Capital Requirements and Restrictions on Retained Earnings - Summary of Actual and Required Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Consolidated
Total Capital to Risk Weighted Assets
Total Capital to Risk Weighted Assets, Actual Amount	$ 350,806	$ 319,340
Total Capital to Risk Weighted Assets, Actual Ratio	12.51%	13.21%
Total Capital to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 294,407	$ 238,719
Total Capital to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	10.50%	9.875%
Tier 1 (Core) Capital to Risk Weighted Assets
Tier 1 (Core) Capital to Risk Weighted Assets, Actual Amount	$ 281,333	$ 249,636
Tier 1 (Core) Capital to Risk Weighted Assets, Actual Ratio	10.03%	10.33%
Tier 1 (Core) Capital to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 238,330	$ 190,371
Tier 1 (Core) Capital to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	8.50%	7.875%
Common equity Tier 1 to Risk Weighted Assets
Common equity Tier 1 to Risk Weighted Assets, Actual Amount	$ 261,333	$ 229,636
Common equity Tier 1 to Risk Weighted Assets, Actual Ratio	9.32%	9.50%
Common equity Tier 1 to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 196,272	$ 154,110
Common equity Tier 1 to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	7.00%	6.375%
Tier 1 (Core) Capital to Average Assets
Tier 1 (Core) Capital to Average Assets, Actual Amount	$ 281,333	$ 249,636
Tier 1 (Core) Capital to Average Assets, Actual Ratio	7.86%	7.87%
Tier 1 (Core) Capital to Average Assets, For Capital Adequacy Purposes, Amount	$ 143,189	$ 126,882
Tier 1 (Core) Capital to Average Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Bank
Total Capital to Risk Weighted Assets
Total Capital to Risk Weighted Assets, Actual Amount	$ 330,321	$ 302,627
Total Capital to Risk Weighted Assets, Actual Ratio	11.87%	12.59%
Total Capital to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 292,271	$ 237,325
Total Capital to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	10.50%	9.875%
Total Capital to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 292,271	$ 240,329
Total Capital to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.50%	10.00%
Tier 1 (Core) Capital to Risk Weighted Assets
Tier 1 (Core) Capital to Risk Weighted Assets, Actual Amount	$ 312,795	$ 284,722
Tier 1 (Core) Capital to Risk Weighted Assets, Actual Ratio	11.24%	11.85%
Tier 1 (Core) Capital to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 236,600	$ 189,259
Tier 1 (Core) Capital to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	8.50%	7.875%
Tier 1 (Core) Capital to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 236,600	$ 192,263
Tier 1 (Core) Capital to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.50%	8.00%
Common equity Tier 1 to Risk Weighted Assets
Common equity Tier 1 to Risk Weighted Assets, Actual Amount	$ 305,416	$ 277,343
Common equity Tier 1 to Risk Weighted Assets, Actual Ratio	10.97%	11.54%
Common equity Tier 1 to Risk Weighted Assets, For Capital Adequacy Purposes Amount	$ 194,847	$ 153,210
Common equity Tier 1 to Risk Weighted Assets, For Capital Adequacy Purposes Ratio	7.00%	6.375%
Common equity Tier 1 to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 194,847	$ 156,214
Common equity Tier 1 to Risk Weighted Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	7.00%	6.50%
Tier 1 (Core) Capital to Average Assets
Tier 1 (Core) Capital to Average Assets, Actual Amount	$ 312,795	$ 284,722
Tier 1 (Core) Capital to Average Assets, Actual Ratio	8.79%	9.12%
Tier 1 (Core) Capital to Average Assets, For Capital Adequacy Purposes, Amount	$ 142,301	$ 124,903
Tier 1 (Core) Capital to Average Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Tier 1 (Core) Capital to Average Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 177,876	$ 156,128
Tier 1 (Core) Capital to Average Assets, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%