Business Description, Organization and Basis of Presentation (Details) (USD $)
In Millions, except Share data, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]    
Limited partners or members ownership interest in Company (in hundredths) 100.00%  
Threshold Amount for Including Institutions in Private Clients $ 25  
AXA and its subsidiaries ownership interest in Holding company (in hundredths) 1.40%  
General Partner: units outstanding (in shares) 100,000 100,000
General partnership interest (in hundredths) 1.00%  
AXA and its subsidiaries economic interest in Company (in hundredths) 62.70%  
AXA and Its Subsidiaries [Member]    
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]    
Limited partners or members ownership interest in Company (in hundredths) 62.20%  
AB Holding [Member]    
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]    
Limited partners or members ownership interest in Company (in hundredths) 36.40%  
Unaffiliated Holders [Member]    
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]    
Limited partners or members ownership interest in Company (in hundredths) 1.40%