Fair Value Measurements - Carrying Amount and Estimated Fair Values (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial Assets
Interest-bearing deposits in other financial institutions	$ 18,086	$ 11,018
Available-for-sale securities	45,044	53,547
Loans, net of allowance	357,356	354,537
Accrued interest receivable	1,505	1,622
Federal Home Loan Bank stock	2,053	2,025
Financial Liabilities
Subordinated debentures	5,000	5,000
Accrued interest payable	254	220
Level 1
Financial Assets
Cash and cash equivalents	7,452	8,542
Interest-bearing deposits in other financial institutions	18,086	11,018
Accrued interest receivable	10	16
Financial Liabilities
Demand and savings deposits	223,484	225,942
Accrued interest payable	15	12
Level 2
Financial Assets
Available-for-sale securities	43,644	52,307
Loans held for sale	347	266
Accrued interest receivable	226	268
Financial Liabilities
Time deposits	138,922	144,558
FHLB advances	39,896	34,897
Accrued interest payable	200	175
Level 3
Financial Assets
Available-for-sale securities	1,400	1,240
Loans, net of allowance	357,117	354,300
Accrued interest receivable	1,269	1,338
Financial Liabilities
Subordinated debentures	2,495	2,495
Accrued interest payable	39	33
Carrying Amount
Financial Assets
Cash and cash equivalents	7,452	8,542
Interest-bearing deposits in other financial institutions	18,086	11,018
Available-for-sale securities	45,044	53,547
Loans, net of allowance	357,356	354,537
Loans held for sale	341	264
Accrued interest receivable	1,505	1,622
Federal Home Loan Bank stock	2,053	2,025
Financial Liabilities
Demand and savings deposits	223,484	225,942
Time deposits	139,113	144,497
FHLB advances	40,000	35,000
Subordinated debentures	5,000	5,000
Accrued interest payable	254	220
Total
Financial Assets
Cash and cash equivalents	7,452	8,542
Interest-bearing deposits in other financial institutions	18,086	11,018
Available-for-sale securities	45,044	53,547
Loans, net of allowance	357,117	354,300
Loans held for sale	347	266
Accrued interest receivable	1,505	1,622
Financial Liabilities
Demand and savings deposits	223,484	225,942
Time deposits	138,922	144,558
FHLB advances	39,896	34,897
Subordinated debentures	2,495	2,495
Accrued interest payable	$ 254	$ 220