Loans, Allowance for Loan Losses and Credit Quality (ALLL - by category) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Summary of changes in allowance for loan losses
Beginning Balance	$ 64,293	$ 60,643
Charge-offs	(559)	(593)
Recoveries	406	312
Provision for loan losses	1,000	500
Ending Balance	65,140	60,862
Ending Balance: Individually Evaluated for Impairment	1,104	1,257	$ 1,079
Ending Balance: Collectively Evaluated for Impairment	64,036	59,605
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	15,760	13,256
Charge-offs	0	(133)
Recoveries	124	12
Provision for loan losses	988	398
Ending Balance	16,872	13,533
Ending Balance: Individually Evaluated for Impairment	58	9	7
Ending Balance: Collectively Evaluated for Impairment	16,814	13,524
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	32,370	31,453
Charge-offs	0	0
Recoveries	33	20
Provision for loan losses	(354)	(14)
Ending Balance	32,049	31,459
Ending Balance: Individually Evaluated for Impairment	75	37	37
Ending Balance: Collectively Evaluated for Impairment	31,974	31,422
Construction Loans [Member]
Summary of changes in allowance for loan losses
Beginning Balance	5,158	5,698
Charge-offs	0	0
Recoveries	0	0
Provision for loan losses	197	(19)
Ending Balance	5,355	5,679
Ending Balance: Individually Evaluated for Impairment	0	0
Ending Balance: Collectively Evaluated for Impairment	5,355	5,679
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,756	1,577
Charge-offs	(145)	(24)
Recoveries	27	9
Provision for loan losses	146	31
Ending Balance	1,784	1,593
Ending Balance: Individually Evaluated for Impairment	1	3	1
Ending Balance: Collectively Evaluated for Impairment	1,783	1,590
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	3,219	2,822
Charge-offs	0	(39)
Recoveries	1	2
Provision for loan losses	14	52
Ending Balance	3,234	2,837
Ending Balance: Individually Evaluated for Impairment	802	944	862
Ending Balance: Collectively Evaluated for Impairment	2,432	1,893
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	5,608	5,390
Charge-offs	(113)	(79)
Recoveries	66	34
Provision for loan losses	(54)	14
Ending Balance	5,507	5,359
Ending Balance: Individually Evaluated for Impairment	161	248	164
Ending Balance: Collectively Evaluated for Impairment	5,346	5,111
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	422	447
Charge-offs	(301)	(318)
Recoveries	155	235
Provision for loan losses	63	38
Ending Balance	339	402
Ending Balance: Individually Evaluated for Impairment	7	16	$ 8
Ending Balance: Collectively Evaluated for Impairment	$ 332	$ 386