Loans, Allowance for Loan Losses, and Credit Quality (Details 10) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
Number of Contracts	17	69
Recorded Investment	$ 3,758	$ 22,574
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	7	16
Recorded Investment	1,170	1,736
Commercial Real Estate Owner Occupied Portfolio [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	10
Recorded Investment	74	4,729
Commercial Real Estate Investor Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	13
Recorded Investment	1,781	10,854
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	5
Recorded Investment	0	1,695
Home Equity Port Folio Segments [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	14
Recorded Investment	109	2,049
Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	1
Recorded Investment	0	12
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	10
Recorded Investment	$ 624	$ 1,499