Allowance for Loan Losses - Performing and Nonperforming Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Performing	$ 157,179	$ 153,472
Nonperforming
Total	157,179	153,472
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing	142,326	140,481
Nonperforming
Total	142,326	140,481
Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing	4,441	4,448
Nonperforming
Total	4,441	4,448
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing	10,412	8,543
Nonperforming
Total	$ 10,412	$ 8,543