Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Selected Quarterly Financial Data (Unaudited) [Abstract]
Net interest income	$ 10,530		$ 9,801		$ 9,439		$ 9,861		$ 8,489		$ 9,453		$ 10,495		$ 9,694		$ 39,631	$ 38,131	$ 29,850
Provision for loan losses	100		0		0		100		151		150		785		160		200	1,246	1,554
Noninterest income	262		319		486		264		143		382		428		482		1,331	1,435	1,643
Noninterest expense	3,939		3,805		3,546		3,675		3,914		3,735		3,449		3,433		14,965	14,531	13,122
Income Before Taxes	6,753		6,315		6,379		6,350		4,567		5,950		6,689		6,583		25,797	23,789	16,817
Income tax expense (benefit)	1,192		(395)		0		0		0		0		0		0		797	0	0
Net Income	$ 5,561		$ 6,710		$ 6,379		$ 6,350		$ 4,567		$ 5,950		$ 6,689		$ 6,583		$ 25,000	$ 23,789	$ 16,817
EPS [Abstract]
Basic (in dollars per share)	$ 0.55	[1]	$ 0.88	[1]	$ 0.88	[1]	$ 0.87	[1]	$ 0.62	[1]	$ 0.82	[1]	$ 0.92	[1]	$ 0.90	[1]	$ 3.08	$ 3.26	$ 2.31
Diluted (in dollars per share)	$ 0.54	[1]	$ 0.87	[1]	$ 0.88	[1]	$ 0.87	[1]	$ 0.62	[1]	$ 0.82	[1]	$ 0.92	[1]	$ 0.90	[1]	$ 3.03	$ 3.26	$ 2.31

[1] The quarterly EPS amounts, when added, may not coincide with the full fiscal year EPS reported on the Consolidated Statements of Income due to differences in the computed weighted average shares outstanding as well as rounding differences.