Loans, Allowance for Loan Losses and Credit Quality (ALLL - by category) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Summary of changes in allowance for loan losses
Beginning Balance	$ 65,960	$ 62,557	$ 64,293	$ 60,643
Charge-offs	(707)	(847)	(1,738)	(2,009)
Recoveries	1,689	450	2,387	1,026
Provision for loan losses	0	1,075	2,000	3,575
Ending Balance	66,942	63,235	66,942	63,235
Ending Balance: Individually Evaluated for Impairment	837	1,097	837	1,097	$ 1,079
Ending Balance: Collectively Evaluated for Impairment	66,105	62,138	66,105	62,138
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	16,857	14,788	15,760	13,256
Charge-offs	0	(218)	0	(355)
Recoveries	1,003	108	1,127	179
Provision for loan losses	(528)	430	445	2,028
Ending Balance	17,332	15,108	17,332	15,108
Ending Balance: Individually Evaluated for Impairment	6	7	6	7	7
Ending Balance: Collectively Evaluated for Impairment	17,326	15,101	17,326	15,101
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	32,660	32,095	32,370	31,453
Charge-offs	(82)	(82)	(82)	(82)
Recoveries	106	29	152	67
Provision for loan losses	(33)	226	211	830
Ending Balance	32,651	32,268	32,651	32,268
Ending Balance: Individually Evaluated for Impairment	41	34	41	34	37
Ending Balance: Collectively Evaluated for Impairment	32,610	32,234	32,610	32,234
Construction Loans [Member]
Summary of changes in allowance for loan losses
Beginning Balance	5,593	5,216	5,158	5,698
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for loan losses	240	(189)	675	(671)
Ending Balance	5,833	5,027	5,833	5,027
Ending Balance: Individually Evaluated for Impairment	0	0	0	0
Ending Balance: Collectively Evaluated for Impairment	5,833	5,027	5,833	5,027
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,768	1,709	1,756	1,577
Charge-offs	(125)	(111)	(319)	(237)
Recoveries	61	10	108	29
Provision for loan losses	48	160	207	399
Ending Balance	1,752	1,768	1,752	1,768
Ending Balance: Individually Evaluated for Impairment	11	1	11	1	1
Ending Balance: Collectively Evaluated for Impairment	1,741	1,767	1,741	1,767
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	3,296	2,909	3,219	2,822
Charge-offs	0	0	0	(148)
Recoveries	140	9	141	12
Provision for loan losses	(88)	153	(12)	385
Ending Balance	3,348	3,071	3,348	3,071
Ending Balance: Individually Evaluated for Impairment	619	874	619	874	862
Ending Balance: Collectively Evaluated for Impairment	2,729	2,197	2,729	2,197
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	5,547	5,468	5,608	5,390
Charge-offs	(28)	(87)	(212)	(261)
Recoveries	194	71	278	128
Provision for loan losses	36	102	75	297
Ending Balance	5,749	5,554	5,749	5,554
Ending Balance: Individually Evaluated for Impairment	155	168	155	168	164
Ending Balance: Collectively Evaluated for Impairment	5,594	5,386	5,594	5,386
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	239	372	422	447
Charge-offs	(472)	(349)	(1,125)	(926)
Recoveries	185	223	581	611
Provision for loan losses	325	193	399	307
Ending Balance	277	439	277	439
Ending Balance: Individually Evaluated for Impairment	5	13	5	13	$ 8
Ending Balance: Collectively Evaluated for Impairment	$ 272	$ 426	$ 272	$ 426