Allowance for Loan Losses Allowance Rollforward (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		$ 76,427	$ 77,263	$ 78,500	$ 75,838
Provision/ (credit) for loan losses		(2,535)	0	(5,668)	(2,500)
Financing Receivable, Allowance for Credit Losses, Charge-offs		(19)	(58)	(3,035)	(112)
Financing Receivable, Allowance for Credit Losses, Recoveries		1,880	1,046	5,956	5,025
Loans and Leases Receivable, Allowance at End of Period		75,753	78,251	75,753	78,251
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		14,343	14,337	15,814	14,114
Provision/ (credit) for loan losses		(1,179)	204	(1,836)	(1,777)
Financing Receivable, Allowance for Credit Losses, Charge-offs		0	(3)	(2,108)	(3)
Financing Receivable, Allowance for Credit Losses, Recoveries		82	83	1,376	2,287
Loans and Leases Receivable, Allowance at End of Period		13,246	14,621	13,246	14,621
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		44,519	43,552	44,215	43,854
Provision/ (credit) for loan losses		(803)	(333)	(2,650)	(1,266)
Financing Receivable, Allowance for Credit Losses, Charge-offs		0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries		1,791	914	3,942	1,545
Loans and Leases Receivable, Allowance at End of Period		45,507	44,133	45,507	44,133
Construction and land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		5,551	5,411	6,322	4,041
Provision/ (credit) for loan losses		(811)	7	(1,809)	234
Financing Receivable, Allowance for Credit Losses, Charge-offs		0	0	(400)	0
Financing Receivable, Allowance for Credit Losses, Recoveries		0	0	627	1,143
Loans and Leases Receivable, Allowance at End of Period		4,740	5,418	4,740	5,418
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		10,634	10,397	10,544	10,374
Provision/ (credit) for loan losses		114	(52)	705	20
Financing Receivable, Allowance for Credit Losses, Charge-offs		0	0	(501)	(49)
Financing Receivable, Allowance for Credit Losses, Recoveries		4	49	4	49
Loans and Leases Receivable, Allowance at End of Period		10,752	10,394	10,752	10,394
Home equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		1,079	1,016	1,085	1,003
Provision/ (credit) for loan losses		60	8	54	21
Financing Receivable, Allowance for Credit Losses, Charge-offs		0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries		0	0	0	0
Loans and Leases Receivable, Allowance at End of Period		1,139	1,024	1,139	1,024
Consumer and other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period		301	508	520	382
Provision/ (credit) for loan losses		84	75	(132)	205
Financing Receivable, Allowance for Credit Losses, Charge-offs		(19)	(55)	(26)	(60)
Financing Receivable, Allowance for Credit Losses, Recoveries		3	0	7	1
Loans and Leases Receivable, Allowance at End of Period		369	528	369	528
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	[1]	0	2,042	0	2,070
Provision/ (credit) for loan losses		0	91	0	63
Loans and Leases Receivable, Allowance at End of Period	[1]	$ 0	$ 2,133	$ 0	$ 2,133

[1] As of December 31, 2015, the unallocated reserve was allocated to the qualitative factors as part of the general reserves (ASC 450).