Loans, Allowance for Loan Losses, and Credit Quality (Details 9) (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	89	413
Recorded Investment	$ 12,096	$ 59,599
Unpaid Principal Balance	15,012	68,950
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	22	85
Recorded Investment	2,844	12,827
Unpaid Principal Balance	5,315	15,834
Commercial Real Estate Owner Occupied Portfolio [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	27
Recorded Investment	2,217	11,978
Unpaid Principal Balance	2,228	12,766
Commercial Real Estate Investor Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	5	25
Recorded Investment	2,035	12,379
Unpaid Principal Balance	2,087	13,569
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	5	31
Recorded Investment	1,960	2,955
Unpaid Principal Balance	1,980	3,549
Home Equity Port Folio Segments [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	28	111
Recorded Investment	1,301	4,870
Unpaid Principal Balance	1,385	6,143
Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	13
Recorded Investment	175	298
Unpaid Principal Balance	175	302
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	25	121
Recorded Investment	1,564	14,292
Unpaid Principal Balance	$ 1,842	$ 16,787