Quarterly Unaudited Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Unaudited Financial Data [Abstract]
Total Interest Income	$ 42,203	$ 39,793	$ 37,967	$ 38,689	$ 39,099	$ 38,810	$ 38,626	$ 37,173	$ 158,652	$ 153,708	$ 133,453
Total Interest Expense	1,582	2,094	2,552	3,263	3,445	3,530	3,253	2,966	9,491	13,194	7,950
Net Interest Income	40,621	37,699	35,415	35,426	35,654	35,280	35,373	34,207	149,161	140,514	125,503
Provision for Credit Losses	2,500	1,700	300	0	0	0	200	0	4,500	200	5,533
Net Interest Income After Provision for Credit Losses	38,121	35,999	35,115	35,426	35,654	35,280	35,173	34,207	144,661	140,314	119,970
Total Non-Interest Income	4,716	4,539	3,514	2,927	4,403	3,974	4,400	4,464	15,696	17,241	15,219
Total Non-Interest Expense	22,046	20,783	19,787	19,790	20,376	20,856	20,565	20,445	82,406	82,242	75,459
Income Before Provision for Income Taxes	20,791	19,755	18,842	18,563	19,681	18,398	19,008	18,226	77,951	75,313	59,730
Provision for Income Taxes	5,298	4,945	4,533	4,441	5,037	4,660	4,903	4,677	19,217	19,277	14,203
Net Income	$ 15,493	$ 14,810	$ 14,309	$ 14,122	$ 14,644	$ 13,738	$ 14,105	$ 13,549	$ 58,734	$ 56,036	$ 45,527
Basic and Diluted Earnings Per Common Share (in dollars per share)	$ 19.54	$ 18.66	$ 18.03	$ 17.80	$ 18.54	$ 17.45	$ 17.92	$ 17.27	$ 74.03	$ 71.18	$ 56.82