Loans, Allowance for Loan Losses and Credit Quality (ALLL - by category) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Summary of changes in allowance for loan losses
Beginning Balance	$ 59,479	$ 57,727	$ 61,566	$ 55,825
Charge-offs	(817)	(1,143)	(5,523)	(2,257)
Recoveries	1,048	671	2,017	2,562
Provision for loan losses	0	950	1,650	2,075
Ending Balance	59,710	58,205	59,710	58,205
Ending Balance: Individually Evaluated for Impairment	1,417	1,893	1,417	1,893	$ 5,214
Ending Balance: Collectively Evaluated for Impairment	58,293	56,312	58,293	56,312
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	13,544	14,027	16,921	13,802
Charge-offs	(124)	(27)	(3,715)	(31)
Recoveries	404	63	604	850
Provision for loan losses	(994)	(189)	(980)	(747)
Ending Balance	12,830	13,874	12,830	13,874
Ending Balance: Individually Evaluated for Impairment	71	134	71	134	3,661
Ending Balance: Collectively Evaluated for Impairment	12,759	13,740	12,759	13,740
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	30,947	29,011	30,369	27,327
Charge-offs	0	(341)	0	(365)
Recoveries	286	124	343	535
Provision for loan losses	(233)	609	288	1,906
Ending Balance	31,000	29,403	31,000	29,403
Ending Balance: Individually Evaluated for Impairment	49	355	49	355	196
Ending Balance: Collectively Evaluated for Impairment	30,951	29,048	30,951	29,048
Construction Loans [Member]
Summary of changes in allowance for loan losses
Beginning Balance	4,814	5,216	4,522	5,366
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for loan losses	806	117	1,098	(33)
Ending Balance	5,620	5,333	5,620	5,333
Ending Balance: Individually Evaluated for Impairment	0	0	0	0
Ending Balance: Collectively Evaluated for Impairment	5,620	5,333	5,620	5,333
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,613	1,441	1,502	1,264
Charge-offs	(164)	(98)	(258)	(191)
Recoveries	17	28	96	122
Provision for loan losses	140	113	266	289
Ending Balance	1,606	1,484	1,606	1,484
Ending Balance: Individually Evaluated for Impairment	1	2	1	2	8
Ending Balance: Collectively Evaluated for Impairment	1,605	1,482	1,605	1,482
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,693	2,578	2,621	2,590
Charge-offs	(43)	0	(182)	(27)
Recoveries	15	130	29	182
Provision for loan losses	111	(44)	308	(81)
Ending Balance	2,776	2,664	2,776	2,664
Ending Balance: Individually Evaluated for Impairment	1,020	1,156	1,020	1,156	1,086
Ending Balance: Collectively Evaluated for Impairment	1,756	1,508	1,756	1,508
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	5,353	4,986	5,238	4,889
Charge-offs	(81)	(154)	(217)	(491)
Recoveries	65	24	167	77
Provision for loan losses	89	196	238	577
Ending Balance	5,426	5,052	5,426	5,052
Ending Balance: Individually Evaluated for Impairment	257	223	257	223	242
Ending Balance: Collectively Evaluated for Impairment	5,169	4,829	5,169	4,829
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	515	468	393	587
Charge-offs	(405)	(523)	(1,151)	(1,152)
Recoveries	261	302	778	796
Provision for loan losses	81	148	432	164
Ending Balance	452	395	452	395
Ending Balance: Individually Evaluated for Impairment	19	23	19	23	$ 21
Ending Balance: Collectively Evaluated for Impairment	$ 433	$ 372	$ 433	$ 372