Business Description and Organization (Details)	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
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%
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)	64.20%
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)	61.00%
Holdings [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)	37.50%
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)	1.50%