Allowance for Loan Losses Allowance Rollforward (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	$ 75,838	$ 76,371
Provision/ (credit) for loan losses	(2,500)us-gaap_ProvisionForLoanAndLeaseLosses	(1,200)us-gaap_ProvisionForLoanAndLeaseLosses
Financing Receivable, Allowance for Credit Losses, Charge-offs	(54)	(145)
Financing Receivable, Allowance for Credit Losses, Recoveries	3,979	1,579
Loans and Leases Receivable, Allowance at End of Period	77,263	76,605
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	14,114	12,837
Provision/ (credit) for loan losses	(1,981)	(927)
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	(49)
Financing Receivable, Allowance for Credit Losses, Recoveries	2,204	339
Loans and Leases Receivable, Allowance at End of Period	14,337	12,200
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	43,854	44,979
Provision/ (credit) for loan losses	(933)	1,057
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	631	330
Loans and Leases Receivable, Allowance at End of Period	43,552	46,366
Construction and land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	4,041	4,465
Provision/ (credit) for loan losses	227	356
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	1,143	151
Loans and Leases Receivable, Allowance at End of Period	5,411	4,972
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	10,374	10,732
Provision/ (credit) for loan losses	72	(1,448)
Financing Receivable, Allowance for Credit Losses, Charge-offs	(49)	(88)
Financing Receivable, Allowance for Credit Losses, Recoveries	0	550
Loans and Leases Receivable, Allowance at End of Period	10,397	9,746
Home equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	1,003	1,020
Provision/ (credit) for loan losses	13	(57)
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0
Loans and Leases Receivable, Allowance at End of Period	1,016	963
Consumer and other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	382	322
Provision/ (credit) for loan losses	130	(193)
Financing Receivable, Allowance for Credit Losses, Charge-offs	(5)	(8)
Financing Receivable, Allowance for Credit Losses, Recoveries	1	209
Loans and Leases Receivable, Allowance at End of Period	508	330
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	2,070	2,016
Provision/ (credit) for loan losses	(28)	12
Loans and Leases Receivable, Allowance at End of Period	$ 2,042	$ 2,028

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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