Quarterly Financial Data - Summary of Quarterly Financial Data (Detail) - 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
Summary of Income:
Interest income	$ 18,139	$ 17,293	$ 17,273	$ 17,464	$ 17,149	$ 17,012	$ 18,283	$ 15,862	$ 70,169	$ 68,306	$ 46,429
Interest expense	2,015	2,269	2,698	3,411	3,813	4,112	3,749	3,085	10,393	14,759	6,572
Net Interest Income Before Provision for Loan Losses	16,124	15,024	14,575	14,053	13,336	12,900	14,534	12,777	59,776	53,547	39,857
Provision for loan loss	1,995	1,987	1,569	1,430	728	247	133	30	6,981	1,138	324
Net Interest Income After Provision for Loan Losses	14,129	13,037	13,006	12,623	12,608	12,653	14,401	12,747	52,795	52,409	39,533
Other income (expense)	(5,662)	(7,340)	(7,041)	(7,546)	(6,756)	(7,419)	(6,673)	(8,799)
Income Before Income Taxes and Equity in Undistributed Earnings of Subsidiaries	8,467	5,697	5,965	5,077	5,852	5,234	7,728	3,948
Income Taxes	1,691	1,287	1,161	972	1,129	959	1,548	724	5,111	4,360	3,301
Net Income	$ 6,776	$ 4,410	$ 4,804	$ 4,105	$ 4,723	$ 4,275	$ 6,180	$ 3,224	$ 20,095	$ 18,402	$ 14,949
Earnings per Common Share	$ 0.60	$ 0.40	$ 0.43	$ 0.37	$ 0.43	$ 0.38	$ 0.56	$ 0.29	$ 1.80	$ 1.66	$ 1.61
Average common shares outstanding	11,177,765	11,142,797	11,129,341	11,134,870	11,137,004	11,121,426	11,106,367	11,089,839	11,061,391	11,030,441	9,179,964