Condensed Statements of Income (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Condensed Statements of Income (unaudited) [Abstract]
Equity in net income attributable to AB Unitholders	$ 51,616	$ 41,371
Income taxes	6,031us-gaap_IncomeTaxExpenseBenefit	5,212us-gaap_IncomeTaxExpenseBenefit
Net income	$ 45,585us-gaap_NetIncomeLoss	$ 36,159us-gaap_NetIncomeLoss
Net income per unit:
Basic (in dollars per share)	$ 0.45	$ 0.38
Diluted (in dollars per share)	$ 0.45	$ 0.38

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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 of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Per unit of ownership amount after tax of income (loss) available to limited partnership (LP) unit-holder and units that would have been outstanding assuming the issuance of limited partner units for dilutive potential units outstanding.

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Per unit of ownership amount after tax of income (loss) available to outstanding limited partnership (LP) unit-holder.

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