Commitments and Contingencies - Summary of The Contractual Amount of Commitments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Loss Contingencies [Line Items]
Contractual amount of commitments, total	$ 163,932	$ 178,683
Commitments to extend credit [Member]
Loss Contingencies [Line Items]
Contractual amount of commitments, total	74,206	92,128
Home Equity Loans
Loss Contingencies [Line Items]
Contractual amount of commitments, total	81,041	78,410
Standby letters of credit [Member]
Loss Contingencies [Line Items]
Contractual amount of commitments, total	$ 8,685	$ 8,145