Net Income per Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Schedule of net (loss) income per unit [Abstract]
Net income - basic	$ 38,231	$ 26,699
Additional allocation of equity in net income attributable to AllianceBernstein resulting from assumed dilutive effect of compensatory options	243	0
Net income - diluted	$ 38,474	$ 26,699
Weighted average units outstanding - basic (in units)	100,297,000	101,767,000
Dilutive effect of compensatory options (in units)	937,000	0
Weighted average units outstanding - diluted (in units)	101,234,000	101,767,000
Basic net income (loss) per unit (in dollars per unit)	$ 0.38	$ 0.26
Diluted net income (loss) per unit (in dollars per unit)	$ 0.38	$ 0.26
Out-of-the-money options from the diluted net income per unit (in units)	3,161,304	8,977,349
Proportional share of the Holding Units held by AllianceBernstein in its consolidated rabbi trust (in hundredths)	37.50%	37.50%