Fair Value Measurement (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Maximum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Weighted Average, Appraisal adjustments	(27.60%)	(50.80%)
Impaired loans liquidation expenses	(8.00%)	(8.00%)
Minimum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Weighted Average, Appraisal adjustments	0.00%	0.00%
Impaired loans liquidation expenses	(5.50%)	(3.90%)
Weighted Average [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Weighted Average, Appraisal adjustments	(11.40%)	(13.70%)
Impaired loans liquidation expenses	(6.70%)	(6.80%)
Discount rate	9.90%	9.80%
Nonrecurring fair value measurements [Member]
Schedule of assets measured at fair value on nonrecurring basis
Impaired loans	3,792	3,866
Mortgage servicing rights	693	825
Nonrecurring fair value measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Impaired loans	3,792	3,866
Other real estate owned and repossessed	5,147	5,988
Mortgage servicing rights	693	825
Discounted Cash Flow [Member] | Maximum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Remaining term of mortgage	26 years 7 months 6 days	27 years
Discount rate	12.00%	12.00%
Discounted Cash Flow [Member] | Minimum [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Remaining term of mortgage	2 years 10 months 24 days	2 years 9 months 18 days
Discount rate	9.00%	9.00%
Discounted Cash Flow [Member] | Weighted Average [Member] | Significant Unobservable Inputs (Level 3) [Member]
Schedule of assets measured at fair value on nonrecurring basis
Weighted average remaining term	15 years 3 months 18 days	15 years 9 months 18 days