- Aging of Past Due Loans by Class of Loan (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	$ 8,570	$ 10,314
Accruing loans past due more than 90 days	2	15
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	11,161	15,064
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	750	2,616
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	8,572	10,329
Financing Receivable, Recorded Investment, Past Due, Total	20,483	28,009
Financing Receivable, Recorded Investment, Current	1,261,164	1,234,968
Total ending loans balance	1,281,647	1,262,977
Construction
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	1,505	2,416
Accruing loans past due more than 90 days	0	0
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	352	1,589
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	0	0
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	1,505	2,416
Financing Receivable, Recorded Investment, Past Due, Total	1,857	4,005
Financing Receivable, Recorded Investment, Current	117,469	109,739
Total ending loans balance	119,326	113,744
1-4 Family residential
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	2,155	2,001
Accruing loans past due more than 90 days	0	0
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	4,913	4,450
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	127	977
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,155	2,001
Financing Receivable, Recorded Investment, Past Due, Total	7,195	7,428
Financing Receivable, Recorded Investment, Current	369,226	361,417
Total ending loans balance	376,421	368,845
Other
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	776	1,357
Accruing loans past due more than 90 days	0	0
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	634	1,639
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	11	273
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	776	1,357
Financing Receivable, Recorded Investment, Past Due, Total	1,421	3,269
Financing Receivable, Recorded Investment, Current	241,150	233,491
Total ending loans balance	242,571	236,760
Commercial loans
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	1,738	1,812
Accruing loans past due more than 90 days	0	0
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	785	769
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	34	175
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	1,738	1,812
Financing Receivable, Recorded Investment, Past Due, Total	2,557	2,756
Financing Receivable, Recorded Investment, Current	158,274	157,302
Total ending loans balance	160,831	160,058
Municipal loans
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	355	709
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	0	0
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	0
Financing Receivable, Recorded Investment, Past Due, Total	355	709
Financing Receivable, Recorded Investment, Current	215,514	220,238
Total ending loans balance	215,869	220,947
Loans to individuals
Financing Receivable, Recorded Investment, Greater than 90 Days Past Due [Line Items]
Nonaccrual loans	2,396	2,728
Accruing loans past due more than 90 days	2	15
Financing Receivable, Recorded Investment, Past Due Loans by Class [Abstract]
Financing Receivable, Recorded Investment, 30 to 59 Days Past Due	4,122	5,908
Financing Receivable, Recorded Investment, 60 to 89 Days Past Due	578	1,191
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,398	2,743
Financing Receivable, Recorded Investment, Past Due, Total	7,098	9,842
Financing Receivable, Recorded Investment, Current	159,531	152,781
Total ending loans balance	$ 166,629	$ 162,623