Regulatory Matters - Schedule of Compliance with Regulatory Capital Requirements (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual Amount	$ 173,225	$ 165,089
Total capital (to risk weighted assets), Actual Ratio	17.90%	18.41%
Tier 1 capital (to risk weighted assets), Actual Amount	161,073	153,829
Tier 1 capital (to risk weighted assets), Actual Ratio	16.64%	17.15%
Tier 1 capital (to leverage assets), Actual Amount	161,073	153,829
Tier 1 capital (to leverage assets), Actual Ratio	12.15%	12.51%
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount	77,426	71,756
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount	38,713	35,878
Tier 1 capital (to leverage assets), For Capital Adequacy Purposes Amount	53,019	49,178
Total capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 capital (to leverage assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	96,783	89,695
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	58,070	53,817
Tier 1 capital (to leverage assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	66,273	61,472
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.00%	6.00%
Tier 1 capital (to leverage assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%
Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual Amount	175,671	172,336
Total capital (to risk weighted assets), Actual Ratio	18.15%	19.22%
Tier 1 capital (to risk weighted assets), Actual Amount	163,519	161,076
Tier 1 capital (to risk weighted assets), Actual Ratio	16.90%	17.97%
Tier 1 capital (to leverage assets), Actual Amount	163,519	161,076
Tier 1 capital (to leverage assets), Actual Ratio	12.33%	13.09%
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount	77,411	71,720
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount	38,706	35,860
Tier 1 capital (to leverage assets), For Capital Adequacy Purposes Amount	53,030	49,226
Total capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 capital (to leverage assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	96,764	89,651
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	58,059	53,790
Tier 1 capital (to leverage assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 66,287	$ 61,533
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.00%	6.00%
Tier 1 capital (to leverage assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%