Net Income Per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Percentage of Limited Partners interest in Company																	99.00%
Net income per unit, basic and diluted [Abstract]
Net income attributable to AB Unitholders	$ 286,335		$ 207,976		$ 177,321		$ 194,320		$ 248,865		$ 187,811		$ 166,252		$ 149,114		$ 865,952	$ 752,042	$ 757,588
Weighted average units outstanding—basic (in units)																	269,058,000	268,075,000	269,236,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)																	27,000	44,000	251,000
Weighted average units outstanding - diluted (in units)																	269,085,000	268,119,000	269,487,000
Basic net income per AB Unit (in dollars per unit)	$ 1.06	[1]	$ 0.77	[1]	$ 0.65	[1]	$ 0.71	[1]	$ 0.92	[1]	$ 0.69	[1]	$ 0.61	[1]	$ 0.55	[1]	$ 3.19	$ 2.78	$ 2.79
Diluted net income per AB Unit (in dollars per unit)	$ 1.06	[1]	$ 0.77	[1]	$ 0.65	[1]	$ 0.71	[1]	$ 0.92	[1]	$ 0.69	[1]	$ 0.61	[1]	$ 0.55	[1]	$ 3.19	$ 2.78	$ 2.78
Options excluded from diluted net income per unit computation due to their anti-dilutive effect (in units)																	29,056	29,056	49,784
AB Holding | AllianceBernstein Corporation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Percentage of General Partnership interest in company																	1.00%

[1] Basic and diluted net income per unit are computed independently for each of the periods presented. Accordingly, the sum of the quarterly net income per unit amounts may not agree to the total for the year.