Investment in AB (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Investment in AB [Abstract]
Investment in AB, beginning of period	$ 1,627,740us-gaap_EquityMethodInvestments
Equity in net income attributable to AB Unitholders	51,616	41,371
Changes in accumulated other comprehensive income (loss)	(4,193)	537
Additional investments with proceeds from exercise of compensatory options to buy AB Holding Units	3,901	4,656
Cash distributions received from AB	(63,184)us-gaap_ProceedsFromDividendsReceived	(63,457)us-gaap_ProceedsFromDividendsReceived
Capital contributions to AB	(6,019)us-gaap_PaymentsOfCapitalDistribution	(5,772)us-gaap_PaymentsOfCapitalDistribution
AB Holding Units retired	(18,821)
AB Holding Units issued to fund long-term incentive compensation plans	806
Change in AB Holding Units held by AB for long-term incentive compensation plans	1,257
Investment in AB, end of period	$ 1,605,141us-gaap_EquityMethodInvestments

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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Cash outflow to owners or shareholders, excluding ordinary dividends. Includes special dividends.

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

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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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