Quarterly Financial Data -- 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 Data [Abstract]
Interest income	$ 13,605	$ 13,446	$ 13,206	$ 13,202	$ 13,903	$ 13,958	$ 13,958	$ 13,948
Interest expense	848	824	865	998	1,214	1,348	1,700	1,895	3,535	6,157	8,504
Net interest income	12,757	12,622	12,341	12,204	12,689	12,610	12,258	12,053	49,924	49,610	48,268
Provision for loan losses	486	975	252	480	896	720	416	615
Net interest income after provision for loan losses	12,271	11,647	12,089	11,724	11,793	11,890	11,842	11,438	47,731	46,963	45,167
Other income	4,380	5,697	4,714	4,550	4,710	4,523	4,497	4,580	19,341	18,310	15,787
Other expense	10,892	11,082	10,918	10,612	10,877	10,562	10,782	10,617	43,504	42,838	43,053
Income before income taxes	5,759	6,262	5,885	5,662	5,626	5,851	5,557	5,401	23,568	22,435	17,901
Income taxes	2,140	2,352	2,220	2,134	2,117	2,204	2,078	2,011	8,846	8,410	6,529
Net income	3,619	3,910	3,665	3,528	3,509	3,647	3,479	3,390	14,722	14,025	11,372
Dividends on preferred shares	1,104	1,104	1,105	1,104	1,104	1,104	1,105	939	4,417	4,252	3,576
Net income available to common stockholders	$ 2,515	$ 2,806	$ 2,560	$ 2,424	$ 2,405	$ 2,543	$ 2,374	$ 2,451	$ 10,305	$ 9,773	$ 7,796
Basic earnings per common share	$ 0.43	$ 0.47	$ 0.43	$ 0.41	$ 0.40	$ 0.42	$ 0.39	$ 0.41	$ 1.74	$ 1.62	$ 1.29
Diluted earnings per common share	$ 0.42	$ 0.47	$ 0.43	$ 0.41	$ 0.40	$ 0.42	$ 0.39	$ 0.41	$ 1.73	$ 1.62	$ 1.29