Net Income per Unit
 3 Months Ended
Mar. 31, 2015
Net Income per Unit [Abstract]  
Net Income per Unit
4.Net Income per Unit

Basic net income per unit is derived by dividing net income by the basic weighted average number of units outstanding for each period. Diluted net income per unit is derived by adjusting net income for the assumed dilutive effect of compensatory options (“Net income – diluted”) and dividing by the diluted weighted average number of units outstanding for each period.

  
Three Months Ended March 31,
 
  
2015
  
2014
 
  
(in thousands, except per unit amounts)
 
     
Net income – basic
 $
45,585
  $
36,159
 
Additional allocation of equity in net income attributable to AB resulting from assumed dilutive effect of compensatory options
  
355
   
296
 
Net income – diluted
 $
45,940
  $
36,455
 
         
Weighted average units outstanding – basic
  
100,548
   
96,114
 
Dilutive effect of compensatory options
  
1,098
   
1,077
 
Weighted average units outstanding – diluted
  
101,646
   
97,191
 
         
Basic net income per unit
 $
0.45
  $
0.38
 
Diluted net income per unit
 $
0.45
  $
0.38
 

As of March 31, 2015 and 2014, we excluded 2,774,117 and 2,828,033 options, respectively, from the diluted net income per unit computation due to their anti-dilutive effect.