Disclosures About Fair Value of Financial Instruments - Reconciliation of beginning and ending balances of recurring fair value measurements using significant unobservable (Details 1) (Fair Value, Measurements, Recurring, Available-for-Sale Securities, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Measurements, Recurring | Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,090	$ 936
Total realized and unrealized gains and losses
Amortization included in net income	11	8
Unrealized gains included in other comprehensive income	150	161
Settlements including pay downs	(54)	(15)
Transfers in and/or out of Level 3
Ending balance	1,197	1,090
Total gains or losses for the period included in net income attributable to the change in unrealized gains or losses related to assets and liabilities still held at the reporting date