Loans - Summary of Composition of Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 1,331,366	$ 1,264,763
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	22,744	33,058
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	149,732	76,675
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	696,272	696,317
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	257,305	286,041
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	10,925	8,824
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	151,275	130,277
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,263	834
Municipal [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 41,850	$ 32,737