Allowance for Loan Losses (Allowance for Loan Losses Rollforward Analysis) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		$ 26,662	$ 25,826	$ 26,004	$ 27,069
Charge-offs		(694)	(2,055)	(1,415)	(4,390)
Recoveries		40	78	319	220
Provision		1,300	1,800	2,400	2,750
Allowance, Ending Balance		27,308	25,649	27,308	25,649
Commercial Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		10,735	10,413	9,971	9,140
Charge-offs		(535)	(1,940)	(935)	(3,271)
Recoveries		0	4	82	21
Provision		1,482	1,981	2,564	4,568
Allowance, Ending Balance		11,682	10,458	11,682	10,458
Commercial Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		1,200	904	1,195	1,758
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Provision		(95)	78	(90)	(776)
Allowance, Ending Balance		1,105	982	1,105	982
Commercial & Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance	[1]	7,067	6,520	6,992	8,202
Charge-offs	[1]	(122)	(3)	(286)	(757)
Recoveries	[1]	8	46	162	134
Provision	[1]	(301)	(59)	(216)	(1,075)
Allowance, Ending Balance	[1]	6,652	6,504	6,652	6,504
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		19,002	17,837	18,158	19,100
Charge-offs		(657)	(1,943)	(1,221)	(4,028)
Recoveries		8	50	244	155
Provision		1,086	2,000	2,258	2,717
Allowance, Ending Balance		19,439	17,944	19,439	17,944
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		5,369	5,469	5,252	5,460
Charge-offs		0	(52)	(32)	(192)
Recoveries		1	5	29	9
Provision		70	(21)	191	124
Allowance, Ending Balance		5,440	5,401	5,440	5,401
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance, Beginning Balance		2,291	2,520	2,594	2,509
Charge-offs		(37)	(60)	(162)	(170)
Recoveries		31	23	46	56
Provision		144	(179)	(49)	(91)
Allowance, Ending Balance		$ 2,429	$ 2,304	$ 2,429	$ 2,304

[1] Commercial & industrial loans.