Commitments - Summary of Commitments to Extend Credit and Standby Letters of Credit (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments to extend credit	$ 285,071	$ 257,195	$ 193,515
Standby letters of credit	$ 8,392	$ 7,665	$ 7,142