Net Income per Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of net (loss) income per unit [Abstract]
Net income - basic	$ 44,134	$ 29,523	$ 123,147	$ 108,030
Additional allocation of equity in net income attributable to AllianceBernstein resulting from assumed dilutive effect of compensatory options	409	183	1,085	771
Net income - diluted	$ 44,543	$ 29,706	$ 124,232	$ 108,801
Weighted average units outstanding - basic (in units)	97,070,000	92,258,000	96,549,000	97,866,000
Dilutive effect of compensatory options (in units)	1,249,000	756,000	1,174,000	994,000
Weighted average units outstanding - diluted (in units)	98,319,000	93,014,000	97,723,000	98,860,000
Basic net income per unit (in dollars per unit)	$ 0.45	$ 0.32	$ 1.28	$ 1.10
Diluted net income per unit (in dollars per unit)	$ 0.45	$ 0.32	$ 1.27	$ 1.10
Out-of-the-money options excluded from the diluted net income per unit (in units)	2,774,117	3,045,173	2,806,033	2,974,935
Schedule of Equity Method Investments [Line Items]
Proportional share of the Holding Units held in consolidated rabbi trust (in hundredths)	35.70%	34.50%	35.60%	36.70%
Unallocated Holding Units Held in Consolidated Rabbi Trust [Member]
Schedule of Equity Method Investments [Line Items]
Proportional share of the Holding Units held in consolidated rabbi trust (in hundredths)		34.50%		36.70%