Regulatory Matters - Schedule of Company's and Bank's Capital Compliance (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 ratio	$ 95,063
Tier 1 leverage ratio	95,063
Tier 1 risk-based capital ratio	95,063
Total risk based capital ratio	$ 100,550
Common equity tier 1 ratio	16.34%
Tier 1 leverage ratio	10.92%
Tier 1 risk-based capital ratio	16.34%
Total risk based capital ratio	17.20%
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 ratio	$ 92,557
Tier 1 leverage ratio	92,557
Tier 1 risk-based capital ratio	92,557
Total risk based capital ratio	$ 98,044
Common equity tier 1 ratio	15.90%
Tier 1 leverage ratio	10.67%
Tier 1 risk-based capital ratio	15.90%
Total risk based capital ratio	16.84%