Regulatory Matters - Additional Information (Detail)	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Minimum ratio of tier 1 capital to total adjusted assets	4.00%
Minimum ratio of common equity tier 1 to risk-weighted assets	6.375%
Minimum ratio of tier 1 leverage ratio, For capital adequacy purposes	7.875%	4.00%
Minimum ratio of total capital to risk-weighted assets	9.875%
Tier 1 capital ratio, To be well capitalized	5.00%
Common equity tier 1 risk-based ratio, To be well capitalized	6.50%
Tier 1 risk-based capital, To be well capitalized under prompt corrective action ratio	8.00%
Total risk-based capital, To be well capitalized under prompt corrective action ratio	10.00%

Common Equity Tier One Capital To Risk Weighted Assets

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

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

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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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