Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
New York City unincorporated business tax (percent)			4.00%
Federal tax rate on partnership gross income (percent)			3.50%
Computation of equity in net income attributable to AllianceBernstein Unitholders [Abstract]
Net income attributable to AB Unitholders	$ 140,954	$ 158,035	$ 415,994	$ 448,820
Multiplied by: weighted average equity ownership interest (percent)	34.80%	35.40%	35.30%	35.80%
Equity in net income attributable to AB Unitholders	$ 49,055	$ 55,925	$ 146,668	$ 160,759
Computation of income tax [Abstract]
AB qualifying revenues	$ 581,410	$ 531,856	$ 1,714,065	$ 1,565,294
Multiplied by: weighted average equity ownership interest for calculating tax (percent)	28.30%	29.80%	29.20%	30.10%
Multiplied by: federal tax (percent)	3.50%	3.50%	3.50%	3.50%
Federal income taxes	$ 5,767	$ 5,549	$ 17,517	$ 16,494
State income taxes	110	118	322	343
Total income taxes	$ 5,877	$ 5,667	$ 17,839	$ 16,837
Effective tax rate (percent)	12.00%	10.10%	12.20%	10.50%
Changes in components for calculation of income tax [Abstract]
Change in net income attributable to AllianceBernstein Unitholders (percent)	(10.80%)		(7.30%)
Change in equity in net income attributable to AllianceBernstein Unitholders (percent)	(12.30%)		(8.80%)
Change in AllianceBernstein qualifying revenues (percent)	9.30%		9.50%
Change in income taxes (percent)	3.70%		6.00%