Quarterly Results of Operations (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Results of Operations [Abstract]
Interest Income	$ 15,081	$ 15,026	$ 14,652	$ 14,109	$ 13,943	$ 13,567	$ 13,258	$ 13,034	$ 13,313	$ 13,049	$ 12,731	$ 12,683	$ 58,868	$ 53,802	$ 51,776
Interest Expense	2,888	2,762	2,565	2,396	2,374	2,330	2,271	2,272	2,214	2,233	2,191	2,165	10,611	9,247	8,803
Net Interest Income	12,193	12,264	12,087	11,713	11,569	11,237	10,987	10,762	11,099	10,816	10,540	10,518	48,257	44,555	42,973
Provision for loan losses	350	370	300	200	250	250	150	200	125				1,220	850	125
Net Income Available to Common Shareholders	$ 1,460	$ 3,751	$ 3,898	$ 3,206	$ 3,237	$ 3,482	$ 4,157	$ 2,365	$ 3,338	$ 3,225	$ 3,218	$ 2,481	$ 12,315	$ 13,241	$ 12,262
Earnings per share, basic	$ 0.20	$ 0.51	$ 0.53	$ 0.44	$ 0.44	$ 0.48	$ 0.56	$ 0.32	$ 0.45	$ 0.44	$ 0.44	$ 0.34	$ 1.67	$ 1.79	$ 1.66
Earnings per share, diluted	$ 0.19	$ 0.50	$ 0.52	$ 0.43	$ 0.43	$ 0.47	$ 0.55	$ 0.31	$ 0.44	$ 0.43	$ 0.43	$ 0.33	$ 1.64	$ 1.76	$ 1.62