Selected Quarterly Financial Data (unaudited) Selected Quarterly Financial Data (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
Selected Quarterly Financial Information [Abstract]
Interest income	$ 15,660	$ 15,147	$ 14,819	$ 14,521	$ 14,434	$ 13,860	$ 13,661	$ 13,346	$ 60,147		$ 55,301		$ 52,741
Interest expense	1,529	1,441	1,465	1,558	1,502	1,571	1,545	1,538	5,993		6,156		7,058
Net interest income	14,131	13,706	13,354	12,963	12,932	12,289	12,116	11,808	54,154		49,145		45,683
Provision for loan losses	450	200	200	0	500	100	150	0	850	[1]	750	[1]	(850)	[1]
Net interest income after provision for loan losses	13,681	13,506	13,154	12,963	12,432	12,189	11,966	11,808	53,304		48,395		46,533
Total noninterest income	2,486	1,935	1,922	1,860	2,803	2,622	2,318	2,553	8,203		10,296		8,494
Total noninterest expense	7,630	7,549	7,443	7,446	9,250	7,386	7,364	8,002	30,068		32,002		30,816
Income before income taxes	8,537	7,892	7,633	7,377	5,985	7,425	6,920	6,359	31,439		26,689		24,211
Income taxes	2,596	2,466	2,361	2,274	147	2,362	2,181	1,959	9,697		6,649		7,320
Net income	$ 5,941	$ 5,426	$ 5,272	$ 5,103	$ 5,838	$ 5,063	$ 4,739	$ 4,400	$ 21,742		$ 20,040		$ 16,891
Basic earnings per common share	$ 0.37	$ 0.34	$ 0.33	$ 0.32	$ 0.36	$ 0.32	$ 0.30	$ 0.28	$ 1.35		$ 1.25		$ 1.02
Diluted earnings per common share	$ 0.37	$ 0.34	$ 0.33	$ 0.32	$ 0.36	$ 0.32	$ 0.30	$ 0.27	$ 1.35		$ 1.25		$ 1.02

[1] The negative provisions for the various segments are either related to the decline in outstanding balances in each of those portfolio segments during the time periods disclosed and/or improvement in the credit quality factors related to those portfolio segments.