Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 21,419	$ 21,891	$ 22,481	$ 22,426	$ 22,549	$ 22,636	$ 22,797	$ 22,965	$ 88,217	$ 90,947	$ 98,372
Interest expense	3,069	3,184	3,231	3,258	3,988	4,189	4,431	4,594	12,742	17,202	23,153
Net interest income	18,350	18,707	19,250	19,168	18,561	18,447	18,366	18,371	75,475	73,745	75,219
Provision for credit losses	(6)	665	695	674	1,108	868	835	1,005	2,028	3,816	4,735
Non-interest income	8,614	6,475	6,376	6,336	7,392	5,038	5,754	5,228	27,801	23,412	23,053
Non-interest expense	18,986	15,199	15,648	16,500	18,763	13,370	13,979	12,919	66,333	59,031	55,579
Income before income taxes	7,984	9,318	9,283	8,330	6,082	9,247	9,306	9,675	34,915	34,310	37,958
Income tax expense	3,560	2,952	2,952	2,668	1,904	2,992	2,894	3,092	12,132	10,882	11,781
Net Income	$ 4,424	$ 6,366	$ 6,331	$ 5,662	$ 4,178	$ 6,255	$ 6,412	$ 6,583	$ 22,783	$ 23,428	$ 26,177
Per common share:
Basic earnings per share	$ 0.58	$ 0.83	$ 0.83	$ 0.74	$ 0.55	$ 0.82	$ 0.83	$ 0.86	$ 2.98	$ 3.06	$ 3.41
Diluted earnings per share	$ 0.58	$ 0.83	$ 0.82	$ 0.74	$ 0.55	$ 0.82	$ 0.83	$ 0.86	$ 2.97	$ 3.05	$ 3.40