Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
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 (loss) attributable to AllianceBernstein Unitholders	$ 114,516	$ 87,278
Multiplied by: weighted average equity ownership interest (in hundredths)	37.50%	37.50%
Equity in net income (loss) attributable to AllianceBernstein Unitholders	42,997	32,707
Computation of income tax [Abstract]
AllianceBernstein qualifying revenues	482,586	449,691
Multiplied by: weighted average equity ownership interest (in hundredths)	27.70%	37.50%
Multiplied by: federal tax (in hundredths)	3.50%	3.50%
Federal income taxes	4,666	5,908
State income taxes	100	100
Income tax expense	$ 4,766	$ 6,008
Effective tax rate (in hundredths)	11.10%	18.40%
Changes in components for calculation of income tax [Abstract]
Increase in net income attributable to AllianceBernstein Unitholders (in hundredths)		31.20%
Increase in equity in net income attributable to AllianceBernstein Unitholders (in hundredths)		31.50%
Increase Decrease in AllianceBernstein qualifying revenues		7.30%
Decrease in Federal income tax (in hundredths)		(21.00%)
Decrease in income taxes (in hundredths)		(20.70%)