Fair Value Disclosures (Details Textual) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Fair Value Disclosures (Additional Textual) [Abstract]
Potential cash payments from contingent consideration, period of measurement (in years)	3 years
Potential cash payments from contingent consideration, end date	Jun. 30, 2015
Carrying amount of impaired loans	$ 41,500,000	$ 45,200,000
Valuation allowance of impaired loans	252,000	208,000
Mortgage servicing rights valuation allowance	263,000	497,000
Mortgage servicing rights carrying amount	5,000,000	4,600,000
Valuation adjustments for loans held for sale	0	0
Fair Value, Measurements, Recurring [Member]
Fair Value Disclosures (Textual) [Abstract]
Assets measured at fair value on a recurring basis	440,600,000	431,281,000
Javers Group [Member] | Maximum [Member]
Fair Value Disclosures (Textual) [Abstract]
Potential cash payments from contingent consideration	1,700,000
Javers Group [Member] | Minimum [Member]
Fair Value Disclosures (Textual) [Abstract]
Potential cash payments from contingent consideration	0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Disclosures (Textual) [Abstract]
Assets measured at fair value on a recurring basis	$ 0	$ 0