Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Data (Unaudited)
Total interest income	$ 10,691	$ 10,630	$ 10,903	$ 10,886	$ 10,893	$ 11,218	$ 11,194	$ 11,129	$ 43,110	$ 44,434	$ 48,365
Total interest expense	1,435	1,529	1,583	1,665	1,771	1,983	2,037	2,046	6,212	7,837	10,998
Net interest income	9,256	9,101	9,320	9,221	9,122	9,235	9,157	9,083	36,898	36,597	37,367
Provision for loan losses	0	325	400	0	0	700	1,075	1,875	725	3,650	8,078
Noninterest income	3,671	3,367	2,821	2,719	4,532	2,696	2,694	2,617	12,578	12,539	13,210
Noninterest expense	9,465	8,896	8,773	8,630	9,645	8,177	8,092	7,814	35,764	33,728	30,964
Income before taxes	3,462	3,247	2,968	3,310	4,009	3,054	2,684	2,011	12,987	11,758	11,535
Income taxes	825	758	682	790	969	683	567	321	3,055	2,540	2,544
Net income	$ 2,637	$ 2,489	$ 2,286	$ 2,520	$ 3,040	$ 2,371	$ 2,117	$ 1,690	$ 9,932	$ 9,218	$ 8,991
Earnings per share - basic and diluted	$ 0.14	$ 0.13	$ 0.12	$ 0.13	$ 0.16	$ 0.13	$ 0.11	$ 0.10