Net Income Per Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Unit [Abstract]
Net income - basic	$ 26,699	$ 43,680
Additional allocation of equity in net income attributable to AllianceBernstein resulting from assumed dilutive effect of compensatory options	0	243
Net income - diluted	$ 26,699	$ 43,923
Weighted average units outstanding - basic (in units)	101,767	104,710
Dilutive effect of compensatory options (in units)	0	803
Weighted average units outstanding - diluted (in units)	101,767	105,513
Basic net income per unit (in dollars per unit)	$ 0.26	$ 0.42
Diluted net income per unit (in dollars per unit)	$ 0.26	$ 0.42
Out-of-the-money options from the diluted net income per unit (in units)	8,977,349	4,692,640
Proportional share of the Holding Units held by AllianceBernstein in its consolidated rabbi trust	37.50%	37.40%