Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 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 attributable to AllianceBernstein Unitholders	$ 120,714	$ 74,185	$ 235,230	$ 161,463
Multiplied by: weighted average equity ownership interest	37.60%	37.50%	37.60%	37.50%
Equity in net income attributable to AllianceBernstein Unitholders	45,440	27,803	88,437	60,510
Computation of income tax [Abstract]
AllianceBernstein qualifying revenues	511,168	485,018	993,754	935,397
Multiplied by: weighted average equity ownership interest for calculating tax	28.30%	37.50%	28.00%	37.50%
Multiplied by: federal tax	3.50%	3.50%	3.50%	3.50%
Federal income taxes	5,064	6,364	9,730	12,272
State income taxes	100	100	200	200
Total income taxes	$ 5,164	$ 6,464	$ 9,930	$ 12,472
Effective tax rate	11.40%	23.20%	11.20%	20.60%
Changes in components for calculation of income tax [Abstract]
Increase in net income attributable to AllianceBernstein Unitholders (in hundredths)	62.70%		45.70%
Increase in equity in net income attributable to AllianceBernstein Unitholders (in hundredths)	63.40%		46.20%
Increase Decrease in AllianceBernstein qualifying revenues	5.40%		6.20%
Decrease in income taxes (in hundredths)	(20.10%)		(20.40%)