Selected Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Data [Abstract]
Interest and dividend income	$ 13,520	$ 13,806	$ 13,351	$ 13,041	$ 53,718	$ 50,749	$ 50,838
Interest expense	2,507	2,429	2,487	2,482	9,905	11,663	13,867
Net interest income	11,013	11,377	10,864	10,559	43,813	39,086	36,971
Provision for loan losses	457	491	428	457	1,833	1,418	1,652
Non-interest income	1,533	1,816	2,293	2,116	7,758	7,566	7,709
Non-interest expense	7,792	7,212	7,361	6,846	29,211	26,860	25,618
Income before income taxes	4,297	5,490	5,368	5,372	20,527	18,374	17,410
Income taxes	1,195	1,623	1,511	1,585	5,914	5,191	4,944
Net income	$ 3,102	$ 3,867	$ 3,857	$ 3,787	$ 14,613	$ 13,183	$ 12,466
Basic earnings per share	$ 0.52	$ 0.65	$ 0.65	$ 0.64	$ 2.47	$ 2.24	$ 2.13
Diluted earnings per share	$ 0.52	$ 0.65	$ 0.65	$ 0.63	$ 2.45	$ 2.22	$ 2.12