Commitments and Contingent Liabilities - Summary of Company's Commitments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Commitments And Contingent Liabilities [Line Items]
Commitments to extend credit	$ 180,733	$ 132,700
Financial standby letters of credit	6,788	8,074
Total Commitments	$ 187,521	$ 140,774