB Unitholders	65,698	$ 49,666
Changes in accumulated other comprehensive income (loss)	3,348	3,235
Additional investments with proceeds from exercise of compensatory options to buy AB Holding Units	4,008	4,468
Cash distributions received from AB	(88,671)	(70,381)
Capital contributions from AB	(1,696)	$ (518)
AB Holding Units retired	(67)
AB Holding Units issued to fund long-term incentive compensation plans	26,338
Change in AB Holding Units held by AB for long-term incentive compensation plans	(5,377)
Investment in AB as of March 31, 2018	1,560,834
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
Change in Equity Method Investment [Roll Forward]
Impact of ABLP's adoption of revenue recognition standard ASC 606	$ 12,549		$ 12,500

Change in Equity Method Investment [Roll Forward]

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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This item represents 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. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Value of units that were previously issued and have been repurchased during the year.

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The cash outflow associated with the acquisition of or advances to an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, and joint venture or equity method investment) or the acquisition of an additional interest in a subsidiary (controlled entity).

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The cash inflow from an entity that is affiliated with the entity by means of direct or indirect ownership.

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Dividends received on equity and other investments during the current period.

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Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Amount of decrease of par value, additional paid in capital (APIC) and retained earnings of common and preferred stock retired from treasury when treasury stock is accounted for under the par value method.

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