Allowance for Credit Losses - Loan Portfolio by Risk Rating (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment
Loans	$ 399,722	$ 428,159
Pass
Financing Receivable, Recorded Investment
Loans	356,142	373,388
Special Mention
Financing Receivable, Recorded Investment
Loans	14,834	17,971
Substandard
Financing Receivable, Recorded Investment
Loans	28,746	36,800
Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Commercial
Financing Receivable, Recorded Investment
Loans	113,077	108,047
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment
Loans	71,439	78,089
Commercial | Agricultural land and production
Financing Receivable, Recorded Investment
Loans	41,638	29,958
Commercial | Pass | Commercial and industrial
Financing Receivable, Recorded Investment
Loans	65,758	70,093
Commercial | Pass | Agricultural land and production
Financing Receivable, Recorded Investment
Loans	41,638	29,958
Commercial | Special Mention | Commercial and industrial
Financing Receivable, Recorded Investment
Loans	844	2,595
Commercial | Special Mention | Agricultural land and production
Financing Receivable, Recorded Investment
Loans	0	0
Commercial | Substandard | Commercial and industrial
Financing Receivable, Recorded Investment
Loans	4,837	5,401
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	234,185	259,241
Real Estate Portfolio Segment | Owner occupied
Financing Receivable, Recorded Investment
Loans	109,231	113,183
Real Estate Portfolio Segment | Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	33,234	33,047
Real Estate Portfolio Segment | Commercial real estate
Financing Receivable, Recorded Investment
Loans	54,146	62,523
Real Estate Portfolio Segment | Agricultural real estate
Financing Receivable, Recorded Investment
Loans	29,408	42,596
Real Estate Portfolio Segment | Other real estate
Financing Receivable, Recorded Investment
Loans	8,166	7,892
Real Estate Portfolio Segment | Pass | Owner occupied
Financing Receivable, Recorded Investment
Loans	101,350	105,308
Real Estate Portfolio Segment | Pass | Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	18,057	15,717
Real Estate Portfolio Segment | Pass | Commercial real estate
Financing Receivable, Recorded Investment
Loans	43,767	47,323
Real Estate Portfolio Segment | Pass | Agricultural real estate
Financing Receivable, Recorded Investment
Loans	27,502	40,808
Real Estate Portfolio Segment | Pass | Other real estate
Financing Receivable, Recorded Investment
Loans	8,166	7,672
Real Estate Portfolio Segment | Special Mention | Owner occupied
Financing Receivable, Recorded Investment
Loans	2,183	3,125
Real Estate Portfolio Segment | Special Mention | Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	3,598	4,056
Real Estate Portfolio Segment | Special Mention | Commercial real estate
Financing Receivable, Recorded Investment
Loans	5,940	5,035
Real Estate Portfolio Segment | Special Mention | Agricultural real estate
Financing Receivable, Recorded Investment
Loans	1,906	1,788
Real Estate Portfolio Segment | Special Mention | Other real estate
Financing Receivable, Recorded Investment
Loans	0	220
Real Estate Portfolio Segment | Substandard | Owner occupied
Financing Receivable, Recorded Investment
Loans	5,698	4,750
Real Estate Portfolio Segment | Substandard | Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	11,579	13,274
Real Estate Portfolio Segment | Substandard | Commercial real estate
Financing Receivable, Recorded Investment
Loans	4,439	10,165
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	52,460	60,871
Consumer | Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	44,335	51,106
Consumer | Consumer and installment
Financing Receivable, Recorded Investment
Loans	8,125	9,765
Consumer | Pass | Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	41,875	46,939
Consumer | Pass | Consumer and installment
Financing Receivable, Recorded Investment
Loans	8,029	9,570
Consumer | Special Mention | Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	279	1,047
Consumer | Special Mention | Consumer and installment
Financing Receivable, Recorded Investment
Loans	84	105
Consumer | Substandard | Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	2,181	3,120
Consumer | Substandard | Consumer and installment
Financing Receivable, Recorded Investment
Loans	12	90
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