Disclosures About Fair Value of Assets and Liabilities - Valuation Methodologies Used for Instruments Measured at Fair Value on Non-Recurring Basis (Details) (Fair Value, Measurements, Nonrecurring, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Impaired loans (collateral dependent)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	$ 14,230	$ 17,703
Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	7,949	7,684
Significant Unobservable Inputs (Level 3) | Impaired loans (collateral dependent)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	14,230	17,703
Significant Unobservable Inputs (Level 3) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	$ 7,949	$ 7,684