Loans, Allowance for Loan Losses, and Credit Quality Loans Modified in a Troubled Debt Restructuring (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Modifications [Line Items]
Number of Loans	74	59	249	202
Recorded Investment	$ 12,898	$ 14,842	$ 38,791	$ 45,865
Unpaid Principal Balance	14,235	15,654	43,394	51,179
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	19	27	58	82
Recorded Investment	5,479	4,984	11,379	15,956
Unpaid Principal Balance	6,384	5,165	14,028	19,053
Commercial Real Estate Owner Occupied Portfolio [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	7	11	17	29
Recorded Investment	3,373	5,747	9,313	11,371
Unpaid Principal Balance	3,488	5,958	9,596	12,116
Commercial Real Estate Investor Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	10	3	18	25
Recorded Investment	1,222	3,201	5,013	12,514
Unpaid Principal Balance	1,304	3,583	5,320	13,400
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3	3	9	8
Recorded Investment	227	45	2,006	864
Unpaid Principal Balance	248	48	2,084	1,214
Home Equity Port Folio Segments [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	16	9	74	33
Recorded Investment	933	619	4,149	1,796
Unpaid Principal Balance	985	652	4,554	1,845
Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	0	5	2	10
Recorded Investment	0	138	187	219
Unpaid Principal Balance	0	140	193	222
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	19	1	71	15
Recorded Investment	1,664	108	6,744	3,145
Unpaid Principal Balance	$ 1,826	$ 108	$ 7,619	$ 3,329