Selected Quarterly Financial Data (Unaudited) (Tables)
 12 Months Ended
Dec. 31, 2016
Notes Tables  
Quarterly Financial Information [Table Text Block]
   
2016 Quarter Ended
  
(Dollars in thousands, except per share
information)
  
December 31,
    
September 30,
    
June 30,
    
March 31,
  
Interest income
   $
19,032
     
18,836
     
18,382
     
18,313
 
Interest expense
    
2,042
     
1,959
     
1,730
     
1,650
 
Net interest income
    
16,990
     
16,877
     
16,652
     
16,663
 
Provision for loan losses
   
441
     
373
     
901
     
1,533
 
Other noninterest income
    
3,472
     
4,002
     
3,357
     
3,125
 
Other noninterest expense
(1)
    
12,140
     
12,632
     
12,254
     
12,053
 
Income before income taxes
    
7,881
     
7,874
     
6,854
     
6,202
 
Income tax expense
   
2,600
     
2,639
     
2,072
     
2,083
 
Net income before minority interest
   
5,281
     
5,235
     
4,782
     
4,119
 
Net income attributable to minority interest
   
374
     
422
     
428
     
340
 
Net income to common shareholders
    
4,907
     
4,813
     
4,354
     
3,779
 
Net earnings per share
   $
0.45
     
0.44
     
0.40
     
0.35
 
Diluted net earnings per share
    
0.44
     
0.43
     
0.39
     
0.34
 
   
2015 Quarter Ended
  
(Dollars in thousands, except per share
information)
  
December 31,
    
September 30,
    
June 30,
    
March 31,
  
Interest income
   $
16,488
     
13,450
     
12,714
     
12,193
 
Interest expense
    
1,507
     
1,191
     
1,071
     
1,027
 
Net interest income
    
14,981
     
12,259
     
11,643
     
11,166
 
Provision for loan losses
   
631
     
201
     
120
     
161
 
Other noninterest income
    
2,298
     
2,353
     
2,206
     
1,764
 
Other noninterest expense
(1)
    
11,606
     
9,895
     
9,616
     
9,290
 
Income before income taxes
    
5,042
     
4,516
     
4,113
     
3,479
 
Income tax expense
   
1,667
     
1,453
     
1,264
     
1,092
 
Net income before minority interest
   
3,375
     
3,063
     
2,849
     
2,387
 
Net income attributable to minority interest
   
437
     
573
     
593
     
466
 
Net income to common shareholders
    
2,938
     
2,490
     
2,256
     
1,921
 
Net earnings per share
   $
0.28
     
0.26
     
0.24
     
0.25
 
Diluted net earnings per share
    
0.28
     
0.26
     
0.24
     
0.25