Note 5 - Loans - Activity in the Allowance for Loan Losses, by Loan Category (Details) - USD ($)
$ 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
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Balance       $ 8,790       $ 11,520 $ 8,790 $ 11,520 $ 14,017      
Charge-offs                 (2,618) (2,635) (1,388)      
Recoveries                 1,094 1,250 4,760      
Provisions (credits) $ 295 $ (234) $ 396 696 $ (1,005) $ (191) $ 345 (494) 1,153 (1,345) (5,869)      
Balance 8,419       8,790       8,419 8,790 11,520      
Specific reserve                       $ 302 $ 381 $ 384
General reserve                       8,117 8,409 11,136
Ending balance 731,758       731,152       731,758 731,152 669,494      
Individually evaluated for impairment                       5,604   9,796
Collectively evaluated for impairment                       726,154 723,191 659,698
Provision (credit) for loan and lease losses 295 $ (234) $ 396 696 (1,005) $ (191) $ 345 (494) 1,153 (1,345) (5,869)      
Loans receivable, gross 731,758       731,152       731,758 731,152 669,494 731,758 731,152 669,494
Individually evaluated for impairment                         7,961  
Residential Portfolio Segment [Member]                            
Ending balance 144,260       130,696       144,260 130,696        
Loans receivable, gross 144,260       130,696       144,260 130,696   144,260 130,696  
Residential Portfolio Segment [Member] | Real Estate Loan [Member]                            
Balance       1,333       1,772 1,333 1,772 2,287      
Charge-offs                 (153) (139) (204)      
Recoveries                 4 58 90      
Provisions (credits)                 (13) (358) (401)      
Balance 1,171       1,333       1,171 1,333 1,772      
Specific reserve                       29 92 51
General reserve                       1,142 1,241 1,721
Ending balance 144,260       130,696       144,260 130,696 122,832      
Individually evaluated for impairment                       1,929   2,487
Collectively evaluated for impairment                       142,331 127,766 120,345
Provision (credit) for loan and lease losses                 (13) (358) (401)      
Loans receivable, gross 144,260       130,696       144,260 130,696 122,832 144,260 130,696 122,832
Individually evaluated for impairment                         2,930  
Commercial Real Estate Portfolio Segment [Member]                            
Ending balance 243,830       245,198       243,830 245,198        
Loans receivable, gross 243,830       245,198       243,830 245,198   243,830 245,198  
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]                            
Balance       3,346       4,663 3,346 4,663 6,017      
Charge-offs                 (398) (912)      
Recoveries                 6 307 362      
Provisions (credits)                 343 (712) (1,716)      
Balance 3,297       3,346       3,297 3,346 4,663      
Specific reserve                       254 287 331
General reserve                       3,043 3,059 4,332
Ending balance 243,830       245,198       243,830 245,198 233,473      
Individually evaluated for impairment                       2,937   6,660
Collectively evaluated for impairment                       240,893 241,367 226,813
Provision (credit) for loan and lease losses                 343 (712) (1,716)      
Loans receivable, gross 243,830       245,198       243,830 245,198 233,473 243,830 245,198 233,473
Individually evaluated for impairment                         3,831  
Construction, Land Acquisition and Development [Member]                            
Ending balance 18,357       30,843       18,357 30,843        
Loans receivable, gross 18,357       30,843       18,357 30,843   18,357 30,843  
Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member]                            
Balance       853       665 853 665 924      
Charge-offs                 (688) (45)      
Recoveries                 9 3,538      
Provisions (credits)                 (594) 876 (3,752)      
Balance 268       853       268 853 665      
Specific reserve                       1 1
General reserve                       268 852 664
Ending balance 18,357       30,843       18,357 30,843 18,835      
Individually evaluated for impairment                       350   256
Collectively evaluated for impairment                       18,007 30,197 18,579
Provision (credit) for loan and lease losses                 (594) 876 (3,752)      
Loans receivable, gross 18,357       30,843       18,357 30,843 18,835 18,357 30,843 18,835
Individually evaluated for impairment                         646  
Commercial and Industrial [Member]                            
Balance       1,205       2,104 1,205 2,104 2,321      
Charge-offs                 (1,107) (180) (217)      
Recoveries                 507 400 262      
Provisions (credits)                 1,131 (1,119) (262)      
Balance 1,736       1,205       1,736 1,205 2,104      
Specific reserve                       18
General reserve                       1,718 1,205 2,104
Ending balance 153,758       149,826       153,758 149,826 132,057      
Individually evaluated for impairment                       91   32
Collectively evaluated for impairment                       153,667 149,623 132,025
Provision (credit) for loan and lease losses                 1,131 (1,119) (262)      
Loans receivable, gross 153,758       149,826       153,758 149,826 132,057 153,758 149,826 132,057
Individually evaluated for impairment                         203  
Consumer Portfolio Segment [Member]                            
Balance       1,494       1,673 1,494 1,673 1,789      
Charge-offs                 (960) (716) (922)      
Recoveries                 568 485 508      
Provisions (credits)                 355 52 298      
Balance 1,457       1,494       1,457 1,494 1,673      
Specific reserve                       1 1 1
General reserve                       1,456 1,493 1,672
Ending balance 127,844       128,533       127,844 128,533 122,092      
Individually evaluated for impairment                       297   361
Collectively evaluated for impairment                       127,547 128,182 121,731
Provision (credit) for loan and lease losses                 355 52 298      
Loans receivable, gross 127,844       128,533       127,844 128,533 122,092 127,844 128,533 122,092
Individually evaluated for impairment                         351  
State and Political Subdivisions [Member]                            
Balance       485       598 485 598 679      
Charge-offs                      
Recoveries                      
Provisions (credits)                 5 (113) (81)      
Balance 490       485       490 485 598      
Specific reserve                      
General reserve                       490 485 598
Ending balance 43,709       46,056       43,709 46,056 40,205      
Individually evaluated for impairment                        
Collectively evaluated for impairment                       43,709 46,056 40,205
Provision (credit) for loan and lease losses                 5 (113) (81)      
Loans receivable, gross 43,709       46,056       43,709 46,056 40,205 43,709 46,056 40,205
Individually evaluated for impairment                          
Unallocated Financing Receivables [Member]                            
Balance       $ 74       $ 45 74 45      
Charge-offs                      
Recoveries                      
Provisions (credits)                 (74) 29 45      
Balance       74       74 45      
Specific reserve                      
General reserve                       74 45
Ending balance                  
Individually evaluated for impairment                        
Collectively evaluated for impairment                      
Provision (credit) for loan and lease losses                 (74) 29 45      
Loans receivable, gross            
Individually evaluated for impairment