Business Description, Organization and Basis of Presentation - Summary of Ownership Structure (Details) - AB	9 Months Ended
	Sep. 30, 2025
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]
Limited partners or members ownership interest in company (percent)	100.00%
EQH and its subsidiaries
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]
Limited partners or members ownership interest in company (percent)	68.50%
AB Holding
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]
Limited partners or members ownership interest in company (percent)	30.80%
Unaffiliated holders
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]
Limited partners or members ownership interest in company (percent)	0.70%