Capital Requirements - Comparison of Capital of Company and Bank with Minimum Regulatory Guidelines (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Regulatory Capital Requirements [Abstract]
Actual amount total capital (to risk weighted assets)	$ 71,318	$ 65,590
Actual ratio total capital (to risk weighted assets)	13.91%	13.47%
Minimum capital requirement amount total capital (to risk weighted assets)	$ 41,029	$ 38,951
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)	$ 51,286	$ 48,689
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)	$ 66,017	$ 60,269
Actual ratio Tier 1 capital (to risk weighted assets)	12.87%	12.38%
Minimum capital requirement amount Tier 1 capital (to risk weighted assets)	$ 30,772	$ 29,213
Minimum capital requirement ratio Tier 1 capital (to risk weighted assets)	6.00%	6.00%
Minimum to be well capitalized under prompt corrective action provisions amount Tier 1 capital (to risk weighted assets)	$ 41,029	$ 38,951
Minimum to be well capitalized under prompt corrective action provisions ratio Tier 1 capital (to risk weighted assets)	8.00%	8.00%
Actual amount common equity Tier 1 capital (to risk weighted assets)	$ 66,017	$ 60,269
Actual ratio common equity Tier 1 capital (to risk weighted assets)	12.87%	12.38%
Minimum capital requirement amount common equity Tier 1 capital (to risk weighted assets)	$ 23,079	$ 21,910
Minimum capital requirement ratio common equity Tier 1 capital (to risk weighted assets)	4.50%	4.50%
Minimum to be well capitalized under prompt corrective action provisions amount common equity Tier 1 capital (to risk weighted assets)	$ 33,336	$ 31,648
Minimum to be well capitalized under prompt corrective action provisions ratio common equity Tier 1 capital (to risk weighted assets)	6.50%	6.50%
Actual amount Tier 1 capital (to average assets)	$ 66,017	$ 60,269
Actual ratio Tier 1 capital (to average assets)	9.06%	8.48%
Minimum capital requirement amount Tier 1 capital (to average assets)	$ 29,154	$ 28,432
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)	$ 36,442	$ 35,540
Minimum to be well capitalized under prompt corrective action provisions ratio Tier 1 capital (to average assets)	5.00%	5.00%

Common Equity Tier One Risk Based Capital

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Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets

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Common Equity Tier One Risk Based Capital Required To Be Well Capitalized

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Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets

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Common Equity Tier One Risk Based Capital To Risk Weighted Assets

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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