Loans, Allowance for Loan Losses and Credit Quality (Modifications which occurred during the period & change in recorded investment) (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018 USD ($) contract	Sep. 30, 2017 USD ($) contract		Sep. 30, 2018 USD ($) contract	Sep. 30, 2017 USD ($) contract
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	8	7		16	44
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 908	$ 815		$ 1,974	$ 6,222
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 928	$ 815	[1]	$ 1,994	$ 6,236
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	2	1		2	9
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 126	$ 196		$ 126	$ 1,575
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 126	$ 196	[1]	$ 126	$ 1,575
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	1	0		2	6
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 205	$ 0		$ 650	$ 1,884
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 205	$ 0	[1]	$ 650	$ 1,884
Small Business [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		2			10
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 183			$ 447
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 183	[1]		$ 447
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	3	0		4	5
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 503	$ 0		$ 652	$ 889
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 523	$ 0		$ 672	$ 900
Consumer Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	2	4		8	14
TROUBLED DEBT RESTRUCTURINGS:
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 74	$ 436		$ 546	$ 1,427
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 74	$ 436	[1]	$ 546	$ 1,430

[1] The post-modification balances represent the legal principal balance of the loan on the date of modification. These amounts may show an increase when modifications include a capitalization of interest.