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
Net (Loss) Income Per Unit [Abstract]
General partnership interest in Company (in hundredths)	1.00%		1.00%
Limited partners interest in company (in hundredths)			99.00%
Net (loss) income attributable to AllianceBernstein Unitholders	$ (44,246,000)	$ 90,981,000	$ 117,217,000	$ 341,592,000
Weighted average units outstanding - basic (in units)	277,612	278,010	277,759	278,035
Dilutive effect of compensatory options to buy Holding Units (in units)	0	0	0	316
Weighted average units outstanding - diluted (in units)	277,612	278,010	277,759	278,351
Basic net income per AllianceBernstein Unit (in dollars per share)	$ (0.16)	$ 0.32	$ 0.42	$ 1.22
Diluted net income per AllianceBernstein Unit (in dollars per share)	$ (0.16)	$ 0.32	$ 0.42	$ 1.21
Pre-tax real estate charges as part of workforce reduction	$ 168,100,000
Options excluded from diluted net income per unit computation due to their anti-dilutive effect (in units)	9,032,095	9,590,691	9,032,095	4,307,713