Regulatory Matters - The Company's Consolidated Capital Ratios and the Bank's Actual Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage capital to adjusted total assets, Actual Amount	$ 100,520	$ 95,709
Tier 1 leverage capital to adjusted total assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	36,417	36,137
Tier 1 leverage capital to adjusted total assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	45,521	45,171
Total capital to risk weighted assets, Actual Amount	105,055	100,535
Total capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	52,049	50,352
Total capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	65,061	62,940
Tier 1 capital to risk weighted assets, Actual Amount	100,520	95,709
Tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	39,037	37,764
Tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	52,049	50,352
Common equity tier 1 capital to risk weighted assets, Actual Amount	100,520	95,709
Common equity tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	$ 29,277	$ 28,323
Tier 1 leverage capital to adjusted total assets, Actual Ratio	11.00%	10.60%
Tier 1 leverage capital to adjusted total assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	4.00%	4.00%
Tier 1 leverage capital to adjusted total assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	5.00%	5.00%
Total capital to risk weighted assets, Actual Ratio	16.20%	16.00%
Total capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	8.00%	8.00%
Total capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	10.00%	10.00%
Tier 1 capital to risk weighted assets, Actual Ratio	15.50%	15.20%
Tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	6.00%	6.00%
Tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	8.00%	8.00%
Common equity tier 1 capital to risk weighted assets, Actual Ratio	15.50%	15.20%
Common equity tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	4.50%	4.50%
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage capital to adjusted total assets, Actual Amount	$ 99,478	$ 95,123
Tier 1 leverage capital to adjusted total assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	36,361	36,090
Tier 1 leverage capital to adjusted total assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	45,451	45,112
Total capital to risk weighted assets, Actual Amount	104,014	99,949
Total capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	51,937	50,314
Total capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	64,922	62,892
Tier 1 capital to risk weighted assets, Actual Amount	99,478	95,123
Tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	38,953	37,735
Tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	51,937	50,314
Common equity tier 1 capital to risk weighted assets, Actual Amount	99,478	95,123
Common equity tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Amount	29,215	28,301
Common equity tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Amount	$ 42,199	$ 40,880
Tier 1 leverage capital to adjusted total assets, Actual Ratio	10.90%	10.50%
Tier 1 leverage capital to adjusted total assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	4.00%	4.00%
Tier 1 leverage capital to adjusted total assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	5.00%	5.00%
Total capital to risk weighted assets, Actual Ratio	16.00%	15.90%
Total capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	8.00%	8.00%
Total capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	10.00%	10.00%
Tier 1 capital to risk weighted assets, Actual Ratio	15.30%	15.10%
Tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	6.00%	6.00%
Tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	8.00%	8.00%
Common equity tier 1 capital to risk weighted assets, Actual Ratio	15.30%	15.10%
Common equity tier 1 capital to risk weighted assets, Minimum Capital Required - Basel III Phase-In Schedule, Ratio	4.50%	4.50%
Common equity tier 1 capital to risk weighted assets, To be Well Capitalized for Prompt Corrective Action Provision, Ratio	6.50%	6.50%