Fair Value Measurement - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets
Available for sale securities	$ 341,538	$ 318,910
Bank owned life insurance	9,764	9,677
Fair Value, Measurements, Recurring [Member]
Assets
Available for sale securities	341,538	318,910
Bank owned life insurance	9,764	9,677
Liabilities
Interest rate swap	675	750
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale securities
Bank owned life insurance
Liabilities
Interest rate swap
Significant Other Observable Inputs (Level 2) [Member]
Assets
Available for sale securities	340,049	317,421
Liabilities
Interest rate swap	675	750
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale securities	340,049	317,421
Bank owned life insurance	9,764	9,677
Liabilities
Interest rate swap	675	750
Significant Unobservable Inputs (Level 3) [Member]
Assets
Available for sale securities	1,489	1,489
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale securities	1,489	1,489
Bank owned life insurance
Liabilities
Interest rate swap