Business Description, Organization and Basis of Presentation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Apr. 03, 2025	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Ownership structure of AB Holding
Units outstanding (in shares)		100,000		100,000
AB Holding units repurchased (in shares)		800,000	100,000
Aggregate purchase price		$ 30.5	$ 4.3
Tender Offer | Subsequent Event
Ownership structure of AB Holding
Cash tender offer to purchase up to (in shares)	46,000,000
Stock repurchased during period (in dollars per share)	$ 38.50
Stock repurchased during period, amount	$ 1,800.0
AB Holding units repurchased (in shares)	19,682,946
Aggregate purchase price	$ 757.8
AB Holding | Subsequent Event
Ownership structure of AB Holding
Economic interest, percentage	17.90%
AB Holding | AllianceBernstein Corporation | General Partnership Interest
Ownership structure of AB Holding
Units outstanding (in shares)		100,000
AB | Subsequent Event
Ownership structure of AB Holding
Economic interest, percentage	68.50%
AB | AllianceBernstein Corporation | General and Limited Partnership Interests
Ownership structure of AB Holding
General partnership interest (percent)		61.90%
AB | AllianceBernstein Corporation | General Partnership Interest
Ownership structure of AB Holding
General partnership interest (percent)		1.00%