Net Income Per Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Schedule of net income per unit [Abstract]
Net income - basic	$ 21,339	$ 35,512	$ 48,038	$ 79,192
Additional allocation of equity in net income attributable to AllianceBernstein resulting from assumed dilutive effect of compensatory options	0	141	0	379
Net income - diluted	$ 21,339	$ 35,653	$ 48,038	$ 79,571
Weighted average units outstanding - basic (in units)	101,424,000	103,969,000	101,595,000	104,339,000
Dilutive effect of compensatory options (in units)	0	556,000	0	682,000
Weighted average units outstanding - diluted (in units)	101,424,000	104,525,000	101,595,000	105,021,000
Basic net income per unit (in dollars per unit)	$ 0.21	$ 0.34	$ 0.47	$ 0.76
Diluted net income per unit (in dollars per unit)	$ 0.21	$ 0.34	$ 0.47	$ 0.76
Out-of-the-money options from the diluted net income per unit (in units)	9,036,845	4,408,829	9,036,845	4,408,829
Proportional share of the Holding Units held by AllianceBernstein in its consolidated rabbi trust (in hundredths)	37.50%	37.40%	37.50%	37.40%