Per Share Data (Computations of Basic Earnings Per Share and Diluted Earnings Per Share) (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
Basic Earnings per Share:
Net Income	$ 7,712	$ 7,721	$ 7,325	$ 7,306	$ 7,644	$ 7,708	$ 6,687	$ 6,305	$ 30,064	$ 28,344	$ 25,413
Weighted Average Shares Outstanding									13,255,002	13,202,822	12,786,065
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:
Net Income	$ 7,712	$ 7,721	$ 7,325	$ 7,306	$ 7,644	$ 7,708	$ 6,687	$ 6,305	$ 30,064	$ 28,344	$ 25,413
Weighted Average Shares Outstanding									13,255,002	13,202,822	12,786,065
Stock Options, Net									3,914	20,356	21,613
Diluted Weighted Average Shares Outstanding									13,258,916	13,223,178	12,807,678
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