Nature of Operations and Summary of Significant Accounting Policies Adoption of ASU No. 2016-09 (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Summary of ASU No. 2016-09 Adoption [Line Items]                      
Income Tax Expense (Benefit) $ (1,199) $ 3,020 $ (1,621) $ (2,356) $ (2,185) $ (2,060) $ (1,962) $ (2,170) $ 2,156 $ 8,377 $ 7,083
Net income $ 3,968 $ 2,665 $ 3,723 $ 4,553 $ 4,083 $ 4,381 $ 3,858 $ 4,192 $ 14,909 $ 16,514 $ 14,139
Effective Income Tax Rate Reconciliation, Percent                 12.63% 33.65% 33.38%
Basic earnings per common share $ 0.46 $ 0.31 $ 0.43 $ 0.52 $ 0.47 $ 0.50 $ 0.45 $ 0.48 $ 1.71 $ 1.90 $ 1.76
Diluted earnings per common share $ 0.46 $ 0.31 $ 0.43 $ 0.52 $ 0.47 $ 0.50 $ 0.45 $ 0.48 $ 1.71 $ 1.90 $ 1.75
Additional Paid in Capital, Common Stock $ 77,542       $ 76,549       $ 77,542 $ 76,549  
Retained Earnings (Accumulated Deficit) $ 91,317       $ 80,584       $ 91,317 $ 80,584  
As Reported                      
Summary of ASU No. 2016-09 Adoption [Line Items]                      
Income Tax Expense (Benefit)   $ (2,895) $ 1,628 $ 2,362              
Net income   $ 2,540 $ 3,716 $ 4,547              
Effective Income Tax Rate Reconciliation, Percent     30.50% 34.20%              
Basic earnings per common share   $ 290 $ 430 $ 520              
Diluted earnings per common share   $ 290 $ 430 $ 520              
Additional Paid in Capital, Common Stock   $ 77,544 $ 77,127 $ 76,851              
Retained Earnings (Accumulated Deficit)   $ 88,255 $ 86,760 $ 84,089              
Ratio of Annualized Net Income to Average Assets   0.56% 0.81% 1.00%              
Ratio of Annualized Net Income to Average Equity   6.38% 9.43% 11.68%              
As Adjusted                      
Summary of ASU No. 2016-09 Adoption [Line Items]                      
Income Tax Expense (Benefit)   $ (3,020) $ 1,621 $ 2,356              
Net income   $ 2,665 $ 3,723 $ 4,553              
Effective Income Tax Rate Reconciliation, Percent     30.30% 34.10%              
Basic earnings per common share   $ 310 $ 430 $ 520              
Diluted earnings per common share   $ 310 $ 430 $ 520              
Additional Paid in Capital, Common Stock   $ 77,419 $ 77,120 $ 76,845              
Retained Earnings (Accumulated Deficit)   $ 88,380 $ 86,767 $ 84,095              
Ratio of Annualized Net Income to Average Assets   0.59% 0.82% 1.00%              
Ratio of Annualized Net Income to Average Equity   6.69% 9.45% 11.70%