Disclosures About Fair Value of Financial Instruments - Fair value measurements of assets and liabilities on nonrecurring basis (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate, held for sale	$ 1,610	$ 2,487
Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,363	5,611
Real estate, held for sale	700	752
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans
Real estate, held for sale
Fair Value Measurements Using Significant Other Observable Inputs ( Level 2) | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans
Real estate, held for sale
Fair Value Measurements Using Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,363	5,611
Real estate, held for sale	$ 700	$ 752