Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Impaired Loans [Member]
Impaired loans	$ 25,279	$ 34,383
Valuation Techniques	Market approach	Market approach
Unobservable Input	Appraised value less selling costs of 5% to 10% Additional discounts of 5% to 50% to appraised value to reflect liquidation value	Appraised value less selling costs of 5% to 10% Additional discounts of 5% to 50% to appraised value to reflect liquidation value
Other Real Estate Owned [Member]
Impaired loans	5,684	6,552
Valuation Techniques	Market approach	Market approach
Unobservable Input	Appraised value less selling costs of 5% to 10	Appraised value less selling costs of 5% to 10
Mortgage Service Rights [Member]
Impaired loans	$ 1,546	$ 1,308
Valuation Techniques	Market approach	Market approach
Unobservable Input	Weighted average prepayment speed of 10.5	Weighted average prepayment speed of 10.5