Allowance for Loan Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Originated Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	$ 1,846,609	$ 1,741,936
Originated Loans [Member] | Commercial Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	1,736,721	1,648,664
Originated Loans [Member] | Commercial Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	38,626	23,680
Originated Loans [Member] | Commercial Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	71,254	69,584
Originated Loans [Member] | Commercial Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	8	8
Originated Loans [Member] | Business Banking Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	399,563	398,435
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	383,016	379,445
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	16,547	18,990
Originated Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	1,931,224	1,858,724
Originated Loans [Member] | Consumer Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	1,922,702	1,847,216
Originated Loans [Member] | Consumer Loans [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	8,522	11,508
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	902,007	848,842
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	894,247	838,816
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	7,760	10,026
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	902,007	848,842
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	894,247	838,816
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	7,760	10,026
Acquired Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	267,500	275,152
Acquired Loans [Member] | Commercial Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	243,041	249,666
Acquired Loans [Member] | Commercial Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	6,989	5,486
Acquired Loans [Member] | Commercial Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	17,470	20,000
Acquired Loans [Member] | Business Banking Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	51,918	58,179
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	47,546	53,264
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	4,372	4,915
Acquired Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	120,316	147,256
Acquired Loans [Member] | Consumer Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	119,525	146,494
Acquired Loans [Member] | Consumer Loans [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	791	762
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	251,751	266,747
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	248,624	262,883
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	3,127	3,864
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	251,751	266,747
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	248,624	262,883
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable	$ 3,127	$ 3,864