Allowance for Loan Losses Allowance Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	$ 78,031	$ 76,427	$ 78,077	$ 78,500
Financing Receivable, Allowance for Credit Losses, Charge-offs	(463)	(19)	(521)	(3,035)
Financing Receivable, Allowance for Credit Losses, Recoveries	3,555	1,880	3,748	5,956
Provision/ (credit) for loan losses	(6,114)	(2,535)	(6,295)	(5,668)
Loans and Leases Receivable, Allowance at End of Period	75,009	75,753	75,009	75,753
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	12,291	14,343	12,751	15,814
Financing Receivable, Allowance for Credit Losses, Charge-offs	(218)	0	(218)	(2,108)
Financing Receivable, Allowance for Credit Losses, Recoveries	67	82	154	1,376
Provision/ (credit) for loan losses	(468)	(1,179)	(1,015)	(1,836)
Loans and Leases Receivable, Allowance at End of Period	11,672	13,246	11,672	13,246
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	51,164	44,519	50,412	44,215
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	3,479	1,791	3,529	3,942
Provision/ (credit) for loan losses	(6,507)	(803)	(5,805)	(2,650)
Loans and Leases Receivable, Allowance at End of Period	48,136	45,507	48,136	45,507
Construction and land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	3,197	5,551	3,039	6,322
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	0	(400)
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0	0	627
Provision/ (credit) for loan losses	388	(811)	546	(1,809)
Loans and Leases Receivable, Allowance at End of Period	3,585	4,740	3,585	4,740
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	10,090	10,634	10,449	10,544
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	(58)	(501)
Financing Receivable, Allowance for Credit Losses, Recoveries	0	4	47	4
Provision/ (credit) for loan losses	192	114	(156)	705
Loans and Leases Receivable, Allowance at End of Period	10,282	10,752	10,282	10,752
Home equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	987	1,079	1,035	1,085
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0	0	0
Provision/ (credit) for loan losses	(58)	60	(106)	54
Loans and Leases Receivable, Allowance at End of Period	929	1,139	929	1,139
Consumer and other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	302	301	391	520
Financing Receivable, Allowance for Credit Losses, Charge-offs	(245)	(19)	(245)	(26)
Financing Receivable, Allowance for Credit Losses, Recoveries	9	3	18	7
Provision/ (credit) for loan losses	339	84	241	(132)
Loans and Leases Receivable, Allowance at End of Period	$ 405	$ 369	$ 405	$ 369