Regulatory Matters - Summary of Capital Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk-weighted assets)	$ 637,377	$ 589,047
Tier 1 capital (to risk-weighted assets)	523,577	477,453
Common equity Tier 1 capital (to risk-weighted assets)	493,577	447,453
Tier 1 capital (to average assets)	$ 523,577	$ 477,453
Total capital (to risk-weighted assets), ratio	13.71%	13.40%
Tier 1 capital (to risk-weighted assets), ratio	11.27%	10.87%
Common equity Tier 1 capital (to risk-weighted assets), ratio	10.62%	10.18%
Tier 1 capital (to average assets), ratio	9.39%	9.12%
Total capital (to risk-weighted assets), For capital adequacy purposes	$ 458,952	$ 406,477
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	366,000	318,590
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	296,285	252,675
Tier 1 capital (to average assets), For capital adequacy purposes	$ 222,982	$ 209,431
Total capital (to risk-weighted assets), For capital adequacy purposes , ratio	10.00%	9.00%
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes, ratio	8.00%	7.00%
Common equity Tier 1 capital (to risk-weighted assets),For capital adequacy purposes, ratio	6.375%	5.75%
Tier 1 capital (to average assets), For capital adequacy purposes, ratio	4.00%	4.00%
Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk-weighted assets)	$ 605,560	$ 563,910
Tier 1 capital (to risk-weighted assets)	565,549	525,979
Common equity Tier 1 capital (to risk-weighted assets)	565,549	525,979
Tier 1 capital (to average assets)	$ 565,549	$ 525,979
Total capital (to risk-weighted assets), ratio	13.06%	12.86%
Tier 1 capital (to risk-weighted assets), ratio	12.20%	12.00%
Common equity Tier 1 capital (to risk-weighted assets), ratio	12.20%	12.00%
Tier 1 capital (to average assets), ratio	10.17%	10.06%
Total capital (to risk-weighted assets), For capital adequacy purposes	$ 457,912	$ 405,552
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	365,170	317,865
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	295,614	252,100
Tier 1 capital (to average assets), For capital adequacy purposes	222,539	209,239
Total capital (to risk - weighted assets), To be well capitalized under prompt corrective action provisions	463,708	438,435
Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions	370,967	350,748
Common equity Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions	301,410	284,983
Tier 1 capital (to average assets), To be well capitalized under prompt corrective action provisions	$ 278,173	$ 261,548
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	8.00%	8.00%
Common equity Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provision, ratio	6.50%	6.50%
Tier 1 capital (to average assets), To be well capitalized under prompt corrective action provisions, ratio	5.00%	5.00%

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

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Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Asset

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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 amount of total capital 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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