Business Description Organization and Basis of Presentation (Details)	3 Months Ended
	Mar. 31, 2018 shares
Ownership structure of AllianceBernstein expressed as a percentage of general and limited partnership interests [Abstract]
AXA and its subsidiaries ownership interest in holding company (percent)	3.90%
General partnership information [Abstract]
General Partnership number of general partnership units owned in Holding Company (in units)	100,000
General partnership interest in Company (percent)	1.00%
AXA and its subsidiaries economic interest in Company (percent)	64.40%
Limited partners or members ownership interest in company (percent)	100.00%
AXA and its subsidiaries
General partnership information [Abstract]
Limited partners or members ownership interest in company (percent)	63.00%
AB Holding
General partnership information [Abstract]
Limited partners or members ownership interest in company (percent)	35.80%
Unaffiliated holders
General partnership information [Abstract]
Limited partners or members ownership interest in company (percent)	1.20%