Loans and Allowance for Loan Losses (Troubled loan receivables, by accrual status) (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Financing Receivable, Impaired [Line Items]    
Accrual $ 2,494 $ 3,137
Nonaccrual 379 3,483
Troubled debt restructurings, total 2,873 6,620
Commercial
   
Financing Receivable, Impaired [Line Items]    
Accrual 330 371
Nonaccrual 40 571
Troubled debt restructurings, total 370 942
Commercial real estate
   
Financing Receivable, Impaired [Line Items]    
Accrual 458 1,889
Nonaccrual 339 382
Troubled debt restructurings, total 797 2,271
Commercial construction
   
Financing Receivable, Impaired [Line Items]    
Accrual 0 46
Nonaccrual 0 295
Troubled debt restructurings, total 0 341
Land and land development loans
   
Financing Receivable, Impaired [Line Items]    
Accrual 1,309 782
Nonaccrual 0 794
Troubled debt restructurings, total 1,309 1,576
Agriculture
   
Financing Receivable, Impaired [Line Items]    
Accrual 110 22
Nonaccrual 0 0
Troubled debt restructurings, total 110 22
Residential real estate
   
Financing Receivable, Impaired [Line Items]    
Accrual 249 0
Nonaccrual 0 1,377
Troubled debt restructurings, total 249 1,377
Consumer
   
Financing Receivable, Impaired [Line Items]    
Accrual 38 27
Nonaccrual 0 64
Troubled debt restructurings, total $ 38 $ 91