Net Income Per Common Share (Tables)
 9 Months Ended
Sep. 30, 2016
Earnings Per Share [Abstract]  
Computation of basic and diluted net income per common share
The following table sets forth the computation of basic and diluted net income per common share for the three months and nine months ended September 30, 2016 and 2015, respectively:
 
Three Months Ended September 30,
 
Nine Months Ended September 30,
 
2016
 
2015
 
2016
 
2015
Net income
$
27,296

 
$
33,647

 
$
79,487

 
$
61,726

 
 
 
 
 
 
 
 
Net income per common share - basic
$
0.57

 
$
0.71

 
$
1.66

 
$
1.30

Net income per common share - diluted
$
0.55

 
$
0.69

 
$
1.61

 
$
1.27

 
 
 
 
 
 
 
 
Weighted average common shares outstanding - basic
48,049

 
47,674

 
47,993

 
47,466

Plus dilutive effect of potential common shares
1,361

 
1,304

 
1,294

 
1,271

Weighted average common shares outstanding - diluted
49,410

 
48,978

 
49,287

 
48,737