Regulatory Capital - Summary of Regulatory Capital Requirement (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 264,452	$ 212,276
Total capital (to risk-weighted assets), Actual, Ratio	13.99%	14.48%
Total capital (to risk-weighted assets), For capital adequacy purposes, Amount	$ 151,223	$ 117,280
Total capital (to risk-weighted assets), For capital adequacy purposes, Ratio	8.00%	8.00%
Tier 1 capital (to average assets), Actual, Amount	$ 249,918	$ 195,775
Tier 1 capital (to average assets), Actual, Ratio	13.22%	13.35%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 113,427	$ 58,659
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	6.00%	4.00%
Common equity tier 1 capital, Actual Amount	$ 204,350
Common equity tier 1 capital, Actual Ratio	10.81%
Common equity tier 1 capital,For capital adequacy purposes, Amount	$ 85,067
Common equity tier 1 capital, For capital adequacy purpose, Ratio	4.50%
Tier 1 capital (to average assets), Actual, Amount	$ 249,918	$ 195,775
Tier 1 capital (to average assets), Actual, Ratio	9.82%	9.76%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 101,800	$ 80,236
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	4.00%	4.00%
Bank [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 237,348	$ 192,604
Total capital (to risk-weighted assets), Actual, Ratio	12.57%	13.08%
Total capital (to risk-weighted assets), For capital adequacy purposes, Amount	$ 151,057	$ 117,801
Total capital (to risk-weighted assets), For capital adequacy purposes, Ratio	8.00%	8.00%
Total capital (to risk-weighted assets), For well capitalized purpose, Amount	$ 188,821	$ 147,251
Total capital (to risk-weighted assets), For well capitalized purpose, Ratio	10.00%	10.00%
Tier 1 capital (to average assets), Actual, Amount	$ 222,814	$ 176,103
Tier 1 capital (to average assets), Actual, Ratio	11.80%	11.96%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 113,295	$ 58,897
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	6.00%	4.00%
Tier 1 capital (to average assets), For well capitalized purpose, Amount	$ 151,060	$ 88,346
Tier 1 capital (to average assets), For well capitalized purposes, Ratio	8.00%	6.00%
Common equity tier 1 capital, Actual Amount	$ 222,814
Common equity tier 1 capital, Actual Ratio	11.80%
Common equity tier 1 capital,For capital adequacy purposes, Amount	$ 84,971
Common equity tier 1 capital, For capital adequacy purpose, Ratio	4.50%
Common equity tier 1 capital, For well capitalized purpose, Amount	$ 122,737
Common equity tier 1 capital, For well capitalized purposes, Ratio	6.50%
Tier 1 capital (to average assets), Actual, Amount	$ 222,814	$ 176,103
Tier 1 capital (to average assets), Actual, Ratio	8.77%	8.80%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 101,626	$ 80,047
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	4.00%	4.00%
Tier 1 capital (to average assets), For well capitalized purpose, Amount	$ 127,032	$ 100,059
Tier 1 capital (to average assets), For well capitalized purposes, Ratio	5.00%	5.00%