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 Data [Abstract]
Interest and Dividend Income, Operating	$ 16,697	$ 14,943	$ 14,172	$ 13,439	$ 13,965	$ 13,807	$ 13,600	$ 13,362	$ 59,251	$ 54,734	$ 53,459
Interest expense	897	947	828	827	844	805	788	815	3,499	3,252	3,535
Net interest income	15,800	13,996	13,344	12,612	13,121	13,002	12,812	12,547	55,752	51,482	49,924
Provision for loan losses	429	481	143	265	134	44	128	323	1,318	629	2,193
Net interest income after provision for loan losses	15,371	13,515	13,201	12,347	12,987	12,958	12,684	12,224	54,434	50,853	47,731
Other income	6,199	5,009	4,537	4,799	4,496	4,402	4,990	4,481	20,544	18,369	19,341
Other expense	14,332	12,882	11,230	10,804	11,243	11,090	11,214	10,960	49,248	44,507	43,504
Income before income taxes	7,238	5,642	6,508	6,342	6,240	6,270	6,460	5,745	25,730	24,715	23,568
Income taxes	2,584	1,979	2,352	2,303	2,330	2,355	2,431	2,138	9,218	9,254	8,846
Net income	4,654	3,663	4,156	4,039	3,910	3,915	4,029	3,607	16,512	15,461	14,722
Dividends on preferred shares	550	550	550	550	839	1,105	1,104	1,104	2,200	4,152	4,417
Net income available to common stockholders	$ 4,104	$ 3,113	$ 3,606	$ 3,489	$ 3,071	$ 2,810	$ 2,925	$ 2,503	$ 14,312	$ 11,309	$ 10,305
Basic earnings per common share	$ 0.49	$ 0.37	$ 0.50	$ 0.50	$ 0.48	$ 0.48	$ 0.49	$ 0.43	$ 1.84	$ 1.88	$ 1.74
Diluted earnings per common share	$ 0.48	$ 0.37	$ 0.49	$ 0.48	$ 0.47	$ 0.47	$ 0.48	$ 0.43	$ 1.81	$ 1.85	$ 1.73