Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Interest Income	$ 21,023	$ 20,419	$ 20,178	$ 20,000	$ 20,532	$ 20,348	$ 19,825	$ 19,681	$ 81,620	$ 80,386	$ 75,672
Net Interest Income	19,438	18,859	18,706	18,549	19,031	18,791	18,321	18,196	75,552	74,339	68,517
Net Income	$ 7,712	$ 7,721	$ 7,325	$ 7,306	$ 7,644	$ 7,708	$ 6,687	$ 6,305	$ 30,064	$ 28,344	$ 25,413
Basic Earnings per Share (in usd per share)	$ 0.58	$ 0.58	$ 0.55	$ 0.55	$ 0.58	$ 0.58	$ 0.51	$ 0.48	$ 2.27	$ 2.15	$ 1.99
Diluted Earnings per Share (in usd per share)	$ 0.58	$ 0.58	$ 0.55	$ 0.55	$ 0.58	$ 0.58	$ 0.51	$ 0.48	$ 2.27	$ 2.14	$ 1.98