Net (Loss) Income Per Unit (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Schedule of net (loss) income per unit [Abstract]
Net (loss) income - basic	$ (23,142,000)	$ 27,003,000	$ 24,896,000	$ 106,195,000
Additional allocation of equity in net (loss) income attributable to AllianceBernstein resulting from assumed dilutive effect of compensatory options	0	0	0	240,000
Net (loss) income - diluted	(23,142,000)	27,003,000	24,896,000	106,435,000
Weighted average units outstanding - basic (in units)	101,333	103,156	101,507	103,915
Dilutive effect of compensatory options (in units)	0	0	0	316
Weighted average units outstanding - diluted (in units)	101,333	103,156	101,507	104,231
Basic net income per unit (in dollars per unit)	$ (0.23)	$ 0.26	$ 0.25	$ 1.02
Diluted net income per unit (in dollars per unit)	$ (0.23)	$ 0.26	$ 0.25	$ 1.02
Out-of-the-money options from the diluted net income per unit (in units)	9,032,095	9,590,691	9,032,095	4,307,713
Proportional share of the Holding Units held by AllianceBernstein in its consolidated rabbi trust (in hundredths)	37.50%	37.50%	37.50%	37.40%
AllianceBernstein [Member]
Schedule of net (loss) income per unit [Abstract]
Net (loss) income - basic	(44,200,000)
Pre-tax real estate charges as part of workforce reduction	$ 168,100,000