Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Income Taxes [Abstract]
New York City unincorporated business tax (in hundredths)					4.00%
Computation of equity in net income attributable to AllianceBernstein Unitholders [Abstract]
Net income attributable to AllianceBernstein Unitholders	$ 74,185		$ 114,139		$ 161,463		$ 250,611
Multiplied by: weighted average equity ownership interest (in hundredths)	37.50%	[1]	37.40%	[1]	37.50%	[1]	37.40%	[1]
Equity in net income attributable to AllianceBernstein Unitholders	27,803		42,745		60,510		93,803
Computation of income tax [Abstract]
Equity Method Investment, Summarized Financial Information, Qualifying Revenue	485,018		543,655		935,397		1,100,042
Multiplied by: weighted average equity ownership interest (in hundredths)	37.50%	[1]	37.40%	[1]	37.50%	[1]	37.40%	[1]
Multiplied by: federal tax (in hundredths)	3.50%		3.50%		3.50%		3.50%
Income taxes	$ 6,464		$ 7,233		$ 12,472		$ 14,611
Effective tax rate (in hundredths)	23.20%		16.90%		20.60%		15.60%
Changes in components for calculation of income tax [Abstract]
Decrease in net income attributable to AllianceBernstein Unitholders (in hundredths)	(35.00%)				(35.60%)
Decrease in equity in net income attributable to AllianceBernstein Unitholders (in hundredths)	(35.00%)				(35.50%)
Decrease in AllianceBernstein qualifying revenue (in hundredths)	(10.80%)				(15.00%)
Decrease in income taxes (in hundredths)	(10.60%)				(14.60%)

[1] Equity in net income attributable to AllianceBernstein Unitholders and income taxes are recorded monthly using equity ownership interest as of each month-end, whereas the weighted average ownership interest shown in the table represents our quarter-end ownership interest. Accordingly, the calculation above will not compute to actual amounts recorded.