Regulatory Requirements and Restrictions - Schedule of Bank's Actual Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2015	Jul. 31, 2013
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio			8.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio			6.00%	4.00%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement Ratio			4.00%
Common Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio			4.50%
Consolidated Entities
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk Based Capital (to Risk Weighted Assets), Actual Amount	$ 51,810	$ 49,305
Total Risk Based Capital (to Risk Weighted Assets), Actual Ratio	15.02%	15.54%
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 27,600	$ 25,380
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Tier 1 Capital (to Risk Weighted Assets), Actual Amount	$ 41,087	$ 38,492
Tier 1 Capital (to Risk Weighted Assets), Actual Ratio	11.91%	12.13%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 20,700	$ 19,035
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier 1 Capital (to Average Assets), Actual Amount	$ 41,087	$ 38,492
Tier 1 Capital (to Average Assets), Actual Ratio	8.66%	8.84%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement Amount	$ 18,967	$ 17,420
Tier 1 Capital (to Average Assets), Minimum Capital Requirement Ratio	4.00%	4.00%
Consolidated Entities | Common Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk Based Capital (to Risk Weighted Assets), Actual Amount	$ 41,087	$ 38,492
Total Risk Based Capital (to Risk Weighted Assets), Actual Ratio	11.91%	12.13%
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 15,525	$ 14,276
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk Based Capital (to Risk Weighted Assets), Actual Amount	$ 46,977	$ 42,923
Total Risk Based Capital (to Risk Weighted Assets), Actual Ratio	13.69%	13.64%
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 27,460	$ 25,176
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Total Risk Based Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 34,325	$ 31,471
Total Risk Based Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets), Actual Amount	$ 43,114	$ 38,986
Tier 1 Capital (to Risk Weighted Assets), Actual Ratio	12.56%	12.39%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 20,595	$ 18,882
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 27,460	$ 25,176
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	8.00%	8.00%
Tier 1 Capital (to Average Assets), Actual Amount	$ 43,114	$ 38,986
Tier 1 Capital (to Average Assets), Actual Ratio	9.18%	9.11%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement Amount	$ 18,793	$ 17,125
Tier 1 Capital (to Average Assets), Minimum Capital Requirement Ratio	4.00%	4.00%
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 23,491	$ 21,406
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%
Subsidiaries | Common Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk Based Capital (to Risk Weighted Assets), Actual Amount	$ 43,114	$ 38,986
Total Risk Based Capital (to Risk Weighted Assets), Actual Ratio	12.56%	12.39%
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Amount	$ 15,446	$ 14,162
Total Risk Based Capital (to Risk Weighted Assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Total Risk Based Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 22,311	$ 20,456
Total Risk Based Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%	6.50%