Allowance for Credit Losses - Loan Portfolio by Risk Rating (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment
Loans	$ 391,272	$ 395,771
Pass
Financing Receivable, Recorded Investment
Loans	346,164	354,169
Special Mention
Financing Receivable, Recorded Investment
Loans	15,120	11,836
Substandard
Financing Receivable, Recorded Investment
Loans	29,988	29,766
Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Commercial
Financing Receivable, Recorded Investment
Loans	101,395	104,555
Commercial \| Commercial and industrial
Financing Receivable, Recorded Investment
Loans	75,511	77,956
Commercial \| Agricultural land and production
Financing Receivable, Recorded Investment
Loans	25,884	26,599
Commercial \| Pass \| Commercial and industrial
Financing Receivable, Recorded Investment
Loans	67,308	71,125
Commercial \| Pass \| Agricultural land and production
Financing Receivable, Recorded Investment
Loans	25,884	26,599
Commercial \| Special Mention \| Commercial and industrial
Financing Receivable, Recorded Investment
Loans	1,796	824
Commercial \| Special Mention \| Agricultural land and production
Financing Receivable, Recorded Investment
Loans	0	0
Commercial \| Substandard \| Commercial and industrial
Financing Receivable, Recorded Investment
Loans	6,407	6,007
Commercial \| Substandard \| Agricultural land and production
Financing Receivable, Recorded Investment
Loans	0	0
Commercial \| Doubtful \| Commercial and industrial
Financing Receivable, Recorded Investment
Loans	0	0
Commercial \| Doubtful \| Agricultural land and production
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment
Financing Receivable, Recorded Investment
Loans	242,505	237,938
Real Estate Portfolio Segment \| Owner occupied
Financing Receivable, Recorded Investment
Loans	104,023	114,444
Real Estate Portfolio Segment \| Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	32,309	33,199
Real Estate Portfolio Segment \| Commercial real estate
Financing Receivable, Recorded Investment
Loans	64,555	53,797
Real Estate Portfolio Segment \| Agricultural real estate
Financing Receivable, Recorded Investment
Loans	31,727	28,400
Real Estate Portfolio Segment \| Other real estate
Financing Receivable, Recorded Investment
Loans	9,891	8,098
Real Estate Portfolio Segment \| Pass \| Owner occupied
Financing Receivable, Recorded Investment
Loans	96,149	107,281
Real Estate Portfolio Segment \| Pass \| Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	18,754	18,517
Real Estate Portfolio Segment \| Pass \| Commercial real estate
Financing Receivable, Recorded Investment
Loans	55,537	44,880
Real Estate Portfolio Segment \| Pass \| Agricultural real estate
Financing Receivable, Recorded Investment
Loans	29,849	26,883
Real Estate Portfolio Segment \| Pass \| Other real estate
Financing Receivable, Recorded Investment
Loans	9,891	8,098
Real Estate Portfolio Segment \| Special Mention \| Owner occupied
Financing Receivable, Recorded Investment
Loans	2,618	1,831
Real Estate Portfolio Segment \| Special Mention \| Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	2,453	3,377
Real Estate Portfolio Segment \| Special Mention \| Commercial real estate
Financing Receivable, Recorded Investment
Loans	3,926	3,952
Real Estate Portfolio Segment \| Special Mention \| Agricultural real estate
Financing Receivable, Recorded Investment
Loans	1,878	1,517
Real Estate Portfolio Segment \| Special Mention \| Other real estate
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Substandard \| Owner occupied
Financing Receivable, Recorded Investment
Loans	5,256	5,332
Real Estate Portfolio Segment \| Substandard \| Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	11,102	11,305
Real Estate Portfolio Segment \| Substandard \| Commercial real estate
Financing Receivable, Recorded Investment
Loans	5,092	4,965
Real Estate Portfolio Segment \| Substandard \| Agricultural real estate
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Substandard \| Other real estate
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Doubtful \| Owner occupied
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Doubtful \| Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Doubtful \| Commercial real estate
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Doubtful \| Agricultural real estate
Financing Receivable, Recorded Investment
Loans	0	0
Real Estate Portfolio Segment \| Doubtful \| Other real estate
Financing Receivable, Recorded Investment
Loans	0	0
Consumer
Financing Receivable, Recorded Investment
Loans	47,372	53,278
Consumer \| Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	39,490	42,932
Consumer \| Consumer and installment
Financing Receivable, Recorded Investment
Loans	7,882	10,346
Consumer \| Pass \| Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	34,989	40,527
Consumer \| Pass \| Consumer and installment
Financing Receivable, Recorded Investment
Loans	7,803	10,259
Consumer \| Special Mention \| Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	2,380	258
Consumer \| Special Mention \| Consumer and installment
Financing Receivable, Recorded Investment
Loans	69	77
Consumer \| Substandard \| Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	2,121	2,147
Consumer \| Substandard \| Consumer and installment
Financing Receivable, Recorded Investment
Loans	10	10
Consumer \| Doubtful \| Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	0	0
Consumer \| Doubtful \| Consumer and installment
Financing Receivable, Recorded Investment
Loans	$ 0	$ 0