Equity and Regulatory Matters - Schedule of Banks Actual and Required Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Leverage tier 1 capital actual amount	$ 35,310	$ 34,868
Common Tier 1 risk based capital actual amount	35,310	34,868
Tier 1 risk based capital actual amount	35,310	34,868
Total risk based capital actual amount	$ 38,522	$ 37,961
Leverage tier 1 capital actual ratio	7.40%	7.40%
Common Tier 1 risk based capital actual ratio	9.60%	11.10%
Tier 1 risk based capital actual ratio	9.60%	11.10%
Total risk based capital actual ratio	10.50%	12.10%
Leverage tier 1 capital for capital adequacy purposes amount	$ 19,049	$ 18,975
Common tier 1 risk based capital for capital adequacy purposes amount	16,510	14,174
Tier 1 risk based capital for capital adequacy purposes amount	22,013	18,898
Total risk based capital for capital adequacy purposes amount	$ 29,351	$ 25,197
Leverage tier 1 capital for capital adequacy purposes ratio	4.00%	4.00%
Common tier 1 risk based capital for capital adequacy purposes ratio	4.50%	4.50%
Tier 1 risk based capital for capital adequacy purposes ratio	6.00%	6.00%
Total risk based capital for capital adequacy purposes ratio	8.00%	8.00%
Leverage tier 1 capital to be well capitalized under prompt corrective action provisions amount	$ 23,811	$ 23,719
Common tier 1 risk based capital to be well capitalized under prompt corrective action provisions amount	23,847	20,473
Tier 1 risk based capital to be well capitalized under prompt corrective action provisions amount	29,351	25,197
Total risk based capital to be well capitalized under prompt corrective action provisions amount	$ 36,688	$ 31,497
Leverage tier 1 capital to be well capitalized under prompt corrective action provisions ratio	5.00%	5.00%
Common tier 1 risk based capital to be well capitalized under prompt corrective action provisions ratio	6.50%	6.50%
Tier 1 risk based capital to be well capitalized under prompt corrective action provisions ratio	8.00%	8.00%
Total risk based capital to be well capitalized under prompt corrective action provisions ratio	10.00%	10.00%

Common Equity Tier One Capital Required To Be Well Capitalized To Risk Weighted Assets

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Common Equity Tier One Risk Based Capital Required For Capital Adequacy

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The minimum Common Tier One Capital Ratio (Common 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 total capital as defined in the regulations.

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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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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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

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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 Risk Based Capital as defined in the regulations.

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