Per Share Data (Computations of Basic Earnings Per Share and Diluted Earnings Per Share) (Details) (USD $) In Thousands, except 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, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic Earnings per Share:
Net Income	$ 7,644	$ 7,708	$ 6,687	$ 6,305	$ 6,589	$ 6,483	$ 6,532	$ 5,809	$ 28,344	$ 25,413	$ 24,055
Weighted Average Shares Outstanding									13,202,822	12,786,065	12,622,049
Basic Earnings (in usd per share)	$ 0.58	$ 0.58	$ 0.51	$ 0.48	$ 0.50	$ 0.51	$ 0.52	$ 0.46	$ 2.15	$ 1.99	$ 1.91
Diluted Earnings per Share:
Net Income	$ 7,644	$ 7,708	$ 6,687	$ 6,305	$ 6,589	$ 6,483	$ 6,532	$ 5,809	$ 28,344	$ 25,413	$ 24,055
Weighted Average Shares Outstanding									13,202,822	12,786,065	12,622,049
Stock Options, Net									20,356	21,613	15,694
Diluted Weighted Average Shares Outstanding									13,223,178	12,807,678	12,637,743
Diluted Earnings (in usd per share)	$ 0.58	$ 0.58	$ 0.51	$ 0.48	$ 0.50	$ 0.51	$ 0.52	$ 0.46	$ 2.14	$ 1.98	$ 1.90