Regulatory Matters - Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2014
Total Capital (to Risk-Weighted Assets):
Total Capital (to Risk-Weighted Assets) Actual, Amount	$ 334,757	$ 249,388
Total Capital (to Risk-Weighted Assets) Actual, Ratio	13.35%	12.91%
Total Capital (to Risk-Weighted Assets) For Capital Adequacy, Amount	$ 200,613	$ 154,589
Total Capital (to Risk-Weighted Assets) For Capital Adequacy, Ratio	8.00%	8.00%
Total Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 250,766	$ 193,237
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):
Tier 1 Capital (to Risk-Weighted Assets) Actual, Amount	$ 267,098	$ 227,907
Tier 1 Capital (to Risk-Weighted Assets) Actual, Ratio	10.65%	11.79%
Tier 1 Capital (to Risk - Weighed Assets) For Capital Adequacy, Amount	$ 150,460	$ 77,295
Tier 1 Capital (to Risk - Weighted Assets) For Capital Adequacy, Ratio	6.00%	4.00%	4.00%
Tier 1 Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 200,613	$ 115,942
Tier 1 Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	6.00%	6.00%
Tier One Common Risk Based Capital [Abstract]
Tier One Common Risk Based Capital	$ 267,098
Tier One Common Risk Based Capital To Risk Weighted Assets	10.65%
Tier One Common Risk Based Capital Required For Capital Adequacy	$ 112,845
Tier One Common Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets	4.50%
Tier One Common Risk Based Capital Required To Be Well Capitalized	$ 162,998
Tier One Common Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets	6.50%
Tier 1 Capital (to Average Assets):
Tier 1 Capital (to Average Assets) Actual, Amount	$ 267,098	$ 227,907
Tier 1 Capital (to Average Assets) Actual, Ratio	9.69%	10.55%
Tier 1 Capital (to Average Assets) For Capital Adequacy, Amount	$ 110,227	$ 86,371
Tier 1 Capital (to Average Assets) For Capital Adequacy, Ratio	4.00%	4.00%
Tier 1 Capital (to Average Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 137,783	$ 107,964
Tier 1 Capital (to Average Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%
Bank [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital (to Risk-Weighted Assets) Actual, Amount	$ 300,527	$ 232,080
Total Capital (to Risk-Weighted Assets) Actual, Ratio	12.09%	12.15%
Total Capital (to Risk-Weighted Assets) For Capital Adequacy, Amount	$ 198,816	$ 152,796
Total Capital (to Risk-Weighted Assets) For Capital Adequacy, Ratio	8.00%	8.00%
Total Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 248,521	$ 190,995
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):
Tier 1 Capital (to Risk-Weighted Assets) Actual, Amount	$ 282,245	$ 210,816
Tier 1 Capital (to Risk-Weighted Assets) Actual, Ratio	11.36%	11.04%
Tier 1 Capital (to Risk - Weighed Assets) For Capital Adequacy, Amount	$ 149,112	$ 76,398
Tier 1 Capital (to Risk - Weighted Assets) For Capital Adequacy, Ratio	6.00%	4.00%
Tier 1 Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 198,816	$ 114,597
Tier 1 Capital (to Risk-Weighted Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	6.00%
Tier One Common Risk Based Capital [Abstract]
Tier One Common Risk Based Capital	$ 282,245
Tier One Common Risk Based Capital To Risk Weighted Assets	11.36%
Tier One Common Risk Based Capital Required For Capital Adequacy	$ 111,834
Tier One Common Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets	4.50%
Tier One Common Risk Based Capital Required To Be Well Capitalized	$ 161,538
Tier One Common Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets	6.50%
Tier 1 Capital (to Average Assets):
Tier 1 Capital (to Average Assets) Actual, Amount	$ 282,245	$ 210,816
Tier 1 Capital (to Average Assets) Actual, Ratio	10.31%	9.80%
Tier 1 Capital (to Average Assets) For Capital Adequacy, Amount	$ 109,480	$ 86,005
Tier 1 Capital (to Average Assets) For Capital Adequacy, Ratio	4.00%	4.00%
Tier 1 Capital (to Average Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 136,850	$ 107,506
Tier 1 Capital (to Average Assets) To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%