Loan Portfolio, Troubled Debt Restructuring (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 Loan Contract	Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
Total TDR	$ 12,000,000
TDR included in nonaccrual loans	7,100,000
TDR performing as agreed	4,900,000
Valuation Allowance related to total TDR	1,500,000	2,000,000
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	3
Pre-Modification Outstanding Recorded Investment	216,000,000
Post-Modification Outstanding Recorded Investment	196,000,000
Number of loans for extended terms	2
Number of loans for modified repayment terms	1
Number of loans for which allowance for loan losses measured under general allowance methodology	2
Recorded investment as TDR for which allowance for loan losses measured under general allowance methodology	148,000
Allowance for loan losses on recorded investment as TDR	0
Number of loans restructured included in non accrual loans	2
Recorded investment restructured as TDR included in non accrual loans	148,000
Real Estate Loans Construction [Member]
Financing Receivable, Modifications [Line Items]
TDR included in nonaccrual loans	62,000
TDR performing as agreed	106,000
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	0
Pre-Modification Outstanding Recorded Investment	0
Post-Modification Outstanding Recorded Investment	0
Real Estate Loans Secured by Farmland [Member]
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	0
Pre-Modification Outstanding Recorded Investment	0
Post-Modification Outstanding Recorded Investment	0
Real Estate Loans Secured by 1 - 4 Family Residential [Member]
Financing Receivable, Modifications [Line Items]
TDR included in nonaccrual loans	2,300,000
TDR performing as agreed	1,800,000
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	1
Pre-Modification Outstanding Recorded Investment	48,000,000
Post-Modification Outstanding Recorded Investment	48,000,000
Other Real Estate Loans [Member]
Financing Receivable, Modifications [Line Items]
TDR included in nonaccrual loans	4,700,000
TDR performing as agreed	2,800,000
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	2
Pre-Modification Outstanding Recorded Investment	168,000,000
Post-Modification Outstanding Recorded Investment	148,000,000
Real Estate Loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	3
Pre-Modification Outstanding Recorded Investment	216,000,000
Post-Modification Outstanding Recorded Investment	196,000,000
Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
TDR included in nonaccrual loans	55,000
TDR performing as agreed	206,000
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	0
Pre-Modification Outstanding Recorded Investment	0
Post-Modification Outstanding Recorded Investment	0
Consumer Loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number Of Contracts	0
Pre-Modification Outstanding Recorded Investment	0
Post-Modification Outstanding Recorded Investment	$ 0