Income Taxes (Tables)
 3 Months Ended
Mar. 31, 2015
Income Taxes [Abstract]  
Computation of Effective Income Tax Rate and Changes in Components of Income Tax
AB Holding’s income tax is computed by multiplying certain AB qualifying revenues (primarily U.S. investment advisory fees and brokerage commissions) by AB Holding’s ownership interest in AB, multiplied by the 3.5% tax rate. AB Holding Units in AB’s consolidated rabbi trust are not treated as outstanding for purposes of calculating AB Holding’s ownership interest in AB.

  
Three Months Ended
March 31,
   
  
2015
 
2014
  
% Change
 
  
(in thousands)
 
      
Net income attributable to AB Unitholders
 
$
141,469
 
 
$
116,725
   
21.2
%
Multiplied by: weighted average equity ownership interest
  
36.5
%
 
35.4
%
 
Equity in net income attributable to AB Unitholders
 
$
51,616
 
 
$
41,371
   
24.8
 
             
AB qualifying revenues
 
$
544,774
 
 
$
499,129
   
9.1
 
Multiplied by: weighted average equity ownership interest for calculating tax
  
31.1
%
  
29.3
%
    
Multiplied by: federal tax
  
3.5
%
  
3.5
%
    
Federal income taxes
  
5,927
   
5,112
     
State income taxes
  
104
   
100
     
Total income taxes
 
$
6,031
 
 
$
5,212
   
15.7
 
             
Effective tax rate
  
11.7
%
  
12.6
%