Capital Requirements - Comparison of Capital of Company and Bank with Minimum Regulatory Guidelines (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual Amount Total Capital (to Risk Weighted Assets)	$ 67,687	$ 66,437
Actual Ratio Total Capital (to Risk Weighted Assets)	18.49%	18.21%
Minimum Capital Requirement Amount Total Capital (to Risk Weighted Assets)	29,285	29,193
Minimum Capital Requirement Ratio Total Capital (to Risk Weighted Assets)	8.00%	8.00%
Actual Amount Tier 1 Capital (to Risk Weighted Assets)	63,041	61,800
Actual Ratio Tier 1 Capital (to Risk Weighted Assets)	17.22%	16.94%
Minimum Capital Requirement Amount Tier 1 Capital (to Risk Weighted Assets)	14,643	14,597
Minimum Capital Requirement Ratio Tier 1 Capital (to Risk Weighted Assets)	4.00%	4.00%
Actual Amount Tier 1 Capital (to Average Assets)	63,041	61,800
Actual Ratio Tier 1 Capital (to Average Assets)	12.05%	11.75%
Minimum Capital Requirement Amount Tier 1 Capital (to Average Assets)	20,931	21,047
Minimum Capital Requirement Ratio Tier 1 Capital (to Average Assets)	4.00%	4.00%
First Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual Amount Total Capital (to Risk Weighted Assets)	63,041	60,578
Actual Ratio Total Capital (to Risk Weighted Assets)	16.99%	16.62%
Minimum Capital Requirement Amount Total Capital (to Risk Weighted Assets)	29,253	29,160
Minimum Capital Requirement Ratio Total Capital (to Risk Weighted Assets)	8.00%	8.00%
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount Total Capital (to Risk Weighted Assets)	36,566	36,450
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio Total Capital (to Risk Weighted Assets)	10.00%	10.00%
Actual Amount Tier 1 Capital (to Risk Weighted Assets)	57,470	55,947
Actual Ratio Tier 1 Capital (to Risk Weighted Assets)	15.72%	15.35%
Minimum Capital Requirement Amount Tier 1 Capital (to Risk Weighted Assets)	14,626	14,580
Minimum Capital Requirement Ratio Tier 1 Capital (to Risk Weighted Assets)	4.00%	4.00%
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount Tier 1 Capital (to Risk Weighted Assets)	21,939	21,870
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio Tier 1 Capital (to Risk Weighted Assets)	6.00%	6.00%
Actual Amount Tier 1 Capital (to Average Assets)	57,470	55,947
Actual Ratio Tier 1 Capital (to Average Assets)	10.99%	10.68%
Minimum Capital Requirement Amount Tier 1 Capital (to Average Assets)	20,917	20,948
Minimum Capital Requirement Ratio Tier 1 Capital (to Average Assets)	4.00%	4.00%
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount Tier 1 Capital (to Average Assets)	$ 26,146	$ 26,184
Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio Tier 1 Capital (to Average Assets)	5.00%	5.00%