Fair Value - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unpaid principal balance of impairment loan at collateral	$ 5,511	$ 5,909
Valuation allowance	603	611
Total impaired loans	10,799	11,792
Foreclosed assets, net	1,464	1,525
Financial instruments measured at fair value on a non-recurring basis [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total impaired loans	$ 4,908	$ 5,298