Fair Value Measurements and Disclosure - Fair Value Estimates (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Financial Assets:
Investment securities	$ 0	$ 0
Quoted Prices In Active Markets for Identical Assets Level 1
Financial Assets:
Investment securities	3,865,000	3,776,000
Loans	0	0
Accrued interest receivable	0	0
Deposits:
Noninterest-bearing	430,210,000	311,950,000
NOW and money market	406,707,000	360,934,000
Savings	94,467,000	80,078,000
Time deposits	0	0
Total deposits	931,384,000	752,962,000
Junior subordinated debt	0	0
Accrued interest payable	0	0
Significant Other Observable Inputs Level 2
Financial Assets:
Investment securities	87,917,000	76,312,000
Loans	0	0
Accrued interest receivable	10,099,000	8,208,000
Deposits:
Noninterest-bearing	0	0
NOW and money market	0	0
Savings	0	0
Time deposits	0	0
Total deposits	0	0
Junior subordinated debt	0	0
Accrued interest payable	36,000	59,000
Significant Unobservable Inputs Level 3
Financial Assets:
Investment securities	0	0
Loans	645,098,000	581,695,000
Accrued interest receivable	0	0
Deposits:
Noninterest-bearing	0	0
NOW and money market	0	0
Savings	0	0
Time deposits	63,931,000	65,236,000
Total deposits	63,931,000	65,236,000
Junior subordinated debt	10,081,000	10,808,000
Accrued interest payable	0	0
Carrying Amount
Financial Assets:
Investment securities	91,782,000	80,088,000
Loans	651,736,000	588,646,000
Accrued interest receivable	10,099,000	8,208,000
Deposits:
Noninterest-bearing	430,028,000	311,950,000
NOW and money market	406,706,000	360,934,000
Savings	94,467,000	80,078,000
Time deposits	63,582,000	65,400,000
Total deposits	994,783,000	818,362,000
Junior subordinated debt	10,081,000	10,808,000
Accrued interest payable	36,000	59,000
Estimated Fair Value
Financial Assets:
Investment securities	91,782,000	80,088,000
Loans	645,098,000	581,695,000
Accrued interest receivable	10,099,000	8,208,000
Deposits:
Noninterest-bearing	430,210,000	311,950,000
NOW and money market	406,707,000	360,934,000
Savings	94,467,000	80,078,000
Time deposits	63,931,000	65,236,000
Total deposits	995,315,000	818,198,000
Junior subordinated debt	10,081,000	10,808,000
Accrued interest payable	$ 36,000	$ 59,000