Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
New York City unincorporated business tax (percent)			4.00%
Federal tax rate on partnership gross income (percent)			3.50%
Computation of equity in net income attributable to AllianceBernstein Unitholders [Abstract]
Equity in net income attributable to AB Unitholders	$ 134,976	$ 139,798	$ 425,539	$ 392,958
Multiplied by: weighted average equity ownership interest	36.30%	35.70%	36.40%	35.60%
Equity in net income attributable to AB Unitholders	$ 48,988	$ 49,876	$ 155,013	$ 139,714
Computation of income tax [Abstract]
AB qualifying revenues	$ 572,391	$ 548,319	$ 1,682,390	$ 1,581,456
Multiplied by: weighted average equity ownership interest for calculating tax	30.80%	29.40%	30.90%	29.40%
Multiplied by: federal tax (percent)	3.50%	3.50%	3.50%	3.50%
Federal income taxes	$ 6,167	$ 5,642	$ 18,171	$ 16,267
State income taxes	134	100	346	300
Total income taxes	$ 6,301	$ 5,742	$ 18,517	$ 16,567
Effective tax rate	12.90%	11.50%	11.90%	11.90%
Changes in components for calculation of income tax [Abstract]
Increase in net income attributable to AllianceBernstein Unitholders (percent)	(3.40%)		8.30%
Increase in equity in net income attributable to AllianceBernstein Unitholders (percent)	(1.80%)		11.00%
Change in AllianceBernstein qualifying revenues (percent)	4.40%		6.40%
Increase in income taxes (percent)	9.70%		11.80%