Transactions with Related Parties - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]
Commitments to extend credit to directors and officers	$ 168,073	$ 118,867
Directors and officers [Member]
Related Party Transaction [Line Items]
Commitments to extend credit to directors and officers	$ 193